bluuebunny/crossref_metadata_2025 huggingface dataset:
Stereotactic body radiotherapy in the treatment of Pancreatic Adenocarcinoma in elderly patients
Authors: Kim Carolyn H , Ling Diane C , Wegner Rodney E , Flickinger John C , Heron Dwight E , Zeh Herbert , Moser Arthur J , Burton Steven A
Published: October 2013

Background

Treatment of pancreatic adenocarcinoma in the elderly is often complicated by comorbidities that preclude surgery, chemotherapy and/or conventional external beam radiation therapy (EBRT). Stereotactic body radiotherapy (SBRT) has thus garnered interest in this setting.

Methods

A retrospective review of 26 patients of age ≥ 80 with pancreatic adenocarcinoma treated with definitive SBRT+/-chemotherapy from 2007–2011 was performed. Twenty-seven percent of patients were stage I, 38% were stage II, 27% were stage III and 8% were stage IV. Patients most commonly received 24 Gy/1 fraction or 30-36 Gy/3 fractions. Kaplan-Meier was used to estimate overall survival (OS), local control (LC), cause specific survival (CSS) and freedom-from-metastatic disease (FFMD).

Results

The median age was 86 (range 80–91), and median follow-up was 11.6 months (3.5-24.6). The median planning target volume was 21.48 cm3(6.1-85.09). Median OS was 7.6 months with 6/12 month OS rates of 65.4%/34.6%, respectively. Median LC was 11.5 months, 6-month and 12-month actuarial LC rates were 60.1% and 41.2%, respectively. There were no independent predictors for LC, but there was a trend for improved LC with prescription dose greater than 20 Gy (p = 0.063). Median CSS was 6.3 months, and 6-month and 12-month actuarial CSS were 53.8% and 23.1%, respectively. Median FFMD was 8.4 months, and 6-month and 12-month actuarial rates were 62.0% and 41.4%, respectively. Nine patients (47%) had local failures, 11 (58%) had distant metastasis, and 7 (37%) had both. There were no acute or late grade 3+ toxicities.

Conclusions

Definitive SBRT is feasible, safe and effective in elderly patients who have unresectable disease, have comorbidities precluding surgery or decline surgery.
Neurosensory development and cell fate determination in the human cochlea
Authors: Locher Heiko , Frijns Johan HM , van Iperen Liesbeth , de Groot John CMJ , Huisman Margriet A , Chuva de Sousa Lopes Susana M
Published: October 2013

Background

Hearing depends on correct functioning of the cochlear hair cells, and their innervation by spiral ganglion neurons. Most of the insight into the embryological and molecular development of this sensory system has been derived from animal studies. In contrast, little is known about the molecular expression patterns and dynamics of signaling molecules during normal fetal development of the human cochlea. In this study, we investigated the onset of hair cell differentiation and innervation in the human fetal cochlea at various stages of development.

Results

At 10 weeks of gestation, we observed a prosensory domain expressing SOX2 and SOX9/SOX10 within the cochlear duct epithelium. In this domain, hair cell differentiation was consistently present from 12 weeks, coinciding with downregulation of SOX9/SOX10, to be followed several weeks later by downregulation of SOX2. Outgrowing neurites from spiral ganglion neurons were found penetrating into the cochlear duct epithelium prior to hair cell differentiation, and directly targeted the hair cells as they developed. Ubiquitous Peripherin expression by spiral ganglion neurons gradually diminished and became restricted to the type II spiral ganglion neurons by 18 weeks. At 20 weeks, when the onset of human hearing is thought to take place, the expression profiles in hair cells and spiral ganglion neurons matched the expression patterns of the adult mammalian cochleae.

Conclusions

Our study provides new insights into the fetal development of the human cochlea, contributing to our understanding of deafness and to the development of new therapeutic strategies to restore hearing.
Impact of breast cancer subtypes on 3-year survival among adolescent and young adult women
Authors: Keegan Theresa H M , Press David J , Tao Li , DeRouen Mindy C , Kurian Allison W , Clarke Christina A , Gomez Scarlett L
Published: October 2013

Introduction

Young women have poorer survival after breast cancer than do older women. It is unclear whether this survival difference relates to the unique distribution of hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2)-defined molecular breast cancer subtypes among adolescent and young adult (AYA) women aged 15 to 39 years. The purpose of our study was to examine associations between breast cancer subtypes and short-term survival in AYA women, as well as to determine whether the distinct molecular subtype distribution among AYA women explains the unfavorable overall breast cancer survival statistics reported for AYA women compared with older women.

Methods

Data for 5,331 AYA breast cancers diagnosed between 2005 and 2009 were obtained from the California Cancer Registry. Survival by subtype (triple-negative; HR+/HER2-; HR+/HER2+; HR-/HER2+) and age-group (AYA versus 40- to 64-year-olds) was analyzed with Cox proportional hazards regression with follow-up through 2010.

Results

With up to 6 years of follow-up and a mean survival time of 3.1 years (SD = 1.5 years), AYA women diagnosed with HR-/HER + and triple-negative breast cancer experienced a 1.6-fold and 2.7-fold increased risk of death, respectively, from all causes (HR-/HER + hazard ratio: 1.55; 95% confidence interval (CI): 1.10 to 2.18; triple-negative HR: 2.75; 95% CI, 2.06 to 3.66) and breast cancer (HR-/HER + hazard ratio: 1.63; 95% CI, 1.12 to 2.36; triple-negative hazard ratio: 2.71; 95% CI, 1.98 to 3.71) than AYA women with HR+/HER2- breast cancer. AYA women who resided in lower socioeconomic status neighborhoods, had public health insurance, and were of Black, compared with White, race/ethnicity experienced worse survival. This race/ethnicity association was attenuated somewhat after adjusting for breast cancer subtypes (hazard ratio, 1.33; 95% CI, 0.98 to 1.82). AYA women had similar all-cause and breast cancer-specific short-term survival as older women for all breast cancer subtypes and across all stages of disease.

Conclusions

Among AYA women with breast cancer, short-term survival varied by breast cancer subtypes, with the distribution of breast cancer subtypes explaining some of the poorer survival observed among Black, compared with White, AYA women. Future studies should consider whether distribution of breast cancer subtypes and other factors, including differential receipt of treatment regimens, influences long-term survival in young compared with older women.
An automated and standardized neural index to quantify patient-ventilator interaction
Authors: Sinderby Christer , Liu Songqiao , Colombo Davide , Camarotta Gianmaria , Slutsky Arthur S , Navalesi Paolo , Beck Jennifer
Published: October 2013

Introduction

The aim of this study was to validate an automated, objective and standardized algorithm for quantifying and displaying patient-ventilator interaction.

Methods

Using a new method to detect patient-ventilator synchrony, the present study re-analyzed previously acquired and published data from 24 mechanically ventilated adult patients (Colombo et al., Crit Care Med. 2011 Nov;39(11):2452–7). Patient-ventilator interactions were evaluated by comparing ventilator pressure and diaphragm electrical activity (EAdi) waveforms, recorded during pressure support ventilation. The EAdi and ventilator pressure waveforms were analyzed for their timings (manually and automatically determined), and the error between the two waveforms was quantified. A new index of patient-ventilator interaction (NeuroSync index), which is standardized and automated, was validated and compared to manual analysis and previously published indices of asynchrony.

Results

The comparison of manual and automated detection methods produced high test-retest and inter-rater reliability (Intraclass correlation coefficient = 0.95). The NeuroSync index increased the sensitivity of detecting dyssynchronies, compared to previously published indices, which were found to only detect asynchronies.

Conclusion

The present study introduces an automated method and the NeuroSync index to determine patient-ventilator interaction with a more sensitive analysis method than those previously described. A dashboard-style of graphical display allows a rapid overview of patient-ventilator interaction and breathing pattern at the bedside.
Pro-adrenomedullin, pro-endothelin-1, procalcitonin, C-reactive protein and mortality risk in critically ill children: a prospective study
Authors: Rey Corsino , García-Hernández Irene , Concha Andrés , Martínez-Camblor Pablo , Botrán Marta , Medina Alberto , Prieto Belén , López-Herce Jesús
Published: October 2013

Introduction

We tested the hypothesis that higher mid-regional pro-adrenomedullin (MR-proADM), carboxy-terminal pro-endothelin-1 (CT-proET-1), procalcitonin (PCT) and C-reactive protein (CRP) plasma concentrations would be associated with increased prediction of mortality risk scores.

Methods

Prospective observational study set in two pediatric intensive care units (PICUs). Two-hundred-thirty-eight patients were included. MR-proADM, CT-proET-1, PCT and CRP levels were compared between children with PRISM III and PIM 2 > p75 (Group A; n = 33) and the rest (Group B; n = 205).

Results

Median (range) MR-proADM levels were 1.39 nmol/L (0.52–12.67) in group A versus 0.54 (0.15–3.85) in group B (P < 0.001). CT-proET-1 levels were 172 pmol/L (27–500) versus 58 (4–447) (P < 0.001). PCT levels were 7.77 ng/mL (0.34–552.00) versus 0.28 (0.02–107.00) (P < 0.001). CRP levels were 6.23 mg/dL (0.08-28.25) versus 1.30 mg/dL (0.00-42.09) (P = 0.210). The area under the ROC curve (AUC) for the differentiation of group A and B was 0.87 (95% CI:0.81–0.821) for MR-proADM, 0.86 (95% CI:0.79–0.92) for CT-proET-1 and 0.84 (95% CI:0.74–0.94) for PCT. A MR-proADM > 0.79 nmol/L had 93% sensitivity and 76% specificity to differentiate groups, whereas a CT-proET-1 > 123 pmol/L had 77% sensitivity and 84% specificity, and a PCT concentration > 2.05 ng/mL had 80% sensitivity and specificity.

Conclusions

In critically ill children, high levels of MR-proADM, CT-proET-1 and PCT were associated with increased prediction of mortality risk scores. MR-proADM, CT-proET-1 and PCT concentrations higher than 0.80 nmol/L, 123 pmol/L and 2 ng/mL, respectively, could be used by clinicians to identify critically ill children at higher prediction of risk death scores.
Structural Health Monitoring of a 54-Story Steel-Frame Building Using a Wave Method and Earthquake Records
Authors: Rahmani Mohammadtaghi , Todorovska Maria I.
Published: October 2013

The variations of identified wave velocities of vertically propagating waves through the structure are investigated for a 54-story steel-frame building in downtown Los Angeles, California, over a period of 19 years since construction (1992–2010), using records of six earthquakes. The set includes all significant earthquakes that shook this building, which produced maximum transient drift ∼0.3% and caused no reported damage. Wave velocity profiles β( z) are identified for the NS, EW, and torsional responses by fitting layered shear beam/torsional shaft models in the recorded responses, by waveform inversion of pulses in impulse response functions. The results suggest variations larger than the estimation error, with a coefficient of variation about 2–4.4%. About 10% permanent reduction of the building stiffness is detected, caused mainly by the Landers and Big Bear earthquake sequence of 28 June 1992, and the Northridge earthquake of 17 January 1994. Permanent changes of comparable magnitude were identified also in the first two apparent modal frequencies, f1; app, and f2; app, which were identified from the peaks of the transfer-function amplitudes.
On the importance of cotranscriptional RNA structure formation
Authors: Lai Daniel , Proctor Jeff R. , Meyer Irmtraud M.
Published: October 2013

The expression of genes, both coding and noncoding, can be significantly influenced by RNA structural features of their corresponding transcripts. There is by now mounting experimental and some theoretical evidence that structure formation in vivo starts during transcription and that this cotranscriptional folding determines the functional RNA structural features that are being formed. Several decades of research in bioinformatics have resulted in a wide range of computational methods for predicting RNA secondary structures. Almost all state-of-the-art methods in terms of prediction accuracy, however, completely ignore the process of structure formation and focus exclusively on the final RNA structure. This review hopes to bridge this gap. We summarize the existing evidence for cotranscriptional folding and then review the different, currently used strategies for RNA secondary-structure prediction. Finally, we propose a range of ideas on how state-of-the-art methods could be potentially improved by explicitly capturing the process of cotranscriptional structure formation.
Novel small RNA expression libraries uncover hsa-miR-30b and hsa-miR-30c as important factors in anoikis resistance
Authors: Moreno-Mateos Miguel A. , Barragán Verónica , Torres Belén , Rodríguez-Mateo Cristina , Méndez-Vidal Cristina , Berezikov Eugene , Mudduluru Giridhar , Allgayer Heike , Pintor-Toro José A.
Published: October 2013

MicroRNAs (miRNAs) have been widely studied in order to elucidate their biological functions. MicroRNA microarrays or miRNA overexpression libraries generated by synthesis and cloning of individual miRNAs have been used to study their different roles. In this work, we have developed a novel methodology to express mature miRNAs and other small RNAs from a double convergent RNA polymerase III promoter. We show that the generated miRNAs function similarly to those processed from primary transcripts or pri-miRNAs. This system allowed us to produce a lentiviral library expressing the whole population of small RNAs present in a metastatic cell line. A functional screening using this library led to the identification of hsa-miR-30b and hsa-miR-30c as negative regulators of cell death induced by loss of attachment (anoikis). Importantly, we demonstrated that the acquisition of anoikis resistance via these miRNAs is achieved through down-regulation of caspase 3 expression. Moreover, overexpression of these miRNAs resulted in a decrease of other types of caspase 3-dependent cell death and enhanced the survival of MCF10A acinar cells in morphogenesis assays, suggesting a putative role as oncomirs. In summary, this novel methodology provides a powerful and effective way for identifying novel small RNAs involved in a particular biological process.
Gentamicin in bone cement
Authors: Chang Y. , Tai C-L. , Hsieh P-H. , Ueng S. W. N.
Published: October 2013

Objectives

The objective of this study is to determine an optimal antibiotic-loaded bone cement (ALBC) for infection prophylaxis in total joint arthroplasty (TJA).

Methods

We evaluated the antibacterial effects of polymethylmethacrylate (PMMA) bone cements loaded with vancomycin, teicoplanin, ceftazidime, imipenem, piperacillin, gentamicin, and tobramycin against methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staph. aureus (MRSA), coagulase-negative staphylococci (CoNS), Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Standardised cement specimens made from 40 g PMMA loaded with 1 g antibiotics were tested for elution characteristics, antibacterial activities, and compressive strength in vitro.

Results

The ALBC containing gentamicin provided a much longer duration of antibiotic release than those containing other antibiotic. Imipenem-loading on the cement had a significant adverse effect on the compressive strength of the ALBC, which made it insufficient for use in prosthesis fixation. All of the tested antibiotics maintained their antibacterial properties after being mixed with PMMA. The gentamicin-loaded ALBC provided a broad antibacterial spectrum against all the test organisms and had the greatest duration of antibacterial activity against MSSA, CoNS, P. aeruginosa and E. coli.

Conclusion

When considering the use of ALBC as infection prophylaxis in TJA, gentamicin-loaded ALBC may be a very effective choice. Cite this article: Bone Joint Res 2013;2:220–6.
Tangent cones to positive-(1,1) De Rham currents
Authors: Bellettini Costante
Published: October 2013

We consider positive-(1,1) De Rham currents in arbitrary almost complex manifolds and prove the uniqueness of the tangent cone at any point where the density does not have a jump with respect to all of its values in a neighborhood. Without this assumption, counterexamples to the uniqueness of tangent cones can be produced already in ℂ
n
, hence our result is optimal. The key idea is an implementation, for currents in an almost complex setting, of the classical blow-up of curves in algebraic or symplectic geometry. Unlike the classical approach in ℂ
n
, we cannot rely on plurisubharmonic potentials.
On the Dedekind completion of function rings
Authors: Mozo Carollo Imanol , Gutiérrez García Javier , Picado Jorge
Published: October 2013

This paper introduces the frame of partially defined real numbers and the lattice-ordered ring of partial real functions on a frame. This is then used to construct the order completion of rings of pointfree continuous real functions. The bounded and integer-valued cases are also analysed. The application of this pointfree approach to the classical case C(X) of the ring of continuous real-valued functions on a topological space X yields a new construction for the Dedekind completion of C(X), considerably more direct and natural than the known procedure using Hausdorff continuous functions.
On Identifying Structural VAR Models via ARCH Effects
Authors: Milunovich George , Yang Minxian
Published: October 2013

Abstract: We consider the local identification of parameters in structural VAR models with ARCH type errors. By establishing a mapping between the structural and reduced-form models, we provide a set of sufficient conditions for the joint identification of all parameters. Under these conditions, as the structural parameters are identified, various restrictions on the parameters can be tested in a standard manner. For example, the significance test for the ARCH effect in the usual GARCH formulation for a structural shock does not suffer the complications caused by a lack of identification encountered in univariate GARCH models.
Divergent Patterns of Nonprofit Financial Distress
Authors: Never Brent
Published: October 2013

Human service nonprofit organizations have increasingly been called upon to produce public services as governments have sought to devolve responsibility to private organizations. Just as stress tests have used accounting indicators to determine the distress of banks, this article uses measures of financial distress (Shumway 2001; Trussel and Greenlee 2004) to understand what types of human service nonprofits are facing difficulties. Joining NCCS Core Files with spatial data from the American Community Survey, I find that there is a positive relationship between financial distress and minority population. The article enters the debate as to how cutting public funding for human services may harm vulnerable communities.
Titration of Syntaxin1 in Mammalian Synapses Reveals Multiple Roles in Vesicle Docking, Priming, and Release Probability
Authors: Arancillo Marife , Min Sang-Won , Gerber Stefan , Münster-Wandowski Agnieszka , Wu Yuan-Ju , Herman Melissa , Trimbuch Thorsten , Rah Jong-Cheol , Ahnert-Hilger Gudrun , Riedel Dietmar , Südhof Thomas C. , Rosenmund Christian
Published: October 2013

Synaptic vesicles undergo sequential steps in preparation for neurotransmitter release. Individual SNARE proteins and the SNARE complex itself have been implicated in these processes. However, discrete effects of SNARE proteins on synaptic function have been difficult to assess using complete loss-of-function approaches. We therefore used a genetic titration technique in cultured mouse hippocampal neurons to evaluate the contribution of the neuronal SNARE protein Syntaxin1 (Stx1) in vesicle docking, priming, and release probability. We generated graded reductions of total Stx1 levels by combining two approaches, namely, endogenous hypomorphic expression of the isoformStx1Band RNAi-mediated knockdown. Proximity of synaptic vesicles to the active zone was not strongly affected. However, overall release efficiency of affected neurons was severely impaired, as demonstrated by a smaller readily releasable pool size, slower refilling rate of primed vesicles, and lower release probability. Interestingly, dose–response fitting of Stx1 levels against readily releasable pool size and vesicular release probability showed similarKd(dissociation constant) values at 18% and 19% of wild-type Stx1, with cooperativity estimates of 3.4 and 2.5, respectively. This strongly suggests that priming and vesicle fusion share the same molecular stoichiometry, and are governed by highly related mechanisms.
Oligodendrocyte/Type-2 Astrocyte Progenitor Cells and Glial-Restricted Precursor Cells Generate Different Tumor Phenotypes in Response to the Identical Oncogenes
Authors: Wang Jun , Bushman Jared , Wang Xi , Mayer-Proschel Margot , Johnson Mahlon , Noble Mark
Published: October 2013

Despite the great interest in identifying the cell-of-origin for different cancers, little knowledge exists regarding the extent to which the specific origin of a tumor contributes to its properties. To directly examine this question, we expressed identical oncogenes in two types of glial progenitor cells, glial-restricted precursor (GRP) cells and oligodendrocyte/type-2 astrocyte progenitor cells (O-2A/OPCs), and in astrocytes of the mouse CNS (either directly purified or generated from GRP cells).In vitro, expression of identical oncogenes in these cells generated populations differing in expression of antigens thought to identify tumor initiating cells, generation of 3D aggregates when grown as adherent cultures, and sensitivity to the chemotherapeutic agent BCNU.In vivo, cells differed in their ability to form tumors, in malignancy and even in the type of host-derived cells infiltrating the tumor mass. Moreover, identical genetic modification of these different cells yielded benign infiltrative astrocytomas, malignant astrocytomas, or tumors with characteristics seen in oligodendrogliomas and small-cell astrocytomas, indicating a contribution of cell-of-origin to the characteristic properties expressed by these different tumors. Our studies also revealed unexpected relationships between the cell-of-origin, differentiation, and the order of oncogene acquisition at different developmental stages in enabling neoplastic growth. These studies thus provide multiple novel demonstrations of the importance of the cell-of-origin in respect to the properties of transformed cells derived from them. In addition, the approaches used enable analysis of the role of cell-of-origin in tumor biology in ways that are not accessible by other more widely used approaches.
Synaptic Regulation of Microtubule Dynamics in Dendritic Spines by Calcium, F-Actin, and Drebrin
Authors: Merriam Elliott B. , Millette Matthew , Lumbard Derek C. , Saengsawang Witchuda , Fothergill Thomas , Hu Xindao , Ferhat Lotfi , Dent Erik W.
Published: October 2013

Dendritic spines are actin-rich compartments that protrude from the microtubule-rich dendritic shafts of principal neurons. Spines contain receptors and postsynaptic machinery for receiving the majority of glutamatergic inputs. Recent studies have shown that microtubules polymerize from dendritic shafts into spines and that signaling through synaptic NMDA receptors regulates this process. However, the mechanisms regulating microtubule dynamics in dendrites and spines remain unclear. Here we show that in hippocampal neurons from male and female mice, the majority of microtubules enter spines from highly localized sites at the base of spines. These entries occur in response to synapse-specific calcium transients that promote microtubule entry into active spines. We further document that spine calcium transients promote local actin polymerization, and that F-actin is both necessary and sufficient for microtubule entry. Finally, we show that drebrin, a protein known to mediate interactions between F-actin and microtubules, acts as a positive regulator of microtubule entry into spines. Together these results establish for the first time the essential mechanisms regulating microtubule entry into spines and contribute importantly to our understanding of the role of microtubules in synaptic function and plasticity.
Medial and Lateral Networks in Anterior Prefrontal Cortex Support Metacognitive Ability for Memory and Perception
Authors: Baird Benjamin , Smallwood Jonathan , Gorgolewski Krzysztof J. , Margulies Daniel S.
Published: October 2013

Convergent evidence indicates that frontopolar Brodmann area 10, and more generally the anterior prefrontal cortex (aPFC), supports the human capacity to monitor and reflect on cognition and experience. An important unanswered question, however, is whether aPFC is a homogeneous region that supports a general-purpose metacognitive ability or whether there could be regional specialization within aPFC with respect to specific types of metacognitive processes. Previous studies suggest that the lateral and medial subdivisions within aPFC may support metacognitive judgments of moment-to-moment perceptual processes and assessments of information from memory stored over longer time scales, respectively. Here we directly compared intraindividual variability in metacognitive capacity for perceptual decisions and memorial judgments and used resting-state functional connectivity (rs-fcMRI) to relate this variability to the connectivity of the medial and lateral regions of aPFC. We found a behavioral dissociation in metacognitive ability for perceptual and memorial judgments. Furthermore, functional connectivity analysis revealed distinct patterns of connectivity that correlated with individual differences in each domain. Metacognitive ability for perceptual decisions was associated with greater connectivity between lateral regions of aPFC and right dorsal anterior cingulate cortex, bilateral putamen, right caudate, and thalamus, whereas metacognitive ability for memory retrieval predicted greater connectivity between medial aPFC and the right central precuneus and intraparietal sulcus/inferior parietal lobule. Together, these results suggest that an individual's capacity for accurate introspection in the domains of perception and memory is related to the functional integrity of unique neural networks anchored in the medial and lateral regions of the aPFC.
Structural Basis of Cerebellar Microcircuits in the Rat
Authors: Cerminara Nadia L. , Aoki Hanako , Loft Michaela , Sugihara Izumi , Apps Richard
Published: October 2013

The topography of the cerebellar cortex is described by at least three different maps, with the basic units of each map termed “microzones,” “patches,” and “bands.” These are defined, respectively, by different patterns of climbing fiber input, mossy fiber input, and Purkinje cell (PC) phenotype. Based on embryological development, the “one-map” hypothesis proposes that the basic units of each map align in the adult animal and the aim of the present study was to test this possibility. In barbiturate anesthetized adult rats, nanoinjections of bidirectional tracer (Retrobeads and biotinylated dextran amine) were made into somatotopically identified regions within the hindlimb C1 zone in copula pyramidis. Injection sites were mapped relative to PC bands defined by the molecular marker zebrin II and were correlated with the pattern of retrograde cell labeling within the inferior olive and in the basilar pontine nuclei to determine connectivity of microzones and patches, respectively, and also with the distributions of biotinylated dextran amine-labeled PC terminals in the cerebellar nuclei. Zebrin bands were found to be related to both climbing fiber and mossy fiber inputs and also to cortical representation of different parts of the ipsilateral hindpaw, indicating a precise spatial organization within cerebellar microcircuitry. This precise connectivity extends to PC terminal fields in the cerebellar nuclei and olivonuclear projections. These findings strongly support the one-map hypothesis and suggest that, at the microcircuit level of resolution, the cerebellar cortex has a common plan of spatial organization for major inputs, outputs, and PC phenotype.
Cell-Specific Fine-Tuning of Neuronal Excitability by Differential Expression of Modulator Protein Isoforms
Authors: Jepson James , Sheldon Amanda , Shahidullah Mohammad , Fei Hong , Koh Kyunghee , Levitan Irwin B.
Published: October 2013

SLOB (SLOWPOKE-binding protein) modulates theDrosophilaSLOWPOKE calcium-activated potassium channel. We have shown previously that SLOB deletion or RNAi knockdown decreases excitability of neurosecretory pars intercerebralis (PI) neurons in the adultDrosophilabrain. In contrast, we found that SLOB deletion/knockdown enhances neurotransmitter release from motor neurons at the fly larval neuromuscular junction, suggesting an increase in excitability. Because two prominent SLOB isoforms, SLOB57 and SLOB71, modulate SLOWPOKE channels in opposite directionsin vitro, we investigated whether divergent expression patterns of these two isoforms might underlie the differential modulation of excitability in PI and motor neurons. By performing detailedin vitroandin vivoanalysis, we found strikingly different modes of regulatory control by theslob57andslob71promoters. Theslob71, but notslob57, promoter contains binding sites for the Hunchback and Mirror transcriptional repressors. Furthermore, several core promoter elements that are absent in theslob57promoter coordinately drive robust expression of a luciferase vector by theslob71promoterin vitro. In addition, we visualized the expression patterns of theslob57andslob71promotersin vivoand found clear spatiotemporal differences in promoter activity. SLOB57 is expressed prominently in adult PI neurons, whereas larval motor neurons exclusively express SLOB71. In contrast, at the larval neuromuscular junction, SLOB57 expression appears to be restricted mainly to a subset of glial cells. Our results illustrate how the use of alternative transcriptional start sites within an ion channel modulator locus coupled with functionally relevant alternative splicing can be used to fine-tune neuronal excitability in a cell-specific manner.
α2δ-1 Gene Deletion Affects Somatosensory Neuron Function and Delays Mechanical Hypersensitivity in Response to Peripheral Nerve Damage
Authors: Patel Ryan , Bauer Claudia S. , Nieto-Rostro Manuela , Margas Wojciech , Ferron Laurent , Chaggar Kanchan , Crews Kasumi , Ramirez Juan D. , Bennett David L. H. , Schwartz Arnold , Dickenson Anthony H. , Dolphin Annette C.
Published: October 2013

The α2δ-1 subunit of voltage-gated calcium channels is upregulated after sensory nerve injury and is also the therapeutic target of gabapentinoid drugs. It is therefore likely to play a key role in the development of neuropathic pain. In this study, we have examined mice in which α2δ-1 gene expression is disrupted, to determine whether α2δ-1 is involved in various modalities of nociception, and for the development of behavioral hypersensitivity after partial sciatic nerve ligation (PSNL). We find that naive α2δ-1−/−mice show a marked behavioral deficit in mechanical and cold sensitivity, but no change in thermal nociception threshold. The lower mechanical sensitivity is mirrored by a reducedin vivoelectrophysiological response of dorsal horn wide dynamic range neurons. The CaV2.2 level is reduced in brain and spinal cord synaptosomes from α2δ-1−/−mice, and α2δ-1−/−DRG neurons exhibit lower calcium channel current density. Furthermore, a significantly smaller number of DRG neurons respond to the TRPM8 agonist menthol. After PSNL, α2δ-1−/−mice show delayed mechanical hypersensitivity, which only develops at 11 d after surgery, whereas in wild-type littermates it is maximal at the earliest time point measured (3 d). There is no compensatory upregulation of α2δ-2 or α2δ-3 after PSNL in α2δ-1−/−mice, and other transcripts, including neuropeptide Y and activating transcription factor-3, are upregulated normally. Furthermore, the ability of pregabalin to alleviate mechanical hypersensitivity is lost in PSNL α2δ-1−/−mice. Thus, α2δ-1 is essential for rapid development of mechanical hypersensitivity in a nerve injury model of neuropathic pain.
Shared Vulnerability of Two Synaptically-Connected Medial Temporal Lobe Areas to Age and Cognitive Decline: A Seven Tesla Magnetic Resonance Imaging Study
Authors: Kerchner Geoffrey A. , Bernstein Jeffrey D. , Fenesy Michelle C. , Deutsch Gayle K. , Saranathan Manojkumar , Zeineh Michael M. , Rutt Brian K.
Published: October 2013

The medial temporal lobe (MTL) is the first brain area to succumb to neurofibrillary tau pathology in Alzheimer's disease (AD). Postmortem human tissue evaluation suggests that this pathology propagates in an ordered manner, with the entorhinal cortex (ERC) and then CA1 stratum radiatum and stratum lacunosum-moleculare (CA1–SRLM)—two monosynaptically connected structures—exhibiting selective damage. Here, we hypothesized that, if ERC and CA1–SRLM share an early vulnerability to AD pathology, then atrophy should occur in a proportional manner between the two structures. We tested this hypothesis in living humans, using ultra-high field 7.0 T MRI to make fine measurements of MTL microstructure. Among a pool of age-matched healthy controls and patients with amnestic mild cognitive impairment and mild AD, we found a significant correlation between ERC and CA1–SRLM size that could not be explained by global atrophy affecting the MTL. Of the various structures that contribute axons or dendrites into the CA1–SRLM neuropil, only ERC emerged as a significant predictor of CA1–SRLM size in a linear regression analysis. In contrast, other synaptically connected elements of the MTL did not exhibit size correlations. CA1–SRLM and ERC structural covariance was significant for older controls and not patients, whereas the opposite pattern emerged for a correlation between CA1–SRLM and episodic memory performance. Interestingly, CA1–SRLM and ERC were the only MTL structures to atrophy in older controls relative to a younger comparison group. Together, these findings suggest that ERC and CA1–SRLM share vulnerability to both age and AD-associated atrophy.
Opposing Action of Nuclear Factor κB and Polo-like Kinases Determines a Homeostatic End Point for Excitatory Synaptic Adaptation
Authors: Mihalas Anca B. , Araki Yoichi , Huganir Richard L. , Meffert Mollie K.
Published: October 2013

Homeostatic responses critically adjust synaptic strengths to maintain stability in neuronal networks. Compensatory adaptations to prolonged excitation include induction of Polo-like kinases (Plks) and degradation of spine-associated Rap GTPase-activating protein (SPAR) to reduce synaptic excitation, but mechanisms that limit overshooting and allow refinement of homeostatic adjustments remain poorly understood. We report that Plks produce canonical pathway-mediated activation of the nuclear factor κB (NF-κB) transcription factor in a process that requires the kinase activity of Plks. Chronic elevated activity, which induces Plk expression, also produces Plk-dependent activation of NF-κB. Deficiency of NF-κB, in the context of exogenous Plk2 expression or chronic elevated neuronal excitation, produces exaggerated homeostatic reductions in the size and density of dendritic spines, synaptic AMPA glutamate receptor levels, and excitatory synaptic currents. During the homeostatic response to chronic elevated activity, NF-κB activation by Plks subsequently opposes Plk-mediated SPAR degradation by transcriptionally upregulating SPAR in mouse hippocampal neuronsin vitroandin vivo. Exogenous SPAR expression can rescue the overshooting of homeostatic reductions at excitatory synapses in NF-κB-deficient neurons responding to elevated activity. Our data establish an integral feedback loop involving NF-κB, Plks, and SPAR that regulates the end point of homeostatic synaptic adaptation to elevated activity and are the first to implicate a transcription factor in the regulation of homeostatic synaptic responses.
The Neural Cell Adhesion Molecule Promotes Maturation of the Presynaptic Endocytotic Machinery by Switching Synaptic Vesicle Recycling from Adaptor Protein 3 (AP-3)- to AP-2-Dependent Mechanisms
Authors: Shetty Aparna , Sytnyk Vladimir , Leshchyns'ka Iryna , Puchkov Dmytro , Haucke Volker , Schachner Melitta
Published: October 2013

Newly formed synapses undergo maturation during ontogenetic development via mechanisms that remain poorly understood. We show that maturation of the presynaptic endocytotic machinery in CNS neurons requires substitution of the adaptor protein 3 (AP-3) with AP-2 at the presynaptic plasma membrane. In mature synapses, AP-2 associates with the intracellular domain of the neural cell adhesion molecule (NCAM). NCAM promotes binding of AP-2 over binding of AP-3 to presynaptic membranes, thus favoring the substitution of AP-3 for AP-2 during formation of mature synapses. The presynaptic endocytotic machinery remains immature in adult NCAM-deficient (NCAM−/−) mice accumulating AP-3 instead of AP-2 and its partner protein AP180 in synaptic membranes and vesicles. NCAM deficiency or disruption of the NCAM/AP-2 complex in wild-type (NCAM+/+) neurons by overexpression of AP-2 binding-defective mutant NCAM interferes with efficient retrieval of the synaptic vesicle v-SNARE synaptobrevin 2. Abnormalities in synaptic vesicle endocytosis and recycling may thus contribute to neurological disorders associated with mutations in NCAM.
Multistate Structural Modeling and Voltage-Clamp Analysis of Epilepsy/Autism Mutation Kv10.2–R327H Demonstrate the Role of This Residue in Stabilizing the Channel Closed State
Authors: Yang Yang , Vasylyev Dmytro V. , Dib-Hajj Fadia , Veeramah Krishna R. , Hammer Michael F. , Dib-Hajj Sulayman D. , Waxman Stephen G.
Published: October 2013

Voltage-gated potassium channel Kv10.2 (KCNH5) is expressed in the nervous system, but its functions and involvement in human disease are poorly understood. We studied a human Kv10.2 channel mutation (R327H) recently identified in a child with epileptic encephalopathy and autistic features. Using multistate structural modeling, we demonstrate that the Arg327 residue in the S4 helix of voltage-sensing domain has strong ionic interactions with negatively charged residues within the S1–S3 helices in the resting (closed) and early-activation state but not in the late-activation and fully-activated (open) state. The R327H mutation weakens ionic interactions between residue 327 and these negatively charged residues, thus favoring channel opening. Voltage-clamp analysis showed a strong hyperpolarizing (∼70 mV) shift of voltage dependence of activation and an acceleration of activation. Our results demonstrate the critical role of the Arg327 residue in stabilizing the channel closed state and explicate for the first time the structural and functional change of a Kv10.2 channel mutation associated with neurological disease.
Gap Junction-Dependent Homolog Avoidance in the Developing CNS
Authors: Baker Michael W. , Yazdani Neema , Macagno Eduardo R.
Published: October 2013

Oppositely directed projections of some homologous neurons in the developing CNS of the medicinal leech (Hirudo verbana), such as the AP cells, undergo a form of contact-dependent homolog avoidance. Embryonic APs extend axons within the connective nerve toward adjacent ganglia, in which they meet and form gap junctions (GJs) with the oppositely directed axons of their segmental homologs, stop growing, and are later permanently retracted (Wolszon et al., 1994a,b). However, early deletion of an AP neuron leads to resumed growth and permanent maintenance of the projections of neighboring APs. Here we test the hypothesis that a GJ-based signaling mechanism is responsible for this instance of homolog avoidance. We demonstrate that selective knockdown of GJ geneHve–inx1expression in single embryonic APs, by expressing a short-hairpin interfering RNA, leads to continued growth of the projections of the cell toward, into, and beyond adjacent ganglia. Moreover, the projections of the APs in adjacent ganglia also resume growth, mimicking their responses to cell deletion. Continued growth was also observed when two different INX1 mutant transgenes that abolish dye coupling between APs were expressed. These include a mutant transgene that effectively downregulates all GJ plaques that include the INX1 protein and a closed channel INX1 mutant that retains the adhesive cellular binding characteristic of INX1 GJs but not the open channel pore function. Our results add GJ intercellular communication to the list of molecular signaling mechanisms that can act as mediators of growth-inhibiting cell–cell interactions that define the topography of neuronal arbors.
Frontal and Parietal Cortical Interactions with Distributed Visual Representations during Selective Attention and Action Selection
Authors: Nelissen Natalie , Stokes Mark , Nobre Anna C. , Rushworth Matthew F. S.
Published: October 2013

Using multivoxel pattern analysis (MVPA), we studied how distributed visual representations in human occipitotemporal cortex are modulated by attention and link their modulation to concurrent activity in frontal and parietal cortex. We detected similar occipitotemporal patterns during a simple visuoperceptual task and an attention-to-working-memory task in which one or two stimuli were cued before being presented among other pictures. Pattern strength varied from highest to lowest when the stimulus was the exclusive focus of attention, a conjoint focus, and when it was potentially distracting. Although qualitatively similar effects were seen inside regions relatively specialized for the stimulus category and outside, the former were quantitatively stronger. By regressing occipitotemporal pattern strength against activity elsewhere in the brain, we identified frontal and parietal areas exerting top-down control over, or reading information out from, distributed patterns in occipitotemporal cortex. Their interactions with patterns inside regions relatively specialized for that stimulus category were higher than those with patterns outside those regions and varied in strength as a function of the attentional condition. One area, the frontal operculum, was distinguished by selectively interacting with occipitotemporal patterns only when they were the focus of attention. There was no evidence that any frontal or parietal area actively inhibited occipitotemporal representations even when they should be ignored and were suppressed. Using MVPA to decode information within these frontal and parietal areas showed that they contained information about attentional context and/or readout information from occipitotemporal cortex to guide behavior but that frontal regions lacked information about category identity.
Doc2b Synchronizes Secretion from Chromaffin Cells by Stimulating Fast and Inhibiting Sustained Release
Authors: Pinheiro Paulo S. , de Wit Heidi , Walter Alexander M. , Groffen Alexander J. , Verhage Matthijs , Sørensen Jakob B.
Published: October 2013

Synaptotagmin-1 and -7 constitute the main calcium sensors mediating SNARE-dependent exocytosis in mouse chromaffin cells, but the role of a closely related calcium-binding protein, Doc2b, remains enigmatic. We investigated its role in chromaffin cells using Doc2b knock-out mice and high temporal resolution measurements of exocytosis. We found that the calcium dependence of vesicle priming and release triggering remained unchanged, ruling out an obligatory role for Doc2b in those processes. However, in the absence of Doc2b, release was shifted from the readily releasable pool to the subsequent sustained component. Conversely, upon overexpression of Doc2b, the sustained component was largely inhibited whereas the readily releasable pool was augmented. Electron microscopy revealed an increase in the total number of vesicles upon Doc2b overexpression, ruling out vesicle depletion as the cause for the reduced sustained component. Further experiments showed that, in the absence of Doc2b, the refilling of the readily releasable vesicle pools is faster, but incomplete. Faster refilling leads to an increase in the sustained component as newly primed vesicles fuse while the [Ca2+]ifollowing stimulation is still high. We conclude that Doc2b acts to inhibit vesicle priming during prolonged calcium elevations, thus protecting unprimed vesicles from fusing prematurely, and redirecting them to refill the readily releasable pool after relaxation of the calcium signal. In sum, Doc2b favors fast, synchronized release, and limits out-of-phase secretion.
Optic Flow Stimuli Update Anterodorsal Thalamus Head Direction Neuronal Activity in Rats
Authors: Arleo Angelo , Déjean Cyril , Allegraud Pierre , Khamassi Mehdi , Zugaro Michael B. , Wiener Sidney I.
Published: October 2013

Head direction (HD) neurons fire selectively according to head orientation in the yaw plane relative to environmental landmark cues. Head movements provoke optic field flow signals that enter the vestibular nuclei, indicating head velocity, and hence angular displacements. To test whether optic field flow alone affects the directional firing of HD neurons, rats walked about on a circular platform as a spot array was projected onto the surrounding floor-to-ceiling cylindrical black curtain. Directional responses in the anterodorsal thalamus of four rats remained stable as they moved about with the point field but in the absence of landmark cues. Then, the spherical projector was rotated about its yaw axis at 4.5°/s for ∼90 s. In 27 sessions the mean drift speed of the preferred directions (PDs) was 1.48°/s (SD=0.78°/s; range: 0.15 to 2.88°/s). Thus, optic flow stimulation entrained PDs, albeit at drift speeds slower than the field rotation. This could be due to conflicts with vestibular, motor command, and efferent copy signals. After field rotation ended, 20/27 PDs drifted back to within 45° of the initial values over several minutes, generally following the shortest path to return to the initial value. Poststimulation drifts could change speed and/or direction, with mean speeds of 0.68±0.64°/s (range 0 to 1.36°/s). Since the HD cell pathway (containing anterodorsal thalamus) is the only known projection of head direction information to entorhinal grid cells and hippocampal place cells, yaw plane optic flow signals likely influence representations in this spatial reference coordinate system for orientation and navigation.