Mammalian cell totipotency is a subject that has fascinated scientists for generations. A long lasting question whether some of the somatic cells retains totipotency was answered by the cloning of Dolly at the end of ...Mammalian cell totipotency is a subject that has fascinated scientists for generations. A long lasting question whether some of the somatic cells retains totipotency was answered by the cloning of Dolly at the end of the 20th century. The dawn of the 218t has brought forward great expectations in harnessing the power of totipotentcy in medicine. Through stem cell biology, it is possible to generate any parts of the human body by stem cell engineering. Considerable resources will be devoted to harness the untapped potentials of stem cells in the foreseeable future which may transform medicine as we know today. At the molecular level, totipotency has been linked to a singular transcription factor and its expression appears to define whether a cell should be totipotent. Named Oct4, it can activate or repress the expression of various genes. Curiously, very little is known about Oct4 beyond its ability to regulate gene expression. The mechanism by which Oct4 specifies totipotency remains entirely unresolved. In this review, we summarizere the structure and function of Oct4 and address to Oct4 function in maintaining totipotency or pluripotency of embryonic stem cels.展开更多
Angiotensin Ⅱ has been reported to have an important role in the fibrotic response to tissue injuries:it stimulates the proliferation of fibroblasts via activation of angiotensin Ⅱ（AT1) receptor.In the present stud...Angiotensin Ⅱ has been reported to have an important role in the fibrotic response to tissue injuries:it stimulates the proliferation of fibroblasts via activation of angiotensin Ⅱ（AT1) receptor.In the present study,whether Ang Ⅱ forming enzymes,angiotensin converting enzyme(ACE) and chymase,which were activated in pulmonary fibrosis induced by paraquat(PQ) were examined in hamsters.PQ was administered subcutaneously once a week at a dose of 6mg·kg^-1 for four weeks and the 18mg·kg^-1 for six weeks.Interstitial and superficial pulmonary fibrosis were found five weeks after administration.Chymase activity was significantly increased in the PQ group when compared with saline group.ACE activity,on the other hand,was not significantly different.There data support the possible role of angiotensin Ⅱ,via activation of chymase,to the PQ-induced pulmonary fibrosis.展开更多
文摘Mammalian cell totipotency is a subject that has fascinated scientists for generations. A long lasting question whether some of the somatic cells retains totipotency was answered by the cloning of Dolly at the end of the 20th century. The dawn of the 218t has brought forward great expectations in harnessing the power of totipotentcy in medicine. Through stem cell biology, it is possible to generate any parts of the human body by stem cell engineering. Considerable resources will be devoted to harness the untapped potentials of stem cells in the foreseeable future which may transform medicine as we know today. At the molecular level, totipotency has been linked to a singular transcription factor and its expression appears to define whether a cell should be totipotent. Named Oct4, it can activate or repress the expression of various genes. Curiously, very little is known about Oct4 beyond its ability to regulate gene expression. The mechanism by which Oct4 specifies totipotency remains entirely unresolved. In this review, we summarizere the structure and function of Oct4 and address to Oct4 function in maintaining totipotency or pluripotency of embryonic stem cels.
文摘Angiotensin Ⅱ has been reported to have an important role in the fibrotic response to tissue injuries:it stimulates the proliferation of fibroblasts via activation of angiotensin Ⅱ（AT1) receptor.In the present study,whether Ang Ⅱ forming enzymes,angiotensin converting enzyme(ACE) and chymase,which were activated in pulmonary fibrosis induced by paraquat(PQ) were examined in hamsters.PQ was administered subcutaneously once a week at a dose of 6mg·kg^-1 for four weeks and the 18mg·kg^-1 for six weeks.Interstitial and superficial pulmonary fibrosis were found five weeks after administration.Chymase activity was significantly increased in the PQ group when compared with saline group.ACE activity,on the other hand,was not significantly different.There data support the possible role of angiotensin Ⅱ,via activation of chymase,to the PQ-induced pulmonary fibrosis.
