The Wiring Economy Principle: Connectivity Determines Anatomy in the Human Brain

Minimization of the wiring cost of white matter fibers in the human brain appears to be an organizational principle. We investigate this aspect in the human brain using whole brain connectivity networks extracted from high resolution diffusion MRI data of 14 normal volunteers. We specifically address the question of whether brain anatomy determines its connectivity or vice versa. Unlike previous studies we use weighted networks, where connections between cortical nodes are real-valued rather than binary off-on connections. In one set of analyses we found that the connectivity structure of the brain has near optimal wiring cost compared to random networks with the same number of edges, degree distribution and edge weight distribution. A specifically designed minimization routine could not find cheaper wiring without significantly degrading network performance. In another set of analyses we kept the observed brain network topology and connectivity but allowed nodes to freely move on a 3D manifold topologically identical to the brain. An efficient minimization routine was written to find the lowest wiring cost configuration. We found that beginning from any random configuration, the nodes invariably arrange themselves in a configuration with a striking resemblance to the brain. This confirms the widely held but poorly tested claim that wiring economy is a driving principle of the brain. Intriguingly, our results also suggest that the brain mainly optimizes for the most desirable network connectivity, and the observed brain anatomy is merely a result of this optimization

Solisluumurtumien konservatiivinen ja operatiivinen hoito : Systemaattinen kirjallisuuskatsaus 1190 potilaasta

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Crucial Role for BAFF-BAFF-R Signaling in the Survival and Maintenance of Mature B Cells

Defects in the expression of either BAFF (B cell activating factor) or BAFF-R impairs B cell development beyond the immature, transitional type-1 stage and thus, prevents the formation of follicular and marginal zone B cells, whereas B-1 B cells remain unaffected. The expression of BAFF-R on all mature B cells might suggest a role for BAFF-R signaling also for their in vivo maintenance. Here, we show that, 14 days following a single injection of an anti-BAFF-R mAb that prevents BAFF binding, both follicular and marginal zone B cell numbers are drastically reduced, whereas B-1 cells are not affected. Injection of control, isotype-matched but non-blocking anti-BAFF-R mAbs does not result in B cell depletion. We also show that this depletion is neither due to antibody-dependent cellular cytotoxicity nor to complement-mediated lysis. Moreover, prevention of BAFF binding leads to a decrease in the size of the B cell follicles, an impairment of a T cell dependent humoral immune response and a reduction in the formation of memory B cells. Collectively, these results establish a central role for BAFF-BAFF-R signaling in the in vivo survival and maintenance of both follicular and marginal zone B cell pools

The Transcription Factor PU.1 Regulates γδ T Cell Homeostasis

T cell development results in the generation of both mature αβ and γδ T cells. While αβ T cells predominate in secondary lymphoid organs, γδ T cells are more abundant in mucosal tissues. PU.1, an Ets family transcription factor, also identified as the spleen focus forming virus proviral integration site-1 (Sfpi1) is essential for early stages of T cell development, but is down regulated during the DN T-cell stage.In this study, we show that in mice specifically lacking PU.1 in T cells using an lck-Cre transgene with a conditional Sfpi1 allele (Sfpi1(lck-/-)) there are increased numbers of γδ T cells in spleen, thymus and in the intestine when compared to wild-type mice. The increase in γδ T cell numbers in PU.1-deficient mice is consistent in γδ T cell subsets identified by TCR variable regions. PU.1-deficient γδ T cells demonstrate greater proliferation in vivo and in vitro.The increase of γδ T cell numbers in Lck-Cre deleter strains, where deletion occurs after PU.1 expression is diminished, as well as the observation that PU.1-deficient γδ T cells have greater proliferative responses than wild type cells, suggests that PU.1 effects are not developmental but rather at the level of homeostasis. Thus, our data shows that PU.1 has a negative influence on γδ T cell expansion

Silencing and Nuclear Repositioning of the λ5 Gene Locus at the Pre-B Cell Stage Requires Aiolos and OBF-1

The chromatin regulator Aiolos and the transcriptional coactivator OBF-1 have been implicated in regulating aspects of B cell maturation and activation. Mice lacking either of these factors have a largely normal early B cell development. However, when both factors are eliminated simultaneously a block is uncovered at the transition between pre-B and immature B cells, indicating that these proteins exert a critical function in developing B lymphocytes. In mice deficient for Aiolos and OBF-1, the numbers of immature B cells are reduced, small pre-BII cells are increased and a significant impairment in immunoglobulin light chain DNA rearrangement is observed. We identified genes whose expression is deregulated in the pre-B cell compartment of these mice. In particular, we found that components of the pre-BCR, such as the surrogate light chain genes λ5 and VpreB, fail to be efficiently silenced in double-mutant mice. Strikingly, developmentally regulated nuclear repositioning of the λ5 gene is impaired in pre-B cells lacking OBF-1 and Aiolos. These studies uncover a novel role for OBF-1 and Aiolos in controlling the transcription and nuclear organization of genes involved in pre-BCR function

Silicon particles as trojan horses for potential cancer therapy

[EN] Background: Porous silicon particles (PSiPs) have been used extensively as drug delivery systems, loaded with chemical species for disease treatment. It is well known from silicon producers that silicon is characterized by a low reduction potential, which in the case of PSiPs promotes explosive oxidation reactions with energy yields exceeding that of trinitrotoluene (TNT). The functionalization of the silica layer with sugars prevents its solubilization, while further functionalization with an appropriate antibody enables increased bioaccumulation inside selected cells. Results: We present here an immunotherapy approach for potential cancer treatment. Our platform comprises the use of engineered silicon particles conjugated with a selective antibody. The conceptual advantage of our system is that after reaction, the particles are degraded into soluble and excretable biocomponents. Conclusions: In our study, we demonstrate in particular, specific targeting and destruction of cancer cells in vitro. The fact that the LD50 value of PSiPs-HER-2 for tumor cells was 15-fold lower than the LD50 value for control cells demonstrates very high in vitro specificity. This is the first important step on a long road towards the design and development of novel chemotherapeutic agents against cancer in general, and breast cancer in particular.The authors acknowledge financial support from the following projects FIS2009-07812, MAT2012-35040, PROMETEO/2010/043, CTQ2011-23167, CrossSERS, FP7 MC-IEF 329131, and HSFP (project RGP0052/2012) and Medcom Tech SA. Xiang Yu acknowledges support by the Chinese government (CSC, Nr. 2010691036).Fenollosa Esteve, R.; Garcia-Rico, E.; Alvarez, S.; Alvarez, R.; Yu, X.; Rodriguez, I.; Carregal-Romero, S.... (2014). Silicon particles as trojan horses for potential cancer therapy. Journal of Nanobiotechnology. 12:1-10. https://doi.org/10.1186/s12951-014-0035-7S11012Prasad PN: Introduction to Nanomedicine and Nanobioengineering. Wiley, New York, 2012.Randall CL, Leong TG, Bassik N, Gracias DH: 3D lithographically fabricated nanoliter containers for drug delivery. Adv Drug Del Rev. 2007, 59: 1547-1561. 10.1016/j.addr.2007.08.024.Reibetanz U, Chen MHA, Mutukumaraswamy S, Liaw ZY, Oh BHL, Venkatraman S, Donath E, Neu BR: Colloidal DNA carriers for direct localization in cell compartments by pH sensoring. Biogeosciences. 2010, 11: 1779-1784.Tasciotti E, Liu X, Bhavane R, Plant K, Leonard AD, Price BK, Cheng MM-C, Decuzzi P, Tour JM, Robertson F, Ferrari M: Mesoporous silicon particles as a multistage delivery system for imaging and therapeutic applications. Nat Nano. 2008, 3: 151-157. 10.1038/nnano.2008.34.Park J-H, Gu L, von Maltzahn G, Ruoslahti E, Bhatia SN, Sailor MJ: Biodegradable luminescent porous silicon nanoparticles for in vivo applications. Nat Mater. 2009, 8: 331-336. 10.1038/nmat2398.Hong C, Lee J, Son M, Hong SS, Lee C: In-vivo cancer cell destruction using porous silicon nanoparticles. Anti-Cancer Drugs. 2011, 22: 971-977. 910.1097/CAD.1090b1013e32834b32859cCanham LT: Device Comprising Resorbable Silicon for Boron Capture Neutron Therapy. UK Patent Nr. 0302283.7. Book Device Comprising Resorbable Silicon for Boron Capture Neutron Therapy. UK Patent Nr. 0302283.7 (Editor ed.^eds.). 2003, UK Patent Nr. 0302283.7, CityXiao L, Gu L, Howell SB, Sailor MJ: Porous silicon nanoparticle photosensitizers for singlet oxygen and their phototoxicity against cancer cells. ACS Nano. 2011, 5: 3651-3659. 10.1021/nn1035262.Gil PR, Parak WJ: Composite nanoparticles take Aim at cancer. ACS Nano. 2008, 2: 2200-2205. 10.1021/nn800716j.Gomella LG: Is interstitial hyperthermia a safe and efficacious adjunct to radiotherapy for localized prostate cancer?. Nat Clin Pract Urol. 2004, 1: 72-73. 10.1038/ncpuro0041.Maier-Hauff K, Ulrich F, Nestler D, Niehoff H, Wust P, Thiesen B, Orawa H, Budach V, Jordan A: Efficacy and safety of intratumoral thermotherapy using magnetic iron-oxide nanoparticles combined with external beam radiotherapy on patients with recurrent glioblastoma multiforme. J Neuro-Oncol. 2011, 103: 317-324. 10.1007/s11060-010-0389-0.Lal S, Clare SE, Halas NJ: Nanoshell-enabled photothermal cancer therapy: Impending clinical impact. Acc Chem Res. 2008, 41: 1842-1851. 10.1021/ar800150g.Lee C, Kim H, Hong C, Kim M, Hong SS, Lee DH, Lee WI: Porous silicon as an agent for cancer thermotherapy based on near-infrared light irradiation. J Mater Chem. 2008, 18: 4790-4795. 10.1039/b808500e.Osminkina LA, Gongalsky MB, Motuzuk AV, Timoshenko VY, Kudryavtsev AA: Silicon nanocrystals as photo- and sono-sensitizers for biomedical applications. Appl Phys B. 2011, 105: 665-668. 10.1007/s00340-011-4562-8.Jain PK, Huang X, El-Sayed IH, El-Sayed MA: Noble metals on the nanoscale: optical and photothermal properties and some applications in imaging, sensing, biology, and medicine. Acc Chem Res. 2008, 41: 1578-1586. 10.1021/ar7002804.Serda RE, Godin B, Blanco E, Chiappini C, Ferrari M: Multi-stage delivery nano-particle systems for therapeutic applications. Biochim Biophys Acta. 1810, 2011: 317-329.Xu R, Huang Y, Mai J, Zhang G, Guo X, Xia X, Koay EJ, Qin G, Erm DR, Li Q, Liu X, Ferrari M, Shen H: Multistage vectored siRNA targeting ataxia-telangiectasia mutated for breast cancer therapy. Small. 2013, 9: 1799-1808. 10.1002/smll.201201510.Park JS, Kinsella JM, Jandial DD, Howell SB, Sailor MJ: Cisplatin-loaded porous Si microparticles capped by electroless deposition of platinum. Small. 2011, 7: 2061-2069. 10.1002/smll.201100438.Xue M, Zhong X, Shaposhnik Z, Qu Y, Tamanoi F, Duan X, Zink JI: pH-operated mechanized porous silicon nanoparticles. J Am Chem Soc. 2011, 133: 8798-8801. 10.1021/ja201252e.Canham LT: Bioactive silicon structure fabrication through nanoetching techniques. Adv Mater. 1995, 7: 1033-1037. 10.1002/adma.19950071215.Popplewell JF, King SJ, Day JP, Ackrill P, Fifield LK, Cresswell RG, Di Tada ML, Liu K: Kinetics of uptake and elimination of silicic acid by a human subject: a novel application of 32Si and accelerator mass spectrometry. J Inorganic Biochem. 1998, 69: 177-180. 10.1016/S0162-0134(97)10016-2.Shabir Q, Pokale A, Loni A, Johnson DR, Canham LT, Fenollosa R, Tymczenko M, Rodr guez I, Meseguer F, Cros A, Cantarero A: Medically biodegradable hydrogenated amorphous silicon microspheres. Silicon. 2011, 3: 173-176. 10.1007/s12633-011-9097-4.Chen Y, Wan Y, Wang Y, Zhang H, Jiao Z: Anticancer efficacy enhancement and attenuation of side effects of doxorubicin with titanium dioxide nanoparticles. Int J Nanomed. 2011, 6: 2321-2326.Mackowiak SA, Schmidt A, Weiss V, Argyo C, von Schirnding C, Bein T, Bräuchle C: Targeted drug delivery in cancer cells with Red-light photoactivated mesoporous silica nanoparticles. Nano Lett. 2013, 13: 2576-2583. 10.1021/nl400681f.Li Z, Barnes JC, Bosoy A, Stoddart JF, Zink JI: Mesoporous silica nanoparticles in biomedical applications. Chem Soc Rev. 2012, 41: 2590-2605. 10.1039/c1cs15246g.O Mara WC, Herring B, Hunt P: Handbook of Semiconductor Silicon Technology. Noyes Publication, New Jersey, 1990.Mikulec FV, Kirtland JD, Sailor MJ: Explosive nanocrystalline porous silicon and its Use in atomic emission spectroscopy. Adv Mater. 2002, 14: 38-41. 10.1002/1521-4095(20020104)14:13.0.CO;2-Z.Clement D, Diener J, Gross E, Kunzner N, Timoshenko VY, Kovalev D: Highly explosive nanosilicon-based composite materials. Phys Stat Sol A. 2005, 202: 1357-1359. 10.1002/pssa.200461102.Canham LT: Silicon quantum wire array fabrication by electrochemical and chemical dissolution of wafers. Appl Phys Lett. 1990, 57: 1046-1049. 10.1063/1.103561.Canham LT: Properties of Porous Silicon. INSPEC, United Kindom, 1997.Heinrich JL, Curtis CL, Credo GM, Sailor MJ, Kavanagh KL: Luminescent colloidal silicon suspensions from porous silicon. Science. 1992, 255: 66-68. 10.1126/science.255.5040.66.Littau KA, Szajowski PJ, Muller AJ, Kortan AR, Brus LE: A luminescent silicon nanocrystal colloid via a high-temperature aerosol reaction. J Phys Chem. 1993, 97: 1224-1230. 10.1021/j100108a019.Menz WJ, Shekar S, Brownbridge GPE, Mosbach S, Kōrmer R, Peukert W, Kraft M: Synthesis of silicon nanoparticles with a narrow size distribution: a theoretical study. J Aerosol Sci. 2012, 44: 46-61. 10.1016/j.jaerosci.2011.10.005.Swihart MT, Girshick SL: Thermochemistry and kinetics of silicon hydride cluster formation during thermal decomposition of silane. J Phys Chem B. 1998, 103: 64-76. 10.1021/jp983358e.Fenollosa R, Ramiro-Manzano F, Tymczenko M, Meseguer F: Porous silicon microspheres: synthesis, characterization and application to photonic microcavities. J Mater Chem. 2010, 20: 5210-5214. 10.1039/c0jm00079e.Ramiro-Manzano F, Fenollosa R, Xifré-Pérez E, Garín M, Meseguer F: Porous silicon microcavities based photonic barcodes. Adv Mater. 2011, 23: 3022-3025. 10.1002/adma.201100986.Kastl L, Sasse D, Wulf V, Hartmann R, Mircheski J, Ranke C, Carregal-Romero S, Martínez-López JA, Fernández-Chacón R, Parak WJ, Elsasser HP, Rivera-Gil P: Multiple internalization pathways of polyelectrolyte multilayer capsules into mammalian cells. ACS Nano. 2013, 7: 6605-6618. 10.1021/nn306032k.Schweiger C, Hartmann R, Zhang F, Parak W, Kissel T, Rivera_Gil P: Quantification of the internalization patterns of superparamagnetic iron oxide nanoparticles with opposite charge. J Nanobiotech. 2012, 10: 28-10.1186/1477-3155-10-28.Sanles-Sobrido M, Exner W, Rodr guez-Lorenzo L, Rodríguez-Gonzílez B, Correa-Duarte MA, Álvarez-Puebla RA, Liz-Marzán LM: Design of SERS-encoded, submicron, hollow particles through confined growth of encapsulated metal nanoparticles. J Am Chem Soc. 2009, 131: 2699-2705. 10.1021/ja8088444.Slamon D, Eiermann W, Robert N, Pienkowski T, Martin M, Press M, Mackey J, Glaspy J, Chan A, Pawlicki M, Pinter T, Valero V, Liu MC, Sauter G, von Minckwitz G, Visco F, Bee V, Buyse M, Bendahmane B, Tabah-Fisch I, Lindsay MA, Riva A, Crown J: Adjuvant trastuzumab in HER2-positive breast cancer. N Engl J Med. 2011, 365: 1273-1283. 10.1056/NEJMoa0910383.Agus DB, Gordon MS, Taylor C, Natale RB, Karlan B, Mendelson DS, Press MF, Allison DE, Sliwkowski MX, Lieberman G, Kelsey SM, Fyfe G: Phase I clinical study of pertuzumab, a novel HER dimerization inhibitor, in patients with advanced cancer. J Clin Oncol. 2005, 23: 2534-2543. 10.1200/JCO.2005.03.184.Colombo M, Mazzucchelli S, Montenegro JM, Galbiati E, Corsi F, Parak WJ, Prosperi D: Protein oriented ligation on nanoparticles exploiting O6-alkylguanine-DNA transferase (SNAP) genetically encoded fusion. Small. 2012, 8: 1492-1497. 10.1002/smll.201102284.Franklin MC, Carey KD, Vajdos FF, Leahy DJ, de Vos AM, Sliwkowski MX: Insights into ErbB signaling from the structure of the ErbB2-pertuzumab complex. Cancer Cell. 2004, 5: 317-328. 10.1016/S1535-6108(04)00083-2.Paris L, Cecchetti S, Spadaro F, Abalsamo L, Lugini L, Pisanu ME, Lorio E, Natali PG, Ramoni C, Podo F: Inhibition of phosphatidylcholine-specific phospholipase C downregulates HER2 overexpression on plasma membrane of breast cancer cells. Breast Cancer Res. 2010, 12: R27-10.1186/bcr2575.Fenollosa R, Meseguer F, Tymczenko M: Silicon colloids: from microcavities to photonic sponges. Adv Mater. 2008, 20: 95-98. 10.1002/adma.200701589.Jasinski JM, Gates SM: Silicon chemical vapor deposition one step at a time: fundamental studies of silicon hydride chemistry. Acc Chem Res. 1991, 24: 9-15. 10.1021/ar00001a002.Xiao Q, Liu Y, Qiu Y, Zhou G, Mao C, Li Z, Yao Z-J, Jiang S: Potent antitumor mimetics of annonaceous acetogenins embedded with an aromatic moiety in the left hydrocarbon chain part. J Med Chem. 2010, 54: 525-533. 10.1021/jm101053k.Allman SA, Jensen HH, Vijayakrishnan B, Garnett JA, Leon E, Liu Y, Anthony DC, Sibson NR, Feizi T, Matthews S, Davis BG: Potent fluoro-oligosaccharide probes of adhesion in toxoplasmosis. ChemBioChem. 2009, 10: 2522-2529. 10.1002/cbic.200900425.Chambers DJ, Evans GR, Fairbanks AJ: Elimination reactions of glycosyl selenoxides. Tetrahedron. 2004, 60: 8411-8419. 10.1016/j.tet.2004.07.005.Tomabechi Y, Suzuki R, Haneda K, Inazu T: Chemo-enzymatic synthesis of glycosylated insulin using a GlcNAc tag. Bioorg Med Chem. 2010, 18: 1259-1264. 10.1016/j.bmc.2009.12.031.Pastoriza-Santos I, Gomez D, Perez-Juste J, Liz-Marzan LM, Mulvaney P: Optical properties of metal nanoparticle coated silica spheres: a simple effective medium approach. Phys Chem Chem Phys. 2004, 6: 5056-5060. 10.1039/b405157b

Specific Humoral Immunity versus Polyclonal B Cell Activation in Trypanosoma cruzi Infection of Susceptible and Resistant Mice

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, affects 10–12 million people in Latin America. Patent parasitemia develops during acute disease. During this phase, polyclonal B cell activation has been reported to generate high levels of serum antibody with low parasite specificity, and delayed protective humoral immunity, which is necessary to prevent the host from succumbing to infection. In this manuscript, data show that relatively resistant mice have improved parasite-specific humoral immunity and decreased polyclonal B cell activation compared to susceptible mice. Parasite-specific humoral immunity was associated with differential expansion of B cell subsets and T cells in the spleen, as well as with increased Th1 and decreased Th2 cytokine production. These data suggest that host susceptibility/genetic biases impact the development of humoral responses to infection. Th2 cytokines are generally associated with improved antibody responses. In the context of T. cruzi infection of susceptible mice, Th2 cytokines were associated with increased total antibody production concomitant with delayed pathogen-specific humoral immunity. This study highlights the need to consider the effect of host biases when investigating humoral immunity to any pathogen that has reported polyclonal B cell activation during infection

The Emergence of Emotions

Emotion is conscious experience. It is the affective aspect of consciousness. Emotion arises from sensory stimulation and is typically accompanied by physiological and behavioral changes in the body. Hence an emotion is a complex reaction pattern consisting of three components: a physiological component, a behavioral component, and an experiential (conscious) component. The reactions making up an emotion determine what the emotion will be recognized as. Three processes are involved in generating an emotion: (1) identification of the emotional significance of a sensory stimulus, (2) production of an affective state (emotion), and (3) regulation of the affective state. Two opposing systems in the brain (the reward and punishment systems) establish an affective value or valence (stimulus-reinforcement association) for sensory stimulation. This is process (1), the first step in the generation of an emotion. Development of stimulus-reinforcement associations (affective valence) serves as the basis for emotion expression (process 2), conditioned emotion learning acquisition and expression, memory consolidation, reinforcement-expectations, decision-making, coping responses, and social behavior. The amygdala is critical for the representation of stimulus-reinforcement associations (both reward and punishment-based) for these functions. Three distinct and separate architectural and functional areas of the prefrontal cortex (dorsolateral prefrontal cortex, orbitofrontal cortex, anterior cingulate cortex) are involved in the regulation of emotion (process 3). The regulation of emotion by the prefrontal cortex consists of a positive feedback interaction between the prefrontal cortex and the inferior parietal cortex resulting in the nonlinear emergence of emotion. This positive feedback and nonlinear emergence represents a type of working memory (focal attention) by which perception is reorganized and rerepresented, becoming explicit, functional, and conscious. The explicit emotion states arising may be involved in the production of voluntary new or novel intentional (adaptive) behavior, especially social behavior

The effect of cognitive fatigue on prefrontal cortex correlates of neuromuscular fatigue in older women

BACKGROUND: As the population of adults aged 65 and above is rapidly growing, it is crucial to identify physical and cognitive limitations pertaining to daily living. Cognitive fatigue has shown to adversely impact neuromuscular function in younger adults, however its impact on neuromuscular fatigue, and associated brain function changes, in older adults is not well understood. The aim of the study was to examine the impact of cognitive fatigue on neuromuscular fatigue and associated prefrontal cortex (PFC) activation patterns in older women. METHODS: Eleven older (75.82 (7.4) years) females attended two sessions and performed intermittent handgrip exercises at 30 % maximum voluntary contraction (MVC) until voluntary exhaustion after a 60-min control (watching documentary) and 60-min cognitive fatigue (performing Stroop Color Word and 1-Back tests) condition. Dependent measures included endurance time, strength loss, PFC activity (measured using fNIRS), force fluctuations, muscle activity, cardiovascular responses, and perceived discomfort. RESULTS: Participants perceived greater cognitive fatigue after the 60-min cognitive fatigue condition when compared to the control condition. While neuromuscular fatigue outcomes (i.e., endurance time, strength loss, perceived discomfort), force fluctuations, and muscle activity were similar across both the control and cognitive fatigue conditions, greater decrements in PFC activity during neuromuscular fatigue development after the cognitive fatigue condition were observed when compared to the control condition. CONCLUSION: Despite similar neuromuscular outcomes, cognitive fatigue was associated with blunted PFC activation during the handgrip fatiguing exercise that may be indicative of neural adaptation with aging in an effort to maintain motor performance. Examining the relationship between cognitive fatigue and neuromuscular output by imaging other motor-related brain regions are needed to provide a better understanding of age-related compensatory adaptations to perform daily tasks that involve some levels of cognitive demand and physical exercise, especially when older adults experience them sequentially