Friedel-Crafts Reaction of Acylsilanes: Highly Chemoselective Synthesis of 1-Hydroxy-bis(indolyl)methanes and 1-Silyl-bis(indolyl)methanes Derivatives.

A novel double Friedel-Crafts reaction of acylsilanes in water is described. This strategy enables synthesis of bis(indolyl)methane derivatives with 1-hydroxy or 1-silyl substituents in moderate to high yield. Compared to the 1-silyl-bis(indolyl)methane derivatives from indole substrate, 1-hydroxy-bis(indolyl)methane derivatives were synthesized from the 5-hydroxyindole, and the hydrogen bonds in the 5-hydroxyindole play a crucial role in regulating the reaction selectivity.

Nucleophilic Allylation of Acylsilanes in Water: An Effective Alternative to Functionalized Tertiary α-Silylalcohols.

A nucleophilic allylation of acylsilanes in water was developed, generating versatile functionalized tertiary α-silyl alcohols in high yields. With the assistance of hydrogen bonding, a reaction model of less reactive acylsilane was achieved. Unlike the conventional strategy, transition metals and an additional Lewis acid catalyst were not required, and rate acceleration was observed in water.

[Efficacy Evaluation of Three Endoscopic Therapies of Isolated Gastric Varices with Modified Tissue Adhesive].

Objective: To evaluate the efficacy of three endoscopic therapies of isolated gastric varices (IGV) with modified tissue adhesive. Methods: A retrospective analysis was conducted with the clinical data of 73 IGV patients who were treated between January 2008 and December 2019 at Beijing Ditan Hospital. Patient clinical data on age, sex, etiology, biochemistry findings, Child-Pugh classification, the type of spontaneous shunt, preoperative bleeding history, and the presence or absence of liver cancer were collected. The three therapies evaluated were endoscopic intravenous injection of tissue glue combined with lauromacrogol, endoscopic clip-assisted intravenous injection of tissue glue combined with lauromacrogol, and endoscopic clip and LOOP-assisted intravenous injection of tissue glue combined with lauromacrogol. Their respective clinical treatment outcomes, including ectopic embolism rate, survival rate, rebleeding rate, amount of lauromacrogol and tissue glue used, the number of endoscopic clips used, and the number of times of the procedure the patient underwent, were evaluated. Results: In the patient baseline data, Child-Pugh grade, preoperative thrombus formation, and the presence or absence of liver cancer, showed significant difference between the three therapies ( P<0.05). There was no significant difference in the rates of ectopic embolism among the three methods ( P>0.05), but no ectopic embolism occurred after endoscopic clip-assisted intravenous injection of tissue glue combined with lauromacrogol, or after endoscopic clip and LOOP-assisted intravenous injection of tissue glue combined with lauromacrogol. There was no significant difference in the survival rate, the rebleeding rate, amount of lauromacrogol and tissue glue used for the three therapies, but there was significant difference in the number of endoscopic clips used and the number of times the procedure was conducted within one year ( P<0.05). Conclusion: The two endoscopic therapies of intravenous injection of modified tissue glue, one assisted by clip and the other assisted by clip and LOOP, can help reduce the number of procedures IGV patients undergo within one year.

Hydrogen-Bond-Assisted Sequential Reaction of Silyl Glyoxylates: Stereoselective Synthesis of Silyl Enol Ethers.

A novel hydrogen-bond-assisted sequential reaction of silyl glyoxylates is described. This method provides an efficient strategy for the synthesis of silyl enol ethers with high selectivity. In these transformations, hydrogen bonds from 2-nitroethanol and its derivatives are critical to the stereochemical outcome. Both E- and Z-isomers are achieved via Henry reaction/Brook rearrangement/elimination and Henry reaction/Brook rearrangement/retro-Henry reaction/elimination processes, respectively (up to 99:1 Z-selectivity, and 9.2:1 E-selectivity).

Clinical Features and Outcomes of Repeated Endoscopic Therapy for Esophagogastric Variceal Hemorrhage in Cirrhotic Patients: Ten-Year Real-World Analysis.

OBJECTIVE: This study is aimed at evaluating the survival of cirrhotic patients with different etiologies after endoscopic therapy for acute variceal bleeding and the effect of repeated endotherapy on patients' prognosis. METHODS: We retrospectively evaluated the clinical features and outcomes between cirrhotic patients with chronic HBV or HCV infections and other etiologies. The 3-year and 5-year survival rates and rehemorrhage rate in one year between the viral and nonviral cirrhosis patients were compared by Kaplan-Meier curves and log-rank test. Cox analysis was used to identify the impact factors that affect the long-term survival of patients with cirrhosis and variceal bleeding after endotherapy. RESULTS: Out of 2665 patients with liver cirrhosis and variceal hemorrhage selected from our medical center between September 2008 and December 2017, a total of 1342 patients were included for analysis. The median follow-up duration was 32.9 months (range 0.16-111.4 months), the 3- and 5-year cumulative survival rates were 75.3% and 52.8%, respectively. The median survival time was significantly longer in viral cirrhosis patients (47.1 months [95% CI: 24.9-69.1]) compared with nonviral cirrhosis patients (37.0 months [95% CI: 25.0-56.0], p = 0.001). The 3-year and 5-year survival rates of the viral group were higher than the nonviral group. The rehemorrhage rate at one year was higher in nonviral patients than in viral patients (p < 0.001). CONCLUSION: Repeated endotherapy combined with effective antiviral therapy is helpful for long-term survival of cirrhotic population with variceal hemorrhage and HBV or HCV infection.

A colorimetric/fluorescence dual-channel probe for highly discriminating detection of cysteine.

In this work, a novel fluorescence (FL) probe for selective and sensitive detection of Cys with colorimetric and FL dual signal changes was reported. The probe was synthesized by two step of sulfonamide reaction coupling between a sulfonyl benzoxadiazole (SBD) dye and dansyl chloride linked with rigid piperazine group. The probe showed a specific off-on response to Cys in aqueous solution with nanomolar LOD, and without interference by a range of amino acids and several competing analytes. Upon addition of Cys, the probe will undergo sequential substitution and intramolecular rearrangement reactions, yielding a 4-amino SBD derivative, which results in generation of strong yellow fluorescence emission at 575 nm accompanied by a two-step red shift in the absorption spectral. Moreover, it can be used for imaging of endogenous Cys in living cells.

The effect of the fibrinolytic enzyme FIIa from Agkistrodon acutus venom on acute pulmonary thromboembolism.

AIM: To evaluate the effects of the fibrinolytic enzyme FII(a) from Agkistrodon acutus venom on acute pulmonary thromboembolism (APT) in animal models. METHODS: Both rabbit and dog APT models were used. For the rabbit APT model, the thrombi weight before and after administration was measured. Central venous pressure (CVP) and mean arterial pressure (MAP) were measured before and 15, 30, 60, and 120 min after the injection of the blood clot. Partial thromboplastin time (APTT), prothrombin time (PT), platelet count, and fibrinogen concentration were measured using auto analyzers. Plasminogen activity was measured based on chromogenic substrates. In the dog APT model, pulmonary blood flow was recorded using pulmonary angiography. RESULTS: Intravenous administration of FIIa (0.1-5.0 mg/kg) improved the APT-induced hemodynamic derangements and reduced thrombi weight. The angiography evidence also showed that the pulmonary emboli had almost disappeared after FII(a) infusion. FII(a) (0.1, 0.5, or 1.0 mg/kg) did not impair the coagulation pathways, although very high doses of FII(a) (5.0 mg/kg) could stimulate the production of plasminogen and result in impairment of the pathways. CONCLUSION: FII(a) could effectively protect against APT via degradation of thrombi with less activation of plasminogen, and may provide a novel fibrinolytic enzyme for targeting the main pathological processes of the disease.

[The relationship between gastroesophageal reflux disease and idiopathic pulmonary interstitial fibrosis].

OBJECTIVE: To determine the prevalence of gastroesophageal reflux disease (GERD) in patients with idiopathic pulmonary interstitial fibrosis (IPIF). METHODS: From December 2006 to January 2008, 24 consecutive patients with IPIF admitted to Beijing Chaoyang Hospital underwent 24-hour esophageal pH monitoring and esophageal manometry. Meanwhile, 23 patients with diffuse parenchymal lung disease (DPLD) (excluding IPIF) admitted to the hospital in the same period served as a control group. Comparison of the prevalence of pathologic esophageal acid exposure GERD symptoms, and ineffective esophageal motility (IEM) between the two groups was made. In this study, nocturnal acid exposure is defined as acid reflux episodes occurring from 10pm to 6am. RESULTS: (1) 16 out of the 24 (66.7%) patients with IPIF were demonstrated to have pathologic esophageal acid exposure; the prevalence of GERD in IPIF patients was significantly higher than that in other DPLD patients, whose prevalence was 26.1% (P < 0.05) ; (2) 87.5% patients with IPIF and GERD (GERD-IPIF) had nocturnal acid exposure episodes; (3) only 37.5% of the GERD-IPIF patients was found to have typical GERD symptoms such as heartburn and regurgitation; (4) The prevalence of IEM was similar in IPIF and other DPLD patients, being 42.9% and 39.1% respectively (P > 0.05). CONCLUSIONS: IPIF patients have higher prevalence of GERD and most of them usually do not show typical reflux symptoms. It is hereby suggested that IPIF patients should be screened with pH monitoring for GERD.

The effect of fibrinolytic enzyme FIIa from Agkistrodon acutus venom on disseminated intravascular coagulation in rabbits.

A novel fibrinolytic enzyme, FII(a), was isolated from Agkistrodon acutus venom, which can degrade fibrin/fibrinogen and dissolve thrombus without activating plasminogen or influencing the activities of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1). In this study, we evaluated the effect of FII(a) on lipopolysaccharide (LPS)-induced experimental disseminated intravascular coagulation (DIC) in rabbits, through the continuous infusion of 100-microg/kg/h LPS for a period of 6 h. Seven groups were established: LPS control, FII(a) (0.1, 0.3, and 0.6 mg/kg/h, respectively), heparin control (100 IU/kg/h), heparin + FII(a) (heparin 100 IU/kg/h associated with FII(a) 0.3 mg/kg/h), and a saline control group. A continuous injection of LPS induced a gradual impairment in hemostatic parameters, kidney fibrin deposition, and a high mortality rate. The intravenous administration of FII(a) improved the concentration of fibrinogen, the activities of protein C, plasminogen, t-PA, antithrombin III (ATIII), and PAI-1. Kidney fibrin deposition and the mortality also decreased. In the in vitro experiments, FII(a) can degrade fibrin/fibrinogen and high-dose FII(a) enhanced the activity of protein C. These findings suggest that the effects of FII(a) on LPS-induced DIC were from fibrinogen degradation and enhanced protein C activity. The simultaneous administration of FII(a) and heparin further improved all the hemostatic parameters, including decreased kidney fibrin deposition, and none of the rabbits died within 24 h, which indicates that the effects were mediated by degradation of fibrin/fibrinogen together with thrombin inhibition. We conclude that FII(a) may be useful in the treatment of DIC.

Enzymological characterization of FII(a), a fibrinolytic enzyme from Agkistrodon acutus venom.

AIM: To study the enzymological characterization of a fibrinolytic enzyme (FII(a)) from Agkistrodon acutus venom. METHODS: The fibrinogenolytic effect and the influences of several protease inhibitors, chelating agents, and metal ions on fibrinogenolytic activity were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The metal content of FII(a) was determined by atomic absorption spectroscopy. RESULTS: After incubation with FII(a) (0.25 g/L), Aalpha-, Bbeta- and gamma-chains of fibrinogen disappeared within 5 min, 30 min, and 8 h , respectively. The molecular weights of major degradation products were 45,000 and 41,000, which were different from those bands produced by plasmin. The fibrinogenolytic activity of FIIa was strongly inhibited by ethylenediamine tetraacetic acid (EDTA), ethyleneglycol tetraacetic acid (EGTA), dithiothreitol and cysteine, but not by phenylmethyl-sulfonyl fluoride and soybean trypsin inhibitor. Zinc (3171+/-25 mg/kg), potassium (489+/-17 mg/kg) and calcium (319+/-13 mg/kg) were found in FIIa. Zn2+, Ca2+ and Mg2+ could recover the fibrinogenolytic activity of FIIa, which was inhibited by EDTA. Only Ca2+ could recover the fibrinogenolytic activity inhibited by EGTA. CONCLUSION: FIIa can degrade the Aalpha-, Bbeta- and gamma-chains of fibrinogen. FII(a) is a metalloproteinase, and Zn2+, Ca2+, and disulfide bonds are necessary for its fibrinogenolytic activity.

Fibrin(ogen)olytic character of FIIa isolated from Agkistrodon acutus venom.

AIM: To investigate the fibrin(ogen)olytic character of FIIa isolated from Agkistrodon acutus venom in vitro and in vivo. METHODS: 125I-labeled human plasma clot lysis was measured in vitro and rabbit carotid artery thrombosis was as an in vivo model. RESULTS: In vitro, urokinase (UK) at 25, 35, 40, 45, 60 kU/L and FIIa at 0.08, 0.23, 0.4, 0.5, and 0.7 g/L resulted an equivalent clot lysis (20%, 40%, 50%, 60%, and 80%). UK at 25 to approximately 60 kU/L induced 27.3%+/-3.6%, 35.2%+/-2.3%, 39.3%+/-2.4%, 44.2%+/-4.6%, and 51.1%+/-1.2% fibrinogen degradation. But FIIa at 0.08 approximately -0.7 g/L induced 95.4%+/-0.3%, >95.6%, >95.6%, >95.6%, >95.6% fibrinogen degradation respectively. In vivo, UK 40 kU/kg and FIIa 1.0 mg/kg reduced the weight of residual thrombus to 9.0+/-2.5 mg and 7.8+/-3.5 mg compared with negative control group (30.0+/-5.4 mg). But the fibrinogen degradation rate after UK 40 kU/kg and FIIa 1.0 mg/kg treatment was 24.4%+/-6.2% and 4.1%+/-7.8%, respectively (P<0.05, n=6). The order of the lysis speed after UK 125 kU/L treatment was platelet poor plasma (PPP) clots>the whole blood clots>platelet rich plasma (PRP) clots. The sequence for FIIa 0.4 g/L was PRP >PPP >whole blood clots. CONCLUSION: At the same percentage of clot lysis, FIIa degraded more fibrinogen than UK did in vitro but less fibrinogen than UK did in vivo. The order of the lysis speed was PPP>whole blood clots>PRP clots for UK and PRP>PPP>whole blood clots for FIIa.

Hemorrhagic activity and mechanism of FIIa, a fibrinolytic enzyme from Agkistrodon acutus venom.

AIM: To study the local hemorrhagic activity of a fibrinolytic enzyme (FII(a)) from Agkistrodon acutus venom and its mechanism. METHODS: The local hemorrhagic activity was determined by subcutaneous injection on the back of mouse. The effects of FIIa on factor X, prothrombin, gelatin, and collagen were visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Platelet aggregation assays were performed in rat platelet-rich plasma (PRP). Human umbilical vein endothelial cells (HUVEC) were cultured and passaged in complete M199 medium. Cell viability and nuclear morphology change were determined by fluorescein diacetate (FDA) staining and Hoechst 33258 staining, respectively. RESULTS: The minimum hemorrhagic dose (MHD) of FIIa was 89 microg. In vitro, FII(a) (0.25 g/L) degraded factor X, prothrombin, collagen, and gelatin, and dose-dependently (0.25, 0.50, 0.75, and 1.00 g/L) inhibited the platelet aggregation induced by ADP in rat PRP. When HUVEC in culture treated with FII(a), HUVEC showed detachment in a dose-dependent manner, but no apoptosis sign was observed. CONCLUSION: FIIa had local hemorrhagic activity, and the mechanism was related to the degradation of factor X, prothrombin, gelatin, and collagen, the inhibition of ADP-induced platelet aggregation, and inducement of HUVEC detachment.