Reactive Dicarbon as a Flexible Ligand for Transition-Metal Coordination and Catalysis.

Dicarbon is a reactive carbon allotrope that naturally exists only in the high-temperature medium of stellar space. We report the successful preparation of a series of bottleable phosphine-stabilized dicarbon (PDC) molecules. We explore the use of these molecules as a new complementary class of carbene-like ligands featuring strong σ-donor (>NHCs and CAAcs) but weak π-acceptor properties. Steric map analysis of PDC based on Cavallo's SambVca program reveals comparable steric volume bulk of 32.5%, similar to the conventional IMes carbene. However, our PDCs exhibit dynamic steric flexibility modulated by the nature of the metal complexes and catalytic reaction environment. We demonstrate the catalytic utility of the PDC framework by its successful implementation for Suzuki-Miyaura cross-coupling and the reductive coupling reaction of an aldehyde and alkyne. Detailed investigations of the reductive coupling reaction reveal an important secondary interaction between PDC and metal complexes, which plays a critical role in the catalytic system.

Etomidate plus propofol versus propofol alone for sedation during gastroscopy: a randomized prospective clinical trial.

BACKGROUND AND AIMS: Sedation with propofol alone during gastroscopy has many side effects. Etomidate has advantages in terms of circulation and respiration compared to propofol. We hypothesized that etomidate plus propofol during gastroscopy would be more safe and effective than propofol alone. METHODS: Four hundred (n = 400) patients were randomly divided into a propofol group (P group) and a etomidate plus propofol group (EP group). The P group was given the first dose of 1 % propofol 1 mg/kg before gastroscopy, and the EP group was given 1 % propofol 0.5 mg/kg plus etomidate 0.1 mg/kg. Repeated doses of 10-20 mg propofol or 5-10 mg propofol plus 1-2 mg etomidate were administered to maintain an adequate level of sedation. The sedation depth was maintained by bispectral index value of 40-60. RESULTS: The EP group had a lower incidence of systolic hypotension (13.0 vs. 32.5 %; P < 0.0001), bradycardia (8.5 vs. 16.5 %; P = 0.0226), mild hypoxemia (6.5 vs. 18.0 %; P = 0.0007), and severe hypoxemia (2.5 vs. 10.0 %; P = 0.0031) compared to the P group. Also, the satisfaction of anesthetist and gastroscopist with EP was higher than that of P group (P < 0.0001; P = 0.018, respectively). CONCLUSION: Etomidate plus propofol had few effects on respiration and circulation in patients undergoing gastroscopy and was more safe and effective than propofol alone.

Mannitol improves cerebral oxygen content and postoperative recovery after prolonged retroperitoneal laparoscopy.

BACKGROUND: Prolonged pneumoperitoneum has cerebral adverse effects that may delay recovery and cause postoperative cognitive changes. The purpose of this study was to investigate the effect of mannitol infusion after pneumoperitoneum initiation on cerebral oxygen balance and quality of postoperative recovery in patients undergoing prolonged retroperitoneal laparoscopy. METHODS: Forty patients scheduled for retroperitoneal laparoscopic radical excision of prostatic carcinoma were randomly divided into two groups (n = 20, each) to receive either 0.5 g/kg of 20% mannitol 150 min after the initiation of pneumoperitoneum or an equal volume of 0.9% normal saline. After surgery, time to extubation and recovery time were recorded. The Observer's Assessment of Alertness/Sedation (OAA/S) scale was used to assess the quality of recovery. The Mini-Mental State Exam (MMSE) was given to test cognitive function preoperatively and at 1, 2, and 3 h after extubation. Blood samples from the jugular bulb and the radial artery were collected for blood gas analysis before CO2 insufflation and at 10, 60, and 180 min after insufflation. RESULTS: In the control group (without mannitol), the difference between arterial and venous oxygen content (CaO2-CvO2) before insufflation (6.21 ± 2.58 mL/dL) was significantly greater than it was 3 h after insufflation (2.63 ± 1.29 mL/dL; p < 0.05). Furthermore, 3 h after insufflation, the CaO2-CvO2 also was higher in the group that had been administered mannitol (5.93 ± 1.98 mL/dL) than it was in the control group at that time (p < 0.05). Lactic acid in both arterial and jugular venous blood of the control group at 3 h postinsufflation (2.39 ± 0.89 and 2.51 ± 0.72 mg/dL, respectively) had increased significantly from the preinsufflation values (1.18 ± 0.82 and 1.1 ± 0.85 mg/dL). In the group that received mannitol, the lactic acid levels 3 h postinsufflation were essentially the same as the preinsufflation values. The recovery and extubation times in those receiving mannitol (12.19 ± 2.12 and 20.14 ± 3.62 min, respectively) were significantly shorter than in the control group (21.25 ± 3.61 and 28.79 ± 4.73 min; p < 0.05). The OAAS scores of the mannitol group at the time of extubation and 10 min afterward was significantly higher than these scores in the control group (p < 0.05). One hour and 2 h after extubation, the cognitive function score of the mannitol group was significantly higher than for the control group (p < 0.05). CONCLUSIONS: After prolonged retroperitoneal laparoscopy, there is an imbalance between oxygen supply and demand. A small dose of mannitol can effectively improve cerebral oxygen metabolism, recovery, and cognitive function after the operation.

Antitubercular chromones and flavonoids from Pisonia aculeata.

Three new chromones, pisonins A (1), B (2), and D (4), two new flavonoids, pisonivanone [(2S)-5,7,2'-trihydroxy-8-methylflavanone] (7) and pisonivanol [(2R,3R)-3,7-dihydroxy-5,6-dimethoxyflavanone] (8), one new isoflavonoid, pisonianone (5,7,2'-trihydroxy-6-methoxy-8-methylisoflavone) (9), and five compounds first isolated from nature, namely, pisonins C (3), E (5), and F (6), pisoniamide (10), and pisonolic acid (11), together with 18 known compounds have been isolated from the methanol extract of the combined stem and root of Pisonia aculeata. Among these isolates, 2, 7, 14, 16, and 19 exhibited antitubercular activities (MICs≤50.0 µg/mL) against Mycobacterium tuberculosis H37Rv in vitro.

Isolable dicarbon stabilized by a single phosphine ligand.

In contrast to naturally occurring F2, O2 and N2, diatomic C2 is an intriguing species that has only been observed indirectly in the gas phase, and because of its high reactivity has eluded isolation in the condensed phase. It has previously been stabilized in L→C2←L compounds but the bonding situation of the central C2 in this motif differs remarkably from that of free C2. Here we have prepared and structurally characterized diatomic C2 as a monoligated complex L→C2 using a bulky phosphine ligand bearing two imidazolidin-2-iminato groups (L is (NHCR=N)2(CH3)P, where NHCR is an N-heterocyclic carbene). The compound is stable in solution at ambient temperature and has also been isolated in the solid state. Reactivity studies, in combination with quantum chemical analysis, suggest that the two carbon atoms of the L→C2 complex both have carbene character. The complex underwent intermolecular C-H bond activation upon thermolysis and exhibited hydroalkoxylation-like reactivity with methanol.

Serum adropin levels are decreased in patients with acute myocardial infarction.

OBJECTIVE: Adropin is a recently identified bioactive protein that is important for energy homeostasis and maintaining insulin sensitivity. We sought to detect serum adropin levels in acute myocardial infarction (AMI) patients. METHODS: We enrolled 138 AMI patients, 114 stable angina pectoris (SAP) patients and 75 controls. Adropin levels were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: Serum adropin levels were significantly lower in patients with AMI compared with SAP patients or controls (P<0.01). Multivariate logistic regression demonstrated that lower adropin was the independent predictor for the presence of AMI in coronary artery disease (CAD) patients (P<0.01). Serum adropin levels were negatively associated with body mass index (BMI) (P<0.01) and triglyceride levels (P<0.05) in AMI patients. CONCLUSION: Decreased serum adropin levels are associated with the presence of AMI in CAD patients. These results revealed that adropin might represent as a novel biomarker for predicting AMI onset in CAD patients.