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Ma H, Ma JX, Xue P, Gao Y, Li YK. Osteoblast proliferation is enhanced upon the insulin receptor substrate 1 overexpression via PI3K signaling leading to down-regulation of NFκB and BAX pathway. Exp Clin Endocrinol Diabetes 2014; 123:126-31. [PMID: 25372512 DOI: 10.1055/s-0034-1390422] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The insulin receptor substrate 1 (IRS1) promotes bone formation via osteoblast proliferation mediated by PI3K/Akt signaling. A reduction in NFκB activity in osteoblasts results in an increase in bone formation. The NFκB signaling pathway leads to increased expression of BAX, which contributes to osteoblast apoptosis. The purpose of this study was to investigate the expression of recombinant plasmid enhanced green fluorescent protein-N1 (pEGFP-N1) that transferred IRS1 gene into osteoblasts in vitro and evaluate the effects of IRS1 overexpression on NFκBp65 and on BAX. Osteoblasts were transfected with pEGFP-N1 or pEGFP-N1 encoding wild-type IRS1 (pEGFP-N1-IRS1). Cell cycle analysis was performed using flow cytometry. The expression levels of NFκBp65 and BAX were measured by Western blotting. Our results revealed that overexpression of IRS1 stimulated osteoblast proliferation, as evidenced by an increase in the number of cells in the S phase compared to controls. IRS1 overexpression in osteoblasts activated the PI3K/Akt pathway, and inhibited expression of NFκBp65 and BAX. When osteoblasts transfected with pEGFP-N1-IRS1 were exposed to a PI3K inhibitor (LY294002), the effects of IRS1 overexpression were reversed. On the basis of our study, it seems that osteoblasts proliferated upon IRS1 overexpression due to inhibition of the NFκB pathway and downregulation of BAX through PI3K/Akt signaling.
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Zhai HF, Zhang P, Wu SQ, He CY, Tang ZT, Jiang H, Sun YL, Bao JK, Nowik I, Felner I, Zeng YW, Li YK, Xu XF, Tao Q, Xu ZA, Cao GH. Anomalous Eu Valence State and Superconductivity in Undoped Eu3Bi2S4F4. J Am Chem Soc 2014; 136:15386-93. [DOI: 10.1021/ja508564s] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Zhang YR, Li YK, Fu CZ, Wang JL, Wang HB, Zan LS. Effects of bovine SMO gene polymorphisms on the body measurement and meat quality traits of Qinchuan cattle. GENETICS AND MOLECULAR RESEARCH 2014; 13:8105-17. [PMID: 25299195 DOI: 10.4238/2014.october.7.5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Beef cattle breeding programs focus on improving important economic traits, including growth rates, and meat quantity and quality. Molecular marker-assisted selection based on genetic variation represents a potential method for breeding genetically improved livestock with better economic traits. Smoothened (SMO) protein is a signal transducer that contributes to the regulation of both osteogenesis and adipogenesis through the hedgehog pathway. In this study, we detected polymorphisms in the bovine SMO gene of Qinchuan cattle, and we analyzed their associations with body measurement traits (BMTs) and meat quality traits (MQTs). Using DNA sequencing and polymerase chain reaction-restriction fragment length polymorphism, 3 novel single nucleotide polymorphisms were identified in the SMO gene of 562 cattle: 1 G > C mutation on exon 9 (G21234C) and 2 C > T mutations on exon 11 (C22424T and C22481T). Association analysis showed that polymorphisms on both the G21234C and C22424T loci significantly affected certain BMTs and MQTs (P < 0.05 or P < 0.01), whereas those on the C22481T locus did not (P > 0.05). Therefore, the SMO gene could be used as a candidate gene to alter BMTs and MQTs in Qinchuan cattle or for marker-assisted selection to breed cattle with superior BMTs and MQTs.
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Yang N, Zan LS, Li YK, Gao JB, Ma XH, Fu CZ, Wang H, Adoligbe C. Polymorphisms in the delta-like 2 homolog gene and their association with growth and meat-quality traits in Qinchuan cattle. GENETICS AND MOLECULAR RESEARCH 2014; 13:2130-9. [PMID: 24737437 DOI: 10.4238/2014.march.24.20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The delta-like 2 homolog (DLK2) modulates adipogenesis, hematopoiesis, osteogenesis, and other cell-differentiation processes. In the present study, we detected potential polymorphisms in the DLK2 gene in 604 individuals of Qinchuan cattle by using PCR-RFLP and DNA-sequencing methods. Herein, we identified five novel single-nucleotide polymorphisms (SNPs) (g.888G>A, g.910A>G, g.995G>A, g.4321A>G, g.4850A>G) and analyzed their association with measured traits. Four of the five analyzed polymorphisms were associated with at least one of the following traits: body weight (BW), chest depth (CD), chest circumference (CC), back fat thickness (BT), and rib-eye area (REA). To the best of our knowledge, our research is the first to report the association of DLK2 gene polymorphisms with growth and meat quality traits in Qinchuan cattle. In summary, the results of our study suggest that the DLK2 gene can be used as a candidate gene in beef cattle breeding.
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Li YK, Huangpu YF, Gao JB, Yang N, Fu CZ, Wang HB, Cheng G, Zan LS. New polymorphisms in the novel LYRM1 gene are associated with body measurement and meat quality traits in Qinchuan cattle. GENETICS AND MOLECULAR RESEARCH 2014; 13:6926-36. [PMID: 24682980 DOI: 10.4238/2014.march.12.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Body measurement and meat quality traits play important roles in the evaluation of productivity in cattle; they are influenced by genetic and environmental factors. Recent studies have shown that LYRM1 is a novel gene related to obesity and may influence fat deposition. We screened for new polymorphisms in the bovine LYRM1 gene and analyzed their association with body measurement and meat quality traits in cattle. DNA samples were obtained from 572 Qinchuan cattle aged from 18 to 24 months. DNA sequencing was used to find the LYRM1 single nucleotide polymorphisms (SNPs). Sequence analysis of LYRM1 revealed four novel SNPs in exon 3: G50A in coding region, C126A, A127T, and T128A in a 3'-untranslated region. G50A, A127T and T128A showed two genotypes: AG and GG, AA and AT, AT and TT, respectively; while C126A showed three genotypes: AA, AC and CC. Analysis showed that these four polymorphisms were significantly associated with body measurement and meat quality traits in the Qinchuan cattle population. We suggest that the LYRM1 gene can be used for marker-assisted selection to improve body measurement and meat quality traits in the Qinchuan cattle population.
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Li TY, Li YK, Chan CM. Who are Prone to Develop Adverse Effects with Oral Tramadol? a Retrospective Cohort Study. HONG KONG J EMERG ME 2014. [DOI: 10.1177/102490791402100101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Objective Oral tramadol is a commonly prescribed analgesic in Hong Kong. Significant adverse effects are frequently observed in our locality. Our study aims to describe the rate of significant adverse effect that warrant discontinuation of oral tramadol and identify the risk factors for development of adverse effect. Design Retrospective cohort study. Methods Adult patients aged greater than 18 years old admitted to the emergency medicine ward of a large-scale local hospital in Hong Kong being prescribed with oral tramadol during in-hospital stay were recruited. Significant adverse effects during the hospital stay were observed as the outcome of interest. Results A total of 575 subjects were recruited. 29.9% experienced significant adverse effects likely related to tramadol. Age (p=0.006; odds ratio [OR] = 1.017, 95% confidence interval [CI] = 1.005-1.029) and sex (p=0.006; OR=1.696, 95% CI= 1.166-2.465) were statistically significant predictors of adverse effects after oral tramadol. Conclusion Our study suggests that female and increasing age patients are significant predictors for the development of adverse effect after taking oral tramadol. Possible adverse effects should be explained to the patients careful especially the higher risk groups. (Hong Kong j. emerg.med. 2014;21:3-9)
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Hui CLM, Lee EHM, Chang WC, Chan SKW, Li YK, Lee JTM, Chen EYH. Sexual dysfunction in Chinese patients with first-episode psychosis: prevalence, clinical correlates and functioning. Schizophr Res 2013; 148:181-2. [PMID: 23791026 DOI: 10.1016/j.schres.2013.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 05/10/2013] [Accepted: 06/02/2013] [Indexed: 11/24/2022]
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Gao JB, Li YK, Yang N, Ma XH, Adoligbe C, Jiang BJ, Fu CZ, Cheng G, Zan LS. Novel SNPs in the exon region of bovine DKK4 gene and their association with body measurement traits in Qinchuan cattle. GENETICS AND MOLECULAR RESEARCH 2013; 12:6664-72. [PMID: 23479175 DOI: 10.4238/2013.february.28.30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The aim of this study was to determine whether single nucleotide polymorphisms (SNPs) of bovine Dickkopf homolog 4 (DKK4) are associated with body measurement traits in Qinchuan cattle. By using PCR-SSCP technology and DNA sequencing, we discovered 5 DKK4 SNPs in Qingchuan cattle, including -65G>A and -77G>T in the 5'-untranslated region, 1532C>G and 1533T>C in exon 2, and 2088C>T in exon 3. The sequencing map showed that 1532C>G and 1533T>C were in close linkage disequilibrium and were treated as 1532C>G-1533T>C in this study. Allele frequencies were calculated and analyzed by the chi-square test, which showed that -65G>A and 1532C>G-1533T>C were in Hardy-Weinberg equilibrium (P > 0.05), whereas -77G>T and 2088C>T were not in all 633 tested Qinchuan cattle individuals (P < 0.01). Gene heterozygosity (HE), effective allele number (NE), and polymorphism information content (PIC) were 0.407, 1.686, and 0.324 at -65G>A; 0.472, 1.894, and 0.361 at -77G>T; 0.476, 1.908, and 0.363 at 1532C>G-1533T>C; and 0.218, 1.279, and 0.195 at 2088C>T. We also evaluated the potential association of these SNPs with body measurement traits in all 633 individuals; the results suggest that several SNPs in Qinchuan cattle DKK4 were significantly associated with body length, hip height, rump length, hip width, heart girth, and pin bone width (P < 0.05 and P < 0.01). These results suggest that bovine DKK4 could be used as candidate gene for Qinchuan cattle breeding.
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Li YK, Shen CY, Guo HJ, Lv C, Yang XJ, Zhang L, Luo YK, Cao GH, Xu ZA. Effect of Zn impurity in K0.8Fe(2-δ-x)Zn(x)Se2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:232202. [PMID: 22588053 DOI: 10.1088/0953-8984/24/23/232202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A series of K(0.8)Fe(2-δ-x)Zn(x)Se(2) single-crystal samples with nominal compositions 0 ≤ x ≤ 0.05 were grown and their physical properties were measured in order to study the effect of Zn impurity. It is found that the Zn impurity (x ≤ 0.02) does not affect the superconducting transition temperature T(c) significantly. Meanwhile the hump in resistivity which corresponds to the transition from the insulating to metallic phase quickly shifts towards low temperatures. The results imply that there should be a phase separation in this system and Zn impurity causes the enhancement of the insulating phase. The negligible effect of Zn impurity on T(c) suggests an s-wave pairing in the superconducting phase. Meanwhile there is a possibility that the Zn impurity may selectively enter into the insulting phase.
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Li YK. Author's Reply: Dear Editor. HONG KONG J EMERG ME 2010. [DOI: 10.1177/102490791001700121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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Li YK, Lin X, Zhou T, Shen JQ, Tao Q, Cao GH, Xu ZA. Superconductivity induced by Ni doping in SmFe(1-x)Ni(x)AsO. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:355702. [PMID: 21828641 DOI: 10.1088/0953-8984/21/35/355702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Superconductivity with a T(c) of about 10 K is observed in the Ni-doped SmFe(1-x)Ni(x)AsO system. The measurements of resistivity and magnetic susceptibility show that the spin-density wave (SDW) order is quickly suppressed with increasing Ni content, and superconductivity emerges as x≥0.04. T(c)(mid) shows a maximum of 10.8 K at x = 0.06, and it drops to lower than 2 K as x>0.12. Meanwhile, the upper critical field (H(c2)(0)) is estimated to be about 40 T for the optimally-doped sample (x = 0.06). The normal state thermopower is negative for all the Ni-doped samples, indicating that an electron-type charge carrier dominates in the transport properties. Moreover, the magnitude of the room-temperature thermopower increases with increasing Ni content, and then shows a broad peak around x = 0.06. We found that there is an obvious correlation between the anomalously enhanced thermopower and superconductivity. A phase diagram is derived based on the transport measurements and a dome-like T(c)(x) curve is established.
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Cheng Y, Liu GR, Guan JT, Guo YL, Li YK, Wu RH. Early diffusion weighted imaging and expression of heat shock protein 70 in newborn pigs with hypoxic ischaemic encephalopathy. Postgrad Med J 2006; 81:589-93. [PMID: 16143690 PMCID: PMC1743356 DOI: 10.1136/pgmj.2004.030114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE To establish a cerebral hypoxia ischaemic model in piglets and to explore the early diffusion weighted imaging (DWI) as well as the expression of heat shock protein 70 (HSP70) with hypoxic ischaemic encephalopathy (HIE). METHODS Twenty four 3 day old piglets were permanently ligated common carotid arteries bilaterally and ventilated with 3% oxygen for 30 minutes, and their brains were examined at three hours, six hours, and 24 hours after hypoxic ischaemia with T2 weighted images and diffusion weighted images. Apparent diffusion coefficient (ADC) values were measured and HSP70 expression was detected in the central and peripheral regions of lesions. RESULTS Abnormal signal intensity was detected on DWI and ADC maps in three hypoxic ischaemic groups. ADC values in the central lesions rapidly decreased, whereas ADC values in the peripheral regions reduced prominently at 24 hours after hypoxic ischaemia. There were significant differences (p<0.01) between ADC values of the central regions and the peripheral regions of lesions. The number of HSP70 positive cells was low at three hours, raised at the highest peak at six hours, and then rapidly decreased. There was statistical difference between HSP70 positive cells in the central regions and those in peripheral regions (p<0.01). CONCLUSION DWI may identify more early lesions, and improve conspicuity in the acute setting. ADC values can be used as an objective measure for hypoxic ischaemic injury. Tissue reversibility can be further reflected according to the information of ADC values and HSP70 immunohistochemical staining.
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Li YK, Chir J, Chen FY. Catalytic mechanism of a family 3 beta-glucosidase and mutagenesis study on residue Asp-247. Biochem J 2001; 355:835-40. [PMID: 11311148 PMCID: PMC1221801 DOI: 10.1042/bj3550835] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A family 3 beta-glucosidase (EC 3.2.1.21) from Flavobacterium meningosepticum has been cloned and overexpressed. The mechanistic action of the enzyme was probed by NMR spectroscopy and kinetic investigations, including substrate reactivity, secondary kinetic isotope effects and inhibition studies. The stereochemistry of enzymic hydrolysis was identified as occurring with the retention of an anomeric configuration, indicating a double-displacement reaction. Based on the k(cat) values with a series of aryl glucosides, a Bronsted plot with a concave-downward shape was constructed. This biphasic behaviour is consistent with a two-step mechanism involving the formation and breakdown of a glucosyl-enzyme intermediate. The large Bronsted constant (beta=-0.85) for the leaving-group-dependent portion (pK(a) of leaving phenols >7) indicates substantial bond cleavage at the transition state. Secondary deuterium kinetic isotope effects with 2,4-dinitrophenyl beta-D-glucopyanoside, o-nitrophenyl beta-D-glucopyanoside and p-cyanophenyl beta-D-glucopyanoside as substrates were 1.17+/-0.02, 1.19+/-0.02 and 1.04+/-0.02 respectively. These results support an S(N)1-like mechanism for the deglucosylation step and an S(N)2-like mechanism for the glucosylation step. Site-directed mutagenesis was also performed to study essential amino acid residues. The activities (k(cat)/K(m)) of the D247G and D247N mutants were 30000- and 200000-fold lower respectively than that of the wild-type enzyme, whereas the D247E mutant retained 20% of wild-type activity. These results indicate that Asp-247 is an essential amino acid. It is likely that this residue functions as a nucleophile in the reaction. This conclusion is supported by the kinetics of the irreversible inactivation of the wild-type enzyme by conduritol-B-epoxide, compared with the much slower inhibition of the D247E mutant and the lack of irreversible inhibition of the D247G mutant.
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Pan IH, Li YK. Rapid process for purification of an extracellular beta-xylosidase by aqueous two-phase extraction. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL SCIENCES AND APPLICATIONS 2001; 754:179-84. [PMID: 11318413 DOI: 10.1016/s0378-4347(00)00604-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A rapid process for purification of an extracellular beta-xylosidase with high purity was developed. The manipulation involved the precipitation of protein from culture medium and the extraction of enzyme from the resuspended crude protein solution by an aqueous-two phase separation. A linear random copolymer, PE62, with 20% ethylene oxide and 80% propylene oxide was employed in both stages of the purification. The enzyme was precipitated effectively by using 10% (w/v) PE62 and 5% (w/v) Na2HPO4. The aqueous two-phase extraction was performed with PE62 (10%)-NaH2PO4 (15%) as phase-forming reagent. SDS-PAGE analysis revealed that the purified enzyme is near homogeneity. The yield is about 100% with a purification factor of 8.8-fold. The whole process can be completed within an hour without any column chromatography.
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Wong CY, Law GT, Shum TT, Wong KY, Li YK. Pulmonary haemorrhage in a patient with Kikuchi disease. Monaldi Arch Chest Dis 2001; 56:118-20. [PMID: 11499298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Kikuchi disease is an immunologic disease and most commonly presents with cervical lymphadenopathy. It is usually self-limiting [1]. It is sometimes associated with systemic lupus erythematosus (SLE) [2], and can be associated with many complications including aseptic meningitis, neuropathy, brachial neuritis. It can also be associated with lymphoma, and may sometimes be misdiagnosed as such [3]. The following is the first reported case of Kikuchi disease associated with pulmonary haemorrhage. The patient died and no other cause of the pulmonary haemorrhage could be identified at post mortem.
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Cheng CY, Li YK. An Aspergillus chitosanase with potential for large-scale preparation of chitosan oligosaccharides. Biotechnol Appl Biochem 2000; 32:197-203. [PMID: 11115392 DOI: 10.1042/ba20000063] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A chitosan-degrading fungus, designated Aspergillus sp. Y2K, was isolated from soil. The micro-organism was used for producing chitosanase (EC 3.2.1.132) in a minimal medium containing chitosan as the sole carbon source. The induced chitosanase was purified to homogeneity from the culture filtrate by concentration and cationic SP-Sepharose chromatography. The purified enzyme is a monomer with an estimated molecular mass of 25 kDa by SDS/PAGE and of 22 kDa by gel-filtration chromatography. pI, optimum pH and optimum temperature values were 8.4, 6.5 and 65-70 degrees C, respectively. The chitosanase is stable in the pH range from 4 to 7.5 at 55 degrees C. Higher deacetylated chitosan is a better substrate. Chitin, xylan, 6-O-sulphated chitosan and O-carboxymethyl chitin were indigestible by the purified enzyme. By endo-splitting activity, the chitosanase hydrolysed chitosan to form chitosan oligomers with chitotriose, chitotetraose and chitopentaose as the major products. The enzyme hydrolyses chitohexaose to form chitotriose, while the chitopentaose and shorter oligomers remain intact. The N-terminal amino acid sequence of the enzyme was determined as YNLPNNLKQIYDDHK, which provides useful information for further gene cloning of this enzyme. A 275 g-scale hydrolysis of chitosan was performed. The product distribution was virtually identical to that of the small-scale reaction. Owing to the simple purification process and high stability of the enzyme, it is potentially valuable for industrial applications.
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Li YK, Yao HJ, Cho YT. Effective induction, purification and characterization of Trichoderma koningii G-39 beta-xylosidase with high transferase activity. Biotechnol Appl Biochem 2000; 31:119-25. [PMID: 10744957 DOI: 10.1042/ba19990072] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A beta-xylosidase was induced and purified from the culture filtrate of Trichoderma koningii G-39, grown in a medium containing 1% oat spelts xylan and 0.1% xylose. The presence of xylose unequivocally enhanced the induction of beta-xylosidase. The purified enzyme, which exhibited a significant alpha-arabinosidase activity, was obtained with high yield simply via ethanol precipitation and a single anion-exchange chromatography and was characterized as a monomeric glycoprotein with an estimated molecular mass of 104 kDa and a pI of 4.6. The K(m) values towards p-nitrophenyl beta-D-xylopyranoside and p-nitrophenyl alpha-L-arabinopyranoside are 0.04 and 7.5 mM, respectively. It is stable at pH 2.5-7.4, 37 degrees C. The pH and temperature optima are in the range of 3.5-4.0 and 55-60 degrees C, respectively. Contrary to most beta-xylosidases from other sources, Hg(2+) (up to 25 mM) has no effect on enzyme activity. Xylose was shown to inhibit the purified enzyme with a moderate K(i) value of 5 mM. The enzyme exhibited transxylosylation activity and was characterized as a 'retaining' enzyme, catalysing the hydrolysis of substrate with the retention of anomeric configuration.
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Abstract
The catalytic mechanism of the beta-xylosidase purified from the culture filtrate of Trichoderma koningii G-39 was investigated. By NMR spectroscopy, the stereochemistry of the enzyme catalyzing the hydrolysis of 2,4-dinitrophenyl and p-nitrophenyl-beta-D-xylosides was found unequivocally to involve retention of the anomeric configuration. Based on the k(cat) values of a series of arylxylosides with leaving group pK(a)s in the range of 4-10, an extended Bronsted plot was constructed with a slope (beta(lg)) near zero. Enzymatic hydrolysis of aryl-beta-D-xylosides in acetate buffer (pH 4.0) containing 3 or 5% methanol showed a constant product ratio (methylxyloside/xylose), indicating the presence of a common intermediate, probably the xylosyl-enzyme intermediate. In the presence of DTT, the k(cat) values of p-cyanophenyl-beta-D-xylopyranoside and p-nitrophenyl-beta-D-xylopyranoside increased greatly. A two-step mechanism involving the formation and breakdown of the xylosyl-enzyme intermediate was therefore proposed. The rate-limiting step is the breakdown of the intermediate. The secondary deuterium kinetic isotope effect (k(H)/k(D)) measured for 2,4-dinitrophenyl-beta-D-xyloside was 1.02+/-0.01, suggesting that the transition state for breakdown of the xylosyl-enzyme intermediate is S(N)2-like.
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Li YK, Zhang YK, Lu CM, Zhong SZ. Changes and implications of blood flow velocity of the vertebral artery during rotation and extension of the head. J Manipulative Physiol Ther 1999; 22:91-5. [PMID: 10073624 DOI: 10.1016/s0161-4754(99)70113-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To study the effects of extension and extension-rotation of the head on the blood flow velocity of the vertebral artery experimentally and clinically. DESIGN Randomized experimental clinical study. SETTING Institute of Clinical Anatomy and Biomechanics and the Department of Ultrasound, NanFang Hospital of the First Military Medical University, Guangzhou, China. SUBJECTS The fresh spines from T1-2 to the occipital bone were obtained from persons who died of acute brain death (n = 10). For the transcranial Doppler measurement, 27 asymptomatic subjects with routine physical examination results and 23 students from the above-mentioned university took part in the test. INTERVENTIONS The instillation experiment in the cadavers was made. Clinical measurements of blood flow velocity in the vertebral artery in the subjects and students were taken and recorded. MAIN OUTCOME MEASURES Changes in the drop of the vertebral artery were measured by the instillation test in the experimental sample. The blood flow velocity was measured with transcranial Doppler sonography during extension and extension-rotation of the head. RESULTS During one-sided rotation of the head with extension of the head, measurements in the contralateral vertebral artery and the bilateral vertebral arteries were both reduced in the instillation experiment. The blood flow velocity in the bilateral vertebral arteries decreased during extension and extension-rotation of the head in the subjects and the students. The pulsatility index in the right vertebral arteries increased more than that in the left in extreme extension and that in the bilateral vertebral arteries in neutral position. CONCLUSIONS Extreme rotation and extension are dangerous to patients who have abnormal vertebral arteries when extreme rotatory and extension manipulations are applied. Doctors should be very careful when rotating the patient's head to the right side.
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Li YK, Zhang YK, Zhong SZ. Diagnostic value on signs of subluxation of cervical vertebrae with radiological examination. J Manipulative Physiol Ther 1998; 21:617-20. [PMID: 9868633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
OBJECTIVE To investigate the relationship between radiographic signs of subluxation in the cervical vertebrae and their clinical diagnostic value. DESIGN Controlled, clinical study. SETTING Institute of Clinical Anatomy and Biomechanics and NanFang Hospital of the First Military Medical University, Guangzhou, China. SUBJECTS Eighty-seven subjects with cervicodynia and 21 asymptomatic volunteers. INTERVENTIONS Radiological signs of subluxation from anteroposterior, lateral, open-mouth and dynamic radiographs of the cervical vertebrae of the subjects were measured and analyzed. MAIN OUTCOME MEASURES The right and left odontoid lateral mass interspace, divergence of the spinous processes, sign of double contour and position of odontoid process were studied. RESULTS The bilateral odontoid lateral mass interspaces were asymmetrical in most cases, and the divergence of spinous processes, sign of double contour and position of odontoid process were also common. Cervical vertebrae C5, C4 and C6 showed no special variations. CONCLUSION There was little evidence to support the contention that signs of subluxation in the cervical vertebrae are of diagnostic significance. Subluxation should be defined in two ways: as a purely roentgenological diagnosis and as a combination of roentgenological signs with clinical signs.
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Li YK, Zhong SZ. Spinal manipulation in China. J Manipulative Physiol Ther 1998; 21:399-401. [PMID: 9726067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Although there is a long history of the use spinal manipulation in China, little has been formally written on this topic. OBJECTIVE To discuss the history and status of Chinese spinal manipulation. DISCUSSION This article describes the history of Chinese spinal manipulation as revealed through past formal textbook publications on this topic, along with journal articles describing both the basic science foundation and clinical applications of such manipulation. In addition, the current status of Chinese spinal manipulation is described. CONCLUSION There is a long history of the use of spinal manipulation throughout China, though some basic problems of application remain. Current research may help to resolve these problems.
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Li YK, Hsu HS, Chang LF, Chen G. New imidazoles as probes of the active site topology and potent inhibitors of beta-glucosidase. J Biochem 1998; 123:416-22. [PMID: 9538223 DOI: 10.1093/oxfordjournals.jbchem.a021953] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Series of 4-arylimidazoles, omega-N-acylhistamines and 4-(omega-phenylalkyl)imidazoles were synthesized in order to probe the active site topology of sweet almond beta-glucosidase. These imidazole derivatives were shown to be very powerful competitive inhibitors. Among the 20 tested compounds, omega-N-benzoylhistamine and 4-(3'-phenylpropyl)imidazole are the most potent inhibitors of the enzyme, with pH-independent Ki values of 0.06 and 0.07 microM, respectively. The inhibition of 4-(omega-phenylalkyl)imidazoles exhibited an interesting trend as to Ki values: 4-phenylimidazole (6.6 microM)>4-benzylimidazole (1.4 microM)>4-(2'-phenylethyl)imidazole (0.82 microM)>4-(3'-phenylpropyl)imidazole (0.07 microM)<4-(4'-phenylbutyl)imidazole (0.13 microM)<4-(5'-phenylpentyl)imidazole (0.3 microM). This revealed that the imidazole and aryl binding sites (which result from favorable interactions within the corresponding glycone and aglycone binding subsites) are separated by the optimal distance equivalent to the length of a -CH2-CH2-CH2- group. Substitutions of the phenyl moieties of 4-phenylimidazole and 4-benzoylhistamine result in weaker inhibition. These classes of imidazoles are particularly powerful inhibitors of sweet almond beta-glucosidase.
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Li YK, Zhu QA, Zhong SZ. The effect of cervical traction combined with rotatory manipulation on cervical nucleus pulposus pressures. J Manipulative Physiol Ther 1998; 21:97-100. [PMID: 9502065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To study experimentally the effect of cervical traction combined with rotatory manipulation on the pressure of the cervical nucleus pulposus. DESIGN Randomized experimental study. SETTING Institute of Clinical Anatomy and Biomechanics, the First Military Medical University, GuangZhou, China. SUBJECTS Twelve fresh cervical spines, from C7 to occipital bone, were obtained from cadavers of patients who had died from acute brain death. INTERVENTION State A: under different traction forces, the cervical spine was rotated. State B: the cervical spine was rotated first and then tractioned. State C: the cervical spine was tractioned and rotated simultaneously. MAIN OUTCOME MEASURES The cervical spine was tractioned and rotated by the Material Test System (MTS), and pressures of the cervical nucleus pulposus of C3-4, C4-5 and C5-6 were measured using pressure sensors. RESULTS (a) When the traction force increased, the pressure fell continuously in the 200-N tractioned spines; the pressure increased slightly when the sample was rotated. (b) The pressure fell to a certain extent when the state of cervical spine was restored. (c) In state A, the pressure fell obviously and increased slightly under a 200-N traction force and then the sample was rotated; in state B, the pressure first increased to a certain extent and then fell slightly and in state C, the pressure underwent no change in the main. CONCLUSIONS The results of this research suggest that rotatory manipulation of cervical spine under traction was the safest of the three procedures and the traction force used in clinical treatment may be a little smaller.
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Tang LY, Qiu HY, Li YK. [The epidemiologic value of polymerase chain reaction to the diagnosis of brucellosis patients]. ZHONGHUA LIU XING BING XUE ZA ZHI = ZHONGHUA LIUXINGBINGXUE ZAZHI 1997; 18:153-5. [PMID: 9812463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
PCR was used to test fifty-four brucellasis patients and thirty-six healthy people as controls, who were all from Man Tang Chuan and Yi He communities, Sui De county, Shan Xi Province, where brucellosis out-break was occurred in 1996. The diagnostic titres of SAT for brucellasis patients was set 1:100++. The positive rates of PCR in patients and controls were 75% and 65.7% respectively, comparing with the positive rates of RBPT 96.3% and 30.6% in the same two groups. At the same time, we also detected eight people who had received immunization one month to thirty-two years ago, with positive rates for PCR and RBPT 100% and 87.5% respectively. The results showed that there was no significant diversity of PCR results among acute, subacute and chronic brucellosis patients. It was revealed that the serological results were related to the course of disease, but the results came out of PCR method which was used to detect target DNA was not influenced by the course of disease.
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Mao SH, Qin JZ, Li YK. [Clinical studies on liangxue piyan granule no. 2 in treating psoriasis]. ZHONGGUO ZHONG XI YI JIE HE ZA ZHI ZHONGGUO ZHONGXIYI JIEHE ZAZHI = CHINESE JOURNAL OF INTEGRATED TRADITIONAL AND WESTERN MEDICINE 1997; 17:219-20. [PMID: 9863096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
OBJECTIVE To observe the effect of Liangxue Piyan granule No. 2 (LPG) on psoriasis. METHODS Ninety-six cases of psoriasis patients were treated with LPG and a control group of 32 cases was set up, which was treated with Fufang Qingdai Capsule (FQC). RESULTS The total effective rate of LPG was 84.7%, that of the control group was 71.9% (P > 0.05), there was no significant difference between two drugs in treatment of psoriasis. The recurrent rate of LPG group (3.6%) was lower than that of control (21.7%), P < 0.01. CONCLUSION This granule provides a better drug for treatment of psoriasis.
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