Endohedral C3 Ca@B39(+) and C2 Ca@B39(+): axially chiral metalloborospherenes based on B39(-).

Using the newly discovered borospherenes C3 B39(-) and C2 B39(-) as molecular devices and based on extensive global-minimum searches and first-principles calculations, we present herein the possibility of the first axially chiral metalloborospherenes C3 Ca@B39(+) (, (1)A) and C2 Ca@B39(+) (, (1)A), which are the global minimum and the second lowest-lying isomer of CaB39(+), respectively. These metalloborospherene species turn out to be charge-transfer complexes Ca(2+)@B39(-) in nature, with the Ca centre on the C3 or C2 molecular axis donating one electron to the B39 cage which behaves like a superhalogen. Molecular orbital analyses indicate that C3/C2 Ca(2+)@B39(-) possess the universal bonding pattern of σ plus π double delocalization, similar to their C3/C2 B39(-) parents. Molecular dynamics simulations show that both C3 Ca@B39(+) () and C2 Ca@B39(+) () are dynamically stable at 200 K, with the former starting to fluctuate structurally at 300 K and the latter at 400 K, again similar to C3/C2 B39(-). The infrared and Raman spectra of C3/C2 Ca@B39(+) (/) are simulated and compared with those of C3/C2 B39(-) to facilitate their forthcoming experimental characterization.

Cage-Like B41 (+) and B42 (2+) : New Chiral Members of the Borospherene Family.

The newly discovered borospherenes B40 (-/0) and B39 (-) mark the onset of a new class of boron nanostructures. Based on extensive first-principles calculations, we introduce herein two new chiral members to the borospherene family: the cage-like C1 B41 (+) (1) and C2 B42 (2+) (2), both of which are the global minima of the systems with degenerate enantiomers. These chiral borospherene cations are composed of twelve interwoven boron double chains with six hexagonal and heptagonal faces and may be viewed as the cuborenes analogous to cubane (C8 H8 ). Chemical bonding analyses show that there exists a three-center two-electron σ bond on each B3 triangle and twelve multicenter two-electron π bonds over the σ skeleton. Molecular dynamics simulations indicate that C1 B41 (+) (1) fluctuates above 300 K, whereas C2 B42 (2+) (2) remains dynamically stable. The infrared and Raman spectra of these borospherene cations are predicted to facilitate their experimental characterizations.

[A clinical study of pituitrin versus norepinephrine in the treatment of patients with septic shock].

OBJECTIVE: To investigate whether pituitrin can lower 28-day mortality as compared with treatment with norepinephrine (NE) in patients with septic shock. METHODS: Randomized, controlled, open-label trial was conducted. One hundred and thirty-nine septic shock patients with dopamine requirements exceeding 5 µg×kg(-1)×min(-1) were divided at random into two groups as the study group and control group. All patients enrolled were treated by the same treatment principle and measures. In patients of study group injection of pituitrin 0.017-0.042 U/min (1.0- 2.5 U/h) was given, and if hemodynamics was still unstable, catecholamines was added to obtain the target blood pressure; while in the control group catecholamines was given to maintain stability of hemodynamics. RESULTS: Among 139 patients enrolled in the study, 66 composed of the clinical study group and 73 in the control group. The main principle of the treatment in the two groups was similar. There was no significant difference in overall 28-day mortality rate between study group and control group (40.9% vs. 46.6%, P > 0.05). In patients whose acute physiology and chronic health evaluation II ( APACHE II ) score was less than 25, the mortality of study group was significantly lower than that of control group [10.3% (3/29) vs. 35.7% (10/28), P < 0.05]. The length of stay in intensive care unit [ICU, days: 5(3,8) vs. 5(3,8)], and duration of mechanical ventilation [days: 4.0 (2.8, 6.0) vs. 4.0 (2.0, 5.0)] were similar in two groups (both P > 0.05). The dosage of NE (µg/min: 7.99 ± 5.02 vs. 10.12 ± 5.12) and heart rate (beat/min: 93.27 ± 7.84 vs. 108.45 ± 12.31) were significantly lower in study group compared with that of control group (both P < 0.05). Serum creatinine and lactate levels in the two groups were similar at baseline, and creatinine [µmol/L: 87.5 (62.8, 157.0) vs. 76.0 (52.5, 117.0)] and lactate level (mmol/L: 3.72 ± 2.47 vs. 3.53 ± 1.86) were still similar in two groups 24 hours later (all P > 0.05). The rate of use of glucocorticoid (43.9% vs. 31.5%) and heparin in small dosage (42.4% vs. 41.1%) had no significant difference between two groups (both P > 0.05). CONCLUSIONS: Combined use of pituitrin in patients with septic shock can reduce the dosage of catecholamines, and decrease the heart rate. Although it can not lower the overall mortality of septic shock, among patients with less severity whose APACHE II score lower than 25, low-dose pituitrin in conjunction with catecholamine vasopressors can reduce 28-day mortality .

Patterns and Drivers of Soil Respiration under Long-Term Citrus reticulate in Southern China.

Soil respiration (Rs) is a major source of carbon emission in terrestrial ecosystems. Despite the fact that the influence of land use practice on Rs has been widely studied, the patterns and drivers on Rs of Citrus reticulata cultivation, a worldwide land use practice are unclear. In this current study, we investigated the influence of long-term cultivation of Citrus reticulata (CO) and of CO intercropped with soybean (CB) on soil nutrients, water availability, and Rs in southern China. Results indicated that after 21 years of cultivation, CO and CB significantly increased total soil carbon (TC), total soil nitrogen (TN), and soil organic matter (OM) at 0-20 cm and 20-40 cm, both at upslope and downslope compared with bare soil (CK). However, soil moisture (SM), dissolved organic carbon (DOC), and microbial biomass carbon (MBC) decreased under CB. In addition, no significant variation was found in soil pH between CK, CO, and CB. Across incubation time (56 days), Rs decreased exponentially with incubation time and CB showed the highest Rs rate irrespective of soil depth or topography. Linear regression further showed TC and TN as the two major factors influencing Rs upslope, while DOC was the dominant factor in regulating Rs downslope. These findings demonstrated that long-term cultivation of citrus significantly changed soil nutrients, water availability, and Rs rate.

Experimental and theoretical evidence of an axially chiral borospherene.

Chirality plays an important role in chemistry, biology, and materials science. The recent discovery of the B40(-/0) borospherenes marks the onset of a class of boron-based nanostructures. Here we report the observation of axially chiral borospherene in the B(39)(-) nanocluster on the bases of photoelectron spectroscopy, global minimum searches, and electronic structure calculations. Extensive structural searches in combination with density functional and CCSD(T) calculations show that B(39)(-) has a C3 cage global minimum with a close-lying C2 cage isomer. Both the C3 and C2 B(39)(-) cages are chiral with degenerate enantiomers. The C3 global minimum consists of three hexagons and three heptagons around the vertical C3 axis. The C2 isomer is built on two hexagons on the top and at the bottom of the cage with four heptagons around the waist. Both the C3 and C2 axially chiral isomers of B(39)(-) are present in the experiment and contribute to the observed photoelectron spectrum. The chiral borospherenes also exhibit three-dimensional aromaticity, featuring σ and π double delocalization for all valence electrons. Molecular dynamics simulations reveal that these chiral B(39)(-) cages are structurally fluxional above room temperature, compared to the highly robust D(2d)B40 borospherene. The current findings add chiral members to the borospherene family and indicate the structural diversity of boron-based nanomaterials.

Construction of alpha-alpha domains structure in recombinant monkey metallothionein-1.

The differences in metal-thiolate coordination and reactivity of mammalian metallothionein (MT) domains are closely related to their distinct, highly conservative cysteine number and position. Monkey metallothionein-1, containing a beta-domain with Cd(3)S(9) cluster and an alpha-domain with Cd(4)S(11) cluster, was used to evaluate the role of cysteine residues in the formation of MT's metal-thiolate clusters. The possible influence of cysteine residues on the binding and stability of MT domains has been examined with the metallothionein mutants: N4C, T27C and N4C/T27C, which possess ten or eleven cysteine residues in the re-constructed beta-domain, respectively. Assisted by study of UV, CD and electrospray ionization mass spectroscopy (ESI-MS) and their reactivity with DTNB (5,5'-dithiobis (2-nitrobenzoic acid)), we found that besides the original alpha-domain, some kinds of new domain containing 4-cadmium-thiolate clusters were formed in the N4C and N4C/T27C mutants of mkMT1. These new domains displayed metal binding and kinetic reactivity with DTNB similar to the alpha-domain. However, the thermal stability of the mutants was less stable than that of WT mkMT1. This might result from the disturbance of the inter-domains hydrogen bonds and of the non-cysteine amino acid residue arrangement.

Blood rheological properties are strongly related to the metabolic syndrome in middle-aged Chinese.

The current investigation sought to evaluate the relation between hemorheological properties and the metabolic syndrome. 1400 office workers aged 35 to 59 years were enrolled in this study. Waist circumference and blood pressure were determined. Plasma high-density lipoprotein (HDL cholesterol), triglyceride, fasting blood glucose, plasma insulin and whole blood viscosity (WBV) at a high-shear rate of 200 s(-1) were measured at the attendance. Metabolic syndrome was defined according to National Cholesterol Education Program (NCEP)/ATP III guidelines. The metabolic syndrome was identified in 18% of this sedentary population. Mean WBV was 4.71+/-0.56 mPa s. One-way ANOVA indicated WBV increased across subjects with 0-4 metabolic syndrome components (F=3.86, p<0.01). The highest vs. lowest quartiles of WBV occurred significantly more often among subjects as the number of metabolic syndrome components increased. Across five categories of the metabolic syndrome, the frequencies of the occurrence of the highest vs. lowest quartiles were: 0.40, 0.87, 1.31, 1.92, and 4.80, respectively, showing a significant correlation (R=0.817, p<0.05). Univariate logistic regression analysis showed that the prevalence of hyperviscosity was predicted positively by waist circumference (OR=1.018, 95% CI: 1.002-1.035, p<0.05) and negatively by HDL cholesterol (OR=0.295, 95% CI: 0.133-0.680, p<0.01), independently of age, sex, and smoking status. In summary, this study has shown that WBV is strongly related to the severity of the metabolic syndrome. We suggest that the hemorheological parameters could potentially be used as an additional indicator of the metabolic syndrome.

Acetonitrile-induced unfolding of the photosystem II manganese-stabilizing protein studied by electrospray mass spectrometry.

In this paper an acetonitrile-induced unfolding of the manganese-stabilizing protein (MSP) of photosystem II was discovered. More distinct unfolding states of MSP were identified than previously by using mainly electrospray ionization mass spectrometry (ESI-MS), together with fluorescence spectra and far-UV circular dichroism (CD) at pH 2.0, 6.2 or 11.6, and with acetonitrile concentrations from 0 to 50%. At pH 6.2 with acetonitrile concentration changing from 0 to 10%, relatively broad charge-state distributions and poor intensity were observed in ESI-MS, indicating the presence of coexisting conformers. It was concluded that the structure of the MSP protein is unlikely to be a tightly folded form. When the concentration of acetonitrile was 20-40%, simulating the state in the biological membrane, changes in the state of unfolding of MSP were observed to a certain extent using ESI-MS, fluorescence and CD spectroscopy. The charge-state distribution in ESI-MS was found to move toward high states (from 13+ to 27+ to 15+ to 31+) with increasing acetonitrile concentration. At pH 2.0, the MSP structure is rearranged into an unfolded state, and at pH 11.6 the MSP structure is induced to assume another unordered state by deprotonation of appropriate residues. An interesting observation was that a second peak envelope emerged with 20-50% acetonitrile in the medium at pH 11.6.