Synthesis of Chiral Diarylmethylamides via Catalytic Asymmetric Aza-Michael Addition of Amides to ortho-Quinomethanes.

Chiral diarylmethylamides are a privileged skeleton in many bioactive molecules. However, the enantioselective synthesis of such molecules remains a long-standing challenge in organic synthesis. Herein, we report a chiral bifunctional squaramide catalyzed asymmetric aza-Michael addition of amides to in situ generated ortho-quinomethanes, affording enantioenriched diarylmethylamides in good yields with excellent enantioselectivities. This work not only provides a new strategy for the construction of the diarylmethylamides but also represents the practicability of amides as nitrogen-nucleophiles in asymmetric organocatalysis.

Diastereo- and Enantioselective Synthesis of Eight-Membered N-Heterocycles from Benzofuran-Derived Azadienes and Ynones.

Enantioselective synthesis of eight-membered N-heterocycles represents a long-standing challenge in organic synthesis. Here, by combining the squaramide and DBU catalysis, a sequential asymmetric conjugate addition/cyclization reaction between benzofuran-derived azadienes and ynones has been well-developed, providing straightforward access to chiral eight-membered N-heterocycles in high yields with stereoselectivities. This protocol features the use of a bifunctional squaramide catalyst for controlling the enantioselectivity of products, while the DBU is utilized to achieve intramolecular cyclization and improve the diastereoselectivity of products.

Metal-free and enantioselective synthesis of 1,4-benzoxazepines from para-quinone methide derivatives and α-bromohydroxamates.

A sequential asymmetric conjugate addition/cyclisation of α-bromohydroxamates with para-quinone methide derivatives has been developed, which provides enantioenriched 1,4-benzoxazepines in generally high yields (up to 95%) and good enantioselectivities (up to 97 : 3 er). This protocol not only offers a novel and straightforward strategy for constructing chiral 1,4-benzoxazepines, but also demonstrates the potential of α-bromohydroxamates as three-atom synthons in asymmetric cyclisation reactions.

Neuroprotective effects of curdione against focal cerebral ischemia reperfusion injury in rats.

BACKGROUND: Curdione is one of the most highly concentrated component of the active constituents in E-zhu, which has been reported to possess a variety of activities. However, the pharmacologic neuroprotective activity of curdione has not been evaluated. The present study aimed to investigate the protective effect of curdione on focal cerebral ischemia reperfusion-induced injury in rats and further exploring the underlying mechanisms. MATERIALS AND METHODS: Adult male Sprague Dawley rats were subjected to middle cerebral artery occlusion (MCAO) surgery for 2 h, followed by reperfusion stage. All animals received treatment once a day for 7 days before surgery and 14 days from 4 h after the reperfusion started. The neurological deficit test and Morris water maze test were performed at 1, 4, 7 and 14 days after MCAO. The infarct size of animals was determined by the 2,3,5-triphenyltetrazolium chloride staining, and pathological brain damage was estimated by hematoxylin-eosin staining. The malonaldehyde (MDA) levels and the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-PX) were detected by enzyme-linked immunosorbent assay. Expression of apoptotic proteins was measured by Western blot. RESULTS: Our results showed that curdione could significantly reduce the infarct size and neurological deficits, promote cognitive function recovery and recover neuronal morphologic damages in MCAO rats. It also blocked the increase of MDA content and elevated the activities of SOD, CAT and GSH-PX. Moreover, curdione attenuated the expression of Cyt-C, c-caspase-3 and c-caspase-9 increased the Bcl-2/Bax ratio and hence decreased the cellular apoptosis. CONCLUSION: Curdione possessed potential neuroprotective effect on rats in the MCAO model. The anti-oxidative and anti-apoptotic properties may be involved in the underlying mechanisms.

[Absolute bioavailability of ginkgolide compounds in rats].

To investigate the pharmacokinetic characteristics and absolute bioavailability of ginkgolide A (GA), ginkgolide B (GB) and bilobalide (BB) in rats. In this experiment, a high-performance liquid chromatography-tandem mass spectrometry (LC-MS/ MS) method was established to determine the plasma concentrations of GA, GB and BB in rats after rats were administrated with the three drugs through ig and iv respectively. The main pharmacokinetic parameters and absolute bioavailability of three ginkgolide compounds were obtained by using pharmacokinetic software DAS 2. 0. After the inject of GA, GB and BB, the results showed Cmax at (513.9 ± 116.9), (701.3 ± 76.0), (5,255.6 ± 476.8) µg · L(-1) and AUC0.24h of (960.9 ± 268.5), (779.5 ± 140.6), (7,409.3 ± 1,181.1) µg · h · L(-1), respectively; after the oral administration, the results showed Cmax at (522.9 ± 39.9), (146.8 ± 31.6), (2,711.9 ± 588.9) µg · L(-1) and AUC0-24 h of (1,760.4 ± 300.7), (636.6 ± 180.3), (16,651.4 ± 1,306.5) µg · h · L(-1), respectively. The absolute bioavailability of GA, GB and BB in rats was (61.1 ± 10.4)%, (27.2 ± 7.7)%, (56.2 ± 4.4)%, respectively. The method established in this experiment has a good specificity and sensitivity and so can be used to study the pharmacokinetics and absolute bioavailability of GA, GB and BB in rats.

Analysis of Geographic and Pairwise Distances among Chinese Cashmere Goat Populations.

This study investigated the geographic and pairwise distances of nine Chinese local Cashmere goat populations through the analysis of 20 microsatellite DNA markers. Fluorescence PCR was used to identify the markers, which were selected based on their significance as identified by the Food and Agriculture Organization of the United Nations (FAO) and the International Society for Animal Genetics (ISAG). In total, 206 alleles were detected; the average allele number was 10.30; the polymorphism information content of loci ranged from 0.5213 to 0.7582; the number of effective alleles ranged from 4.0484 to 4.6178; the observed heterozygosity was from 0.5023 to 0.5602 for the practical sample; the expected heterozygosity ranged from 0.5783 to 0.6464; and Allelic richness ranged from 4.7551 to 8.0693. These results indicated that Chinese Cashmere goat populations exhibited rich genetic diversity. Further, the Wright's F-statistics of subpopulation within total (FST) was 0.1184; the genetic differentiation coefficient (GST) was 0.0940; and the average gene flow (Nm) was 2.0415. All pairwise FST values among the populations were highly significant (p<0.01 or p<0.001), suggesting that the populations studied should all be considered to be separate breeds. Finally, the clustering analysis divided the Chinese Cashmere goat populations into at least four clusters, with the Hexi and Yashan goat populations alone in one cluster. These results have provided useful, practical, and important information for the future of Chinese Cashmere goat breeding.

Depolarization-induced Ca2+ entry preferentially evokes release of large quanta in the developing Xenopus neuromuscular junction.

The amplitude histogram of spontaneously occurring miniature synaptic currents (mSCs) is skewed positively at developing Xenopus neuromuscular synapses formed in culture. To test whether the quantal size of nerve-evoked quanta (eSCs) distributes similarly, we compared the amplitude histogram of single quantum eSCs in low external Ca(2+) with that of mSCs and found that nerve stimulation preferentially released large quanta. Depolarization of presynaptic terminals by elevating [K(+)] in the external solution or by direct injection of current through a patch pipette increased the mSC frequency and preferentially, but not exclusively, evoked the release of large quanta, resulting in a second broad peak in the amplitude histogram. Formation of the second peak under these conditions was blocked by the N-type Ca(2+) channel blocker, ω-conotoxin GVIA. In contrast, when the mSC frequency was elevated by thapsigargin- or caffeine-induced mobilization of internal Ca(2+), formation of the second peak did not occur. We conclude that the second peak in the amplitude histogram is generated by Ca(2+) influx through N-type Ca(2+) channels, causing a local elevation of internal Ca(2+). The mSC amplitude in the positively skewed portion of the histogram varied over a wide range. A competitive blocker of acetylcholine (ACh) receptors, d-tubocurarine, reduced the amplitude of smaller mSCs in this range relatively more than that of larger mSCs, suggesting that this variation in the mSC amplitude is due to variable amounts of ACh released from synaptic vesicles. We suggest that Ca(2+) influx through N-type Ca(2+) channels preferentially induces release of vesicles with large ACh content.

[Effects of Rhizoma zingiberis and Pericarpium citri reticulatae extracts on myocardial ischemia in rats].

OBJECTIVE: To observe the effects of Rhizoma Zingiberis and Pericarpium Citri Reticulatae extracts on acute myocardial ischemia rats and explore the mechanism. METHODS: The model of myocardial ischemia in rats was established by ligating the front descending anterior branch of the coronary artery. With Fufang Danshen Pill as positive control drug,the effects of Rhizoma Zingiberis and Pericarpium Citri Reticulatae extracts on the electrocardiogram (ECG), the extension of myocardial infarction, the hemorheology indexes, lactic dehydrogenase (LDH), creatine kinase (CK), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) in rats were evaluated. RESULTS: Rhizoma Zingiberis and Pericarpium Citri Reticulatae extracts decreased the ST-segment of ECG (P < 0.01), reduced the extension of myocardial infarction (P < 0.05), decreased the contents of CK and LDH in serum (P < 0.01 or P < 0.05), improved hemorheology (P < 0.05), increased SOD and GSH-Px activity and decreased MDA content (P < 0.05). CONCLUSION: Rhizoma Zingiberis and Pericarpium Citri Reticulatae extracts have protective effect on myocardial ischemia in rats, and its mechanism may be related to inhibiting lipid peroxidation.

The antithrombotic effect of borneol related to its anticoagulant property.

Borneol is consumed excessively in China and Southeast Asian countries particularly in combined formula for preventing cardiovascular disease, but few studies were conducted on its effects on thrombosis. In this study, the antithrombotic and antiplatelet activities of borneol were investigated on thrombosis in vivo and on platelet aggregation ex-vivo. In addition, the coagulation parameters and influence on fibrinolytic activity were also assessed. The results showed that borneol had concentration dependent inhibitory effects on arterio-venous shunt and venous thrombosis but no effect on ADP and AA-induced platelet aggregation. Meanwhile, borneol prolonged the coagulation parameters for prothrombin time (PT) and thrombin time (TT), but did not show any fibrinolytic activity. It suggested that the antithrombotic activity of borneol and its action in combined formula for preventing cardiovascular diseases might be due to anticoagulant activity rather than antiplatelet activity.

[Osteoid osteoma of the mandibular condyle: report of one case].

Osteoid Osteoma is rare in mandibular condyle. A case of osteoid osteoma in the condyle was reported in this paper. The clinical manifestation, radiographic characteristic, pathologic diagnosis were discussed. Nidus is the key in diagnosing osteoid osteoma, and the final diagnosis is based on pathological findings.

[Construction of hyaluronidase gene mutant of Enterococcus faecium and the function of hyaluronidase gene].

OBJECTIVE: To construct a hyaluronidase (hyl) gene mutant strain of Enterococcus faecium and to study the function of hyl gene. METHODS: An isogenic hyl-deficient mutant (*hyl) with suicide plasmid pTX4577 was constructed and screened by allelic replacement. The mutant strain and wild type strain TX2466 were cultured to observe the growth curves. Both *hyl and TX2466 strains were cultured in solid with kanamycin (KAN) to detect the tolerance to KAN. The study of virulence in mice peritonitis and rabbit endocarditis models in vivo were made. RESULTS: A mutant strain, *hyl, was selected by KAN and identified by PCR, pulsed field gel electrophoresis, and Southern blotting. The growth ability of the *hyl strain was remarkably reduced in comparison with the wide-type strain. The survival rate of the mice within 100 h after the inoculation of Enterococcus faecium. TX2466 was 0, significantly lower than that of the *hyl group (50%, P<0.01). The numbers of colonies in the aortic valve and ventricular wall vegetations of the TX2466 group rabbits were (3.04+/-0.63)x10(6) and (6.87+/-0.58)x10(6) CFU/g respectively, both significantly higher than those of the *hyl group [(0.21+/-0.06)x10(6) and (0.66+/-0.05)x10(6) CFU/g respective, both P<0.01]. CONCLUSION: Probably a major virulence factor of Enterococcus faecalis, hyl gene is important in the pathogenesis of this bacterium.

Golli protein negatively regulates store depletion-induced calcium influx in T cells.

Calcium influx is crucial for T cell activation and differentiation. The detailed regulation of this process remains unclear. We report here that golli protein, an alternatively spliced product of the myelin basic protein gene, plays a critical role in regulating calcium influx in T cells. Golli-deficient T cells were hyperproliferative and showed enhanced calcium entry upon T cell receptor stimulation. We further found that golli regulates calcium influx in T cells through the inhibition of the store depletion-induced calcium influx. Mutation of the myristoylation site on golli disrupted its association with the plasma membrane and reversed its inhibitory action on Ca2+ influx, indicating that membrane association of golli was essential for its inhibitory action. These results indicate that golli functions in a unique way to regulate T cell activation through a mechanism involving the modulation of the calcium homeostasis.

Electrophysiological properties of BK channels in Xenopus motor nerve terminals.

Single channel properties of Ca(2+)-activated K(+) (BK or Maxi-K) channels have been investigated in presynaptic membranes in Xenopus motoneurone-muscle cell cultures. The occurrence and density of BK channels increased with maturation/synaptogenesis and was not uniform: highest at the release face of bouton-like synaptic varicosities in contact with muscle cells, and lowest in varicosities that did not contact muscle cells. The Ca(2+) affinity of the channel (K(d)= 7.7 microM at a membrane potential of +20 mV) was lower than those of BK channels that have been characterized in other terminals. Hill coefficients varied between 1.5 and 2.8 at different potentials and open probability increased e-fold per 16 mV change in membrane potential over a range of [Ca(2+)](i) from 1 microM to 1 mM. The maximal activation rate of ensembled single BK channel currents was in the submillisecond range at > or =+20 mV. The activation rate increased approximately 10-fold in response to a [Ca(2+)](i) increase from 1 to 100 microM, but increased only approximately 2-fold with a voltage change from +20 to +130 mV. The fastest activation kinetics of BK channels in cell-attached patches resembled that in inside-out patches with [Ca(2+)](i) of 100 microM or more, suggesting that many BK channels are located very close to calcium channels. Given the low Ca(2+) affinity and rapid Ca(2+) binding/unbinding properties, we conclude that BK channels in this preparation are adapted to play an important role in regulation of neurotransmitter release, and they are ideal reporters of local [Ca(2+)] at the inner membrane surface.