Learned association between context and drug abuse is essential for the drug conditioned place preference （CPP）, which is an animal model widely used to measure drug reward. Synaptic plasticity, in the form of long-...Learned association between context and drug abuse is essential for the drug conditioned place preference （CPP）, which is an animal model widely used to measure drug reward. Synaptic plasticity, in the form of long-term potentiation （LTP） and depression （LTD）, is regarded as a proposed cellular substrate of learning and memory. However, the exact role of LTP/LTD in addiction is not known yet. Therefore, by bioinformatics we designed peptides aiming to interfere with LTP and LTD respectively, to study their individual role in the expression of morphine CPP. We found that the interfering peptide Pep-A2 can specifically block hippocampal LTP in CA1 region, whereas Pep-A3 can block LTD in this region. Treatment of either of their cell penetrating forms （Tat-A2 or Tat-A3） before test can block the expression of Morphine CPP in mice. These results suggested that both LTP and LTD are required in the drug-associated learning and memory.展开更多
AIM: To evaluate measurements of intragastric pH with the Bravo capsule system over a prolonged time.METHODS: A Bravo capsule was placed inside the rat gastric body and pH was studied for periods up to five consecutiv...AIM: To evaluate measurements of intragastric pH with the Bravo capsule system over a prolonged time.METHODS: A Bravo capsule was placed inside the rat gastric body and pH was studied for periods up to five consecutive days.For comparison,a gastric fistula model was used.Effects of ghrelin and esomeprazole,with or without pentagastrin,on gastric pH were studied.In addition,effects of esomeprazole on plasma ghrelin,gastrin and somatostatin were analyzed.RESULTS: All rats recovered after surgery.The average 24-h pH during free feeding was 2.3 ± 0.1 (n = 20) with a variation of 18% ± 6% over 5 d.Ghrelin,2400 pmol/kg,t.i.d.increased pH from 1.7 ± 0.1 to 3.1 ± 0.3 (P < 0.01) as recorded with the Bravo system.After esomeprazole (1 mg/kg,3 mg/kg and 5 mg/kg) there was a dose-dependent pH increase of maximally 3.4 ± 0.1,with day-to-day variation over the entire period of 8% ± 3%.The fistula and pH studies generated similar results.Acid inhibition with esomeprazole increased plasma ghrelin from 10 ± 2 pmol/L to 65 ± 26 pmol/L (P < 0.001),and somatostatin from 10 ± 2 pmol/L to 67 ± 18 pmol/L (P < 0.001).CONCLUSION: pH measurements with the Bravo capsule are reliable,and comparable to those of the gastric fistula model.The Bravo system optimizes accurate intragastric pH monitoring over prolonged periods and allows both short-and long-term evaluation of effects of drugs and hormones.展开更多
Myostatin is a member of the transforming growth factor-β(TGF-β) super-family and functions as a negative regulator of muscle growth.Binding of the specific receptor,Activin receptor IIB(Act RIIB),with myostatin or ...Myostatin is a member of the transforming growth factor-β(TGF-β) super-family and functions as a negative regulator of muscle growth.Binding of the specific receptor,Activin receptor IIB(Act RIIB),with myostatin or other related TGF-β members,could be inhibited by the activin-binding protein follistatin(Fst) in mammals.Overexpressing Fst in mouse skeletal muscle leads to muscle hypertrophy and hyperplasia.To determine if Fst has similar roles in fish,we generated transgenic zebrafish expressing high levels of zebrafish Fst1 using the promoter of the zebrafish skeletal muscle-specific gene,myosin,light polypeptide 2,skeletal muscle(Mylz2).Independent transgenic zebrafish lines exhibited elevated expression levels of myogenic regulatory genes MyoD and Pax7 in muscle cells.Adult Fst1 overexpressing transgenic zebrafish exhibited a slight body weight increase.The high level of Fst1 expression dramatically increased myofiber numbers in skeletal muscle,without significantly changing the fiber size.Our findings suggest that Fst1 overexpression can promote zebrafish muscle growth by enhancing myofiber hyperplasia.展开更多
In this paper a delayed mathematical model for tumor growth under the action of external inhibitors is studied. The delay represents the time taken for cells to undergo mitosis. External inhibitor means that an inhibi...In this paper a delayed mathematical model for tumor growth under the action of external inhibitors is studied. The delay represents the time taken for cells to undergo mitosis. External inhibitor means that an inhibitor is either developed from the immune system of the body or administered by medical treatment to distinguish with that secreted by tumor itself. Non-negativity of solutions is studied. Local and global stabilities of the stationary solutions are proved for some parameter values. The analysis of the effect of inhibitor＇s parameters on tumor＇s growth is presented. The results show that dynamical behavior of solutions of this model is similar to that of solutions for corresponding nondelayed model for some parameter values.展开更多
基金supported by the National Natural Science Foundation of China(3053025030623007)
文摘Learned association between context and drug abuse is essential for the drug conditioned place preference （CPP）, which is an animal model widely used to measure drug reward. Synaptic plasticity, in the form of long-term potentiation （LTP） and depression （LTD）, is regarded as a proposed cellular substrate of learning and memory. However, the exact role of LTP/LTD in addiction is not known yet. Therefore, by bioinformatics we designed peptides aiming to interfere with LTP and LTD respectively, to study their individual role in the expression of morphine CPP. We found that the interfering peptide Pep-A2 can specifically block hippocampal LTP in CA1 region, whereas Pep-A3 can block LTD in this region. Treatment of either of their cell penetrating forms （Tat-A2 or Tat-A3） before test can block the expression of Morphine CPP in mice. These results suggested that both LTP and LTD are required in the drug-associated learning and memory.
文摘AIM: To evaluate measurements of intragastric pH with the Bravo capsule system over a prolonged time.METHODS: A Bravo capsule was placed inside the rat gastric body and pH was studied for periods up to five consecutive days.For comparison,a gastric fistula model was used.Effects of ghrelin and esomeprazole,with or without pentagastrin,on gastric pH were studied.In addition,effects of esomeprazole on plasma ghrelin,gastrin and somatostatin were analyzed.RESULTS: All rats recovered after surgery.The average 24-h pH during free feeding was 2.3 ± 0.1 (n = 20) with a variation of 18% ± 6% over 5 d.Ghrelin,2400 pmol/kg,t.i.d.increased pH from 1.7 ± 0.1 to 3.1 ± 0.3 (P < 0.01) as recorded with the Bravo system.After esomeprazole (1 mg/kg,3 mg/kg and 5 mg/kg) there was a dose-dependent pH increase of maximally 3.4 ± 0.1,with day-to-day variation over the entire period of 8% ± 3%.The fistula and pH studies generated similar results.Acid inhibition with esomeprazole increased plasma ghrelin from 10 ± 2 pmol/L to 65 ± 26 pmol/L (P < 0.001),and somatostatin from 10 ± 2 pmol/L to 67 ± 18 pmol/L (P < 0.001).CONCLUSION: pH measurements with the Bravo capsule are reliable,and comparable to those of the gastric fistula model.The Bravo system optimizes accurate intragastric pH monitoring over prolonged periods and allows both short-and long-term evaluation of effects of drugs and hormones.
基金supported by the National Natural Science Foundation of China (Grant No. 30671600)the National Basic Research Program of China (Grant Nos. 2010CB126302,2009CB118701)
文摘Myostatin is a member of the transforming growth factor-β(TGF-β) super-family and functions as a negative regulator of muscle growth.Binding of the specific receptor,Activin receptor IIB(Act RIIB),with myostatin or other related TGF-β members,could be inhibited by the activin-binding protein follistatin(Fst) in mammals.Overexpressing Fst in mouse skeletal muscle leads to muscle hypertrophy and hyperplasia.To determine if Fst has similar roles in fish,we generated transgenic zebrafish expressing high levels of zebrafish Fst1 using the promoter of the zebrafish skeletal muscle-specific gene,myosin,light polypeptide 2,skeletal muscle(Mylz2).Independent transgenic zebrafish lines exhibited elevated expression levels of myogenic regulatory genes MyoD and Pax7 in muscle cells.Adult Fst1 overexpressing transgenic zebrafish exhibited a slight body weight increase.The high level of Fst1 expression dramatically increased myofiber numbers in skeletal muscle,without significantly changing the fiber size.Our findings suggest that Fst1 overexpression can promote zebrafish muscle growth by enhancing myofiber hyperplasia.
文摘In this paper a delayed mathematical model for tumor growth under the action of external inhibitors is studied. The delay represents the time taken for cells to undergo mitosis. External inhibitor means that an inhibitor is either developed from the immune system of the body or administered by medical treatment to distinguish with that secreted by tumor itself. Non-negativity of solutions is studied. Local and global stabilities of the stationary solutions are proved for some parameter values. The analysis of the effect of inhibitor＇s parameters on tumor＇s growth is presented. The results show that dynamical behavior of solutions of this model is similar to that of solutions for corresponding nondelayed model for some parameter values.
