[Case Analysis of Heavy Air Pollution Process in Xi'an Using Multi-source Data].

Air pollution continues to be a serious problem in Xi'an. A heavy pollution process and formation mechanism were investigated in Xi'an in January 2019 using multi-source methods (such as material balance and sulfur/nitrogen oxidation rate (SOR/NOR)). The multi-source data included the concentrations of PM2.5, PM10, SO2, NO2, CO, and O3; the chemical components of PM2.5; the meteorological records of ground and vertical observations; the atmospheric reanalysis data. Three phases were obtained including the accumulation phase (P1), maintenance phase (P2), and dispersion phase (P3) during the pollution period. The pollution event was primarily attributed to the superposition of adverse weather conditions and feedback effects. During the periods of P1 and P2, the area of Xi'an was affected by blocking and zonal westerly airflow at 500 hPa (with flat westerly airflow) and uniform-distribution pressure at sea level with a limited pressure gradient and stable weather conditions, and the easterly wind was dominant at 925 hPa; not all of these factors were conducive to the pollutant diffusion. An interaction feedback mechanism between meteorological conditions and heavy pollution could be studied using the ground-based microwave radiometer. The correlations between PM2.5 and inversions of water vapor density, relative humidity, air temperature, and temperature inversion were significant with coefficients of 0.86, 0.62, 0.53, and 0.38, respectively. The feedback mechanism was primarily manifested as follows:with the pollutant accumulation, the radiative cooling effect could lead to or strengthen the occurrence and intensity of temperature inversion, decrease the mixed layer height, and cause moisture accumulation. High humidity could further maintain the pollution by accelerating the secondary formation and promoting the hygroscopic growth of aerosol particles. Therefore, the dominant chemical components to PM2.5were secondary inorganic ions (SO42-+NO3-+NH4+, SNA) and "other" components during the period of P2, with contributions of 43.2% and 23.1%, respectively. In addition, the peak values of PM2.5, SOR, NOR, and the light extinction coefficients all occurred on the same days (January 3 and 6), indicating that the effect of secondary formation was important for both heavy pollution events and visibility. The total contribution of NH4NO3, organic matter (OM), (NH4)2SO4, and EC to the light extinction coefficient was more than 85%. Limited variations in the proportion for components were observed in three phases. During the period of P3, the strong cold air in the mid-lower atmosphere was conducive to the dry and clean air sinking and the pressure gradient at sea level increasing. These were beneficial to the diffusion of air pollutants and water vapor.

(S)-Benzyl 2-amino-3-(4-hydroxy-phen-yl)propanoate.

The title compound, C(16)H(17)NO(3), adopts a folded conformation in the crystal structure. The crystal packing is stabilized by inter-molecular O-H⋯O and N-H⋯O hydrogen-bonding inter-actions. The absolute configuration was assigned assuming that the absolute configuration of the starting material l-tyrosine was retained during the synthesis.

N-Benzyl-2-propynamide.

Pale-yellow crystals of the title compound, C(10)H(9)NO, have been obtained by the reaction of benzyl-amine and methyl propiolate. Weak inter-molecular hydrogen bonding is observed between acetyl-enic H and carbonyl O atoms. The crystal packing is stabilized by these C-H⋯O and by N-H⋯O inter-molecular hydrogen-bonding inter-actions.

Benzyl 2,5-dioxopyrrolidin-1-yl carbonate.

The asymmetric unit of the title compound, C(12)H(11)NO(5), contains two independent mol-ecules with similar geometric parameters but different orientations of the phenyl rings. The mol-ecular packing is stabilized by weak nonclassical C-H⋯O hydrogen-bonding inter-actions.

[Therapeutic mechanisms of interferon-beta and intravenous immunoglobulin for experimental peripheral neuropathy].

OBJECTIVE: To explore the therapeutic mechanisms of interferon-beta (IFN-beta) and intravenous immunoglobulin (IVIG) for experimental peripheral neuropathy induced by Campilobacter jejuni (Cj) lipopolysaccharide (LPS). METHOD: Forty healthy Wistar rats weighing 205 - 230 g were divided into IFN-beta, IVIG, IFN-beta plus IVIG and control groups. After the immune neuropathy was induced in the rats by Cj LPS, IFN-beta (1.3 microg/kg) was given by subcutaneous injection to the rats every other day for 6 weeks; IVIG [400 mg/(kg x d)] was given to the rats for five days, every other week for two times and IFN-beta [1.3 microg/(kg x d)] and IVIG [400 mg/(kg x d)] were given to the rats on the same days. Meanwhile, the control group was given PBS. The sera were collected in the 2nd, 4th and 6th week after therapy, the titers of anti-GM(1) IgG, MMP-9 and TNF-alpha in sera of immunized rats were measured by ELISA; histological study of sciatic nerve was performed and IgG on sciatic nerve was detected by immunohistochemistry in the 6th week. RESULTS: (1) There were no significant differences in titers of anti-GM(1) IgG, MMP-9 and TNF-alpha among the 3 therapeutic groups and control group after therapy for 2 weeks (P > 0.05). (2) The titers of anti- GM(1) IgG, MMP-9 or TNF-alpha in the control group were much higher than those of the IFN-beta group, the IVIG group or the IFN-beta and IVIG group after therapy for 4 weeks (P > 0.01) and there were no significant differences in titers of antibody among the 3 therapeutic groups (P > 0.05); the titers of MMP-9 or TNF-alpha in the IFN-beta and IVIG group were lower than those of the IFN-beta group or the IVIG group (P < 0.05). (3) The titers of anti-GM(1) IgG, MMP-9 or TNF-alpha in the control group were much higher than those of the IFN-beta group, the IVIG group or the IFN-beta with IVIG group after therapy for 6 weeks (P > 0.01); the IFN-beta with IVIG group had much lower levels of all indexes than the IFN-beta group or the IVIG group (P < 0.01). CONCLUSION: IFN-beta and IVIG showed therapeutic effects on immune peripheral neuropathy through inhibiting the humoral and cellular immunity simultaneously in the peripheral neuropathy induced by CJ LPS, treatment with combined IFN-beta and IVIG was more effective.

[Damage to peripheral nerves induced by Campylobacter jejuni exotoxin].

OBJECTIVE: To explore the pathogenesis of the damage to peripheral nerves induced by Campylobacter jejuni exotoxin (CJT). METHODS: (1) Animal models: (1) The CJT was extracted from PEN 19-CJ and injected perineurally and intravenously to Wistar rats. (2) The sera and the supernatants of peripheral blood mononuclear cells (PBMCs), taken from the rats immunized with the CJT, were injected perineurally at sciatic nerves of experimental rats and intravenously, respectively. (2) Histopathologic study of sciatic nerves: the animals were sacrificed and their sciatic nerves were examined for tease fibers, transverse section with toluidine blues staining and electron microscopy. (3) Immunohistochemistry: sections of sciatic nerves of either normal rats or human which were incubated with CJT and the sciatic nerves with pathological changes induced by CJT were obtained for observation of the binding capability of CJT with peripheral nerves by SABC and FITC-immunofluorescence methods, and nucleic acid hybridization techniques for detection of TNF-alpha mRNA expression in pathological sciatic nerves samples. RESULTS: (1) Remarkable peripheral neuropathies with axon degeneration and/or demyelination were found in the nerves induced by both CJT injection perineurally and intravenously. The axon degeneration was more obvious. Pathological changes were identified in 76.8% (2,763/3,600) of teasing fibers after perineural injection, but only 9.6% (230/2,400) of fibers were damaged in control group (P < 0.01). The peak severity of fiber damage was found on the 3rd day after CJT intravenous injection with the incidence of abnormal fibers was 19.5% (390/2,000), and abnormalities of 15.5% (310/2000) on the 14th day. However, no abnormal changes were demonstrated in control group (P < 0.01). So was in the groups injected with anti-CJT sera and the supernatants of PBMCs compared with control (P > 0.05). (2) Binding of CJT to the nerve was found dominant in the sciatic nerves taken from normal rats or human either incubated with CJT or in the pathological sciatic nerves induced by CJT to various degrees. The binding of CJT to all these nerves was determined. (3) After intravenous injection with CJT, no histopathologic change could be found in the other viscera of the rats, with the exception of remarkable pathological change in peripheral nerves. CONCLUSIONS: (1) CJT could remarkably damage the peripheral nerves in rats. Specific pathogenicity of CJT to peripheral nerves was well shown, because no histopathologic abnormalities could be found in the other viscera, such as brain, liver and kidney etc. although there was remarkable pathological change along the peripheral nerve in the animals. (2) No immunological pathogenicity of CJT could be demonstrated in the nerves of rats after immunization with CJT.

[Experimental study on the therapeutic mechanism of high dose intravenous immunoglobulin in treatment of immune-mediated peripheral neuropathy].

OBJECTIVE: To explore the therapeutic basis of high dose intravenous immunoglobulin (IVIg) in treatment of peripheral neuropathy induced by Campylobacter jejuni lipopolysaccharide (CJ LPS). METHOD: (1) IVIg (400 mg/kg x d) was given to the rats on the different days respectively during the immunization with CJ LPS. Histological study of sciatic nerve was performed on the 35 th day after immunization. The titer of anti-CJ LPS antibody in sera of immunized rats was measured by ELISA; IgG deposition was detected by immunohistochemistry and expression of TNF-alpha mRNA in the pathological nerves by in situ hybridization histochemistry. (2) When PBMCs were stimulated by CJ LPS in vitro, IVIg was added into culture medium at the doses of 1, 2.5, 5, and 10 mg/ml, respectively. Pathological examination of sciatic nerve was performed on the 7th day after perineural injection of the supernatants. Expression of TNF-alpha mRNA in PBMCs stimulated by CJ LPS in medium was detected by in situ hybridization histochemistry after adding IVIg. RESULTS: (1) The rate of abnormal fibers appearance in IVIg group (1.0%) was much lower than that of the control group (15.0%) after immunization with CJ LPS, P < 0.01. The titer of antibody in control group was 9 times higher than that of IVIg group. There was no expression of immunoglobulin and TNF-alphamRNA in peripheral nerves in IVIg group, but high expression was found in control group in which no IVIg was injected. (2) The expression rates of TNF-alphamRNA on the PBMCs in IVIg group (1.0%) was much lower than that of control group (9.5%). (3) When the PBMCs of normal rats were stimulated by CJ LPS, the expression rates of TNF-alphamRNA in PBMCs of 5 mg/ml IVIg group (3.0%) or 10 mg/ml IVIg group (2.0%) were much lower than that of 1 mg/ml IVIg group (15.0%) or 2.5 mg/ml IVIg group (11.5%), P < 0.01. The rate of abnormal fibers appearance in 5 mg/ml IVIg group (9.8%) or 10 mg/ml IVIg group (8.5%) was much lower than that of 1 mg/ml IVIg group (50.0%), 2.5 mg/ml IVIg group (41.0%) or control group (50.8%) after the perineural injection with the supernatants, respectively, P < 0.01. CONCLUSION: The therapeutic effect of high dose IVIg might be associated with inhibition of the humoral and cellular immunity simultaneously in peripheral neuropathy induced by CJ LPS.