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X Q Lin

Publications and source records attributed to X Q Lin.

9 recordsLinked to original sources
PubMed2001

Pre-concentration of non-uniform field electrophoresis for sample introduction of capillary electrophoresis.

A new sample introduction method of capillary electrophoresis, in which field-amplified sample injection was combined with a pre-concentration of non-uniform field electrophoresis, is presented in this paper. With an additional pre-concentration voltage applied to sample solution, a non-uniform electric field was generated, with which analytical cations or anions were pre-concentrated around an electrode adjacent to the injection end of capillary. After the pre-concentration, analytical ions were injected into the capillary and stacked at the boundary between sample and buffer solution inside capillary by field-amplified injection technique. In contrast to the conventional field-amplified injection, larger concentration factor and higher analytical sensitivity were obtained with the improved pre-concentration method. Its concentration factor was about 10 approximately 15 fold as that of field-amplified sample injection.

Electrophoresis, Capillary↗
PubMed2001

Comparison of genomic and predicted amino acid sequences of respiratory and enteric bovine coronaviruses isolated from the same animal with fatal shipping pneumonia.

The complete genome sequences are reported here of two field isolates of bovine coronavirus (BCoV), which were isolated from respiratory and intestinal samples of the same animal experiencing fatal pneumonia during a bovine shipping fever epizootic. Both genomes contained 31028 nucleotides and included 13 open reading frames (ORFs) flanked by 5'- and 3'-untranslated regions (UTRs). ORF1a and ORF1b encode replicative polyproteins pp1a and pp1ab, respectively, that contain all of the putative functional domains documented previously for the closest relative, mouse hepatitis virus. The genomes of the BCoV isolates differed in 107 positions, scattered throughout the genome except the 5'-UTR. Differences in 25 positions were non-synonymous and were located in all proteins except pp1b. Six replicase mutations were identified within or immediately downstream of the predicted largest pp1a-derived protein, p195/p210. Single amino acid changes within p195/p210 as well as within the S glycoprotein might contribute to the different phenotypes of the BCoV isolates.

Amino Acid Sequence↗
PubMed2001

[Study on sampling preconcentration method combining electrostacking with isotachophoresis in capillary electrophoresis].

A sampling preconcentration method combining electrostacking with isotachophoresis is presented in this paper. The optimum conditions for electrostacking and isotachophoresis were investigated. With the preconcentration conditions of 70 s electrostacking and 40 s isotachophoresis, two medicines, propranolol and metoprolol, with similar structures were separated by capillary zone electrophoresis. The working voltage for all the steps was 15 kV. Being adjusted to pH 4.0, 30 mmol/L NaAc-HAc, 30 mmol/L beta-alanine-HAc and 1.5 mmol/L NaAc-HAc were employed as the background, viz. leading, terminating and sample buffer solutions respectively. In comparing with the conventional electro-migration injection, the enhancement factors in peak height of the present method were about 250 and 160 for propranolol and metoprolol respectively. Total analysis time was similar to that of the conventional one.

Electrolytes↗
PubMed2000

Antibody responses to respiratory coronavirus infections of cattle during shipping fever pathogenesis.

Antibody responses against respiratory bovine coronavirus (RBCV) infections were monitored in cattle from the onset of a naturally occurring severe shipping fever (SF) epizootic to complete recovery of affected cattle or fatal outcomes. The infection with RBCV was detected in nasal secretions of 86 cattle, and 81 of them developed acute respiratory tract disease, including fatal pneumonia. Cattle nasally shedding RBCV at the beginning of the epizootic experienced characteristic primary immune responses with specific antibodies for hemagglutinin-esterase (HE) and spike (S) glycoproteins. Virus shedding in nasal secretions of the majority of the cattle ceased between days 7 and 14 with the appearance of HE- and S-specific antibodies. Nasal samples and lung tissues from 9 of the 10 fatal cases had high titers of RBCV, but these cattle had only IgM responses to RBCV infections. Cattle remaining negative in RBCV isolation tests entered this epizootic with antibodies against HE and S. Protection against respiratory tract disease was apparently associated with high level of opsonic and virus-neutralizing IgG2. The HE and S glycoproteins were recognized earliest by the bovine immune system while the N protein induced antibody responses during the later stage of initial infection and the early stage of reinfection. The membrane (M) glycoprotein was the least immunogenic of the major viral structural proteins.

Animals↗
PubMed2000

Temperature-sensitive acetylesterase activity of haemagglutinin-esterase specified by respiratory bovine coronaviruses.

Numerous respiratory bovine coronaviruses (RBCV) were isolated recently from nasal swab samples and lung tissues of feedlot cattle with acute respiratory tract disease. These newly emerging RBCV isolates exhibited distinct phenotypic features that differentiated them from enteropathogenic bovine coronaviruses (EBCV). The RBCV strains had a receptor-destroying enzyme function mediated by acetylesterase (AE) activity of the haemagglutinin-esterase (HE) glycoprotein. The HE genes of wild-type EBCV strain LY138 and RBCV strains OK-0514 (OK) and LSU-94LSS-051 (LSU) were cloned, sequenced and transiently expressed in COS-7 cells. The enzymic properties of HE proteins in COS-7 cellular extracts and in purified virus preparations were assayed at room temperature, 37 degrees C and 39 degrees C by two different assays. One assay used p-nitrophenyl acetate (PNPA) as substrate and detected serine-esterase activity; the second assay monitored AE function with bovine submaxillary mucin (BSM) as substrate. The PNPA tests confirmed that HE proteins of EBCV and RBCV were functionally expressed in transfected COS-7 cells. Time-dependent determination of the AE activity of purified RBCV OK and LSU particles showed lower AE activity at 39 degrees C than at 37 degrees C, whereas the purified EBCV LY particles retained full AE activity at both 37 degrees C and 39 degrees C. Transiently expressed RBCV HE exhibited a marked reduction of AE activity after 40 min of assay time at 37 degrees C. In contrast, the AE activity of the transiently expressed EBCV HE remained stable beyond 40 min. The deduced amino-acid sequences of the HE proteins specified by the RBCV strains OK and LSU contained specific amino-acid changes in comparison with the EBCV LY strain, which may be responsible for the observed enzymic differences. These results are consistent with the hypothesis that RBCV strains have evolved to selectivelyreplicate in respiratory tissues and that HE may play a role in this tissue tropism.

Acetates↗
PubMed1989

[Determination of the contents of mineral elements in the soil where the jinin big-wild ginseng grows].

The element contents in the soil where the Jilin Big-Wild Ginseng grows were determined with plasma emission spectrometry. 23 elements in the soil were found, of which 12 are macro and trace elements indispensable to Ginseng growth. This study provides a scientific basis for selecting suitable soil for planting wild ginseng, or for creating optimum soil conditions for the bumper harvest and high quality of Ginseng.

Calcium↗
PubMedDate not supplied

Long-lasting chemiluminescence of luminol on electrochemically pre-oxidized platinum electrodes in NaOH solution.

A long-lasting bright chemiluminescence (CL) of luminol was generated at polycrystalline platinum electrodes with open circuit. The CL can last for several hours with the presence of O(2) in the solution when the electrode was preoxidized at potentials more positive than 1.10 V vs. SCE. The effects of the varieties of solution conditions and surface states of the electrode on the CL intensity and the interfacial potential of the electrode were investigated. It was proposed that PtO was generated at the pre-oxidized potentials and played a role of catalyst of luminol oxidation for generating the CL. The redox couple of PtO/Pt(active) at the electrode surface was maintained in the presence of O(2) and luminol, and generated the interfacial potential more positive than 140 mV. Mathematical treatment of the reaction mechanism was conducted, which led to an approximated expression of a steady CL intensity (I(CL)) as a function of the pre-polarization potential (E( h)) and time (tau( h)) of the electrode. An empirical equation, (I(CL))(4/3) = 3480(-1 + 0.82E( h) + 0.037 ln tau( h)), was estimated from the experimental data.

Electrochemistry↗