Effect of electro-acupuncture on substance P, its receptor and corticotropin-releasing hormone in rats with irritable bowel syndrome

AIM： To investigate the effect and mechanism of electro-acupuncture lEA） at ST25 and ST37 on irritable bowel syndrome （IBS） of rats. METHODS： A total of 21 male Sprague-Dawley rats were randomly divided into normal group, model group and EA group. A rat model of IBS was established by constraining the limbs and distending the colorectum of rats. Rats in EA group received bilateral EA at ST25 and ST37 with a sparse and intense waveform at a frequency of 2/50 Hz for 15 min, once a day for 7 d as a course. Rats in normal and model groups were stimulated by distending colorectum （CR）. An abdominal withdrawal reflex （AWR） scoring system was used to evaluate improvements in visceral hypersensitivity. Toluidine blue-improved method, immunohistochemistry and radioimmunoassay were used to observe mucosal mast cells （MC）, changes of substance P （SP） and substance P receptor （SPR） in colon and change of corticotropin-releasing hormone （CRH） in hypothalamus. RESULTS： The threshold of visceral sense was significantly lower in model group than in normal group,and significantly higher in EA group than in model group. The number of mucosal MC was greater in model group than in normal group and significantly smaller in EA group than in model group. The CRH level in hypothalamus of rats was significantly higher in model group than in normal group, which was remarkably decreased after electro-acupuncture treatment. The SP and SPR expression in colon of rats in model group was decreased after electro-acupuncture treatment. CONCLUSION： EA at ST25 and ST37 can decrease the number of mucosal MC and down-regulate the expression of CRH in hypothalamus, and the expression of SP and SPR in colon of rats with IBS.

Unanticipated Bond Failure over Supporting Band Beams in Grouted Post-Tensioned Slab Tendons with Little or No Initial Prestress

After grouting the ducts in a large band beam and one-way slab post-tensioned floor system in a large shopping mall （in excess of 1.5 km2 in plan）, doubts arose concerning the level of initial prestress and the strength and serviceability of the slabs was questioned. To assess the strength of the slabs, it was assumed, as a worst case scenario, that some spans may have been constructed with zero initial prestress. Load tests on prototype specimens, with similar dimensions and reinforcement quantities as the floor slabs, were performed to assess the stress development in initially unstressed, but fully grouted, tendons. Unexpected bond failures occurred at the junctions of slab and band beam where the abrupt change in section depth caused a sudden change in tendon stress. The maximum stress that was developed in the initially unstressed tendons at these locations was about 60% of the strength of the tendons.

Newly Discovered Virus Associated Enzyme Capable of Alteration of Nucleic Acid Structures through Phosphotriester/-Diester Bonds

A newly discovered enzyme, that can catalyze the formation of phosphotriester/-diester bonds between nucleic acids, was found to be associated with plant and animal viruses; （i.e. southern bean mosaic virus, brome mosaic virus, influenza virus, avian virus and mouse retrovirus）. A partially purified enzyme from maize developing endosperms was prepared through 15%-35% ammonium sulfate fractionation, DEAE-cellulose anion exchange column chromatography and Sephadex GI50 gel filtration. The enzyme preparation was then used to demonstrate its main functional characteristics. The enzyme can use varieties of short and long chain length of nucleotides as substrates. However, the enzyme requires at least a minimum of 3 to 4 units of nucleotide chain length for the reaction to occur. The enzyme activity shows an optimum reaction in 50 mM sodium acetate buffer at pH 5.4 and is significantly inhibited by 6-azauridine as compared to other nucleotide analogs. By analyzing the data documented in literature and the results from the present study of the association of this enzyme with viruses and the distinctive inhibitory effect of 6-azauridine, it is speculated that this enzyme is likely associated with many other plant and animal viruses. The association of this enzyme on the surface of virus particles can be explored as a common antigen for developing a versatile antiviral vaccine.

郑孙买地券“酒醉”补议

本文对新近发表的郑孙买地券中的"酒醉物故"一语进行补释,认为此语并非实指因醉酒而亡,应当是古人对死的一种讳称,这一讳称当与道教信仰有着很大关系。

N-phosphoryl amino acid models for P–N bonds in prebiotic chemical evolution

Post-translational modification of proteins by N-phosphorylation of the basic amino acid residues plays important roles in biological processes. The high-energy P–N bond might have contributed to the evolution of prebiotic chemistry. N-phosphoryl amino acids(PAAs) can serve as interesting small molecular models for the study of P–N bonds in prebiotic chemical evolution. PAAs are capable of simultaneously producing several important biomolecules such as polypeptides and oligonucleotides under mild reaction conditions. In this review, we describe the chemistry of PAAs, discusse their likely prebiotic origins and their reactivity and how they relate to biological P–N bond species. We also depict a possible prebiotic scenario mediated by PAAs in which PAAs may have acted as one of the essential forces driving prebiotic biomolecules to the first protocell.

Point defects in L1_0 FePt studied by molecular dynamics simulations based on an analytic bond-order potential

The point defects and their related physical properties in L10 FePt are investigated by molecular dynamics simulations based on an analytic bond-order potential. The calculated results agree well with the experimental value, indicating that the analytic bond-order potential is suitable to describe the structural properties and surface energies of the FePt alloy in the L10 phase. However, the calculated vacancy formation energy of an Fe atom is higher than that of a Pt atom, which disagrees with some other previously calculated results. This result indicates that the analytic bond-order potential is unable to describe the related point defect properties. The analytic bond-order potential needs to be modified in order to study these defect properties of an FePt alloy.