Values of the second thermodynamic dissociation constant pK2 of the protonated form of monosodium 1,4-piperazinediethanesulfonate (PIPES) have been determined at twelve different temperatures in the temperature range ...Values of the second thermodynamic dissociation constant pK2 of the protonated form of monosodium 1,4-piperazinediethanesulfonate (PIPES) have been determined at twelve different temperatures in the temperature range from (278.15 to 328.15) K including the body temperature 310.15 K by measurement of the electromotive-force for cells without liquid junction of the type: Pt (s), H2 (g), 101.325 kPa|Na-PIPES (m1) + Na 2-PIPES (m2) + NaCl (m3)|AgCl (s), Ag (s), where m1, m2 and m3 indicate the molalities of the corresponding species at 1 atm = 101.325 kPa in SI units. The pK2 values for the dissociation of Na-PIPES are represented by the equation: pK2 = -1303.76/T + 48.369 - 6.46889 lnT with an uncertainty of ± 0.001. The values of pK2 for Na-PIPES were found to be 7.1399 ± 0.0004 at 298.15 K and 7.0512 ± 0.0004 at 310.15 K, respectively, and indicate that this buffer would be useful as pH standard in the range of physiological application. Standard thermodynamic quantities for the acidic dissociation process of Na-PIPES have been derived from the temperature coefficients of the pK2. These values are compared with those of structurally related N-substituted PIPERAZINE and TAURINE at 298.15 K.展开更多
The second acidic dissociation constants of protonated piperazine-N,N′-bis-2-hydroxypropane-sulfonic acid (POPSO sesquisodium salt) have been determined at 12 different temperatures from (278.15 to 328.15) K includin...The second acidic dissociation constants of protonated piperazine-N,N′-bis-2-hydroxypropane-sulfonic acid (POPSO sesquisodium salt) have been determined at 12 different temperatures from (278.15 to 328.15) K including 310.15 K. Electromotive-force measurement technique was used employing hydrogen-silver chloride cells without liquid junction. The results of pK2 are given by the equation: pK2 = -1041.77/T + 51.0459 - 6.97646lnT. The uncertainty of the fit is ±0.0008. At 289.15 K, pK2 = 7.8029;whereas, at 310.15 K (body temperature), pK2 = 7.6862. Thus, the buffer solutions of POPSO and its sodium salt are useful for pH control in the physiological pH region of (7.0 to 8.5). The changes of Gibbs free energy (G°), enthalpy (H°), entropy (S°) and heat capacity Cp° were computed from the temperature derivative of the pK2 for the dissociation of the zwitterionic acid POPSO±-3 = POPSO-4 + H+ in the standard state. At 298.15 K, these results are compared with those of similar components, which are the derivatives of the parent compounds TAURINE, PIPERAZINE and MORPHOLINE.展开更多
AIM： TO study the implication of prokineticin 1 （PKI/EGVEGF） and prokineticin 2 （PK2/13v8） in hepatocellular carcinoma angiogenesis.METHODS： The gene induction of PK1/EG-VEGF and PK2/Bv8 was investigated in 10 n...AIM： TO study the implication of prokineticin 1 （PKI/EGVEGF） and prokineticin 2 （PK2/13v8） in hepatocellular carcinoma angiogenesis.METHODS： The gene induction of PK1/EG-VEGF and PK2/Bv8 was investigated in 10 normal, 28 fibrotic and 28 tumoral livers by using real time PCR. Their expression was compared to the expression of VEGF （an angiogenesis marker）, vWF （an endothelial cell marker） and to CD68 （a monocyte/macrophage marker）. Furthermore, the rnRNA levels of PK1/EG-VEGF, PK2/Bv8, prokineticin receptor 1 and 2 were evaluated by real time PCR in isolated liver cell populations. Finally, PK2/Bv8 protein was detected in normal liver paraffin sections and in isolated liver cells by immunohistochernistry and immunocytochemistry.RESULTS： PK2/Bv8 mRNA but not PK1/EG-VEGF was expressed in all types of normal liver samples examined. In the context of liver tumor development, we reported that PK2/13v8 correlates only with CD68 and showed a significant decrease in expression as the pathology evolves towards cancer. Whereas, VEGF and vWF mRNA were significantly upregulated in both fibrosis and HCC,as expected. In addition, out of all isolated liver cells examined, only Kupffer cells （liver resident macrophages） express significant levels of PK2/Bv8 and its receptors, prokineticin receptor 1 and 2.CONCLUSION： In normal liver PK2/Bv8 and its receptors were specifically expressed by Kupffer cells. PK2/Bv8 expression decreased as the liver evolves towards cancer and did not correlate with HCC angiogenesis.展开更多
文摘Values of the second thermodynamic dissociation constant pK2 of the protonated form of monosodium 1,4-piperazinediethanesulfonate (PIPES) have been determined at twelve different temperatures in the temperature range from (278.15 to 328.15) K including the body temperature 310.15 K by measurement of the electromotive-force for cells without liquid junction of the type: Pt (s), H2 (g), 101.325 kPa|Na-PIPES (m1) + Na 2-PIPES (m2) + NaCl (m3)|AgCl (s), Ag (s), where m1, m2 and m3 indicate the molalities of the corresponding species at 1 atm = 101.325 kPa in SI units. The pK2 values for the dissociation of Na-PIPES are represented by the equation: pK2 = -1303.76/T + 48.369 - 6.46889 lnT with an uncertainty of ± 0.001. The values of pK2 for Na-PIPES were found to be 7.1399 ± 0.0004 at 298.15 K and 7.0512 ± 0.0004 at 310.15 K, respectively, and indicate that this buffer would be useful as pH standard in the range of physiological application. Standard thermodynamic quantities for the acidic dissociation process of Na-PIPES have been derived from the temperature coefficients of the pK2. These values are compared with those of structurally related N-substituted PIPERAZINE and TAURINE at 298.15 K.
文摘The second acidic dissociation constants of protonated piperazine-N,N′-bis-2-hydroxypropane-sulfonic acid (POPSO sesquisodium salt) have been determined at 12 different temperatures from (278.15 to 328.15) K including 310.15 K. Electromotive-force measurement technique was used employing hydrogen-silver chloride cells without liquid junction. The results of pK2 are given by the equation: pK2 = -1041.77/T + 51.0459 - 6.97646lnT. The uncertainty of the fit is ±0.0008. At 289.15 K, pK2 = 7.8029;whereas, at 310.15 K (body temperature), pK2 = 7.6862. Thus, the buffer solutions of POPSO and its sodium salt are useful for pH control in the physiological pH region of (7.0 to 8.5). The changes of Gibbs free energy (G°), enthalpy (H°), entropy (S°) and heat capacity Cp° were computed from the temperature derivative of the pK2 for the dissociation of the zwitterionic acid POPSO±-3 = POPSO-4 + H+ in the standard state. At 298.15 K, these results are compared with those of similar components, which are the derivatives of the parent compounds TAURINE, PIPERAZINE and MORPHOLINE.
基金INSERM,the Ministère de l'Education Nationale de la Recherche et de la Technologie,the Région Bretagne.No.2079
文摘AIM： TO study the implication of prokineticin 1 （PKI/EGVEGF） and prokineticin 2 （PK2/13v8） in hepatocellular carcinoma angiogenesis.METHODS： The gene induction of PK1/EG-VEGF and PK2/Bv8 was investigated in 10 normal, 28 fibrotic and 28 tumoral livers by using real time PCR. Their expression was compared to the expression of VEGF （an angiogenesis marker）, vWF （an endothelial cell marker） and to CD68 （a monocyte/macrophage marker）. Furthermore, the rnRNA levels of PK1/EG-VEGF, PK2/Bv8, prokineticin receptor 1 and 2 were evaluated by real time PCR in isolated liver cell populations. Finally, PK2/Bv8 protein was detected in normal liver paraffin sections and in isolated liver cells by immunohistochernistry and immunocytochemistry.RESULTS： PK2/Bv8 mRNA but not PK1/EG-VEGF was expressed in all types of normal liver samples examined. In the context of liver tumor development, we reported that PK2/13v8 correlates only with CD68 and showed a significant decrease in expression as the pathology evolves towards cancer. Whereas, VEGF and vWF mRNA were significantly upregulated in both fibrosis and HCC,as expected. In addition, out of all isolated liver cells examined, only Kupffer cells （liver resident macrophages） express significant levels of PK2/Bv8 and its receptors, prokineticin receptor 1 and 2.CONCLUSION： In normal liver PK2/Bv8 and its receptors were specifically expressed by Kupffer cells. PK2/Bv8 expression decreased as the liver evolves towards cancer and did not correlate with HCC angiogenesis.
