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Abstract
Representations of sensory stimuli in the cerebral cortex can undergo progressive remodelling according to the behavioural importance of the stimuli. The cortex receives widespread projections from dopamine neurons in the ventral tegmental area (VTA), which are activated by new stimuli or unpredicted rewards, and are believed to provide a reinforcement signal for such learning-related cortical reorganization. In the primary auditory cortex (AI) dopamine release has been observed during auditory learning that remodels the sound-frequency representations. Furthermore, dopamine modulates long-term potentiation, a putative cellular mechanism underlying plasticity. Here we show that stimulating the VTA together with an auditory stimulus of a particular tone increases the cortical area and selectivity of the neural responses to that sound stimulus in AI. Conversely, the AI representations of nearby sound frequencies are selectively decreased. Strong, sharply tuned responses to the paired tones also emerge in a second cortical area, whereas the same stimuli evoke only poor or non-selective responses in this second cortical field in naive animals. In addition, we found that strong long-range coherence of neuronal discharge emerges between AI and this secondary auditory cortical area.
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2
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Ramsay AJ, Husband AJ, Ramshaw IA, Bao S, Matthaei KI, Koehler G, Kopf M. The role of interleukin-6 in mucosal IgA antibody responses in vivo. Science 1994; 264:561-3. [PMID: 8160012 DOI: 10.1126/science.8160012] [Citation(s) in RCA: 373] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/29/2023]
Abstract
In mice with targeted disruption of the gene that encodes interleukin-6 (IL-6), greatly reduced numbers of immunoglobulin A (IgA)-producing cells were observed at mucosae and grossly deficient local antibody responses were recorded after mucosal challenge with either ovalbumin or vaccinia virus. The IgA response in the lungs was completely restored after intranasal infection with recombinant vaccinia viruses engineered to express IL-6. These findings demonstrate a critical role for IL-6 in vivo in the development of local IgA antibody responses and illustrate the effectiveness of vector-directed cytokine gene therapy.
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Bao S, Thrall BD, Miller DL. Transfection of a reporter plasmid into cultured cells by sonoporation in vitro. ULTRASOUND IN MEDICINE & BIOLOGY 1997; 23:953-9. [PMID: 9300999 DOI: 10.1016/s0301-5629(97)00025-2] [Citation(s) in RCA: 339] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 05/05/2023]
Abstract
Cultured Chinese hamster ovary cells were exposed to 2.25-MHz ultrasound in sterile 4.5-mL polyethylene chambers and tested for cell lysis, sonoporation and DNA transfection. Ten percent of Albunex, a gas-body-based ultrasound contrast agent, was added to ensure cavitation nucleation, and the chambers were rotated at 60 rpm to promote cavitation activity during the 1-min exposures. Uptake of large fluorescent dextran molecules by some cells was observed for spatial peak pressure amplitudes as low as 0.1 MPa, which indicates transient permeabilization and resealing, i.e., sonoporation, of these cells during exposure. Significant lysis occurred for 0.2 MPa, and increased rapidly for exposures above the apparent cavitation threshold (using the H2O2 production test) of about 0.4 MPa spatial peak pressure amplitude. In the DNA transfection tests, 20 micrograms/mL luciferase reporter plasmid was added to the suspension during exposure, and cells were assayed for proliferation ability and luciferase gene expression 2 days after exposure. Cell proliferation was greatly reduced above the cavitation threshold. Luciferase production was significant for 0.20-MPa exposure, and reached 0.33 ng per 10(6) cells at 0.8-MPa exposure. The luciferase production was great for cells exposed in medium supplemented with serum than for cells exposed in serum-free medium. Cells harvested for exposure either in the log phase or in the stationary phase of culture gave similar proliferation and transfection results. The effects essentially disappeared when the Albunex was omitted from the suspension and the tube was not rotated. Thus, sonoporation by ultrasonic cavitation in the rotating tube system yields plasmid transfection with subsequent transient gene expression.
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Abstract
Oxygen is an essential regulator of cellular metabolism, survival, and proliferation. Cellular responses to oxygen levels are monitored, in part, by the transcriptional activity of the hypoxia inducible factors (HIFs). Under hypoxia, HIFs regulate a variety of pro-angiogenic and pro-glycolysis pathways. In solid cancers, regions of hypoxia are commonly present throughout the tissue because of the chaotic vascular architecture and regions of necrosis. In these regions, the hypoxic state fluctuates in a spatial and temporal manner. Transient hypoxic cycling causes an increase in the activity of the HIF proteins above what is typical for non-pathologic tissue. The extent of hypoxia strongly correlates to poor patient survival, therapeutic resistance and an aggressive tumour phenotype, but the full contribution of hypoxia and the HIFs to tumour biology is an area of active investigation. Recent reports link resistance to conventional therapies and the metastatic potential to a stem-like tumour population, termed cancer stem cells (CSCs). We and others have shown that within brain tumours CSCs reside in two niches, a perivascular location and the surrounding necrotic tissue. Restricted oxygen conditions increase the CSC fraction and promote acquisition of a stem-like state. Cancer stem cells are critically dependant on the HIFs for survival, self-renewal, and tumour growth. These observations and those from normal stem cell biology provide a new mechanistic explanation for the contribution of hypoxia to malignancy. Further, the presence of hypoxia in tumours may present challenges for therapy because of the promotion of CSC phenotypes even upon successful killing of CSCs. The current experimental evidence suggests that CSCs are plastic cell states governed by microenvironmental conditions, such as hypoxia, that may be critical for the development of new therapies targeted to disrupt the microenvironment.
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Zhang LI, Bao S, Merzenich MM. Persistent and specific influences of early acoustic environments on primary auditory cortex. Nat Neurosci 2001; 4:1123-30. [PMID: 11687817 DOI: 10.1038/nn745] [Citation(s) in RCA: 331] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/09/2022]
Abstract
This study demonstrates that the adult form of 'tonotopic maps' of sound frequency in the rat primary auditory cortex (A1) arises from parallel developmental processes involving two cortical zones: the progressive differentiation and refinement of selectively tone-responsive receptive fields within an initially broadly-tuned posterior zone, and the progressive loss of tone-evoked, short-latency response over an initially large, very broadly tuned anterior zone. The formation of tonotopic maps in A1 was specifically influenced by a rat pup's early acoustic environments. Exposure to pulsed tones resulted in accelerated emergence and an expansion of A1 representations of those specific tone frequencies, as well as a deteriorated tonotopicity and broader-than-normal receptive fields. Thus, auditory experiences during early postnatal development are important in shaping the functional development of auditory cortical representations of specific acoustic environments.
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Shibuki K, Gomi H, Chen L, Bao S, Kim JJ, Wakatsuki H, Fujisaki T, Fujimoto K, Katoh A, Ikeda T, Chen C, Thompson RF, Itohara S. Deficient cerebellar long-term depression, impaired eyeblink conditioning, and normal motor coordination in GFAP mutant mice. Neuron 1996; 16:587-99. [PMID: 8785056 DOI: 10.1016/s0896-6273(00)80078-1] [Citation(s) in RCA: 323] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 02/02/2023]
Abstract
Mice devoid of glial fibrillary acidic protein (GFAP), an intermediate filament protein specifically expressed in astrocytes, develop normally and do not show any detectable abnormalities in the anatomy of the brain. In the cerebellum, excitatory synaptic transmission from parallel fibers (PFs) or climbing fibers (CFs) to Purkinje cells is unaltered, and these synapses display normal short-term synaptic plasticity to paired stimuli in GFAP mutant mice. In contrast, long-term depression (LTD) at PF-Purkinje cell synapses is clearly deficient. Furthermore, GFAP mutant mice exhibited a significant impairment of eyeblink conditioning without any detectable deficits in motor coordination tasks. These results suggest that GFAP is required for communications between Bergmann glia and Purkinje cells during LTD induction and maintenance. The data support the notion that cerebellar LTD is a cellular mechanism closely associated with eyeblink conditioning, but is not essential for motor coordination tasks tested.
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Shou W, Aghdasi B, Armstrong DL, Guo Q, Bao S, Charng MJ, Mathews LM, Schneider MD, Hamilton SL, Matzuk MM. Cardiac defects and altered ryanodine receptor function in mice lacking FKBP12. Nature 1998; 391:489-92. [PMID: 9461216 DOI: 10.1038/35146] [Citation(s) in RCA: 309] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 02/06/2023]
Abstract
FKBP12, a cis-trans prolyl isomerase that binds the immunosuppressants FK506 and rapamycin, is ubiquitously expressed and interacts with proteins in several intracellular signal transduction systems. Although FKBP12 interacts with the cytoplasmic domains of type I receptors of the transforming growth factor-beta (TGF-beta) superfamily in vitro, the function of FKBP12 in TGF-beta superfamily signalling is controversial. FKBP12 also physically interacts stoichiometrically with multiple intracellular calcium release channels including the tetrameric skeletal muscle ryanodine receptor (RyR1). In contrast, the cardiac ryanodine receptor, RyR2, appears to bind selectively the FKBP12 homologue, FKBP12.6. To define the functions of FKBP12 in vivo, we generated mutant mice deficient in FKBP12 using embryonic stem (ES) cell technology. FKBP12-deficient mice have normal skeletal muscle but have severe dilated cardiomyopathy and ventricular septal defects that mimic a human congenital heart disorder, noncompaction of left ventricular myocardium. About 9% of the mutants exhibit exencephaly secondary to a defect in neural tube closure. Physiological studies demonstrate that FKBP12 is dispensable for TGF-beta-mediated signalling, but modulates the calcium release activity of both skeletal and cardiac ryanodine receptors.
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MESH Headings
- Abnormalities, Multiple/embryology
- Abnormalities, Multiple/etiology
- Abnormalities, Multiple/genetics
- Activins
- Amino Acid Isomerases/deficiency
- Amino Acid Isomerases/genetics
- Amino Acid Isomerases/physiology
- Animals
- Brain/abnormalities
- Brain/embryology
- Cardiomyopathy, Dilated/embryology
- Cardiomyopathy, Dilated/etiology
- Cardiomyopathy, Dilated/genetics
- Carrier Proteins/genetics
- Carrier Proteins/physiology
- DNA-Binding Proteins/genetics
- DNA-Binding Proteins/physiology
- Female
- Fetal Death
- Gene Deletion
- Heart Defects, Congenital/embryology
- Heart Defects, Congenital/etiology
- Heart Defects, Congenital/genetics
- Heart Septal Defects/embryology
- Heart Septal Defects/etiology
- Heart Septal Defects/genetics
- Heat-Shock Proteins/genetics
- Heat-Shock Proteins/physiology
- Inhibins/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Muscle, Skeletal/metabolism
- Ryanodine Receptor Calcium Release Channel/metabolism
- Signal Transduction
- Tacrolimus Binding Proteins
- Transforming Growth Factor beta/metabolism
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309 |
8
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Chen C, Kano M, Abeliovich A, Chen L, Bao S, Kim JJ, Hashimoto K, Thompson RF, Tonegawa S. Impaired motor coordination correlates with persistent multiple climbing fiber innervation in PKC gamma mutant mice. Cell 1995; 83:1233-42. [PMID: 8548809 DOI: 10.1016/0092-8674(95)90148-5] [Citation(s) in RCA: 280] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/31/2023]
Abstract
It is generally believed that a smooth execution of a compound movement, or motor coordination, requires learning of component movements as well as experience-based refinement of the motor program as a whole. PKC gamma mutant mice display impaired motor coordination but intact eyeblink conditioning, a form of component movement learning. Cerebellar long-term depression, a putative cellular mechanism for component motor learning, is also unimpaired. Thus, PKC gamma mutant mice are defective in refinement of the motor program. In the accompanying paper, we demonstrate that innervation of multiple climbing fibers onto Purkinje cells persists in adulthood in these mutant mice. We propose that this defective elimination of surplus climbing fibers underlies motor discoordination.
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Mugler JP, Bao S, Mulkern RV, Guttmann CR, Robertson RL, Jolesz FA, Brookeman JR. Optimized single-slab three-dimensional spin-echo MR imaging of the brain. Radiology 2000; 216:891-9. [PMID: 10966728 DOI: 10.1148/radiology.216.3.r00au46891] [Citation(s) in RCA: 260] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/11/2022]
Abstract
The development and optimization of spin-echo-based, single-slab, three-dimensional techniques for magnetic resonance imaging of the whole brain are described. T1-weighted and T2-weighted image sets with a volume resolution of 1 mm(3) and fluid-attenuated inversion-recovery image sets with a volume resolution of 3 mm(3) were obtained in acquisition times of less than 10 minutes per image set.
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10
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Bao S, Tibbetts RS, Brumbaugh KM, Fang Y, Richardson DA, Ali A, Chen SM, Abraham RT, Wang XF. ATR/ATM-mediated phosphorylation of human Rad17 is required for genotoxic stress responses. Nature 2001; 411:969-74. [PMID: 11418864 DOI: 10.1038/35082110] [Citation(s) in RCA: 198] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/03/2023]
Abstract
Genotoxic stress triggers the activation of checkpoints that delay cell-cycle progression to allow for DNA repair. Studies in fission yeast implicate members of the Rad family of checkpoint proteins, which includes Rad17, Rad1, Rad9 and Hus1, as key early-response elements during the activation of both the DNA damage and replication checkpoints. Here we demonstrate a direct regulatory linkage between the human Rad17 homologue (hRad17) and the checkpoint kinases, ATM and ATR. Treatment of human cells with genotoxic agents induced ATM/ATR-dependent phosphorylation of hRad17 at Ser 635 and Ser 645. Overexpression of a hRad17 mutant (hRad17AA) bearing Ala substitutions at both phosphorylation sites abrogated the DNA-damage-induced G2 checkpoint, and sensitized human fibroblasts to genotoxic stress. In contrast to wild-type hRad17, the hRad17AA mutant showed no ionizing-radiation-inducible association with hRad1, a component of the hRad1-hRad9-hHus1 checkpoint complex. These findings demonstrate that ATR/ATM-dependent phosphorylation of hRad17 is a critical early event during checkpoint signalling in DNA-damaged cells.
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11
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Ognjanovic S, Bao S, Yamamoto SY, Garibay-Tupas J, Samal B, Bryant-Greenwood GD. Genomic organization of the gene coding for human pre-B-cell colony enhancing factor and expression in human fetal membranes. J Mol Endocrinol 2001; 26:107-17. [PMID: 11241162 DOI: 10.1677/jme.0.0260107] [Citation(s) in RCA: 184] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 12/18/2022]
Abstract
Pre-B-cell colony enhancing factor (PBEF) was first isolated from an activated peripheral blood lymphocyte cDNA library and was found to be involved in the maturation of B-cell precursors. It was subsequently identified as one of the genes upregulated by distending the human fetal membranes in vitro. Here we report on the genomic organization of this gene, which is composed of 11 exons and 10 introns, spanning 34.7 kb of genomic DNA. Neither the gene nor the protein has any homology with other cytokines in any currently available database. The use of two promoters (proximal and distal) may result in differential, tissue specific expression of the PBEF transcripts. The 5'-flanking region lacks the classical sequence motif that would place it with the hematopoietic cytokines; however, it has several putative regulatory elements, suggesting that this gene may be chemically and mechanically responsive to inducers of transcription. The three PBEF mRNA transcripts were observed in both normal and infected human fetal membranes but were significantly upregulated (P<0.05) in severe infection. The PBEF protein was immunolocalized, in both normal and infected tissues, to both the normal fetal cells of the amnion and chorion and the maternal decidua of the membranes, and to the invading neutrophils. These stained strongly and were likely to contribute to the increased expression in infection. The amniotic epithelial cell line (WISH cells) has been used as a model to study PBEF gene modulation. Lipopolysaccharide, interleukin (IL)-1beta, tumour necrosis factor (TNF)alpha and IL-6 all significantly increased the expression of PBEF in 4 h of treatment. The addition of dexamethasone to IL-1beta and TNFalpha significantly reduced the response of PBEF to these cytokines. IL-8 treatment failed to alter PBEF gene expression. Thus PBEF is a cytokine expressed in the normal fetal membranes and upregulated when they are infected. It is likely to have a central role in the mechanism of infection-induced preterm birth.
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12
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Ernst M, Inglese M, Waring P, Campbell IK, Bao S, Clay FJ, Alexander WS, Wicks IP, Tarlinton DM, Novak U, Heath JK, Dunn AR. Defective gp130-mediated signal transducer and activator of transcription (STAT) signaling results in degenerative joint disease, gastrointestinal ulceration, and failure of uterine implantation. J Exp Med 2001; 194:189-203. [PMID: 11457894 PMCID: PMC2193459 DOI: 10.1084/jem.194.2.189] [Citation(s) in RCA: 167] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/20/2023] Open
Abstract
The receptor subunit gp130 transduces multiple cell type-specific activities of the leukemia inhibitory factor (LIF)/interleukin (IL)-6 family of cytokines through the signal transducer and activator of transcription (STAT) and src homology 2 domain-bearing protein tyrosine phosphatase (SHP)-2/ras/Erk pathways. To define STAT-dependent physiological responses, we generated mice with a COOH-terminal gp130(DeltaSTAT) "knock-in" mutation which deleted all STAT-binding sites. gp130(DeltaSTAT) mice phenocopyed mice deficient for IL-6 (impaired humoral and mucosal immune and hepatic acute phase responses) and LIF (failure of blastocyst implantation). However, unlike mice with null mutations in any of the components in the gp130 signaling pathway, gp130(DeltaSTAT) mice also displayed gastrointestinal ulceration and a severe joint disease with features of chronic synovitis, cartilaginous metaplasia, and degradation of the articular cartilage. Mitogenic hyperresponsiveness of synovial cells to the LIF/IL-6 family of cyto-kines was caused by sustained gp130-mediated SHP-2/ras/Erk activation due to impaired STAT-mediated induction of suppressor of cytokine signaling (SOCS) proteins which normally limits gp130 signaling. Therefore, the joint pathology in gp130(DeltaSTAT) mice is likely to arise from the disturbance of the otherwise balanced activation of the SHP-2/ras/Erk and STAT signaling cascades emanating from gp130.
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167 |
13
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Bao S, Beagley KW, France MP, Shen J, Husband AJ. Interferon-gamma plays a critical role in intestinal immunity against Salmonella typhimurium infection. Immunology 2000; 99:464-72. [PMID: 10712678 PMCID: PMC2327174 DOI: 10.1046/j.1365-2567.2000.00955.x] [Citation(s) in RCA: 142] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella bacteria are a major cause of food-borne infectious diarrhoea and there is great interest in understanding the pathogenesis of Salmonella infection and in vaccine development. Potential vaccines include the aromatic mutants of S. typhimurium. Such non-lethal Aro mutants have also been useful for studying Salmonella infections in mouse models. Studies of systemic infection, using these Aro mutants, in both normal and cytokine gene knockout mice, indicate that interferon-gamma (IFN-gamma) plays a key role in the resolution of Salmonella infection. The present studies have investigated the outcome of oral infection in mice with attenuated Salmonella because this infection route mimics natural infection in humans. In IFN-gamma gene knockout (IFN-gamma-/-) mice, intestinal immunity was impaired and oral challenge resulted in disseminated septicaemia 2 weeks later. No dissemination of infection was seen in wild-type mice. In wild-type mice, both CD4 and CD8 cell numbers increased in the gut following Salmonella challenge, together with increased expression of major histocompatibility complex (MHC) II and vascular cell adhesion molecule-1 (VCAM-1). No such changes were seen in IFNgamma-/- mice. Following oral challenge, antilipopolysaccharide (LPS) and antiphosphoryl choline antibodies increased by more than 100-fold in both serum and faecal pellet extracts of IFNgamma-/- mice compared with wild-type mice. Our data show that IFN-gamma production is essential for resolution of enteric Salmonella infection and that antibody has little effect on this process.
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142 |
14
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King PDC, Hatch RC, Bianchi M, Ovsyannikov R, Lupulescu C, Landolt G, Slomski B, Dil JH, Guan D, Mi JL, Rienks EDL, Fink J, Lindblad A, Svensson S, Bao S, Balakrishnan G, Iversen BB, Osterwalder J, Eberhardt W, Baumberger F, Hofmann P. Large tunable Rashba spin splitting of a two-dimensional electron gas in Bi2Se3. PHYSICAL REVIEW LETTERS 2011; 107:096802. [PMID: 21929260 DOI: 10.1103/physrevlett.107.096802] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Academic Contribution Register] [Received: 05/24/2011] [Indexed: 05/13/2023]
Abstract
We report a Rashba spin splitting of a two-dimensional electron gas in the topological insulator Bi(2)Se(3) from angle-resolved photoemission spectroscopy. We further demonstrate its electrostatic control, and show that spin splittings can be achieved which are at least an order-of-magnitude larger than in other semiconductors. Together these results show promise for the miniaturization of spintronic devices to the nanoscale and their operation at room temperature.
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139 |
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Thompson RF, Bao S, Chen L, Cipriano BD, Grethe JS, Kim JJ, Thompson JK, Tracy JA, Weninger MS, Krupa DJ. Associative learning. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1997; 41:151-89. [PMID: 9378587 DOI: 10.1016/s0074-7742(08)60351-7] [Citation(s) in RCA: 125] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 02/05/2023]
Abstract
This chapter reviews evidence demonstrating the essential role of the cerebellum and its associated circuitry in the learning and memory of classical conditioning of discrete behavioral responses (e.g., eyeblink, limb flexion, head turn). It now seems conclusive that the memory traces for this basic category of associative learning are formed and stored in the cerebellum. Lesion, neuronal recording, electrical microstimulation, and anatomical procedures have been used to identify the essential conditioned stimulus (CS) circuit, including the pontine mossy fiber projections to the cerebellum; the essential unconditioned stimulus (US) reinforcing or teaching circuit, including neurons in the inferior olive (dorsal accessory olive) projecting to the cerebellum as climbing fibers; and the essential conditioned response (CR) circuit, including the interpositus nucleus, its projection via the superior cerebellar peduncle to the magnocellular red nucleus, and rubral projections to premotor and motor nuclei. Each major component of the eyeblink CR circuit was reversibly inactivated both in trained animals and over the course of training. In all cases in trained animals, inactivation abolished the CR (and the UR as well when motor nuclei were inactivated). When animals were trained during inactivation (and not exhibiting CRs) and then tested without inactivation, animals with inactivation of the motor nuclei, red nucleus, and superior peduncle had fully learned, whereas animals with inactivation of a very localized region of the cerebellum (anterior interpositus and overlying cortex) had not learned at all. Consequently, the memory traces are formed and stored in the cerebellum. Several alternative possibilities are considered and ruled out. Both the cerebellar cortex and the interpositus nucleus are involved in the memory storage process, suggesting that a phenomenon-like long-term depression (LTD) is involved in the cerebellar cortex and long-term potentiation (LTP) is involved in the interpositus. The experimental findings reviewed in this chapter provide perhaps the first conclusive evidence for the localization of a basic form of memory storage to a particular brain region, namely the cerebellum, and indicate that the cerebellum is indeed a cognitive machine.
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Review |
28 |
125 |
16
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Kim JJ, Shih JC, Chen K, Chen L, Bao S, Maren S, Anagnostaras SG, Fanselow MS, De Maeyer E, Seif I, Thompson RF. Selective enhancement of emotional, but not motor, learning in monoamine oxidase A-deficient mice. Proc Natl Acad Sci U S A 1997; 94:5929-33. [PMID: 9159177 PMCID: PMC20883 DOI: 10.1073/pnas.94.11.5929] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 02/04/2023] Open
Abstract
Mice deficient in monoamine oxidase A (MAOA), an enzyme that metabolizes monoamines such as norepinephrine and serotonin, have elevated norepinephrine and serotonin levels in the frontal cortex, hippocampus, and cerebellum, compared with normal wild-type mice. Since monoamines in these areas are critically involved in a variety of behaviors, we examined learning and memory (using emotional and motor tasks) in MAOA mutant mice. The MAOA-deficient mice exhibited significantly enhanced classical fear conditioning (freezing to both tone and contextual stimuli) and step-down inhibitory avoidance learning. In contrast, eyeblink conditioning was normal in these mutant mice. The female MAOA-deficient mice also displayed normal species-typical maternal behaviors (nesting, nursing, and pup retrieval). These results suggest that chronic elevations of monoamines, due to a deletion of the gene encoding MAOA, lead to selective alterations in emotional behavior.
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Bao S, Obata Y, Carroll J, Domeki I, Kono T. Epigenetic modifications necessary for normal development are established during oocyte growth in mice. Biol Reprod 2000; 62:616-21. [PMID: 10684802 DOI: 10.1095/biolreprod62.3.616] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/01/2022] Open
Abstract
The ability of maternal chromatin to support full-term development is attained during oocyte growth. The aim of this study was to identify when during the growth phase the maternal chromatin developed the capacity to support term development. Mature metaphase II-arrested oocytes that contained chromatin from oocytes at different stages of oocyte growth were constructed by micromanipulation. The oocytes were fertilized in vitro, developed to the blastocyst stage in vitro, and transferred to recipients to assay developmental potential. The results demonstrate, firstly, that the origin of the maternal chromatin has no effect on the rate of oocyte maturation, fertilization, or development to the blastocyst in vitro. Secondly we demonstrate that maternal chromatin is first competent to support development to term during the latter half of oocyte growth when oocytes are 60-69 microm in diameter in juvenile mice or 50-59 microm in diameter in adult mice. These data show that epigenetic modifications necessary for postimplantation development occur during a specific phase of oocyte growth.
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113 |
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Shi Q, Bao S, Song L, Wu Q, Bigner DD, Hjelmeland AB, Rich JN. Targeting SPARC expression decreases glioma cellular survival and invasion associated with reduced activities of FAK and ILK kinases. Oncogene 2007; 26:4084-94. [PMID: 17213807 DOI: 10.1038/sj.onc.1210181] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/08/2022]
Abstract
Secreted protein acidic and rich in cysteine (SPARC) is an extracellular glycoprotein expressed in several solid cancers, including malignant gliomas, upon adoption of metastatic or invasive behaviors. SPARC expression in glioma cells promotes invasion and survival under stress, the latter process dependent on SPARC activation of AKT. Here we demonstrate that downregulation of SPARC expression with short interfering RNA (siRNA) in glioma cells decreased tumor cell survival and invasion. SPARC siRNA reduced the activating phosphorylation of AKT and two cytoplasmic kinases, focal adhesion kinase (FAK) and integrin-linked kinase (ILK). We determined the contributions of FAK and ILK to SPARC effects using SPARC protein and cell lines engineered to overexpress SPARC. SPARC activated FAK and ILK in glioma cells previously characterized as responsive to SPARC. Downregulation of either FAK or ILK expression inhibited SPARC-mediated AKT phosphorylation, and targeting both FAK and ILK attenuated AKT activation more potently than targeting either FAK or ILK alone. Decreased SPARC-mediated AKT activation correlated with a reduction in SPARC-dependent invasion and survival upon the downregulation of FAK and/or ILK expression. These data further demonstrate the role of SPARC in glioma tumor progression through the activation of intracellular kinases that may provide novel therapeutic targets for advanced cancers.
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106 |
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Di Bartolo BA, Chan J, Bennett MR, Cartland S, Bao S, Tuch BE, Kavurma MM. TNF-related apoptosis-inducing ligand (TRAIL) protects against diabetes and atherosclerosis in Apoe ⁻/⁻ mice. Diabetologia 2011; 54:3157-67. [PMID: 21965021 DOI: 10.1007/s00125-011-2308-0] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Received: 07/19/2011] [Accepted: 08/09/2011] [Indexed: 12/19/2022]
Abstract
AIMS/HYPOTHESIS TNF-related apoptosis-inducing ligand (TRAIL) is implicated in the regulation of diabetes and is reduced in patients with cardiovascular disease. Although TRAIL receptors are widespread, and TRAIL can promote cell proliferation and apoptosis, it is not known how TRAIL might protect against diabetes and atherosclerosis. METHODS We examined the development of atherosclerosis and diabetes in Apoe (-/-), Trail (also known as Tnfsf10)( -/- ) Apoe ( -/- ) and Trail ( -/- ) mice that were fed a high-fat diet. Plasma cholesterol, triacylglycerol, glucose and insulin, as well as changes in various metabolic enzymes and regulators were assessed. Glucose and insulin tolerance tests were performed. Pancreatic islets were examined for insulin and beta cell dysfunction (apoptosis and macrophage infiltration). RESULTS Compared with Apoe ( -/- ) mice, Trail ( -/- ) Apoe ( -/- ) and Trail ( -/- ) mice exhibited several features of diabetes, including increased weight, hyperglycaemia, reduced plasma insulin, impaired glucose tolerance, beta cell dysfunction, reduced islet insulin, macrophage infiltration and increased apoptosis. Trail ( -/- ) Apoe ( -/- ) mice had increased plasma cholesterol, triacylglycerol, and VLDL- and LDL-cholesterol, and increased expression of genes involved in cholesterol synthesis and lipogenesis. Trail ( -/- ) Apoe ( -/- ) mice also had increased atherosclerosis, with several features of plaque instability. CONCLUSIONS/INTERPRETATION We show for the first time that TRAIL deficiency promotes numerous features of diabetes that are typical of human disease, and are associated with reduced insulin and pancreatic inflammation/apoptosis. TRAIL also regulates cholesterol and triacylglycerol homeostasis in Apoe ( -/- ) mice by increasing the expression of genes involved in (1) cholesterol synthesis and absorption, and (2) triacylglycerol production.
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Miller DL, Bao S, Morris JE. Sonoporation of cultured cells in the rotating tube exposure system. ULTRASOUND IN MEDICINE & BIOLOGY 1999; 25:143-149. [PMID: 10048811 DOI: 10.1016/s0301-5629(98)00137-9] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Academic Contribution Register] [Indexed: 05/23/2023]
Abstract
Suspensions of Chinese hamster ovary cells were exposed to ultrasound in the presence of fluorescent dextran to determine the conditions needed for sonoporation with uptake of the large molecules. Albunex, a gas-body- based ultrasound contrast agent, was added to enhance cavitation. Ultrasound was continuous wave at frequencies of 1.0, 1.68, 2.25, 3.3, 5.3, and 7.15 MHz. Sterile 4.5-mL exposure chambers were rotated at 60 rpm to promote cavitation activity during the 1-min exposures. After exposure, cells were tested for sonoporation by counting fluorescent cells and for cell lysis by counting cells stained by trypan blue. Sonoporation was a sensitive bioeffects indicator that was detected at pressure amplitudes lower than were needed for transient cavitation or cavitation-induced cell lysis. For 10% Albunex, apparent thresholds for sonoporation, which were comparable to the levels required to perturb the gas bodies, were 0.084 MPa (spatial peak negative pressure amplitude) from 1.0-3.3 MHz and 0.27 MPa at 5.3 and 7.15 MHz. Sonoporation decreased slightly if the tube was not rotated. The effects increased for increasing Albunex concentration (with rotation). The plating efficiency of cells exposed to 0.2 MPa at 2.25 MHz and sorted by a flow cytometer was 19% (3.6% standard deviation [SD]) for fluorescent cells, compared to 67% (1% SD) for nonfluorescent exposed cells and 62% (6% SD) for sham-exposed cells. The reduced viability represents an important consideration for possible applications of sonoporation.
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Chen L, Bao S, Qiao X, Thompson RF. Impaired cerebellar synapse maturation in waggler, a mutant mouse with a disrupted neuronal calcium channel gamma subunit. Proc Natl Acad Sci U S A 1999; 96:12132-7. [PMID: 10518588 PMCID: PMC18424 DOI: 10.1073/pnas.96.21.12132] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/18/2022] Open
Abstract
The waggler, a neurological mutant mouse with a disrupted putative neuronal Ca(2+) channel gamma subunit, exhibits a cerebellar granule cell-specific brain-derived neurotrophic factor deficit, severe ataxia, and impaired eyeblink conditioning. Here, we show that multiple synapses of waggler cerebellar granule cells are arrested at an immature stage during development. Synaptic transmission is reduced at parallel fiber-Purkinje cell synapses. The Golgi cell-granule cell synaptic currents show immature kinetics associated with reduced gamma-aminobutyric acid type A receptor alpha6 subunit expression in granule cells. In addition, the mossy fiber-granule cell synapses exhibit N-methyl-D-aspartate (NMDA) receptor-mediated excitatory postsynaptic currents (EPSCs), but not alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated EPSCs. Our results suggest that voltage-dependent Ca(2+) channels are involved in synapse maturation. This deficient synaptic transmission in the waggler cerebellum may account for their behavioral deficits.
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Gockel CM, Bao S, Beagley KW. Transcutaneous immunization induces mucosal and systemic immunity: a potent method for targeting immunity to the female reproductive tract. Mol Immunol 2000; 37:537-44. [PMID: 11163403 DOI: 10.1016/s0161-5890(00)00074-2] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 11/29/2022]
Abstract
Female BALB/c mice were immunized with tetanus toxoid (TT) admixed with cholera toxin by direct application to shaved skin (Transcutaneous immunization, TCI). Tetanus toxoid-specific IgG and IgA in serum, saliva, vaginal lavage and fecal pellets were assayed by ELISA. Tetanus toxoid specific antibody-secreting cell (ASC) numbers were also determined by immunohistochemistry in sections of vagina, uterus, salivary gland and small intestine of immunized mice. TCI elicited significant levels of TT-specific IgG in serum, saliva and vaginal lavage, with the greatest increases over background seen in saliva (80-400 fold) and vaginal lavage (2-87 fold). TCI induced only modest levels of IgA in any of the samples tested (range 2-7 fold increase). In the absence of cholera toxin, application of TT alone did not result in detectable TT-specific antibodies in mucosal secretions. ASCs were found in all tissues following TCI. Cells were most frequent in uterus and vaginal tissues with ASC numbers less frequent in small intestine and salivary gland. This suggests that local production, rather than transudation from serum, is a major contributor of antibody in reproductive tract secretions. Further studies focussed on the role of sex hormones and immune induction following TCI. Animals immunized at the stage of oestrus cycle at which estrogen is abundant (Estrus), showed significantly lower levels of TT-specific IgG in vaginal lavage samples. Collectively, these data confirm the findings of Glenn and colleagues (1998), who showed TCI using cholera toxin can elicit high levels of serum IgG to both the toxin and co-administered antigen and further demonstrates that this route of immunization is particularly effective at eliciting humoral immunity in saliva and in the female reproductive tract.
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Li H, Sherman DM, Bao S, Sherman LA. Pattern of cyanophycin accumulation in nitrogen-fixing and non-nitrogen-fixing cyanobacteria. Arch Microbiol 2001; 176:9-18. [PMID: 11479698 DOI: 10.1007/s002030100281] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Received: 07/14/2000] [Accepted: 03/23/2001] [Indexed: 11/30/2022]
Abstract
The temporal and spatial accumulation of cyanophycin was studied in two unicellular strains of cyanobacteria, the diazotrophic Cyanothece sp. strain ATCC 51142 and the non-diazotrophic Synechocystis sp. strain PCC 6803. Biochemistry and electron microscopy were used to monitor the dynamics of cyanophycin accumulation under nitrogen-sufficient and nitrogen-deficient conditions. In Cyanothece sp. ATCC 51142 grown under 12 h light/12 h dark nitrogen-fixing conditions, cyanophycin was temporally regulated relative to nitrogenase activity and accumulated in granules after nitrogenase activity commenced. Cyanophycin granules reached a maximum after the peak of nitrogenase activity and eventually were utilized completely. Knock-out mutants were constructed in Synechocystis sp. PCC 6803 cphA and cphB genes to analyze the function of these genes and cyanophycin accumulation under nitrogen-deficient growth conditions. The mutants grew under such conditions, but needed to degrade phycobilisomes as a nitrogen reserve. Granules could be seen in some wild-type cells after treatment with chloramphenicol, but were never found in Delta cphA and Delta cphB mutants. These results led to the conclusion that cyanophycin is temporally and spatially regulated in nitrogen-fixing strains such as Cyanothece sp. ATCC 51142 and represents a key nitrogen reserve in these organisms. However, cyanophycin appeared to play a less important role in the non-diazotrophic unicellular strains and phycobilisomes appeared to be the main nitrogen reserve.
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Bao S, Kennedy A, Wojciechowski B, Wallace P, Ganaway E, Garvey WT. Expression of mRNAs encoding uncoupling proteins in human skeletal muscle: effects of obesity and diabetes. Diabetes 1998; 47:1935-40. [PMID: 9836527 DOI: 10.2337/diabetes.47.12.1935] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Academic Contribution Register] [Indexed: 11/13/2022]
Abstract
To explore the potential role of the uncoupling protein (UCP) family in human obesity and diabetes, we have used the reverse transcription-polymerase chain reaction to quantify UCP mRNA expression in human skeletal muscle. Levels of mRNA for UCP2, and for both short (UCP3S) and long (UCP3L) forms of UCP3, were highly correlated in individuals, indicating that gene transcription of these UCPs may be coordinately regulated by common mechanisms. In normal glucose-tolerant individuals, muscle UCP2 mRNA levels were positively correlated with percentage of body fat and with BMI (r = 0.6 and P < 0.05 for both). UCP3S mRNA levels were also positively correlated with percentage of body fat (r = 0.52, P < 0.05), and UCP3L mRNA tended to increase as a function of obesity (0.05 < P < 0.1). UCP mRNA levels, however, were not correlated with resting metabolic rate. UCP3S and UCP3L mRNA levels (P < 0.05) and the UCP2 mRNA level (P = 0.09) were increased by 1.8- to 2.7-fold in type 2 diabetes, an effect that could not be explained by obesity. No significant difference was found for UCP2, UCP3S, or UCP3L mRNA levels between insulin-sensitive and insulin-resistant nondiabetic subgroups. We conclude that 1) skeletal muscle mRNA levels encoding UCP2 and UCP3 are correlated among individuals and may be coordinately regulated; 2) UCP3 expression is not regulated by differential effects on UCP3L and UCP3S forms of the mRNA; and 3) UCP mRNA expression tends to increase in muscle as a function of obesity but not of resting metabolic rate or insulin resistance, and is increased in patients with type 2 diabetes.
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Fang Y, Shen J, Yao M, Beagley KW, Hambly BD, Bao S. Granulocyte-macrophage colony-stimulating factor enhances wound healing in diabetes via upregulation of proinflammatory cytokines. Br J Dermatol 2009; 162:478-86. [PMID: 19799605 DOI: 10.1111/j.1365-2133.2009.09528.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Academic Contribution Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND Chronic ulceration, especially in diabetes, remains a substantial clinical problem. Exogenous granulocyte-macrophage colony-stimulating factor (GM-CSF) is efficacious in the treatment of chronic wound healing in both animal models and patients, but its role in diabetic wounds remains to be explored. Objectives Using a diabetic mouse model, to investigate the role of GM-CSF in wound healing. METHODS Clinical observation, histopathology, immunohistochemistry and cytokine assays. RESULTS There was a significant reduction (50%) in GM-CSF production in the wounds of the diabetics compared with nondiabetics. Exogenous GM-CSF substantially enhanced the wound healing in diabetic mice, accompanied by increased interleukin-6 and monocyte chemoattractant protein-1 production. The elevated cytokines correlated with increased neovascularization, and infiltration of macrophages and neutrophils. GM-CSF showed no beneficial effects in nondiabetic wound healing. CONCLUSIONS Our results provide useful guidelines for the clinical management of chronic ulceration in diabetes.
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