Search

Nuclear magnetic resonance (NMR) spectroscopy is an important tool for studying the structures of molecules and materials. Mainly due to their high costs, the NMR spectrometers are often not available for teaching experiments. Teaching NMR experiments cannot be performed routinely and effectively also because that the students are not able to understand the principles underlying the operational steps without proper and adequate training. In this work, a virtual NMR spectrometer (VMRS1.0) for teaching experiments, which is based on numerical computational simulation technology and can be operated like a real spectrometer, is presented. With the VMRS1.0, the students can perform basic NMR experiments, including tuning, shimming, field lock, power adjustment for radio frequency, selecting samples, acquiring data, fast Fourier transform and spectrum processing (i.e., phase correction, integration, chemical shift correction, auto peak finding and J-coupling constant measurement). In addition to the routine one-dimensional NMR experiments, more complicated experiments such as decoupling, DEPT and HMQC can also be performed on the VMRS1.0. With the virtual NMR spectrometer developed, the students can practice their experimental skills and gain deeper understandings of the underlying principles in a more easy and cost-efficient way.

Diffusion ordered spectroscopy (DOSY) is widely used to measure molecular self-diffusion coefficient. In DOSY spectra, the digital resolution of the diffusional coefficient dimension could have notable effects on the measurement accuracy under certain circumstances. In this study, we first assessed the deviation range of the DOSY experiment itself systematically. The magnitudes and sources of deviation induced by digital resolution were then investigated by applying a variety of digital resolutions into the processing of DOSY spectra. It was proposed that relative digital resolution could be compared to relative molecular diffusion coefficient changes, demonstrating directly the effects of digital resolution on diffusion coefficient measurement.

Planar chirality in 2'substituted ferrocene ligands and its role in enantioselectivity in Pd-catalyzed allylic substitution.

Aim: To investigate the metabolic profiles of xenograft pancreatic cancer before and after radiotherapy by high-resolution magic angle spinning proton magnetic resonance spectroscopy (HRMAS (1)H NMR) combined with principal components analysis (PCA) and evaluate the radiotherapeutic effect., Methods: The nude mouse xenograft model of human pancreatic cancer was established by injecting human pancreatic cancer cell SW1990 subcutaneously into the nude mice. When the tumors volume reached 800 mm(3), the mice received various radiation doses. Two weeks later, tumor tissue sections were prepared for running the NMR measurements. (1)H NMR and PCA were used to determine the changes in the metabolic profiles of tumor tissues after radiotherapy. Metabolic profiles of normal pancreas, pancreatic tumor tissues, and radiation- treated pancreatic tumor tissues were compared., Results: Compared with (1)H NMR spectra of the normal nude mouse pancreas, the levels of choline, taurine, alanine, isoleucine, leucine, valine, lactate, and glutamic acid of the pancreatic cancer group were increased, whereas an opposite trend for phosphocholine, glycerophosphocholine, and betaine was observed. The ratio of phosphocholine to creatine, and glycerophosphocholine to creatine showed noticeable decrease in the pancreatic cancer group. After further evaluation of the tissue metabolic profile after treatment with three different radiation doses, no significant change in metabolites was observed in the (1)H NMR spectra, while the inhibition of tumor growth was in proportion to the radiation doses. However, PCA results showed that the levels of choline and betaine were decreased with the increased radiation dose, and conversely, the level of acetic acid was dramatically increased., Conclusion: The combined methods were demonstrated to have the potential for allowing early diagnosis and assessment of pancreatic cancer response to radiotherapy.

Objective: To explore the changes of sublingual microcirculation in elderly patients with severe sepsis/septic shock., Methods: Twenty-three patients with sepsis, 10 patients without sepsis and 10 healthy elderly patients were enrolled. Sublingual microcirculation was evaluated by sidestream darkfield (SDF) imaging. And the 28-day mortality rates of all septic patients were recorded., Results: Compared with the healthy group, all elderly patients had significant sublingual microcirculation dysfunctions. Compared with the severe septic and nonseptic patients, perfused vessel density (PDV) , proportion of perfused vessels (PPV) and microvascular flow index (MFI) of septic shocks were significantly lower. Compared with the severe septic patients, PDV, PPV and MFI instead of lactate and MAP of septic shocks were significantly lower from Day 1 to Day 3. The values of PDV, PPV, MFI and lactate but not MAP of the surviving septic patients were significantly higher than those of the deceased ones., Conclusions: The elderly patients with septic shock have severe sublingual microcirculatory alterations. And these abnormalities are more marked in septic shock patients. Nonsurvivors showed more severe alterations than survivors. Microcirculatory alterations may be measured to guide the therapy.

Objective: To evaluate stroke volume variation (SVV) as a predictor of fluid responsiveness in mechanically ventilated (MV) elderly patients with severe sepsis., Methods: A prospective observation of 31 fluid challenges during fluid resuscitation for treatment of hemodynamic instability in 17 elderly MV patients with severe sepsis was conducted. SVV was measured by pulse indicator continuous cardiac output (PiCCO) system. Fluid responsiveness was defined as the changes in cardiac index (CI) increase after fluid loading (DeltaCI) > or =10%. The changes in hemodynamic parameters and lung water index were observed at the onset of and after fluid therapy. The correlation between DeltaCI and SVV or central venous pressure (CVP) were analyzed., Results: SVV was decreased significantly after fluid loading [(6.6+/-2.1)% vs.(12.1+/-3.7)%, P<0.01], whereas CVP increased significantly [(12.5+/-3.6) mm Hg vs. (8.9+/-4.1) mm Hg, 1 mm Hg=0.133 kPa, P<0.01]. DeltaCI in response to fluid loading were positively correlated to initial values of SVV (r=0.447, P=0.012), but there was no relationship between CVP and DeltaCI (r=-0.082, P=0.674). The areas under the receiver operating characteristic curve (ROC curve) for SVV was 0.672 [95% confidence interval (95%CI) 0.463-0.885] and CVP was 0.336 (95%CI 0.133-0.539), respectively. A SVV value of 11.5% had the sensitivity of 71% and specificity of 67% for prediction of fluid responsiveness., Conclusion: Functional hemodynamic parameter SVV can predict fluid responsiveness in elderly MV patients with severe sepsis during fluid resuscitation, it may serve as a useful index for guiding fluid therapy in elderly patients with severe sepsis.

This paper describes the self-assembly of a new class of three-component dynamic [2]catenanes, which are driven or stabilized by intramolecular hydrogen bonding, coordination, and electrostatic interaction. One of the component molecules 2, consisting of an aromatic oligoamide spacer and two peripheral zinc porphyrin units, was designed to adopt a folded preorganized conformation, which is stabilized by consecutive intramolecular three-centered hydrogen bonds. Component molecule 3 is a linear secondary ammonium bearing two peripheral pyridine units, which was designed to form a 1:1 complex with 24-crown-8 (5). The 1H NMR and UV-vis experiments in CDCl3-CD3CN (4:1 v/v) revealed that, due to the preorganized U-shaped feature, 2 could efficiently bind 3 through the cooperative zinc-pyridine coordination to generate highly stable 1:1 complex 2.3. Adding 5 to the 1:1 solution of 2 and 3 led to the formation of dynamic three-component [2]catenane 2.3.5 as a result of the threading of 3 through 5. 1H NMR studies indicated that in the 1:1:1 solution (3 mM) [2]catenane 2.3.5 was generated in 55% yield at 25 degrees C. The yield was increased with the reduction of the temperature and [2]catenane could be produced quantitatively in a 1:1:2 solution ([2]=3 mM) at -13 degrees C. Replacing 3 with 1,2-bis(4,4'-bipyridinium)ethane (4) in the three-component solution could also give rise to similar dynamic [2]catenane 2.4.5 albeit in slightly lower yield.

Objective: To investigate the expression profile of integrin genes in heart of septic rat and relevant mechanisms responsible for sepsis-induced heart injury., Methods: Twelve 3-month-old male Wistar rats were randomized to 2 equal groups, sepsis model group (CLP group) undergoing ligation and perforation with needle of the distal caecum so as to establish sepsis model, and sham operation group (Sham group), undergoing sham operation only serve as controls. Twenty-four later the hearts of rats were rapidly excised. After determination of the hemodynamic parameters by using Langendorff apparatus, the isolated hearts were cut into 2 parts vertically to undergo histopathological examination and analysis of the expression of integrin genes by oligonucleotide microarrays respectively., Results: No overt pathological changes were detected in the hearts of septic rats, however, the cardiac output, stroke volume, heart rate, left ventricular developed pressure, left ventricular end-diastolic pressure, and maximum rate of left ventricular pressure rise of the CLP group were 29.4+/-3.3 ml/min, 0.12+/-0.01 ml, 256+/-6 bpm, 75.6+/-4.9 mm Hg, 7.5+/-0.3 mm Hg, and 2167+/-159 mm Hg/s respectively, all significantly than those of the Sham group (57.8+/-2.4 ml/min, 0.18+/-0.01 ml, 302+/-12 bpm, 90.0+/-2.7 mmHg, 8.0+/-0.3 mmHg. and 2601+/-34 mmHg/s respectively, all P<0.01). Microarray analysis showed that 20 out of 24 integrin genes were up-regulated by more than 2 times in the septic rat heart, among which the integrin alphaV and beta2 genes were upregulated and the expression of integrin beta1 gene was relatively insufficient., Conclusion: Maladjustment in expression of integrin genes is present in the septic rat heart. Up-regulation of integrin alphaV and beta2 genes may accelerate the heart injury mediated by inflammatory mediators, and the relatively insufficient expression of integrin beta1 gene may contribute to cardiac dysfunction.

The stacking interactions between FH--N hydrogen-bonded foldamers 1-3, bis-foldamer 4, and tris-foldamer 5 and C(60) and C(70) are described. Compound 4 contains two folded units, which are connected by an isophthalamide linker, whereas 5 has a C(3)-symmetrical discotic structure, in which three folded units are connected by a benzene-1,3,5-tricarboxamide unit. UV/Vis, fluorescence, and NMR experiments have revealed that the foldamers or folded units strongly stack with fullerenes in chloroform. The (apparent) association constants of the respective complexes have been determined by a fluorescence titration method. The strong association is tentatively attributed to intermolecular cooperative fluorophenylpi and solvophobic interactions. A similar but weaker interaction has also been observed between an MeOH--N hydrogen-bonded foldamer and fullerenes. AFM studies have revealed that the surfaces of 3 and 4 show fibrous networks, while the surface of 5 shows particles. In sharp contrast, mixtures of 3 and 4 with C(60) have been shown to generate thinner separated fibrils, whereas a mixture of 5 and C(60) produces honeycomb-like nano networks, for which a columnar cooperative stacking pattern is proposed. The results demonstrate the usefulness of FH--N hydrogen-bonded folded structures in the construction of nanoscaled materials.

Objective: To evaluate the impacts of glutamine (Gln) and recombinant human growth hormone (rhGH) intensified nutrition support on critically ill elderly patients., Methods: Ninety critically ill aged patients were included in a prospective, randomized and controlled clinical study, and randomly divided into three groups: group A (standard nutrition support), group B (standard nutrition support+10% Gln 100 ml/d), group C (standard nutrition support+ Gln 100 ml/d+rhGH 10 U/d). Before treatment and then 7 and 14 days after treatment, blood samples were collected for analysis of serum proteins including albumin (ALB), pre-albumin (PAB), C-reactive protein (CRP), immunoglobulin G (IgG). Meanwhile, the variables including T-cell subsets, CD14 human leukocyte antigen (locus) DR (CD14 HLA-DR), and total lymphocytes were measured. The changes in acute physiology and chronic health evaluation II (APACHE II) and multiple organ dysfunction syndrome (MODS) scores, the durations of intensive care unit (ICU) stay and mechanical ventilation, and 28-day survival rate were recorded., Results: Comparing with group A and B, the levels of serum ALB, PAB and IgG were significantly elevated in group C. The T-cell subsets, CD14 HLA-DR and the number of total lymphocytes were markedly higher in group C (P<0.01), and the APACHE II and MODS scores were decreased significantly in group C (P<0.05 or P<0.01). The levels of serum CRP were lowered significantly in group C (P<0.01). There were no significant differences in the durations of ICU stay, mechanical ventilation and 28-day survival rate among three groups (all P>0.05)., Conclusion: Gln and rhGH intensified nutrition support can improve nutritional condition and immune function, downregulate the inflammatory response in the critically ill elderly patients.

Several pentaerythritol-derived oligoglycols 1 with free hydroxyl groups are readily prepared by a convergent approach. Quantitative (13)C NMR proves to be an efficient tool for the characterization of oligoglycols. The corresponding telluride of oligoglycol 17 is synthesized and used as a good catalyst for Wittig-type reactions in preparing both disubstituted and trisubstituted olefins in good to high yields.

Palladium-catalyzed asymmetric allylic substitutions using thioether and phosphino derivatives of ferrocenyloxazoline as ligands have been investigated with a focus on studying the role of planar chirality. In allylic alkylation, up to 98% ee and 95% ee were achieved with S,N- and P,N-ligands, respectively. In allylic amination, 97% ee was realized with P,N-ligands in the presence of TBAF. Several palladium allylic complexes were characterized by X-ray diffraction and/or solution NMR. Thioether derivatives of ferrocenyloxazolines with only planar chirality showed lower enantioselectivity in the allylic alkylation except 5c because of the formation of a new chirality on sulfur atom during the coordination of sulfur with palladium. On the other hand, in the planar chiral P,N-ligands without central chirality, (Sp)-11a-c there was no such disturbance and comparatively higher enantioselectivity in both palladium-catalyzed allylic alkylation and amination was provided.