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Ablikim M, Bai JZ, Ban Y, Bian JG, Cai X, Chang JF, Chen HF, Chen HS, Chen HX, Chen JC, Chen J, Chen J, Chen ML, Chen YB, Chi SP, Chu YP, Cui XZ, Dai HL, Dai YS, Deng ZY, Dong LY, Du SX, Du ZZ, Fang J, Fang SS, Fu CD, Fu HY, Gao CS, Gao YN, Gong MY, Gong WX, Gu SD, Guo YN, Guo YQ, Guo ZJ, Harris FA, He KL, He M, He X, Heng YK, Hu HM, Hu T, Huang GS, Huang L, Huang XP, Ji XB, Jia QY, Jiang CH, Jiang XS, Jin DP, Jin S, Jin Y, Lai YF, Li F, Li G, Li HB, Li HH, Li J, Li JC, Li QJ, Li RB, Li RY, Li SM, Li WG, Li XL, Li XQ, Li XS, Liang YF, Liao HB, Liu CX, Liu F, Liu F, Liu HM, Liu JB, Liu JP, Liu RG, Liu ZA, Liu ZX, Lu F, Lu GR, Lu JG, Luo CL, Luo XL, Ma FC, Ma JM, Ma LL, Ma QM, Ma XY, Mao ZP, Mo XH, Nie J, Nie ZD, Olsen SL, Peng HP, Qi ND, Qian CD, Qin H, Qiu JF, Ren ZY, Rong G, Shan LY, Shang L, Shen DL, Shen XY, Sheng HY, Shi F, Shi X, Sun HS, Sun SS, Sun YZ, Sun ZJ, Tang X, Tao N, Tian YR, Tong GL, Varner GS, Wang DY, Wang JX, Wang JZ, Wang K, Wang L, Wang LS, Wang M, Wang P, Wang PL, Wang SZ, Wang WF, Wang YF, Wang Z, Wang Z, Wang Z, Wang ZY, Wei CL, Wei DH, Wu N, Wu YM, Xia XM, Xie XX, Xin B, Xu GF, Xu H, Xu Y, Xue ST, Yan ML, Yang F, Yang HX, Yang J, Yang SD, Yang YX, Ye M, Ye MH, Ye YX, Yi LH, Yi ZY, Yu CS, Yu GW, Yuan CZ, Yuan JM, Yuan Y, Yue Q, Zang SL, Zeng Y, Zeng Y, Zhang BX, Zhang BY, Zhang CC, Zhang DH, Zhang HY, Zhang J, Zhang JY, Zhang JW, Zhang LS, Zhang QJ, Zhang SQ, Zhang XM, Zhang XY, Zhang YJ, Zhang YY, Zhang Y, Zhang ZP, Zhang ZQ, Zhao DX, Zhao JB, Zhao JW, Zhao MG, Zhao PP, Zhao WR, Zhao XJ, Zhao YB, Zhao ZG, Zheng HQ, Zheng JP, Zheng LS, Zheng ZP, Zhong XC, Zhou BQ, Zhou GM, Zhou L, Zhou NF, Zhu KJ, Zhu QM, Zhu YC, Zhu YS, Zhu Y, Zhu ZA, Zhuang BA, Zou BS. Observation of two new N* peaks in J/psi-->ppi-n and ppi+n decays. PHYSICAL REVIEW LETTERS 2006; 97:062001. [PMID: 17026161 DOI: 10.1103/physrevlett.97.062001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2004] [Indexed: 05/12/2023]
Abstract
The decay J/psi-->NNpi provides an effective isospin 1/2 filter for the piN system due to isospin conservation. Using 58x10(6) J/psi decays collected with the Beijing Electromagnetic Spectrometer at the Beijing Electron Positron Collider, more than 100 thousand J/psi-->ppi-n+c.c. events are obtained. Besides the two well-known N* peaks at around 1500 MeV/c2 and 1670 MeV/c2, there are two new, clear N* peaks in the ppi invariant mass spectrum around 1360 MeV/c2 and 2030 MeV/c2 with statistical significance of 11sigma and 13sigma, respectively. We identify these as the first direct observation of the N*(1440) peak and a long-sought missing N* peak above 2 GeV/c2 in the piN invariant mass spectrum.
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Ablikim M, Bai JZ, Ban Y, Bian JG, Cai X, Chang JF, Chen HF, Chen HS, Chen HX, Chen JC, Chen J, Chen J, Chen ML, Chen YB, Chi SP, Chu YP, Cui XZ, Dai HL, Dai YS, Deng ZY, Dong LY, Du SX, Du ZZ, Fang J, Fang SS, Fu CD, Fu HY, Gao CS, Gao YN, Gong MY, Gong WX, Gu SD, Guo YN, Guo YQ, Guo ZJ, Harris FA, He KL, He M, He X, Heng YK, Hu HM, Hu T, Huang GS, Huang L, Huang XP, Ji XB, Jia QY, Jiang CH, Jiang XS, Jin DP, Jin S, Jin Y, Lai YF, Li F, Li G, Li HH, Li J, Li JC, Li QJ, Li RB, Li RY, Li SM, Li WG, Li XL, Li XQ, Li XS, Liang YF, Liao HB, Liu CX, Liu F, Liu F, Liu HM, Liu JB, Liu JP, Liu RG, Liu ZA, Liu ZX, Lu F, Lu GR, Lu JG, Luo CL, Luo XL, Ma FC, Ma JM, Ma LL, Ma QM, Ma XY, Mao ZP, Mo XH, Nie J, Nie ZD, Olsen SL, Peng HP, Qi ND, Qian CD, Qin H, Qiu JF, Ren ZY, Rong G, Shan LY, Shang L, Shen DL, Shen XY, Sheng HY, Shi F, Shi X, Sun HS, Sun SS, Sun YZ, Sun ZJ, Tang X, Tao N, Tian YR, Tong GL, Varner GS, Wang DY, Wang JX, Wang JZ, Wang K, Wang L, Wang LS, Wang M, Wang P, Wang PL, Wang SZ, Wang WF, Wang YF, Wang Z, Wang Z, Wang Z, Wang ZY, Wei CL, Wei DH, Wu N, Wu YM, Xia XM, Xie XX, Xin B, Xu GF, Xu H, Xu Y, Xue ST, Yan ML, Yang F, Yang HX, Yang J, Yang SD, Yang YX, Ye M, Ye MH, Ye YX, Yi LH, Yi ZY, Yu CS, Yu GW, Yuan CZ, Yuan JM, Yuan Y, Yue Q, Zang SL, Zeng Y, Zeng Y, Zhang BX, Zhang BY, Zhang CC, Zhang DH, Zhang HY, Zhang J, Zhang JY, Zhang JW, Zhang LS, Zhang QJ, Zhang SQ, Zhang XM, Zhang XY, Zhang YJ, Zhang YY, Zhang Y, Zhang ZP, Zhang ZQ, Zhao DX, Zhao JB, Zhao JW, Zhao MG, Zhao PP, Zhao WR, Zhao XJ, Zhao YB, Zhao ZG, Zheng HQ, Zheng JP, Zheng LS, Zheng ZP, Zhong XC, Zhou BQ, Zhou GM, Zhou L, Zhou NF, Zhu KJ, Zhu QM, Zhu YC, Zhu YS, Zhu Y, Zhu ZA, Zhuang BA, Zou BS. Observation of a threshold enhancement in the plambda invariant-mass spectrum. PHYSICAL REVIEW LETTERS 2004; 93:112002. [PMID: 15447331 DOI: 10.1103/physrevlett.93.112002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2004] [Indexed: 05/24/2023]
Abstract
An enhancement near the m(p)+M(Lambda) mass threshold is observed in the combined pLambda and pLambda invariant-mass spectrum from J/psi-->pK(-)Lambda;+c.c. decays. It can be fit with an S-wave Breit-Wigner resonance with a mass m=2075+/-12(stat)+/-5(syst) MeV and a width of Gamma=90+/-35(stat)+/-9(syst) MeV; it can also be fit with a P-wave Breit-Wigner resonance. Evidence for a similar enhancement is also observed in psi(')-->pK(-)Lambda;+c.c. decays. The analysis is based on samples of 5.8x10(7)J/psi and 1.4x10(7)psi(') decays accumulated in the BES II detector at the Beijing Electron-Positron Collider.
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Bai JZ, Ban Y, Bian JG, Cai X, Chang JF, Chen HF, Chen HS, Chen HX, Chen J, Chen JC, Chen J, Chen ML, Chen YB, Chi SP, Chu YP, Cui XZ, Dai HL, Dai YS, Deng ZY, Dong LY, Du SX, Du ZZ, Fang J, Fang SS, Fu CD, Fu HY, Fu LP, Gao CS, Gao ML, Gao YN, Gong MY, Gong WX, Gu SD, Guo YN, Guo YQ, Guo ZJ, Han SW, Harris FA, He J, He KL, He M, He X, Heng YK, Hu HM, Hu T, Huang GS, Huang L, Huang XP, Ji XB, Jia QY, Jiang CH, Jiang XS, Jin DP, Jin S, Jin Y, Lai YF, Li F, Li G, Li HH, Li J, Li JC, Li QJ, Li RB, Li RY, Li SM, Li W, Li WG, Li XL, Li XQ, Li XS, Liang YF, Liao HB, Liu CX, Liu F, Liu F, Liu HM, Liu JB, Liu JP, Liu RG, Liu Y, Liu ZA, Liu ZX, Lu GR, Lu F, Lu JG, Luo CL, Luo XL, Ma FC, Ma JM, Ma LL, Ma XY, Mao ZP, Meng XC, Mo XH, Nie J, Nie ZD, Olsen SL, Peng HP, Qi ND, Qian CD, Qin H, Qiu JF, Ren ZY, Rong G, Shan LY, Shang L, Shen DL, Shen XY, Sheng HY, Shi F, Shi X, Song LW, Sun HS, Sun SS, Sun YZ, Sun ZJ, Tang X, Tao N, Tian YR, Tong GL, Varner GS, Wang DY, Wang JZ, Wang L, Wang LS, Wang M, Wang M, Wang P, Wang PL, Wang SZ, Wang WF, Wang YF, Wang Z, Wang Z, Wang Z, Wang ZY, Wei CL, Wu N, Wu YM, Xia XM, Xie XX, Xin B, Xu GF, Xu H, Xu Y, Xue ST, Yan ML, Yan WB, Yang F, Yang HX, Yang J, Yang SD, Yang YX, Yi LH, Yi ZY, Ye M, Ye MH, Ye YX, Yu CS, Yu GW, Yuan CZ, Yuan JM, Yuan Y, Yue Q, Zang SL, Zeng Y, Zhang BX, Zhang BY, Zhang CC, Zhang DH, Zhang HY, Zhang J, Zhang JM, Zhang JY, Zhang JW, Zhang LS, Zhang QJ, Zhang SQ, Zhang XM, Zhang XY, Zhang Y, Zhang YJ, Zhang YY, Zhang ZP, Zhang ZQ, Zhao DX, Zhao JB, Zhao JW, Zhao PP, Zhao WR, Zhao XJ, Zhao YB, Zhao ZG, Zheng HQ, Zheng JP, Zheng LS, Zheng ZP, Zhong XC, Zhou BQ, Zhou GM, Zhou L, Zhou NF, Zhu KJ, Zhu QM, Zhu Y, Zhu YC, Zhu YS, Zhu ZA, Zhuang BA, Zou BS. Observation of the decay psi(2S)-->K0SK0L. PHYSICAL REVIEW LETTERS 2004; 92:052001. [PMID: 14995298 DOI: 10.1103/physrevlett.92.052001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2003] [Indexed: 05/24/2023]
Abstract
The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.
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Shi ZJ, Sun DJ, Wang ZJ, Tao ZH, Pan SX, Liu XJ, Zhang SQ, Ou ZY, Zhu SZ, Li QJ, Chang J, Wu RZ, Deng SS, Zheng XQ. A brief introduction to the research achievement on the strategy and technical measures for interrupting the transmission of lymphatic filariasis in China. ZHONGGUO JI SHENG CHONG XUE YU JI SHENG CHONG BING ZA ZHI = CHINESE JOURNAL OF PARASITOLOGY & PARASITIC DISEASES 2003; 19:110-2. [PMID: 12572001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
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Bai JZ, Ban Y, Bian JG, Cai X, Chang JF, Chen HF, Chen HS, Chen J, Chen J, Chen JC, Chen YB, Chi SP, Chu YP, Cui XZ, Dai YM, Dai YS, Dong LY, Du SX, Du ZZ, Dunwoodie W, Fang J, Fang SS, Fu CD, Fu HY, Fu LP, Gao CS, Gao ML, Gao YN, Gong MY, Gong WX, Gu SD, Guo YN, Guo YQ, Guo ZJ, Han SW, Harris FA, He J, He KL, He M, He X, Heng YK, Hong T, Hu HM, Hu T, Huang GS, Huang L, Huang XP, Izen JM, Ji XB, Jiang CH, Jiang XS, Jin DP, Jin S, Jin Y, Jones BD, Ke ZJ, Kong D, Lai YF, Li F, Li G, Li HH, Li J, Li JC, Li K, Li QJ, Li RB, Li RY, Li W, Li WG, Li XQ, Li XS, Liu CF, Liu CX, Liu F, Liu F, Liu HM, Liu JB, Liu JP, Liu RG, Liu Y, Liu ZA, Liu ZX, Lou XC, Lu GR, Lu F, Lu HJ, Lu JG, Lu ZJ, Luo XL, Ma EC, Ma FC, Ma JM, Malchow R, Mao ZP, Meng XC, Mo XH, Nie J, Nie ZD, Olsen SL, Paluselli D, Peng HP, Qi ND, Qian CD, Qiu JF, Rong G, Shen DL, Shen H, Shen XY, Sheng HY, Shi F, Song LW, Sun HS, Sun SS, Sun YZ, Sun ZJ, Tang SQ, Tang X, Tian D, Tian YR, Toki W, Tong GL, Varner GS, Wang J, Wang JZ, Wang L, Wang LS, Wang M, Wang M, Wang P, Wang PL, Wang WF, Wang YF, Wang Z, Wang Z, Wang Z, Wang ZY, Wei CL, Wu N, Xia XM, Xie XX, Xu GF, Xu Y, Xue ST, Yan ML, Yan WB, Yang GA, Yang HX, Yang J, Yang SD, Ye MH, Ye YX, Ying J, Yu CS, Yu GW, Yuan CZ, Yuan JM, Yuan Y, Yue Q, Zang SL, Zeng Y, Zhang BX, Zhang BY, Zhang CC, Zhang DH, Zhang HY, Zhang J, Zhang JM, Zhang JW, Zhang LS, Zhang QJ, Zhang SQ, Zhang XY, Zhang YJ, Zhang Y, Zhang YY, Zhang ZP, Zhao DX, Zhao J, Zhao JW, Zhao PP, Zhao WR, Zhao YB, Zhao ZG, Zheng JP, Zheng LS, Zheng ZP, Zhong XC, Zhou BQ, Zhou GM, Zhou L, Zhou NF, Zhu KJ, Zhu QM, Zhu Y, Zhu YC, Zhu YS, Zhu ZA, Zhuang BA, Zou BS. Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays. PHYSICAL REVIEW LETTERS 2003; 91:022001. [PMID: 12906471 DOI: 10.1103/physrevlett.91.022001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2003] [Indexed: 05/24/2023]
Abstract
We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.
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Li QJ, Janssen LJ. Membrane currents in canine bronchial artery and their regulation by excitatory agonists. Am J Physiol Lung Cell Mol Physiol 2002; 282:L1358-65. [PMID: 12003793 DOI: 10.1152/ajplung.00421.2001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The bronchial vasculature plays an important role in airway physiology and pathophysiology. We investigated the ion currents in canine bronchial smooth muscle cells using patch-clamp techniques. Sustained outward K(+) current evoked by step depolarizations was significantly inhibited by tetraethylamonium (1 and 10 mM) or by charybdotoxin (10(-6) M) but was not significantly affected by 4-aminopyridine (1 or 5 mM), suggesting that it was primarily a Ca(2+)-activated K(+) current. Consistent with this, the K(+) current was markedly increased by raising external Ca(2+) to 4 mM but was decreased by nifedipine (10(-6) M) or by removing external Ca(2+). When K(+) currents were blocked (by Cs(+) in the pipette), step depolarizations evoked transient inward currents with characteristics of L-type Ca(2+) current as follows: 1) activation that was voltage dependent (threshold and maximal at -50 and -10 mV, respectively); 2) inactivation that was time dependent and voltage dependent (voltage causing 50% maximal inactivation of -26 +/- 22 mV); and 3) blockade by nifedipine (10(-6) M). The thromboxane mimetic U-46619 (10(-6) M) caused a marked augmentation of outward K(+) current (as did 10 mM caffeine) lasting only 10-20 s; this was followed by significant suppression of the K(+) current lasting several minutes. Phenylephrine (10(-4) M) also suppressed the K(+) current to a similar degree but did not cause the initial transient augmentation. None of these three agonists elicited inward current of any kind. We conclude that bronchial arterial smooth muscle expresses Ca(2+)-dependent K(+) channels and voltage-dependent Ca(2+) channels and that its excitation does not involve activation of Cl(-) channels.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Animals
- Bronchial Arteries/cytology
- Bronchial Arteries/drug effects
- Bronchial Arteries/physiology
- Caffeine/pharmacology
- Calcium/metabolism
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/metabolism
- Cell Separation
- Dogs
- In Vitro Techniques
- Membrane Potentials/drug effects
- Membrane Potentials/physiology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Patch-Clamp Techniques
- Potassium/metabolism
- Potassium Channel Blockers/pharmacology
- Potassium Channels, Calcium-Activated/drug effects
- Potassium Channels, Calcium-Activated/metabolism
- Vasoconstrictor Agents/pharmacology
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Bai JZ, Ban Y, Bian JG, Chen AD, Chen HF, Chen HS, Chen JC, Chen XD, Chen YB, Cheng BS, Chi SP, Chu YP, Choi JB, Cui XZ, Dai YS, Dong LY, Du ZZ, Dunwoodie W, Fu HY, Fu LP, Gao CS, Gu SD, Guo YN, Guo ZJ, Han SW, Han Y, Harris FA, He J, He JT, He KL, He M, He X, Hong T, Heng YK, Hu GY, Hu HM, Hu QH, Hu T, Huang GS, Huang XP, Huang YZ, Izen JM, Ji XB, Jiang CH, Jin Y, Jones BD, Kang JS, Ke ZJ, Kim HJ, Kim SK, Kim TY, Kong D, Lai YF, Li D, Li HB, Li HH, Li J, Li JC, Li PQ, Li QJ, Li RY, Li W, Li WG, Li XN, Li XQ, Liu B, Liu F, Liu F, Liu HM, Liu J, Liu JP, Liu TR, Liu RG, Liu Y, Liu ZX, Lou XC, Lu GR, Lu F, Lu JG, Lu ZJ, Luo XL, Ma EC, Ma JM, Malchow R, Mao HS, Mao ZP, Meng XC, Mo XH, Nie J, Nie ZD, Olsen SL, Paluselli D, Park H, Qi ND, Qi XR, Qian CD, Qiu JF, Que YK, Rong G, Shao YY, Shen BW, Shen DL, Shen H, Shen XY, Sheng HY, Shi F, Shi HZ, Song XF, Suh JY, Sun HS, Sun LF, Sun YZ, Tang SQ, Toki W, Tong GL, Varner GS, Wang J, Wang JZ, Wang L, Wang LS, Wang P, Wang PL, Wang SM, Wang YY, Wang ZY, Wei CL, Wu N, Xi DM, Xia XM, Xie XX, Xu GF, Xu Y, Xue ST, Yan WB, Yan WG, Yang CM, Yang CY, Yang GA, Yang HX, Yang W, Yang XF, Ye MH, Ye SW, Ye YX, Yu CS, Yu CX, Yu GW, Yuan Y, Zhang BY, Zhang C, Zhang CC, Zhang DH, Zhang HL, Zhang HY, Zhang J, Zhang JW, Zhang L, Zhang LS, Zhang P, Zhang QJ, Zhang SQ, Zhang XY, Zhang YY, Zhang ZP, Zhao DX, Zhao HW, Zhao J, Zhao JW, Zhao M, Zhao PP, Zhao WR, Zhao YB, Zhao ZG, Zheng JP, Zheng LS, Zheng ZP, Zhou BQ, Zhou GM, Zhou L, Zhu KJ, Zhu QM, Zhu YC, Zhu YS, Zhu ZA, Zhuang BA, Zou BS. Measurements of the cross section for e(+)e(-) --> hadrons at center-of-mass energies from 2 to 5 GeV. PHYSICAL REVIEW LETTERS 2002; 88:101802. [PMID: 11909342 DOI: 10.1103/physrevlett.88.101802] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2001] [Indexed: 05/23/2023]
Abstract
We report values of R = sigma(e(+)e(-)-->hadrons)/sigma(e(+)e(-)-->mu(+)mu(-)) for 85 center-of-mass energies between 2 and 5 GeV measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider.
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Li QJ, Ashraf FM, Rana TS, Tuli S, Mai EL, Adler RA, Reviglio VE, O'Brien TP. Long-term survival of allogeneic donor cell-derived corneal epithelium in limbal deficient rabbits. Curr Eye Res 2001; 23:336-45. [PMID: 11910522 DOI: 10.1076/ceyr.23.5.336.5442] [Citation(s) in RCA: 8] [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
PURPOSE To investigate the capability of cultivated allogeneic epithelial stem cells to restore a functional ocular surface in a limbal deficient cornea; to verify the long term survival of epithelial allograft; and to examine the host immune response to heterologous cell transplant in a rabbit model. METHODS Limbal deficiency was established by performing limbectomy on rabbits (n = 100). Corneal epithelial stem cells were obtained from the limbus and replicated in vitro without a supporting layer. The cell (3 x 10(5)) suspension was then transplanted via topical application as eye drops. Animals were divided into allograft, autograft, and control groups. Females were used as recipients and males as donors for the allograft. Corneas were collected at 7, 14, 21, 40 days as well as 2, 3, 7 and 8 months after cell transplantation. Experimental corneas were evaluated by histology, immunofluorescence, immunohistochemistry and Y chromosome analysis. RESULTS A well-differentiated corneal epithelium was recognized at 14 to 40 days after cell transfer overlying an infiltrated corneal stroma. Corneal re-epitheliazation was confirmed in 31 of 36 allograft corneas. No significant immune rejection was noted. Stromal abnormality caused by previous limbal deficiency was mostly resolved three months after the regeneration of corneal epithelium. CONCLUSIONS Transplanted corneal epithelial stem cells were able to differentiate into normal corneal epithelium in vivo without the use of membrane scaffolding. This non-autologous donor cell-derived corneal epithelium survived up to 8 months without immunosuppression and was able to reverse the stromal scarring. Thus, cultivated epithelial stem cells have great potential as an alternative to multiple-surgical procedures in the treatment of limbal deficiency states.
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Li QJ, Ashraf MF, Shen DF, Green WR, Stark WJ, Chan CC, O'Brien TP. The role of apoptosis in the pathogenesis of Fuchs endothelial dystrophy of the cornea. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 2001; 119:1597-604. [PMID: 11709009 DOI: 10.1001/archopht.119.11.1597] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To investigate the potential role of apoptosis in the pathogenesis of Fuchs endothelial dystrophy of the cornea. METHODS Twenty-one corneal buttons from patients with Fuchs dystrophy and 15 control corneas were studied. Apoptosis was assessed by the in situ end-labeling of double-stranded DNA breaks, and by immunohistochemical characterization of cellular markers associated with apoptosis (Fas, FasL, Bcl-2, and Bax). Expression of Bcl-2 and Bax mRNA in the corneal stroma and endothelium was separately analyzed by a semiquantitative reverse transcriptase polymerase chain reaction. Furthermore, cultivated keratocytes generated from diseased corneal buttons and donor rims were exposed to camptothecin, an apoptotic inducer, for 6 and 24 hours. They were then examined for protein and messenger RNA (mRNA) expression of apoptotic regulatory molecules. RESULTS DNA fragmentation was seen in the epithelium, stroma, and endothelium in 6 of 7 corneas with Fuchs dystrophy. A statistically significant difference was identified in the expression of Bax and its mRNA in the stroma, but not in the endothelium of Fuchs dystrophy corneas. Following exposure to camptothecin, keratocytes from patients with Fuchs dystrophy responded with an increased level of Bax and a low level of Bcl-2. This trend was distinctively different from the response of normal keratocytes. CONCLUSIONS The evidence in this study points to a disease-related disturbance in the regulation of apoptosis in Fuchs dystrophy. Our findings suggest that excessive apoptosis may be an important mechanism in the pathogenesis of Fuchs dystrophy.
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Zhou AM, Li QJ, Chen XL, Li WB. [Increase in amount and affinity of adenosine receptor in rat hippocampal cellular membranes induced by cerebral ischemic preconditioning and its protective effects on the neurons]. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2001; 53:265-9. [PMID: 11930203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
To determine the role of adenosine (ADO) receptor in the induction of brain ischemic tolerance, changes in amount and affinity of ADO receptor in rat hippocampal cellular membranes after transient ischemia were investigated using radioligand binding method. Ischemia for 6 min resulted in an apparent delayed neuron death (DND) in the hippocampus, while ischemia for 3 min did not cause DND. Preconditioning ischemia for 3 min could apparently decrease DND caused by ischemia for 6 min after the preconditioning at an interval of 1 d reperfusion. In correspondence with the histological changes, ischemia for 3 min caused an increase in amount and affinity of ADO receptor at 1 or 3 days after reperfusion (P<0.05 vs sham), while ischemia for 6 min caused a decrease in the amount and an increase in the affinity (P<0.05 vs sham). Compared with the rats suffering from ischemia for 6 min followed by reperfusion for 4 h and 1 or 3 d, the amount and affinity of ADO receptor increased in rats with preconditioning ischemia (3 min) 1 d before the ischemia for 6 min. The above results showed that cerebral ischemic preconditioning increased the amount and affinity of ADO receptor in hippocampal cellular membranes, and resisted the down-regulating of ADO receptor caused by severe ischemia, suggesting an important role of the increase in amount and affinity of ADO receptor in the induction of brain ischemic tolerance.
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O'Brien TP, Li QJ, Sauerburger F, Reviglio VE, Rana T, Ashraf MF. The role of matrix metalloproteinases in ulcerative keratolysis associated with perioperative diclofenac use. Ophthalmology 2001; 108:656-9. [PMID: 11297478 DOI: 10.1016/s0161-6420(00)00590-x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
OBJECTIVE To investigate the role of matrix metalloproteinases (MMPs) in the pathogenesis of ulcerative keratolysis associated with topical use of generic diclofenac preoperatively and postoperatively. To characterize the inflammatory response of the cornea in this case of ulcerative keratolysis. DESIGN Case report with clinicopathologic correlation. MAIN OUTCOME MEASURES Corneal culture for microbial growth. Clinical and histopathologic examinations including routine histolopathologic, immunofluorescent, and immunohistochemical studies. RESULTS Microscopic examination of the corneal button disclosed fibrinous material with neutrophils and mononuclear inflammatory cells. The corneal epithelial basement membrane was irregularly thickened and patchy. Immunohistochemical staining detected weak staining of MMP-1 and a strong presence of MMP-8 in the epithelium. MMP-8 and 9 were also present in areas of leukocytic infiltration. MMP-2 appeared in a few stromal cells. Macrophages and leukocytes were the predominant infiltrating cells. CONCLUSIONS A nonspecific inflammatory response occurred in this case of ulcerative keratolysis. Corneal epithelial cells are capable of secreting MMP-1 and 8 and may participate in the stromal degradation and repair process of the ulcerative keratolysis associated with topical nonsteroidol antiinflammatory use.
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Li QJ, Xu ZF, Kress WJ, Xia YM, Zhang L, Deng XB, Gao JY, Bai ZL. Pollination: flexible style that encourages outcrossing. Nature 2001; 410:432. [PMID: 11260703 DOI: 10.1038/35068635] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Jiang Q, Ewing JR, Zhang ZG, Zhang RL, Hu J, Divine GW, Arniego P, Li QJ, Chopp M. Magnetization transfer MRI: application to treatment of middle cerebral artery occlusion in rat. J Magn Reson Imaging 2001; 13:178-84. [PMID: 11169822 DOI: 10.1002/1522-2586(200102)13:2<178::aid-jmri1027>3.0.co;2-d] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The temporal profiles of MRI parameters which use quantitative estimates of magnetization transfer were measured in 22 male Wistar rats subjected to middle cerebral artery occlusion, with and without therapeutic intervention with an anti-ICAM-1 monoclonal antibody. Two measures were used: the value of a magnetization transfer-related parameter in a predetermined region of interest, and the area of damage, as measured by changes in this parameter. In both groups, the value and area of damage of the inverse of the apparent forward transfer rate for magnetization transfer (1/k(fa)) significantly increased from the preischemic values (P < 0.05), as did T1 under an off-resonance partial saturation of the macromolecular pool (T1sat), and T1 (P < 0.05). Moreover, the increase in the value and total area of damage, as measured by 1/k(fa), T1, and T1sat in the treated group, was smaller compared to that of the untreated group, with significant differences detected between groups at 5, 24, and 48 hours. Our data suggest that a quantitative measure of MT may provide a sensitive and early method to detect the efficacy of therapeutic intervention in experimental stroke.
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Zeng JB, Li WB, Li QJ, Chen XL, Zhou AM, Ling YL. [MK-801 attenuates NOS expression and NO content in the spinal cord of rats with inflammatory pain]. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2001; 53:55-60. [PMID: 11354799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Abstract
Using NADPH-d histochemistry, the effect of NMDA receptor antagonist MK-801 on the expression of nitric oxide synthase (NOS) in the dorsal horn of the spinal cord was investigated during inflammatory pain and hyperalgesia induced by injection of formalin into the right hind paw. The course of the change in the nitric oxide (NO) content of the lumbar intumescence was observed by measuring the ratio of nitrate/nitrite (NO3T/NO2T) and also the end product of NO. The results showed that the NOS expression and NO contents significantly increased 24 h after formalin injection, which were substantially inhibited when MK-801 was intrathecally injected 15 min prior to formalin injection or 12 h after formalin injection. The results suggest that the increases in the expression of NOS and NO contents in the dorsal horn of the spinal cord are mediated by activation of NMDA receptors during pain and hyperalgesia after formalin injection.
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Li QJ, Vaingankar S, Sladek FM, Martins-Green M. Novel nuclear target for thrombin: activation of the Elk1 transcription factor leads to chemokine gene expression. Blood 2000; 96:3696-706. [PMID: 11090049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
Thrombin is primarily known for its role in homeostasis and thrombosis. However, this enzyme also plays important roles in wound healing and pathologic situations such as inflammation and tumorigenesis. Among the molecules stimulated by thrombin in these latter processes are the stress response proteins, chemokines. Chemokines are also known for their roles in inflammatory responses and tumor development. These correlative observations strongly suggest that chemokines may be mediators of some of thrombin's functions in these processes. Elucidation of the molecular mechanisms of stimulation of chemokines by thrombin may help to unravel the ways in which their expression can be modulated. Up-regulation of the chemokine 9E3/cCAF by thrombin occurs via its proteolytically activated receptor with subsequent transactivation of the epidermal growth factor receptor tyrosine kinase. This study shows that stimulation by thrombin very rapidly activates this chemokine at the transcriptional level, that 2 Elk1 binding elements located between -534 and -483 bp of the promoter are major thrombin response elements, that activation occurs via the Elk1 transcription factor, and that the latter is directly activated by MEK1/ERK2. The common occurrence of Elk1 binding domains in the promoters of immediate early response genes suggests that it may be characteristically involved in gene activation by stress-inducing agents. (Blood. 2000;96:3696-3706)
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Li QJ, Lu S, Ye RD, Martins-Green M. Isolation and characterization of a new chemokine receptor gene, the putative chicken CXCR1. Gene 2000; 257:307-17. [PMID: 11080597 DOI: 10.1016/s0378-1119(00)00385-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study delineates the isolation and characterization of a novel chemokine receptor gene, the putative chicken CXC receptor 1 (cCXCR1). Using a human CXCR1 probe, we isolated several positive clones from a chicken genomic library. One of the clones contained a fragment of approximately 5000bp that hybridized strongly with the hCXCR1 probe. This fragment was sequenced and subjected to a variety of computer analyses. The open reading frame for this gene predicts a seven transmembrane domain protein with all the characteristics of a chemokine receptor and with 67% sequence homology to hCXCR1, 65% to hCXCR2 and also with considerable sequence homology to other human chemokine receptors such as hCXCR4 (50%), hCCR2 (49%) and hCCR1 (49%). However, the homology to a previously isolated potential G-protein-coupled receptor for chickens (AvCRL1) is only 47%. Using 5' RACE, two transcription initiation sites were identified suggesting the potential for the expression of two protein isoforms (I and II) in vivo. The promoter for the putative cCXCR1 contains a variety of consensus transcription factor binding elements that can potentially be involved in the expression of this chicken receptor upon stimulation by stress-inducing agents. RT-PCR analysis was used to determine the pattern of expression of the larger isoform (I) of this receptor in a variety of tissues. This form of the receptor is expressed primarily in the organs of the gastrointestinal tract, tissues that are frequently exposed to stress-inducing agents, but not in the central nervous system, tissues that are protected from insult by the blood barrier. Using the same RT-PCR approach we show that stress-inducing agents, such as 'first-hand' and 'second-hand' cigarette smoke components, tumor promoters and thrombin, differentially stimulate the expression of the isoform I in primary fibroblasts. Thrombin is an enzyme that plays many important roles in thrombosis, angiogenesis and wound healing and exposure to both cigarette smokes and/or to tumor promoters can lead to tumorigenesis. Therefore, upregulation of chemokines and their receptors by stress-inducing agents can confer highly regulated modulation of cellular responses to traumatic and pathological situations.
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Wang RP, Lin Q, Li QJ, Lu GW. [Effect of sodium nitroprusside on the spontaneous and induced responses of rat spinal cord dorsal horn neurons]. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2000; 52:407-10. [PMID: 11941396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The present study was performed on anesthetized and paralyzed Wistar rats. Extracellular recordings were made from the lumbar enlargement of the spinal cord using carbon filament electrodes. NO donor sodium nitroprusside (SNP) was locally microdialyzed to the spinal cord, and effects of NO on spontaneous response and the responses induced by mechanical stimulation of the hind-foot were observed. After dialyzing for 10~20 min, SNP at a concentration of 1 micromol/L increased the induced responses to innocuous mechanical stimulation and decreased those to noxoius mechanical stimulation. The induced responses to both innocuous and noxious mechanical stimulations were all decreased after dialyzing the same dose of SNP for 20~30 min. The decrease was shown within 7~15 min dialysis when SNP was used at a concentration of 20 micromol/L. SNP at both concentrations of 1 and 20 micromol/L increased spontaneous spikes of the recorded spinal units. These effects were shown preferentially in deep units. The data suggest that in the deeper neurons of the spinal cord NO of different concentrations has different effects on transmission of nociceptive and nonnociceptive signals induced by mechanical stimulation, and No is involved in the antinociception in spinal neurons and facilitates their spontaneous activity.
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Guo H, Li QJ, Lu GW. Effects of ketamine on neuronal activity of the spinal dorsal horn in rats with unilateral hindpaw inflammation. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2000; 52:351-3. [PMID: 11951122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
A total of 32 units were extracellularly recorded from the spinal dorsal horn of rats. Unitary discharges evoked by stimulation of A and C fiber in ipsilateral lateral and medial plantar nerve were increased after carrageenan injection to the plantar area. The evoked responses to both A and C fiber were significantly decreased or even disappeared after administration of ketamine. The windup phenomenon was observed in neurons located deeply in the dorsal horn following carrageenan injection and was significantly suppressed or abolished after ketamine administration. The results above show NMDA receptor appears to be involved in the increase of excitability and the development of windup phenomenon in the spinal cord dorsal horn associated with carrageenan induced inflammation.
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Wang RP, Li QJ, Lu GW. [Interaction between pelvic and pudendal afferent inputs in lumbar-sacral spinal cord in rats]. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 2000; 52:115-8. [PMID: 11961579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Time-dependent inhibition is one of the means to study the interactions between peripheral inputs. The present study was performed on anesthetized and paralyzed Wistar rats using the technique of conditioning-testing stimulation. Electric stimulation (1.5 3 folds of the threshold intensity) was given to pelvic and pudendal nerves. Extracellular recordings were made from convergent neurons at L(6)-S(1) segments of the spinal dorsal horn. Stimulus intervals between conditioning and testing stimulation were measured when a half of the testing responses were inhibited by conditioning responses or the inhibition just began to occur. The time-dependent inhibition was seen in neurons situated deeper than 300 m beneath the dorsal surface of the spinal cord, and not in more superficial neurons. The inhibition intervals were in the range of 1 360 ms and became longer when conditioning stimulation was given to the pelvic nerve. The inhibition intervals were 1 3 ms in superficial neurons (<300 micrometer) and no apparent time-dependent inhibition occurred. The inhibition in deeper neurons was partially reduced by cold block conducted at segments C(5-6) and the blockage was more significant when conditioning stimulation was applied to the pelvic nerve. These findings suggest that the inputs from the pelvic and pudendal nerves may converge on single neurons at deeper lumbosacral dorsal horn and the pudendal nerve induced responses are more likely to be inhibited in these neurons, which may be further strengthened by superspinal structures.
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Li QJ, Song HP. [Screening of all types of alleles of (A-C)n dinucleotide tandem repeat sequence of aldose reductase gene]. HUNAN YI KE DA XUE XUE BAO = HUNAN YIKE DAXUE XUEBAO = BULLETIN OF HUNAN MEDICAL UNIVERSITY 2000; 25:9-11. [PMID: 12212264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
The screening method of seven alleles (Z-6, Z-4, Z-2, Z, Z + 2, Z + 4 and Z + 6) in the (A-C)n dinucleotide tandem repeat sequence was studied. These alleles constitute a microsatellite DNA marker upstream of the transcription initiation site on the aldose reductase gene. At first, genoimic DNAs were isolated from leucocyte pellets, and the region containing the dinucleotide repeats was amplified by PCR with a pair of amplification primers that flanked 132-144 bp region. Then, the PCR products of the DNA samples whose alleles belonged to homozygotes were selected, purified, and sequenced directly in order to find out the types of alleles. Finally, using Z-2 allele as a marker, the samples containing Z-2 allele were detected by 12% fromamide-urea gel electrophoresis together with silver-staining. This method is simple, quick and accurate. It facilitates the screening of a large number of samples and is also suitable for identification of other dinucleotide tandem repeat sequences.
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Li QJ, Li WB, Zeng JB, Wang HG. [Effects of L-NNA on postsynaptically evoked potential of oculomotoneurons in cats]. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 1999; 51:623-9. [PMID: 11498931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
The present study was performed to explore the effect of endogenous nitric oxide (NO) on synaptic transmission between neurons located in Forel's field H (FFH) and vertical oculomotoneurons (OMNs) innervating the inferior oblique (IO) muscle in cats. The amplitude of monosynaptic excitatory field potential in the IO OMNs pool induced by stimulating FFH began to decrease gradually 2-3 min after intracarotid administration of L-NNA, an NO synthase inhibitor, reached its minimum by 6-10 min, and was followed by a slow recovery. This effect of L-NNA could be prevented by pre-administration of NO precursor L-arginine, without changing the field potential by itself. The results suggest that there is an endogenous NO release in the oculomotor nuclear, which can potentiate synaptic transmission between FFH neurons and OMNs.
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Li QJ, Pazdera TM, Minden JS. Drosophila embryonic pattern repair: how embryos respond to cyclin E-induced ectopic division. Development 1999; 126:2299-307. [PMID: 10207153 DOI: 10.1242/dev.126.10.2299] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Drosophila melanogaster embryo ordinarily undergoes thirteen cycles of rapid syncytial division followed by three rounds of cellular division for most cells. Strict regulation of the number of divisions is believed to be essential for normal patterning and development. To determine how the embryo responds to hyperplastic growth, we have examined epidermal development in embryos that experience additional rounds of mitosis as the result of ectopic Cyclin E expression. We observed that the cell density in the epidermis nearly doubled within 1 hour of Cyclin E induction. The spacing and width of the ENGRAILED and wingless stripes was unchanged, but the cell density within the stripes was increased. By 4 hours after Cyclin E induction, the cell density had returned to almost normal values. The embryos developed, albeit more slowly, to produce viable larvae and adults. The excess cells were removed by apoptosis in a reaper-dependent fashion as evidenced by increased reaper expression. Embryos lacking cell death in the abdomen exhibited changes in ENGRAILED expression. In addition, germband retraction and dorsal closure were slower than normal. Ectopic Cyclin E expression in cell-death-deficient embryos exacerbated the germband retraction and ENGRAILED-expression defects.
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Sun XL, Jayaram HN, Gharehbaghi K, Li QJ, Xiao X, Antony AC. Modulation of the cytotoxicity of 3'-azido-3'-deoxythymidine and methotrexate after transduction of folate receptor cDNA into human cervical carcinoma: identification of a correlation between folate receptor expression and thymidine kinase activity. Cancer Res 1999; 59:940-6. [PMID: 10029088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Cervical carcinoma is an AIDS-defining illness. The expression of folate receptors (FRs) in cervical carcinoma (HeLa-IU1) cells was modulated by stable transduction of FR cDNA encapsidated in recombinant adeno-associated virus-2 in the sense and antisense orientation (sense and antisense cells, respectively). Although sense cells proliferated slower than antisense or untransduced cells in vivo and in vitro in 2% (but not 10%) FCS, [methyl-3H]thymidine incorporation into DNA was significantly increased in sense cells in 10% serum; therefore, the basis for this discrepancy was investigated. The activity of thymidine kinase (TK) was subsequently directly correlated with the extent of FR expression in single cell-derived clones of transduced cells. This elevated TK activity was not a result of recruitment of the salvage pathway based on the presence of adequate dTTP pools, normal thymidylate synthase (TS) activity, persistence of increased thymidine incorporation despite the exogenous provision of excess 5,10-methylene-tetrahydrofolate, and documentation of adequate folates in sense cells. The increase in TK activity conferred significant biological properties to sense cells (but not antisense or untransduced cells) as demonstrated by augmented phosphorylation of 3'-azido-3'-deoxythymidine (AZT) and concomitantly greater sensitivity to the cytotoxic effects of AZT. Conversely, sense cells were highly resistant to methotrexate, but this was reversed by the addition of AZT. The direct correlation of FR expression and TK activity indicates a previously unrecognized consequence of FR overexpression.
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Vermeulen NP, Commandeur JN, Groot EJ, Wormhoudt LW, Ramnatshing S, Li QJ, Brakenhoff JP. Toxicity of fotemustine in rat hepatocytes and mechanism-based protection against it. Chem Biol Interact 1998; 110:139-58. [PMID: 9609383 DOI: 10.1016/s0009-2797(98)00004-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Fotemustine is a relatively novel DNA-alkylating 2-chloroethyl-substituted N-nitrosourea (CENU) drug, clinically used for the treatment of disseminated malignant melanoma in different visceral and non-visceral tissues. Thrombocytopenia has been observed in patients treated with fotemustine and liver and renal toxicities as well. In this study, firstly the metabolism of fotemustine was investigated in vitro and secondly the undesired cytotoxicity of fotemustine as well as different ways of protection against it. In rat hepatocytes, chosen as a model system, fotemustine was shown to cause lactate dehydrogenase (LDH) leakage, glutathione (GSH) depletion, GSSG-formation and lipid peroxidation (LPO). A reactive metabolite, DEP-isocyanate, is most likely responsible for these undesired cytotoxic effects. Based on the observed cytotoxicity mechanisms, chemoprotection with several sulfhydryl-containing nucleophiles and antioxidants was investigated. The sulfhydryl nucleophiles; GSH, N-acetyl-L-cysteine (NAC) and glutathione isopropylester (GSH-IP) protected almost completely against fotemustine-induced LDH-leakage and LPO. NAC and GSH protected partly against fotemustine-induced GSH-depletion. The antioxidant, vitamin E protected completely against fotemustine-induced LPO, but only partly against fotemustine-induced LDH-leakage and not against GSH-depletion. Ebselen, a peroxidase-mimetic organoselenium compound, did not show protective effects against the cytotoxicity of fotemustine, possibly because GSH is required for the bioactivation of ebselen. It is concluded that co-administration of sulfhydryl nucleophiles, in particular NAC and GSH-IP, possibly in combination with antioxidants, such as vitamin E, are effective against the toxicity of fotemustine in vitro. It might, therefore, be worthwhile to investigate the cytoprotective potency of these agents against undesired toxicities of fotemustine in vivo as well.
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Li QJ, Li WB, Chen XL. [Monosynaptic transmission between mesodiencephalic neurons and motoneurons innervating extraocular inferior oblique muscle in cats]. SHENG LI XUE BAO : [ACTA PHYSIOLOGICA SINICA] 1998; 50:49-54. [PMID: 11324517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
The present study was performed to define the synaptic connection of neurons located within the dorsal mesodiencephalic junction with motoneurons innervating extraocular inferior oblique muscle (IOMN) using electrophysiologic, especially spike-triggered averaging technique in cats. In response to electric shocks applied to the medial part of Forel's field H (FFH) located in the mesodiencephalic junction, excitatory monosynaptic field potentials were observed in the IOMN pool. Moreover, while the spontaneous discharges of FFH neurons were used to trigger the activity of IOMN pool from which the induced potential changes were averaged, an excitatory monosynaptic field potential was also obtained. These results indicate that the mesodiencephalic neurons connect with and activate the IOMNs monosynaptically, and drive vertical eye movements via such a way.
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