The cascade reaction of tyrosine phosphorylation provides an attractive mechanism to regulate the metabolism and growth of normal and transformed cells. Thus, considerable effort has been made to identify the cellular...The cascade reaction of tyrosine phosphorylation provides an attractive mechanism to regulate the metabolism and growth of normal and transformed cells. Thus, considerable effort has been made to identify the cellular substrates of the tyrosine kinases. In this work, the activity of the Insulin receptor tyrosine kinase and endogenous substrate in transformed lymphocytes were studied. Purified human T lymphocytes incubated with phytohemagglutinin (PHA) for 72 hours served as transformed cells, when labeled with [32P] - orthophosphate it appeared that the insulin-dependent protein kinase activity in the transformed cells increased 9- fold. In search for the physiologically significant substrates by using polyclonal antiphosphotyrosine antibody to immunoprecipitate phosphotyrosine-containing proteins that produced in the intact cell during insulin stimulation, a protein with molecular weight of 45kDa as identified and designated as PP45, which occurred during the 5 minutes response of lymphocytes to insulin.展开更多
Objective: To observe the specific binding of [￣3H] histamine on the membrane fraction of guinea pig myocardium. Methods: The isolated guinea Pig heart was homogenized and membrane fraction of myocardium was incubate...Objective: To observe the specific binding of [￣3H] histamine on the membrane fraction of guinea pig myocardium. Methods: The isolated guinea Pig heart was homogenized and membrane fraction of myocardium was incubated with [￣3H] histamine for 30 min at 37 ℃ The incubation was ended by rapid filtration over glass fiber filter and radioactivity was measured by liquid scintillation spectrometry. Results : Chemical sympathectomy induced by 6OHDA decreased the specific binding of [￣3H] histamine to 77. 3% and 80. 1% of the control values when the concentrations of [￣3H] histamine were 0 . 5 and 1 nmol/ L respectively. In the presence of (R)-α-methylhistamine (1 μmol/L), the binding of [￣3H] histamine was reduced by 35. 9% or 39. 5%. In the 6-hydroxydopamine treated membrane fraction, (R)-α-methylhistarnine only slightly inhibrted the specific binding of [￣3H] histmaine by 6. 8% and 11. 5% which were dramatically less than those depressed by (R)-α-methylhistamine in normal membrane fractions. Conclusion : The results indicate that following chemical sympathectomy, some presynaptic binding sites of [￣3H]histamine located on sympathetic nerve terminals are lost . which could bind (R)-α-methylhistamine and might be H_3-subtype of histamine receptors.展开更多
The use of a metallo cavitand for the selective sequestration of n-alkanes from their mixtures with isooctane is described.Competition experiments and NMR spectroscopy are used to show the preference of a water-solubl...The use of a metallo cavitand for the selective sequestration of n-alkanes from their mixtures with isooctane is described.Competition experiments and NMR spectroscopy are used to show the preference of a water-soluble cavitand host for vips that are hydro-phobic and have narrow or flat shapes.The host showed selectivity for trans 1,4-dimethylcyclohexane over the cis-isomers.The sep-arations of n-alkanes from isooctane by gas/liquid adsorption and a liquid/liquid extraction are detailed.展开更多
文摘The cascade reaction of tyrosine phosphorylation provides an attractive mechanism to regulate the metabolism and growth of normal and transformed cells. Thus, considerable effort has been made to identify the cellular substrates of the tyrosine kinases. In this work, the activity of the Insulin receptor tyrosine kinase and endogenous substrate in transformed lymphocytes were studied. Purified human T lymphocytes incubated with phytohemagglutinin (PHA) for 72 hours served as transformed cells, when labeled with [32P] - orthophosphate it appeared that the insulin-dependent protein kinase activity in the transformed cells increased 9- fold. In search for the physiologically significant substrates by using polyclonal antiphosphotyrosine antibody to immunoprecipitate phosphotyrosine-containing proteins that produced in the intact cell during insulin stimulation, a protein with molecular weight of 45kDa as identified and designated as PP45, which occurred during the 5 minutes response of lymphocytes to insulin.
文摘Objective: To observe the specific binding of [￣3H] histamine on the membrane fraction of guinea pig myocardium. Methods: The isolated guinea Pig heart was homogenized and membrane fraction of myocardium was incubated with [￣3H] histamine for 30 min at 37 ℃ The incubation was ended by rapid filtration over glass fiber filter and radioactivity was measured by liquid scintillation spectrometry. Results : Chemical sympathectomy induced by 6OHDA decreased the specific binding of [￣3H] histamine to 77. 3% and 80. 1% of the control values when the concentrations of [￣3H] histamine were 0 . 5 and 1 nmol/ L respectively. In the presence of (R)-α-methylhistamine (1 μmol/L), the binding of [￣3H] histamine was reduced by 35. 9% or 39. 5%. In the 6-hydroxydopamine treated membrane fraction, (R)-α-methylhistarnine only slightly inhibrted the specific binding of [￣3H] histmaine by 6. 8% and 11. 5% which were dramatically less than those depressed by (R)-α-methylhistamine in normal membrane fractions. Conclusion : The results indicate that following chemical sympathectomy, some presynaptic binding sites of [￣3H]histamine located on sympathetic nerve terminals are lost . which could bind (R)-α-methylhistamine and might be H_3-subtype of histamine receptors.
基金supported as the Key Medical Research Project for SARS Prevention sponsored by the Ministry of Science and Technology of China and by Guangdong Province
基金the National Natural Science Foundation of China(Nos.21801164 and 22071144)Shanghai University(N.13-G210-20-201).Dr.Yang Yu thanks the Program for Professor of Special Appointment(Dongfang Scholarship)of the Shanghai Education Committee.
文摘The use of a metallo cavitand for the selective sequestration of n-alkanes from their mixtures with isooctane is described.Competition experiments and NMR spectroscopy are used to show the preference of a water-soluble cavitand host for vips that are hydro-phobic and have narrow or flat shapes.The host showed selectivity for trans 1,4-dimethylcyclohexane over the cis-isomers.The sep-arations of n-alkanes from isooctane by gas/liquid adsorption and a liquid/liquid extraction are detailed.
