OBJECTIVE Hepatocellular carcinoma(HCC)is the fifth most common malignancy worldwide and the third cause of global cancer mortality.Activation of signal transducer and activator of transcription 3(STAT3)is commonly ob...OBJECTIVE Hepatocellular carcinoma(HCC)is the fifth most common malignancy worldwide and the third cause of global cancer mortality.Activation of signal transducer and activator of transcription 3(STAT3)is commonly observed in tumor cells and is a critical mediator of on cogenic signaling in HCC and controls the expression of several genes involved in proliferation,survival,metastasis and angiogenesis.Current drug-targeted therapies,besides being expensive,are associated with serious side effects and morbidity.Thus,novel agents that can suppress STAT3 activation have potential for both prevention and treatment of HCC.In the present report,we investigated whether the potent HAT/KAT inhibitor,garcinol,(apolyisoprenylatedbenzophenone),could suppress STAT3 activation in HCC cells and in nude mice model.METHODS The effect of garcinol on HCC cell lines wasdetermined by MTT assay,immunoblotting,DNA binding assays,immuno-fluorescenceand immune-histochemical analysis.The effect of garcinolon the inhibition of tumor growth in vivo was also investigated using HCCxenograft tumor modelin athymic nu/nu mice.RESULTS We found that garcinol could inhibit constitutive STAT3 activation in a dose-and time-dependent manner both by inhibiting STAT3 phosphorylation and acetylation in HCC cells.When investigated for molecular mechanism(s),we found that garcinol interferes with the dimer formation of STAT3 thereby inhibits its nuclear localization.Computational modeling showed that garcinol could bind to the SH2 domain of STAT3 and suppresses its dimerization in vitro.To understand the cellular mechanism(s)of inhibition of STAT3 function by garcinol,we observed that upon inhibition of STAT3 dimerization bygarcinol,STAT3 DNA binding ability gets repressed.The inhibition of STAT3 activation by garcinol led to the suppression of various gene products involved in proliferation,survival,and angiogenesis.Finally,when administered i.p.,garcinol inhibited the growth of human HCC xenograft tumors in athymic nu/nu mice.CONCLUSION Results frominvitroand in vivo studies suggest that garcinol exerts its anti-proliferative and pro-apoptotic effects through suppression of STAT3 signaling cascade in HCC by inhibiting its phosphorylation,acetylation and ultimately dimerization.展开更多
Mesenchymal stem cells(MSCs)represent the most clinically used stem cells in regenerative medicine.However,due to the disadvantages with primary MSCs,such as limited cell proliferative capacity and rarity in the tissu...Mesenchymal stem cells(MSCs)represent the most clinically used stem cells in regenerative medicine.However,due to the disadvantages with primary MSCs,such as limited cell proliferative capacity and rarity in the tissues leading to limited MSCs,gradual loss of differentiation during in vitro expansion reducing the efficacy of MSC application,and variation among donors increasing the uncertainty of MSC efficacy,the clinical application of MSCs has been greatly hampered.MSCs derived from human pluripotent stem cells(hPSC-MSCs)can circumvent these problems associated with primary MSCs.Due to the infinite selfrenewal of hPSCs and their differentiation potential towards MSCs,hPSC-MSCs are emerging as an attractive alternative for regenerative medicine.This review summarizes the progress on derivation of MSCs from human pluripotent stem cells,disease modelling and drug screening using hPSC-MSCs,and various applications of hPSC-MSCs in regenerative medicine.In the end,the challenges and concerns with hPSC-MSC applications are also discussed.展开更多
Leukemia, like many other cancers, is thought to arise from a small population of stem cells that have the capacity to self-renewal extensively and to initiate, sustain or regenerate the disease. Elimination of the le...Leukemia, like many other cancers, is thought to arise from a small population of stem cells that have the capacity to self-renewal extensively and to initiate, sustain or regenerate the disease. Elimination of the leukemia stem cells （LSCs） will likely be essential, and probably sufficient, for curing this disease.Recent studies have shown that LSCs can be derived from early hematopoietic progenitors as well as more differentiated derivatives; the key feature being these cells have acquired an increased proliferative capacity and the ability to self-renew extensively. Genes that make this possible are attractive drug targets for treating leukemia. In our laboratory we have developed a novel in vitro genetic screen that uses retroviral insertional mutagenesis as a tool for identifying genes that are able to convert both normal hematoooietic progenitors and committed mveloid progenitor cells into cells that resemble LSCs.展开更多
Chromatin modification contributes to pluripotency maintenance in embryonic stem cells(ESCs).However,the related mechanisms remain obscure.Here,we show that Npac,a"reader"of histone H3 lysine 36 trimethylati...Chromatin modification contributes to pluripotency maintenance in embryonic stem cells(ESCs).However,the related mechanisms remain obscure.Here,we show that Npac,a"reader"of histone H3 lysine 36 trimethylation(H3K36me3),is required to maintain mouse ESC(mESC)pluripotency since knockdown of Npac causes mESC differentiation.Depletion of Npac in mouse embryonic fibroblasts(MEFs)inhibits reprogramming efficiency.Furthermore,our chromatin immunoprecipitation followed by sequencing(ChIP-seq)results of Npac reveal that Npac co-localizes with histone H3K36me3 in gene bodies of actively transcribed genes in mESCs.Interestingly,we find that Npac interacts with positive transcription elongation factor b(p-TEFb),Ser2-phosphorylated RNA PolⅡ(RNA PolⅡSer2P),and Ser5-phosphorylated RNA PolⅡ(RNA PolⅡSer5 P).Furthermore,depletion of Npac disrupts transcriptional elongation of the pluripotency genes Nanog and Rif1.Taken together,we propose that Npac is essential for the transcriptional elongation of pluripotency genes by recruiting p-TEFb and interacting with RNA PolⅡSer2P and Ser5P.展开更多
Dear Editor,Head and neck squamous cell carcinoma(HNSCC)is the sixth most common cancer globally[1,2].Despite the improvement in treatment modalities,up to 50%of HNSCC patients still develop recurrent/metastatic(R/M)d...Dear Editor,Head and neck squamous cell carcinoma(HNSCC)is the sixth most common cancer globally[1,2].Despite the improvement in treatment modalities,up to 50%of HNSCC patients still develop recurrent/metastatic(R/M)disease[3],and platinum-based chemotherapy with cetuximab and/or pembrolizumab has become the standard of care[4].However,R/M HNSCC is challenging to treat,the prognosis is poor,and there is an unmet need for new therapeutic targets.展开更多
BACKGROUND： Inhibitory signals, i.e. neurite growth inhibitors （NGIs）, presenting on central nervous system （CNS） myelin have been shown to play a crucial role in inhibiting lesioned axonal sprouting and leading ...BACKGROUND： Inhibitory signals, i.e. neurite growth inhibitors （NGIs）, presenting on central nervous system （CNS） myelin have been shown to play a crucial role in inhibiting lesioned axonal sprouting and leading to less functional recovery. Vaccines targeting NGIs may provide multifactorial protection against brain insults by overcoming the inhibitory effects of these NGIs and boosting the body＇s immune repair mechanisms. OBJECTIVE： To evaluate the effect of poststroke DNA immunization against NGIs on the rehabilitation for sensorimotor function of rat models of local cerebral ischemia. DESIGN： Completely randomized grouping design, and controlled experiment. SETTING： Brain Injury Research Laboratory, Department of Neurosurgery, National Neuroscience Institute, Singapore. MATERIALS： Sixty adult male Sprague-Dawley rats ranging in age from 45 to 120 days and in weight from 180 to 250 grams were provided by Animal Center of Department of Anatomy, Faculty of Medicine, National University of Singapore. pcDNA3.1（＋）-neurite growth inhibitors （pcDNA-NGIs） a gift was provided by Dr. Xiao from Department of Clinical Research, Singapore General Hospital, Singapore. METHODS： The experiment was carried out at Brain Injury Research Laboratory, Department of Neurosurgery, National Neuroscience Institute, Singapore from August 2003 to April 2005. （1）The involved rats were randomized into 3 groups： pcDNA-NGIs group （group A）, pcDNA3.1 （＋） group （group B） and model group （group C）, with 20 rats in each group. Left focal cerebral ischemia （FCI） was permanently induced through middle cerebral artery occlusion （MCAO） with the assistance of an operating microscope. Successful MCAO was determined by a 20% decrease to baseline in the ipsilateral cerebral blood flow. 100 μg of pcDNA-NGIs eluted in phosphate-buffered saline （PBS） was intramuscularly injected into the tibial muscle once a week after MCAO for 6 weeks in group A. As control, pcDNA3.1 （＋） was also administrated in the same way in group B and nothing was administrated in group C. （2） The modified neurological severity score （mNSS）, a composite of motor, sensory, reflex and balance tests, was used to test the sensorimotor deficit. The mNSS was graded on a scale of 0 - 18, i.e. normal score was 0, maximal deficit score was 18, and 1 point was warded for the inability to perform the tasks or the lack of a tested reflex. （3） The newly generated axons of corticorubral projection were traced by stereotaxic guided injection of 100 g/L biotinylated dextran amine. Rats were sacrificed two weeks after tracing, and cryostat coronal sections of midbrains （30μm） were reacted to BDA according to the manufacturer＇s instruction by the free-floating method. Images were captured on a DM RXA2 LEICA Microscope with a Spot Digital Camera system （Germany）, and the numbers of labeled axons on the denervated side in four standard coronal sections including the red nucleus were manually quantified. MAIN OUTCOME MEASURES： （1） The number of newly generated axons of corticorubral projection. （2）The improvement in sensorimotor deficit. RESULTS： All the involved 60 rats entered the stage of final analysis. （1） The number of newly generated axons of corticorubral projection of rats： Only ipsilateral axons of CRP were noted with little evidence of fibers crossing to the contralateral red nucleus in rats of groups B and C. More BDA-positive fibers crossing the midline and terminating in the contralateral red nucleus in appropriate target areas mirroring the non-differentiated red nucleus were found in rats of group A. Quantitative analysis showed that BDA-labeled axons in the denervated side of rats in group A were more than those in group B （P 〈 0.05）. （2） Improvement in sensorimotor deficit of rats： At 2 weeks after immunization, significant improvement in sensorimotor deficit was found in rats of group A. There were significant differences of improvement in sensorimotor deficit of rats between group A and group B or group C at 12 and 14 weeks after immunization （P 〈 0.05）. CONCLUSION： （1） Poststroke DNA immunization against NGIs leads to increased sensorimotor recovery following FCI and compensatory newly growth of axons from corticorubral projection.展开更多
BACKGROUND： Inhibitory signals, i.e. neurite growth inhibitors （NGIs）, presenting on central nervous system （CNS） myelin have been shown to play a crucial role in inhibiting lesioned axonal sprouting and leading ...BACKGROUND： Inhibitory signals, i.e. neurite growth inhibitors （NGIs）, presenting on central nervous system （CNS） myelin have been shown to play a crucial role in inhibiting lesioned axonal sprouting and leading to less functional recovery. Vaccines targeting NGIs may provide multifactorial protection against brain insults by overcoming the inhibitory effects of these NGIs and boosting the immune repair mechanisms of body. OBJECTIVE： To evaluate the effect of pre-stroke DNA immunization against NGIs on the rehabilitation for sensorimotor function of rat models of focal cerebral ischemia. DESIGN： A completely randomized design, and controlled experiment. SETTING： Brain Injury Research Laboratory, Department of Neurosurgery, National Neuroscience Institute, Singapore. MATERIALS： Sixty adult male Sprague-Dawley rats ranging in age from 45 to 120 days and in body mass from 180 to 250 g were provided by the Animal Center of Department of Anatomy, Faculty of Medicine, National University of Singapore. pcDNA3.1（＋）-neurite growth inhibitors （pcDNA-NGIs） a gift was provided by Dr. Xiao from the Department of Clinical Research, Singapore General Hospital, Singapore. METHODS： The experiment was carried out at Brain Injury Research Laboratory, Department of Neurosurgery, National Neuroscience Institute, Singapore from August 2003 to April 2005. ① The involved rats were randomized into 3 groups： model group （group A）, pcDNA3.1（＋） group （group B） and pcDNA-NGIs group （group C）, with 20 rats in each group. Left focal cerebral ischemia was permanently induced through middle cerebral artery occlusion with the assistance of an operating microscope. Successful middle cerebral artery occlusion was determined by a 20% decrease to baseline in the ipsilateral cerebral blood flow. 100 μg of pcDNA-NGIs eluted in phosphate-buffered saline （PBS） was intramuscularly injected into the tibial muscle once a week before middle cerebral artery occlusion for 6 weeks in group C. As control, pcDNA3.1 （＋） was also administrated in the same way in group B and nothing was administrated in group A. ② The modified neurological severity score （mNSS）, a composite of motor, sensory, reflex and balance tests, was used to test the sensorimotor deficit. The mNSS was graded on 0-18, i.e. normal score was 0, maximal deficit score was 18, and 1 point was warded for the inability to perform the tasks or the lack of a tested reflex. ③ The newly generated axons of corticorubral projection were traced by stereotaxic guided injection of 100 g/L biotinylated dextran amine （BDA）. Rats were sacrificed two weeks after tracing, and cryostat coronal sections of midbrains （30 μm） were reacted to BDA according to the manufacturer＇s instruction by the free-floating method. Images were captured on a DM RXA2 LEICA Microscope with a Spot Digital Camera system （Germany）, and the numbers of labeled axons on the denervated side in four standard coronal sections including the red nucleus were manually quantified. MAIN OUTCOME MEASURES： ① The number of newly generated axons of corticorubral projection; ② The improvement of the sensorimotor deficit. RESULTS： All the involved 60 rats entered the final analysis. ① The number of newly generated axons of corticorubral projection of rats： Only ipsilateral axons of corticorubral projiction were noted with little evidence of fibers crossing to the contralateral red nucleus in rats of groups A and B. More BDA-positive fibers crossing the midline and terminating in the contralateral red nucleus in appropriate target areas mirroring the non-differentiated red nucleus were found in rats of group C. Quantitative analysis showed that BDA-labelled axons in the denervated side of rats in group C were more than those in group B （P 〈 0.05）. ② The improvement of the sensorimotor deficit： At two weeks after middle cerebral artery occlusion, significant improvement in sensorimotor deficit was found in rats of group C. There was significant difference of improvement in sensorimotor deficit of rats between group C and group B or group A at eight and 10 weeks after middle cerebral artery occlusion （P 〈 0.05）. CONCLUSION： Pre-stroke DNA immunization against NGIs led to increased sensorimotor recovery following focal cerebral ischemia and compensatory newly growth of axons from corticorubral projection.展开更多
Cancer gene discovery continues to drive current cancer research with the promise of identifying new diagnostic markers and therapeutic targets by elucidating novel genetic interactions that promote or sustain tumor f...Cancer gene discovery continues to drive current cancer research with the promise of identifying new diagnostic markers and therapeutic targets by elucidating novel genetic interactions that promote or sustain tumor formation. Sleeping Beauty（SB） transposoniated insertional mutagenesis has emerged as an exciting approach to identify novel cancer-causing genes in the mouse. The SB transposon faithfully ＂hops＂ throughout the genome by a cut-and-paste mechanism mediated by the ubiquitous expression of the SB transposase. Initial tumor data generated using an SB transposon harboring the MSCV promoter demonstrated a bias towards hematopoietic tumors. More recently, experiments using a modified SB transposon containing the CAG promoter have generated cohorts of mice with solid tumors, primarily carcinomas, which in some cases metastasize. Many animals also develop multiple, inde- pendent primary tumors. These data demonstrate the utility of the SB transposition system for cancer gene discovery across organ systems.展开更多
Microarray technology can be employed to quantitatively measure the expression of thousands of genes in a single experiment. It has become one of the main tools for global gene expression analysis in molecular biology...Microarray technology can be employed to quantitatively measure the expression of thousands of genes in a single experiment. It has become one of the main tools for global gene expression analysis in molecular biology research in recent years. The large amount of expression data generated by this technology makes the study of certain complex biological problems possible, and machine learning methods are expected to play a crucial role in the analysis process. In this paper, we present our results from integrating the self-organizing map （SOM） and the support vector machine （SVM） for the analysis of the various functions of zebrafish genes based on their expression. The most distinctive characteristic of our zebrafish gene expression is that the number of samples of different classes is imbalanced. We discuss how SOM can be used as a data-filtering tool to improve the classification performance of the SVM on this data set.展开更多
Embryogenesis is central to the life cycle of higher plants,which starts from division of the single-cell zygote and culminates in formation of the mature embryo with major cell precursors.Such a process generally inv...Embryogenesis is central to the life cycle of higher plants,which starts from division of the single-cell zygote and culminates in formation of the mature embryo with major cell precursors.Such a process generally involves tightly orchestrated cell division,differentiation,and pattern formation.展开更多
基金The project supported in part by agrant from National Medical Research Council of Singapore
文摘OBJECTIVE Hepatocellular carcinoma(HCC)is the fifth most common malignancy worldwide and the third cause of global cancer mortality.Activation of signal transducer and activator of transcription 3(STAT3)is commonly observed in tumor cells and is a critical mediator of on cogenic signaling in HCC and controls the expression of several genes involved in proliferation,survival,metastasis and angiogenesis.Current drug-targeted therapies,besides being expensive,are associated with serious side effects and morbidity.Thus,novel agents that can suppress STAT3 activation have potential for both prevention and treatment of HCC.In the present report,we investigated whether the potent HAT/KAT inhibitor,garcinol,(apolyisoprenylatedbenzophenone),could suppress STAT3 activation in HCC cells and in nude mice model.METHODS The effect of garcinol on HCC cell lines wasdetermined by MTT assay,immunoblotting,DNA binding assays,immuno-fluorescenceand immune-histochemical analysis.The effect of garcinolon the inhibition of tumor growth in vivo was also investigated using HCCxenograft tumor modelin athymic nu/nu mice.RESULTS We found that garcinol could inhibit constitutive STAT3 activation in a dose-and time-dependent manner both by inhibiting STAT3 phosphorylation and acetylation in HCC cells.When investigated for molecular mechanism(s),we found that garcinol interferes with the dimer formation of STAT3 thereby inhibits its nuclear localization.Computational modeling showed that garcinol could bind to the SH2 domain of STAT3 and suppresses its dimerization in vitro.To understand the cellular mechanism(s)of inhibition of STAT3 function by garcinol,we observed that upon inhibition of STAT3 dimerization bygarcinol,STAT3 DNA binding ability gets repressed.The inhibition of STAT3 activation by garcinol led to the suppression of various gene products involved in proliferation,survival,and angiogenesis.Finally,when administered i.p.,garcinol inhibited the growth of human HCC xenograft tumors in athymic nu/nu mice.CONCLUSION Results frominvitroand in vivo studies suggest that garcinol exerts its anti-proliferative and pro-apoptotic effects through suppression of STAT3 signaling cascade in HCC by inhibiting its phosphorylation,acetylation and ultimately dimerization.
文摘Mesenchymal stem cells(MSCs)represent the most clinically used stem cells in regenerative medicine.However,due to the disadvantages with primary MSCs,such as limited cell proliferative capacity and rarity in the tissues leading to limited MSCs,gradual loss of differentiation during in vitro expansion reducing the efficacy of MSC application,and variation among donors increasing the uncertainty of MSC efficacy,the clinical application of MSCs has been greatly hampered.MSCs derived from human pluripotent stem cells(hPSC-MSCs)can circumvent these problems associated with primary MSCs.Due to the infinite selfrenewal of hPSCs and their differentiation potential towards MSCs,hPSC-MSCs are emerging as an attractive alternative for regenerative medicine.This review summarizes the progress on derivation of MSCs from human pluripotent stem cells,disease modelling and drug screening using hPSC-MSCs,and various applications of hPSC-MSCs in regenerative medicine.In the end,the challenges and concerns with hPSC-MSC applications are also discussed.
文摘Leukemia, like many other cancers, is thought to arise from a small population of stem cells that have the capacity to self-renewal extensively and to initiate, sustain or regenerate the disease. Elimination of the leukemia stem cells （LSCs） will likely be essential, and probably sufficient, for curing this disease.Recent studies have shown that LSCs can be derived from early hematopoietic progenitors as well as more differentiated derivatives; the key feature being these cells have acquired an increased proliferative capacity and the ability to self-renew extensively. Genes that make this possible are attractive drug targets for treating leukemia. In our laboratory we have developed a novel in vitro genetic screen that uses retroviral insertional mutagenesis as a tool for identifying genes that are able to convert both normal hematoooietic progenitors and committed mveloid progenitor cells into cells that resemble LSCs.
基金supported by Singapore National Medical Research Council(Grant No.CBRG14nov065)the Macao Science and Technology Development Fund,China(Grant No.FDCT-18-033-SKL-016A)。
文摘Chromatin modification contributes to pluripotency maintenance in embryonic stem cells(ESCs).However,the related mechanisms remain obscure.Here,we show that Npac,a"reader"of histone H3 lysine 36 trimethylation(H3K36me3),is required to maintain mouse ESC(mESC)pluripotency since knockdown of Npac causes mESC differentiation.Depletion of Npac in mouse embryonic fibroblasts(MEFs)inhibits reprogramming efficiency.Furthermore,our chromatin immunoprecipitation followed by sequencing(ChIP-seq)results of Npac reveal that Npac co-localizes with histone H3K36me3 in gene bodies of actively transcribed genes in mESCs.Interestingly,we find that Npac interacts with positive transcription elongation factor b(p-TEFb),Ser2-phosphorylated RNA PolⅡ(RNA PolⅡSer2P),and Ser5-phosphorylated RNA PolⅡ(RNA PolⅡSer5 P).Furthermore,depletion of Npac disrupts transcriptional elongation of the pluripotency genes Nanog and Rif1.Taken together,we propose that Npac is essential for the transcriptional elongation of pluripotency genes by recruiting p-TEFb and interacting with RNA PolⅡSer2P and Ser5P.
基金This work was supported by funding from the National Medical Research Council NMRC/CSA-INV/0025/2017,MOH-000375-01 and NCCRF-YR2018-JAN-SUG2Su Bin Lim is supported by the National Research Foundation of Korea(2021R1F1A1064122,2020R1A6A1A03043539,and 2020M3A9D8037604)and the new faculty research fund of Ajou University School of Medicine.
文摘Dear Editor,Head and neck squamous cell carcinoma(HNSCC)is the sixth most common cancer globally[1,2].Despite the improvement in treatment modalities,up to 50%of HNSCC patients still develop recurrent/metastatic(R/M)disease[3],and platinum-based chemotherapy with cetuximab and/or pembrolizumab has become the standard of care[4].However,R/M HNSCC is challenging to treat,the prognosis is poor,and there is an unmet need for new therapeutic targets.
基金the grants from the National Medical Research Council and Health Research of Singapore
文摘BACKGROUND： Inhibitory signals, i.e. neurite growth inhibitors （NGIs）, presenting on central nervous system （CNS） myelin have been shown to play a crucial role in inhibiting lesioned axonal sprouting and leading to less functional recovery. Vaccines targeting NGIs may provide multifactorial protection against brain insults by overcoming the inhibitory effects of these NGIs and boosting the body＇s immune repair mechanisms. OBJECTIVE： To evaluate the effect of poststroke DNA immunization against NGIs on the rehabilitation for sensorimotor function of rat models of local cerebral ischemia. DESIGN： Completely randomized grouping design, and controlled experiment. SETTING： Brain Injury Research Laboratory, Department of Neurosurgery, National Neuroscience Institute, Singapore. MATERIALS： Sixty adult male Sprague-Dawley rats ranging in age from 45 to 120 days and in weight from 180 to 250 grams were provided by Animal Center of Department of Anatomy, Faculty of Medicine, National University of Singapore. pcDNA3.1（＋）-neurite growth inhibitors （pcDNA-NGIs） a gift was provided by Dr. Xiao from Department of Clinical Research, Singapore General Hospital, Singapore. METHODS： The experiment was carried out at Brain Injury Research Laboratory, Department of Neurosurgery, National Neuroscience Institute, Singapore from August 2003 to April 2005. （1）The involved rats were randomized into 3 groups： pcDNA-NGIs group （group A）, pcDNA3.1 （＋） group （group B） and model group （group C）, with 20 rats in each group. Left focal cerebral ischemia （FCI） was permanently induced through middle cerebral artery occlusion （MCAO） with the assistance of an operating microscope. Successful MCAO was determined by a 20% decrease to baseline in the ipsilateral cerebral blood flow. 100 μg of pcDNA-NGIs eluted in phosphate-buffered saline （PBS） was intramuscularly injected into the tibial muscle once a week after MCAO for 6 weeks in group A. As control, pcDNA3.1 （＋） was also administrated in the same way in group B and nothing was administrated in group C. （2） The modified neurological severity score （mNSS）, a composite of motor, sensory, reflex and balance tests, was used to test the sensorimotor deficit. The mNSS was graded on a scale of 0 - 18, i.e. normal score was 0, maximal deficit score was 18, and 1 point was warded for the inability to perform the tasks or the lack of a tested reflex. （3） The newly generated axons of corticorubral projection were traced by stereotaxic guided injection of 100 g/L biotinylated dextran amine. Rats were sacrificed two weeks after tracing, and cryostat coronal sections of midbrains （30μm） were reacted to BDA according to the manufacturer＇s instruction by the free-floating method. Images were captured on a DM RXA2 LEICA Microscope with a Spot Digital Camera system （Germany）, and the numbers of labeled axons on the denervated side in four standard coronal sections including the red nucleus were manually quantified. MAIN OUTCOME MEASURES： （1） The number of newly generated axons of corticorubral projection. （2）The improvement in sensorimotor deficit. RESULTS： All the involved 60 rats entered the stage of final analysis. （1） The number of newly generated axons of corticorubral projection of rats： Only ipsilateral axons of CRP were noted with little evidence of fibers crossing to the contralateral red nucleus in rats of groups B and C. More BDA-positive fibers crossing the midline and terminating in the contralateral red nucleus in appropriate target areas mirroring the non-differentiated red nucleus were found in rats of group A. Quantitative analysis showed that BDA-labeled axons in the denervated side of rats in group A were more than those in group B （P 〈 0.05）. （2） Improvement in sensorimotor deficit of rats： At 2 weeks after immunization, significant improvement in sensorimotor deficit was found in rats of group A. There were significant differences of improvement in sensorimotor deficit of rats between group A and group B or group C at 12 and 14 weeks after immunization （P 〈 0.05）. CONCLUSION： （1） Poststroke DNA immunization against NGIs leads to increased sensorimotor recovery following FCI and compensatory newly growth of axons from corticorubral projection.
基金the grants from the National Medical Research Council and Singhealth Research of Singapore
文摘BACKGROUND： Inhibitory signals, i.e. neurite growth inhibitors （NGIs）, presenting on central nervous system （CNS） myelin have been shown to play a crucial role in inhibiting lesioned axonal sprouting and leading to less functional recovery. Vaccines targeting NGIs may provide multifactorial protection against brain insults by overcoming the inhibitory effects of these NGIs and boosting the immune repair mechanisms of body. OBJECTIVE： To evaluate the effect of pre-stroke DNA immunization against NGIs on the rehabilitation for sensorimotor function of rat models of focal cerebral ischemia. DESIGN： A completely randomized design, and controlled experiment. SETTING： Brain Injury Research Laboratory, Department of Neurosurgery, National Neuroscience Institute, Singapore. MATERIALS： Sixty adult male Sprague-Dawley rats ranging in age from 45 to 120 days and in body mass from 180 to 250 g were provided by the Animal Center of Department of Anatomy, Faculty of Medicine, National University of Singapore. pcDNA3.1（＋）-neurite growth inhibitors （pcDNA-NGIs） a gift was provided by Dr. Xiao from the Department of Clinical Research, Singapore General Hospital, Singapore. METHODS： The experiment was carried out at Brain Injury Research Laboratory, Department of Neurosurgery, National Neuroscience Institute, Singapore from August 2003 to April 2005. ① The involved rats were randomized into 3 groups： model group （group A）, pcDNA3.1（＋） group （group B） and pcDNA-NGIs group （group C）, with 20 rats in each group. Left focal cerebral ischemia was permanently induced through middle cerebral artery occlusion with the assistance of an operating microscope. Successful middle cerebral artery occlusion was determined by a 20% decrease to baseline in the ipsilateral cerebral blood flow. 100 μg of pcDNA-NGIs eluted in phosphate-buffered saline （PBS） was intramuscularly injected into the tibial muscle once a week before middle cerebral artery occlusion for 6 weeks in group C. As control, pcDNA3.1 （＋） was also administrated in the same way in group B and nothing was administrated in group A. ② The modified neurological severity score （mNSS）, a composite of motor, sensory, reflex and balance tests, was used to test the sensorimotor deficit. The mNSS was graded on 0-18, i.e. normal score was 0, maximal deficit score was 18, and 1 point was warded for the inability to perform the tasks or the lack of a tested reflex. ③ The newly generated axons of corticorubral projection were traced by stereotaxic guided injection of 100 g/L biotinylated dextran amine （BDA）. Rats were sacrificed two weeks after tracing, and cryostat coronal sections of midbrains （30 μm） were reacted to BDA according to the manufacturer＇s instruction by the free-floating method. Images were captured on a DM RXA2 LEICA Microscope with a Spot Digital Camera system （Germany）, and the numbers of labeled axons on the denervated side in four standard coronal sections including the red nucleus were manually quantified. MAIN OUTCOME MEASURES： ① The number of newly generated axons of corticorubral projection; ② The improvement of the sensorimotor deficit. RESULTS： All the involved 60 rats entered the final analysis. ① The number of newly generated axons of corticorubral projection of rats： Only ipsilateral axons of corticorubral projiction were noted with little evidence of fibers crossing to the contralateral red nucleus in rats of groups A and B. More BDA-positive fibers crossing the midline and terminating in the contralateral red nucleus in appropriate target areas mirroring the non-differentiated red nucleus were found in rats of group C. Quantitative analysis showed that BDA-labelled axons in the denervated side of rats in group C were more than those in group B （P 〈 0.05）. ② The improvement of the sensorimotor deficit： At two weeks after middle cerebral artery occlusion, significant improvement in sensorimotor deficit was found in rats of group C. There was significant difference of improvement in sensorimotor deficit of rats between group C and group B or group A at eight and 10 weeks after middle cerebral artery occlusion （P 〈 0.05）. CONCLUSION： Pre-stroke DNA immunization against NGIs led to increased sensorimotor recovery following focal cerebral ischemia and compensatory newly growth of axons from corticorubral projection.
文摘Cancer gene discovery continues to drive current cancer research with the promise of identifying new diagnostic markers and therapeutic targets by elucidating novel genetic interactions that promote or sustain tumor formation. Sleeping Beauty（SB） transposoniated insertional mutagenesis has emerged as an exciting approach to identify novel cancer-causing genes in the mouse. The SB transposon faithfully ＂hops＂ throughout the genome by a cut-and-paste mechanism mediated by the ubiquitous expression of the SB transposase. Initial tumor data generated using an SB transposon harboring the MSCV promoter demonstrated a bias towards hematopoietic tumors. More recently, experiments using a modified SB transposon containing the CAG promoter have generated cohorts of mice with solid tumors, primarily carcinomas, which in some cases metastasize. Many animals also develop multiple, inde- pendent primary tumors. These data demonstrate the utility of the SB transposition system for cancer gene discovery across organ systems.
文摘Microarray technology can be employed to quantitatively measure the expression of thousands of genes in a single experiment. It has become one of the main tools for global gene expression analysis in molecular biology research in recent years. The large amount of expression data generated by this technology makes the study of certain complex biological problems possible, and machine learning methods are expected to play a crucial role in the analysis process. In this paper, we present our results from integrating the self-organizing map （SOM） and the support vector machine （SVM） for the analysis of the various functions of zebrafish genes based on their expression. The most distinctive characteristic of our zebrafish gene expression is that the number of samples of different classes is imbalanced. We discuss how SOM can be used as a data-filtering tool to improve the classification performance of the SVM on this data set.
基金grants from the National Key R&D Program of China(2018YFA0903202)the China Postdoctoral Science Foundation(230210538)。
文摘Embryogenesis is central to the life cycle of higher plants,which starts from division of the single-cell zygote and culminates in formation of the mature embryo with major cell precursors.Such a process generally involves tightly orchestrated cell division,differentiation,and pattern formation.
