bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma acetate, gluconate and interleukin-6 profiles during and after cardiopulmonary bypass: a comparison of Plasma-Lyte 148 with a bicarbonate-balanced solution
Authors: Davies Paul G , Venkatesh Balasubramanian , Morgan Thomas J , Presneill Jeffrey J , Kruger Peter S , Thomas Bronwyn J , Roberts Michael S , Mundy Julie
Published: January 2011

Introduction

As even small concentrations of acetate in the plasma result in pro-inflammatory and cardiotoxic effects, it has been removed from renal replacement fluids. However, Plasma-Lyte 148 (Plasma-Lyte), an electrolyte replacement solution containing acetate plus gluconate is a common circuit prime for cardio-pulmonary bypass (CPB). No published data exist on the peak plasma acetate and gluconate concentrations resulting from the use of Plasma-Lyte 148 during CPB.

Methods

Thirty adult patients were systematically allocated 1:1 to CPB prime with either bicarbonate-balanced fluid (24 mmol/L bicarbonate) or Plasma-Lyte 148. Arterial blood acetate, gluconate and interleukin-6 (IL-6) levels were measured immediately before CPB (T1), three minutes after CPB commencement (T2), immediately before CPB separation (T3), and four hours post separation (T4).

Results

Acetate concentrations (normal 0.04 to 0.07 mmol/L) became markedly elevated at T2, where the Plasma-Lyte group (median 3.69, range (2.46 to 8.55)) exceeded the bicarbonate group (0.16 (0.02 to 3.49), P < 0.0005). At T3, levels had declined but the differential pattern remained apparent (Plasma-Lyte 0.35 (0.00 to 1.84) versus bicarbonate 0.17 (0.00 to 0.81)). Normal circulating acetate concentrations were not restored until T4. Similar gluconate concentration profiles and inter-group differences were seen, with a slower T3 decay. IL-6 increased across CPB, peaking at T4, with no clear difference between groups.

Conclusions

Use of acetate containing prime solutions result in supraphysiological plasma concentrations of acetate. The use of acetate-free prime fluid in CPB significantly reduced but did not eliminate large acetate surges in cardiac surgical patients. Complete elimination of acetate surges would require the use of acetate free bolus fluids and cardioplegia solutions.

Trial registration

Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610000267055
Invasive ventilation modes in children: a systematic review and meta-analysis
Authors: Duyndam Anita , Ista Erwin , Houmes Robert Jan , van Driel Bionda , Reiss Irwin , Tibboel Dick
Published: January 2011

Introduction

The purpose of the present study was to critically review the existing body of evidence on ventilation modes for infants and children up to the age of 18 years.

Methods

The PubMed and EMBASE databases were searched using the search terms 'artificial respiration', 'instrumentation', 'device', 'devices', 'mode', and 'modes'. The review included only studies comparing two ventilation modes in a randomized controlled study and reporting one of the following outcome measures: length of ventilation (LOV), oxygenation, mortality, chronic lung disease and weaning. We quantitatively pooled the results of trials where suitable.

Results

Five trials met the inclusion criteria. They addressed six different ventilation modes in 421 children: high-frequency oscillation (HFO), pressure control (PC), pressure support (PS), volume support (VS), volume diffusive respirator (VDR) and biphasic positive airway pressure. Overall there were no significant differences in LOV and mortality or survival rate associated with the different ventilation modes. Two trials compared HFO versus conventional ventilation. In the pooled analysis, the mortality rate did not differ between these modes (odds ratio = 0.83, 95% confidence interval = 0.30 to 1.91). High-frequency ventilation (HFO and VDR) was associated with a better oxygenation after 72 hours than was conventional ventilation. One study found a significantly higher PaO2/FiO2 ratio with the use of VDR versus PC ventilation in children with burns. Weaning was studied in 182 children assigned to either a PS protocol, a VS protocol or no protocol. Most children could be weaned within 2 days and the weaning time did not significantly differ between the groups.

Conclusions

The literature provides scarce data for the best ventilation mode in critically ill children beyond the newborn period. There is no evidence, however, that high-frequency ventilation reduced mortality and LOV. Longer-term outcome measures such as pulmonary function, neurocognitive development, and cost-effectiveness should be considered in future studies.
Defining potentially conserved RNA regulons of homologous zinc-finger RNA-binding proteins
Authors: Scherrer Tanja , Femmer Christian , Schiess Ralph , Aebersold Ruedi , Gerber André P
Published: January 2011

Background

Glucose inhibition of gluconeogenic growth suppressor 2 protein (Gis2p) and zinc-finger protein 9 (ZNF9) are conserved yeast and human zinc-finger proteins. The function of yeast Gis2p is unknown, but human ZNF9 has been reported to bind nucleic acids, and mutations in the ZNF9 gene cause the neuromuscular disease myotonic dystrophy type 2. To explore the impact of these proteins on RNA regulation, we undertook a systematic analysis of the RNA targets and of the global implications for gene expression.

Results

Hundreds of mRNAs were associated with Gis2p, mainly coding for RNA processing factors, chromatin modifiers and GTPases. Target mRNAs contained stretches of G(A/U)(A/U) trinucleotide repeats located in coding sequences, which are sufficient for binding to both Gis2p and ZNF9, thus implying strong structural conservation. Predicted ZNF9 targets belong to the same functional categories as seen in yeast, indicating functional conservation, which is further supported by complementation of the large cell-size phenotype of gis2 mutants with ZNF9. We further applied a matched-sample proteome-transcriptome analysis suggesting that Gis2p differentially coordinates expression of RNA regulons, primarily by reducing mRNA and protein levels of genes required for ribosome assembly and by selectively up-regulating protein levels of myosins.

Conclusions

This integrated systematic exploration of RNA targets for homologous RNA-binding proteins indicates an unexpectedly high conservation of the RNA-binding properties and of potential targets, thus predicting conserved RNA regulons. We also predict regulation of muscle-specific genes by ZNF9, adding a potential link to the myotonic dystrophy related phenotypes seen in ZNF9 mouse models.
Comparative and functional genomics provide insights into the pathogenicity of dermatophytic fungi
Authors: Burmester Anke , Shelest Ekaterina , Glöckner Gernot , Heddergott Christoph , Schindler Susann , Staib Peter , Heidel Andrew , Felder Marius , Petzold Andreas , Szafranski Karol , Feuermann Marc , Pedruzzi Ivo , Priebe Steffen , Groth Marco , Winkler Robert , Li Wenjun , Kniemeyer Olaf , Schroeckh Volker , Hertweck Christian , Hube Bernhard , White Theodore C , Platzer Matthias , Guthke Reinhard , Heitman Joseph , Wöstemeyer Johannes , Zipfel Peter F , Monod Michel , Brakhage Axel A
Published: January 2011

Background

Millions of humans and animals suffer from superficial infections caused by a group of highly specialized filamentous fungi, the dermatophytes, which exclusively infect keratinized host structures. To provide broad insights into the molecular basis of the pathogenicity-associated traits, we report the first genome sequences of two closely phylogenetically related dermatophytes, Arthroderma benhamiae and Trichophyton verrucosum, both of which induce highly inflammatory infections in humans.

Results

97% of the 22.5 megabase genome sequences of A. benhamiae and T. verrucosum are unambiguously alignable and collinear. To unravel dermatophyte-specific virulence-associated traits, we compared sets of potentially pathogenicity-associated proteins, such as secreted proteases and enzymes involved in secondary metabolite production, with those of closely related onygenales (Coccidioides species) and the mould Aspergillus fumigatus. The comparisons revealed expansion of several gene families in dermatophytes and disclosed the peculiarities of the dermatophyte secondary metabolite gene sets. Secretion of proteases and other hydrolytic enzymes by A. benhamiae was proven experimentally by a global secretome analysis during keratin degradation. Molecular insights into the interaction of A. benhamiae with human keratinocytes were obtained for the first time by global transcriptome profiling. Given that A. benhamiae is able to undergo mating, a detailed comparison of the genomes further unraveled the genetic basis of sexual reproduction in this species.

Conclusions

Our results enlighten the genetic basis of fundamental and putatively virulence-related traits of dermatophytes, advancing future research on these medically important pathogens.
Troponin T is essential for sarcomere assembly in zebrafish skeletal muscle
Authors: Ferrante Maria I. , Kiff Rebecka M. , Goulding David A. , Stemple Derek L.
Published: January 2011

In striated muscle, the basic contractile unit is the sarcomere, which comprises myosin-rich thick filaments intercalated with thin filaments made of actin, tropomyosin and troponin. Troponin is required to regulate Ca2+-dependent contraction, and mutant forms of troponins are associated with muscle diseases. We have disrupted several genes simultaneously in zebrafish embryos and have followed the progression of muscle degeneration in the absence of troponin. Complete loss of troponin T activity leads to loss of sarcomere structure, in part owing to the destructive nature of deregulated actin–myosin activity. When troponin T and myosin activity are simultaneously disrupted, immature sarcomeres are rescued. However, tropomyosin fails to localise to sarcomeres, and intercalating thin filaments are missing from electron microscopic cross-sections, indicating that loss of troponin T affects thin filament composition. If troponin activity is only partially disrupted, myofibrils are formed but eventually disintegrate owing to deregulated actin–myosin activity. We conclude that the troponin complex has at least two distinct activities: regulation of actin–myosin activity and, independently, a role in the proper assembly of thin filaments. Our results also indicate that sarcomere assembly can occur in the absence of normal thin filaments.
Annexin A1 is a new functional linker between actin filaments and phagosomes during phagocytosis
Authors: Patel Devang M. , Ahmad Syed Furquan , Weiss Dieter G. , Gerke Volker , Kuznetsov Sergei A.
Published: January 2011

Remodelling of the actin cytoskeleton plays a key role in particle internalisation and the phagosome maturation processes. Actin-binding proteins (ABPs) are the main players in actin remodelling but the precise role of these proteins in phagocytosis needs to be clarified. Annexins, a group of ABPs, are known to be present on phagosomes. Here, we identified annexin A1 as a factor that binds to isolated latex bead phagosomes (LBPs) in the presence of Ca2+ and facilitates the F-actin–LBP interaction in vitro. In macrophages the association of endogenous annexin A1 with LBP membranes was strongly correlated with the spatial and temporal accumulation of F-actin at the LBP. Annexin A1 was found on phagocytic cups and around early phagosomes, where the F-actin was prominently concentrated. After uptake was completed, annexin A1, along with F-actin, dissociated from the nascent LBP surface. At later stages of phagocytosis annexin A1 transiently concentrated only around those LBPs that showed transient F-actin accumulation (‘actin flashing’). Downregulation of annexin A1 expression resulted in impaired phagocytosis and actin flashing. These data identify annexin A1 as an important component of phagocytosis that appears to link actin accumulation to different steps of phagosome formation.
Bax-derived membrane-active peptides act as potent and direct inducers of apoptosis in cancer cells
Authors: Valero Juan Garcia , Sancey Lucie , Kucharczak Jérôme , Guillemin Yannis , Gimenez Diana , Prudent Julien , Gillet Germain , Salgado Jesús , Coll Jean-Luc , Aouacheria Abdel
Published: January 2011

Although many cancer cells are primed for apoptosis, they usually develop resistance to cell death at several levels. Permeabilization of the outer mitochondrial membrane, which is mediated by proapoptotic Bcl-2 family members such as Bax, is considered as a point of no return for initiating apoptotic cell death. This crucial role has placed Bcl-2 family proteins as recurrent targets for anticancer drug development. Here, we propose and demonstrate a new concept based on minimal active versions of Bax to induce cell death independently of endogenous Bcl-2 proteins. We show that membrane-active segments of Bax can directly induce the release of mitochondria-residing apoptogenic factors and commit tumor cells promptly and irreversibly to caspase-dependent apoptosis. On this basis, we designed a peptide encompassing part of the Bax pore-forming domain, which can target mitochondria, induce cytochrome c release and trigger caspase-dependent apoptosis. Moreover, this Bax-derived ‘poropeptide’ produced effective tumor regression after peritumoral injection in a nude mouse xenograft model. Thus, peptides derived from proteins that form pores in the mitochondrial outer membrane represent novel templates for anticancer agents.
The Stil protein regulates centrosome integrity and mitosis through suppression of Chfr
Authors: Castiel Asher , Danieli Michal Mark , David Ahuvit , Moshkovitz Sharon , Aplan Peter D. , Kirsch Ilan R. , Brandeis Michael , Krämer Alwin , Izraeli Shai
Published: January 2011

Stil (Sil, SCL/TAL1 interrupting locus) is a cytosolic and centrosomal protein expressed in proliferating cells that is required for mouse and zebrafish neural development and is mutated in familial microcephaly. Recently the Drosophila melanogaster ortholog of Stil was found to be important for centriole duplication. Consistent with this finding, we report here that mouse embryonic fibroblasts lacking Stil are characterized by slow growth, low mitotic index and absence of clear centrosomes. We hypothesized that Stil regulates mitosis through the tumor suppressor Chfr, an E3 ligase that blocks mitotic entry in response to mitotic stress. Mouse fibroblasts lacking Stil by genomic or RNA interference approaches, as well as E9.5 Stil−/− embryos, express high levels of the Chfr protein and reduced levels of the Chfr substrate Plk1. Exogenous expression of Stil, knockdown of Chfr or overexpression of Plk1 reverse the abnormal mitotic phenotypes of fibroblasts lacking Stil. We further demonstrate that Stil increases Chfr auto-ubiquitination and reduces its protein stability. Thus, Stil is required for centrosome organization, entry into mitosis and cell proliferation, and these functions are at least partially mediated by Chfr and its targets. This is the first identification of a negative regulator of the Chfr mitotic checkpoint.
Prescriber Compliance with a New Computerized Insulin Guideline for Noncritically III Adults
Authors: Clemens Evan , Cutler Timothy , Canaria Janice , Pandya Komal , Parker Patricia
Published: January 2011

BACKGROUND:

In March 2008, the University of California, Davis Medical Center (UCDMC), implemented a guideline for the inpatient management of diabetes in noncritically ill adults. In accordance with national guidelines, all patients with type 2 diabetes are prescribed basal, nutritional, and correctional insulin. The guideline was added to the electronic medical record as a standardized physician order set in April 2008 and provider training on the insulin guideline occurred in May 2008.

OBJECTIVE:

To evaluate provider compliance with a new electronic standardized insulin order set in a hospital setting.

METHODS:

All patients with insulin orders admitted to the general internal medicine service between June 1, 2008, and November 1, 2008, were evaluated in this single-center retrospective chart review at UCDMC in Sacramento. Patients older than 18 years with a history of type 2 diabetes were included in the analysis. Insulin orders were categorized as preferred (followed the guideline) or nonpreferred regimens (did not follow all components of the guideline).

RESULTS:

A total of 265 patients were identified during the study period. The preferred regimen was ordered in 82 (30.9%) of the evaluated patient admissions. Of the 183 (69.1%) nonpreferred regimens, more than half (54.6%) contained correctional insulin alone; 84.2% of patient admissions prescribed nonpreferred regimens lacked nutritional insulin. Average admission blood glucose readings were higher in the preferred versus nonpreferred regimen group (224.4 vs 164.8 mg/dL, p < 0.001).

CONCLUSIONS:

The preferred regimen was not prescribed for the majority of patients admitted with a history of type 2 diabetes, despite computerized decision support. Nutritional insulin was the most common missing component in the nonpreferred regimens. Baseline clinical factors, educational modalities, and guideline content may have influenced prescribing patterns.
Convergent synthesis of new types of stabilized carotenoid compounds
Authors: Kim Soo Bong , Kim Hyungjun , Lim Boram , Meang Juwan , Bae Sung-Hee , Choi Eunho , Oh Jung Taek , Hong Inseok , Jung Se-Young , Yeo Jung Eun , Koo Sangho
Published: January 2011

A convergent synthetic method for new types of carotenoid compounds containing phenyl substituents at C(13) and C(13') has been developed by the coupling of allylic sulfone and 2,7-diphenyloct-4-enedials, followed by the double elimination strategy. These carotenoid compounds are fairly stable and legitimate candidates for nanosized molecular wires, which show diverse conductance values according to the electronic nature of the substituent group in the phenyl ring.
Unusual Pungency from Extra-Virgin Olive Oil Is Attributable to Restricted Spatial Expression of the Receptor of Oleocanthal
Authors: Peyrot des Gachons Catherine , Uchida Kunitoshi , Bryant Bruce , Shima Asako , Sperry Jeffrey B. , Dankulich-Nagrudny Luba , Tominaga Makoto , Smith Amos B. , Beauchamp Gary K. , Breslin Paul A. S.
Published: January 2011

Oleocanthal, a major phenolic compound in extra-virgin olive oil with antiinflammatory properties, elicits an unusual oral pungency sensed almost exclusively in the throat. This contrasts with most other common oral irritants, such as cinnamaldehyde, capsaicin, and alcohol, which irritate mucus membranes throughout the oral cavity. Here, we show that this rare irritation pattern is a consequence of both the specificity of oleocanthal for a single sensory receptor and the anatomical restriction of this sensory receptor to the pharynx, within the oral cavity. We demonstrate,in vitro, that oleocanthal selectively activates the hTRPA1 channel in HEK 293 cells and that its ability to excite the trigeminal nervous system in rodents requires a functional TRPA1. Moreover, we similarly demonstrate that the over-the-counter analgesic, ibuprofen, which elicits the same restricted pharyngeal irritation as oleocanthal, also specifically excites rodent sensory neurons via TRPA1. Using human sensory psychophysical studies and immunohistochemical TRPA1 analyses of human oral and nasal tissues, we observe an overlap of the anatomical distribution of TRPA1 and the regions irritated by oleocanthal in humans. These results suggest that aTRPA1(ANKTM1) gene product mediates the tissue sensitivity to oleocanthal within the oral cavity. Furthermore, we demonstrate that, despite the fact that oleocanthal possesses the classic electrophilic reactivity of many TRPA1 agonists, it does not use the previously identified activation mechanism via covalent cysteine modification. These findings provide an anatomical and molecular explanation for a distinct oral sensation that is elicited by oleocanthal and ibuprofen and that is commonly experienced around the world when consuming many extra-virgin olive oils.
Increased Neurotransmitter Release at the Neuromuscular Junction in a Mouse Model of Polyglutamine Disease
Authors: Rozas José L. , Gómez-Sánchez Leonardo , Tomás-Zapico Cristina , Lucas José J. , Fernández-Chacón Rafael
Published: January 2011

In Huntington's disease (HD), the expansion of polyglutamine (polyQ) repeats at the N terminus of the ubiquitous protein huntingtin (htt) leads to neurodegeneration in specific brain areas. Neurons degenerating in HD develop synaptic dysfunctions. However, it is unknown whether mutant htt impacts synaptic function in general. To investigate that, we have focused on the nerve terminals of motor neurons that typically do not degenerate in HD. Here, we have studied synaptic transmission at the neuromuscular junction of transgenic mice expressing a mutant form of htt (R6/1 mice). We have found that the size and frequency of miniature endplate potentials are similar in R6/1 and control mice. In contrast, the amplitude of evoked endplate potentials in R6/1 mice is increased compared to controls. Consistent with a presynaptic increase of release probability, synaptic depression under high-frequency stimulation is higher in R6/1 mice. In addition, no changes were detected in the size and dynamics of the recycling synaptic vesicle pool. Moreover, we have found increased amounts of the synaptic vesicle proteins synaptobrevin 1,2/VAMP 1,2 and cysteine string protein-α, and the SNARE protein SNAP-25, concomitant with normal levels of other synaptic vesicle markers. Our results reveal that the transgenic expression of a mutant form of htt leads to an unexpected gain of synaptic function. That phenotype is likely not secondary to neurodegeneration and might be due to a primary deregulation in synaptic protein levels. Our findings could be relevant to understand synaptic toxic effects of proteins with abnormal polyQ repeats.
Gdf11 Facilitates Temporal Progression of Neurogenesis in the Developing Spinal Cord
Authors: Shi Yingtang , Liu Jeh-Ping
Published: January 2011

Various types of neurons and glia are generated following a precise spatial and temporal order during neurogenesis. The mechanisms that control this sequential generation of neuronal and glial cell types from the same progenitor population are not well understood. Growth differentiation factor 11 (Gdf11) belongs to the TGF-β family of proteins and is expressed transiently in newly born neurons adjacent to the progenitor domain in the developing spinal cord. We examined the phenotypes ofGdf11−/−mouse embryos and found that without Gdf11, neuronal differentiation in the spinal cord progresses at a slower rate. Higher progenitor proliferation rate, along with a delay in gliogenesis, is also observed inGdf11−/−spinal cord but only after the peak ofGdf11expression, indicating that Gdf11 can cause long-lasting changes in progenitor properties. These changes can be preservedin vitro, as neurospheres derived fromGdf11−/−and wild-type littermates at a stage after, but not before the onset ofGdf11expression, exhibit differences in proliferation and differentiation potential. Moreover, these changes in progenitor properties can be inducedin vitroby the addition of Gdf11. We also demonstrate that the effects of Gdf11 on progenitor cells are associated with its ability to upregulate p57Kip2and p27Kip1while downregulating Pax6 expression. These results support a model in which Gdf11 secreted by newly born neurons in the developing spinal cord facilitates the temporal progression of neurogenesis by acting as a positive feedback signal on the progenitor cells to promote cell cycle exit and decrease proliferation ability, thus changing their differentiation potential.
Spasmodic Dysphonia: a Laryngeal Control Disorder Specific to Speech: Figure 1.
Authors: Ludlow Christy L.
Published: January 2011

Spasmodic dysphonia (SD) is a rare neurological disorder that emerges in middle age, is usually sporadic, and affects intrinsic laryngeal muscle control only during speech. Spasmodic bursts in particular laryngeal muscles disrupt voluntary control during vowel sounds in adductor SD and interfere with voice onset after voiceless consonants in abductor SD. Little is known about its origins; it is classified as a focal dystonia secondary to an unknown neurobiological mechanism that produces a chronic abnormality of laryngeal motor neuron regulation during speech. It develops primarily in females and does not interfere with breathing, crying, laughter, and shouting. Recent postmortem studies have implicated the accumulation of clusters in the parenchyma and perivascular regions with inflammatory changes in the brainstem in one to two cases. A few cases with single mutations inTHAP1, a gene involved in transcription regulation, suggest that a weak genetic predisposition may contribute to mechanisms causing a nonprogressive abnormality in laryngeal motor neuron control for speech but not for vocal emotional expression. Research is needed to address the basic cellular and proteomic mechanisms that produce this disorder to provide intervention that could target the pathogenesis of the disorder rather than only providing temporary symptom relief.
DrosophilaAmyloid Precursor Protein-Like Is Required for Long-Term Memory
Authors: Goguel Valérie , Belair Anne-Laure , Ayaz Derya , Lampin-Saint-Amaux Aurélie , Scaplehorn Niki , Hassan Bassem A. , Preat Thomas
Published: January 2011

The amyloid precursor protein (APP) plays an important role in Alzheimer's disease (AD), a progressive neurodegenerative pathology that first manifests as a decline of memory. While the main hypothesis for AD pathology centers on the proteolytic processing of APP, very little is known about the physiological function of the APP protein in the adult brain. Likewise, whether APP loss of function contributes to AD remains unclear.Drosophilahas been used extensively as a model organism to study neuronal function and pathology. In addition, many of the molecular mechanisms underlying memory are thought to be conserved from flies to mammals, prompting us to study the function of APPL, the fly APP ortholog, during associative memory. It was previously shown that APPL expression is highly enriched in the mushroom bodies (MBs), a specialized brain structure involved in olfactory memory. We analyzed memory in flies in which APPL expression has been silenced specifically and transiently in the adult MBs. Our results show that in adult flies, APPL is not required for learning but is specifically involved in long-term memory, a long lasting memory whose formation requiresde novoprotein synthesis and is thought to require synaptic structural plasticity. These data support the hypothesis that disruption of normal APP function may contribute to early AD cognitive impairment.
Multiple Reference Frames for Saccadic Planning in the Human Parietal Cortex
Authors: Pertzov Yoni , Avidan Galia , Zohary Ehud
Published: January 2011

We apply functional magnetic resonance imaging and multivariate analysis methods to study the coordinate frame in which saccades are represented in the human cortex. Subjects performed a memory-guided saccade task in which equal-amplitude eye movements were executed from several starting points to various directions. Response patterns during the memory period for same-vector saccades were correlated in the frontal eye fields and the intraparietal sulcus (IPS), indicating a retinotopic representation. Interestingly, response patterns in the middle aspect of the IPS were also correlated for saccades made to the same destination point, even when their movement vector was different. Thus, this region also contains information about saccade destination in (at least) a head-centered coordinate frame. This finding may explain behavioral and neuropsychological studies demonstrating that eye movements are also anchored to an egocentric or an allocentric representation of space rather than strictly to the retinal visual input and that parietal cortex is involved in maintaining these representations of space.
A Critical Time Window for the Recruitment of Bulbar Newborn Neurons by Olfactory Discrimination Learning
Authors: Belnoue Laure , Grosjean Noelle , Abrous Djoher Nora , Koehl Muriel
Published: January 2011

In the mammalian brain, the dentate gyrus and the olfactory bulb are regions where new neurons are continuously added. While the functional consequences of continuous hippocampal neurogenesis have been extensively studied, the role of olfactory adult-born neurons remains elusive. In particular, the involvement of these newborn neurons in odor processing is still a matter of debate. We demonstrate a critical impact of both the age of new neurons and the memory processes involved (learning vs recall) in the recruitment of newborn cells. Thus, odor stimulation preferentially recruited immature neurons over more mature ones (2 weeks old vs 5 and 9 weeks old), whereas associative learning based on odor discrimination preferentially recruited mature neurons (5–9 weeks old). Furthermore, while mature neurons were activated by this associative learning, they were not activated by long-term memory recall, indicating that the contribution of newborn neurons in olfactory functions depends also on the memory process involved. Our data thus show that newborn neurons are indeed involved in odor processing and that their recruitment is age- and memory process-dependent.
Axonal Degeneration Is Mediated by the Mitochondrial Permeability Transition Pore
Authors: Barrientos Sebastian A. , Martinez Nicolas W. , Yoo Soonmoon , Jara Juan S. , Zamorano Sebastian , Hetz Claudio , Twiss Jeffery L. , Alvarez Jaime , Court Felipe A.
Published: January 2011

Axonal degeneration is an active process that has been associated with neurodegenerative conditions triggered by mechanical, metabolic, infectious, toxic, hereditary and inflammatory stimuli. This degenerative process can cause permanent loss of function, so it represents a focus for neuroprotective strategies. Several signaling pathways are implicated in axonal degeneration, but identification of an integrative mechanism for this self-destructive process has remained elusive. Here, we show that rapid axonal degeneration triggered by distinct mechanical and toxic insults is dependent on the activation of the mitochondrial permeability transition pore (mPTP). Both pharmacological and genetic targeting of cyclophilin D, a functional component of the mPTP, protects severed axons and vincristine-treated neurons from axonal degeneration inex vivoandin vitromouse and rat model systems. These effects were observed in axons from both the peripheral and central nervous system. Our results suggest that the mPTP is a key effector of axonal degeneration, upon which several independent signaling pathways converge. Since axonal and synapse degeneration are increasingly considered early pathological events in neurodegeneration, our work identifies a potential target for therapeutic intervention in a wide variety of conditions that lead to loss of axons and subsequent functional impairment.
MicroRNA miR-9 Modifies Motor Neuron Columns by a Tuning Regulation of FoxP1 Levels in Developing Spinal Cords
Authors: Otaegi Gaizka , Pollock Andrew , Hong Janet , Sun Tao
Published: January 2011

The precise organization of motor neuron subtypes in a columnar pattern in developing spinal cords is controlled by cross-interactions of multiple transcription factors and segmental expressions of Hox genes and their accessory proteins. Accurate expression levels and domains of these regulators are essential for organizing spinal motor neuron columns and axonal projections to target muscles. Here, we show that microRNA miR-9 is transiently expressed in a motor neuron subtype and displays overlapping expression with its target gene FoxP1. Overexpression or knockdown of miR-9 alters motor neuron subtypes, switches columnar identities, and changes axonal innervations in developing chick spinal cords. miR-9 modifies spinal columnar organization by specifically regulating FoxP1 protein levels, which in turn determine distinct motor neuron subtypes. Our findings demonstrate that miR-9 is an essential regulator of motor neuron specification and columnar formation. Moreover, the overlapping expression of miR-9 and its target FoxP1 further illuminates the importance of fine-tuning regulation by microRNAs in motor neuron development.
A Novel Role for γ-Secretase: Selective Regulation of Spontaneous Neurotransmitter Release from Hippocampal Neurons
Authors: Pratt Kara G. , Zhu Ping , Watari Hirofumi , Cook David G. , Sullivan Jane M.
Published: January 2011

With a multitude of substrates, γ-secretase is poised to control neuronal function through a variety of signaling pathways. Presenilin 1 (PS1) is an integral component of γ-secretase and is also a protein closely linked to the etiology of Alzheimer's disease (AD). To better understand the roles of γ-secretase and PS1 in normal and pathological synaptic transmission, we examined evoked and spontaneous neurotransmitter release in cultured hippocampal neurons derived from PS1 knock-out (KO) mice. We found no changes in the size of evoked synaptic currents, short-term plasticity, or apparent calcium dependence of evoked release. The rate of spontaneous release from PS1 KO neurons was, however, approximately double that observed in wild-type (WT) neurons. This increase in spontaneous neurotransmission depended on calcium influx but did not require activation of voltage-gated calcium channels or presynaptic NMDA receptors or release of calcium from internal stores. The rate of spontaneous release from PS1 KO neurons was significantly reduced by lentivirus-mediated expression of WT PS1 or familial AD-linked M146V PS1, but not the D257A PS1 mutant that does not support γ-secretase activity. Treatment of WT neuronal cultures with γ-secretase inhibitor mimicked the loss of PS1, leading to a selective increase in spontaneous release without any change in the size of evoked synaptic currents. Together, these results identify a novel role for γ-secretase in the control of spontaneous neurotransmission through modulation of low-level tonic calcium influx into presynaptic axon terminals.
Dendritic Calcium Activity Precedes Inspiratory Bursts in preBötzinger Complex Neurons
Authors: Del Negro Christopher A. , Hayes John A. , Rekling Jens C.
Published: January 2011

Medullary interneurons of the preBötzinger complex assemble excitatory networks that produce inspiratory-related neural rhythms, but the importance of somatodendritic conductances in rhythm generation is still incompletely understood. Synaptic input may cause Ca2+accumulation postsynaptically to evoke a Ca2+-activated inward current that contributes to inspiratory burst generation. We measured Ca2+transients by two-photon imaging dendrites while recording neuronal somata electrophysiologically. Dendritic Ca2+accumulation frequently precedes inspiratory bursts, particularly at recording sites 50–300 μm distal from the soma. Preinspiratory Ca2+transients occur in hotspots, not ubiquitously, in dendrites. Ca2+activity propagates orthodromically toward the soma (and antidromically to more distal regions of the dendrite) at rapid rates (300–700 μm/s). These high propagation rates suggest that dendritic Ca2+activates an inward current to electrotonically depolarize the soma, rather than propagate as a regenerative Ca2+wave. These data provide new evidence that respiratory rhythmogenesis may depend on dendritic burst-generating conductances activated in the context of network activity.
Changes in Hippocampal Neuronal Activity During and After Unilateral Selective Hippocampal IschemiaIn Vivo
Authors: Barth Albert M. I. , Mody Istvan
Published: January 2011

The hippocampal formation is one of the brain regions most sensitive to ischemic damage. However, there are no studies about changes in hippocampal neuronal activity during and after a selective unilateral hippocampal ischemia. We developed a novel unilateral cerebrovascular ischemia model in mice that selectively shuts down blood supply to the ipsilateral hippocampal formation. Using a modified version of the photothrombotic method, we stereotaxically targeted the initial ascending part of the longitudinal hippocampal artery in urethane anesthetized and rose bengal-injected mice. To block blood flow in the targeted artery, we photoactivated the rose bengal by illuminating the longitudinal hippocampal artery through an optical fiber inserted into the brain.In vivofield potential recordings in the CA1 region of the hippocampus before, during and after the induction of ischemia demonstrated a high-frequency discharge (HFD) reaching frequencies of >300 Hz and lasting 7–24 s during the illumination consistent with a massive synchronous neuronal activity. The HFD was invariably followed by a DC voltage shift and a decreased activity at both low (30–57 Hz)- and high (63–119 Hz)-gamma frequencies. This decrease in gamma activity lasted for the entire duration of the recordings (∼160 min) following ischemia. The contralateral hippocampus displayed HFDs but with different frequency spectra and without DC voltage shifts or long-lasting decreases in gamma oscillations. Our findings reveal for the first time the acute effects of unilateral hippocampal ischemia on ensemble hippocampal neuronal activities.
A Rat Model of Progressive Nigral Neurodegeneration Induced by the Parkinson's Disease-Associated G2019S Mutation in LRRK2
Authors: Dusonchet Julien , Kochubey Olexiy , Stafa Klodjan , Young Samuel M. , Zufferey Romain , Moore Darren J. , Schneider Bernard L. , Aebischer Patrick
Published: January 2011

The G2019S mutation in the leucine-rich repeat kinase 2 (LRRK2) gene is the most common genetic cause of Parkinson's disease (PD), accounting for a significant proportion of both autosomal dominant familial and sporadic PD cases. Our aim in the present study is to generate a mammalian model of mutant G2019S LRRK2 pathogenesis, which reproduces the robust nigral neurodegeneration characteristic of PD. We developed adenoviral vectors to drive neuron-specific expression of full-length wild-type or mutant G2019S human LRRK2 in the nigrostriatal system of adult rats. Wild-type LRRK2 did not induce any significant neuronal loss. In contrast, under the same conditions and levels of expression, G2019S mutant LRRK2 causes a progressive degeneration of nigral dopaminergic neurons. Our data provide a novel rat model of PD, based on a prevalent genetic cause, that reproduces a cardinal feature of the disease within a rapid time frame suitable for testing of neuroprotective strategies.
Attentional Modulation of Alpha Oscillations in Macaque Inferotemporal Cortex
Authors: Mo Jue , Schroeder Charles E. , Ding Mingzhou
Published: January 2011

Recent work reported the observation of alpha frequency oscillations (8–12 Hz) in several regions of macaque visual cortex, including V2, V4, and inferotemporal cortex (IT). While alpha-related physiology in V2 and V4 appears consistent with a role in attention-related suppression, in IT, alpha reactivity appears conflicted with such a role. We addressed this issue directly by analyzing laminar profiles of local field potentials and multiunit activities from the IT of macaque monkeys during performance of an intermodal selective attention task (visual versus auditory). We found that (1) before visual stimulus onset (−200 to 0 ms), attention to visual input increased ongoing alpha power in IT relative to attention to auditory input, and (2) in contrast to the prevailing view of alpha inhibition, the increased ongoing alpha activity is accompanied by increased concurrent multiunit firing and facilitates visual stimulus processing. These results suggest that ongoing alpha oscillations in IT play a different functional role than that in the occipital cortex and may be part of the neuronal mechanism representing task-relevant information.
Mitochondrial Reactive Oxygen Species Are Activated by mGluR5 through IP3and Activate ERK and PKA to Increase Excitability of Amygdala Neurons and Pain Behavior
Authors: Li Zhen , Ji Guangchen , Neugebauer Volker
Published: January 2011

Reactive oxygen species (ROS) such as superoxide are emerging as important signaling molecules in physiological plasticity but also in peripheral and spinal cord pain pathology. Underlying mechanisms and pain-related ROS signaling in the brain remain to be determined. Neuroplasticity in the amygdala plays a key role in emotional-affective pain responses and depends on group I metabotropic glutamate receptors (mGluRs) and protein kinases. Using patch-clamp, live-cell imaging, and behavioral assays, we tested the hypothesis that mitochondrial ROS links group I mGluRs to protein kinase activation to increase neuronal excitability and pain behavior. Agonists for mGluR1/5 (DHPG) or mGluR5 (CHPG) increased neuronal excitability of neurons in the laterocapsular division of the central nucleus of the amygdala (CeLC). DHPG effects were inhibited by an mGluR5 antagonist (MTEP), IP3receptor blocker (xestospongin C), or ROS scavengers (PBN, tempol), but not by an mGluR1 antagonist (LY367385) or NO synthase inhibitor (l-NAME). Tempol inhibited the effects of IP3but not those of a PKC activator, indicating that ROS activation was IP3mediated. Live-cell imaging in CeLC-containing brain slices directly showed DHPG-induced and synaptically evoked mitochondrial superoxide production. DHPG also increased pain-related vocalizations and spinal reflexes through a mechanism that required mGluR5, IP3, and ROS. Combined application of inhibitors of ERK (U0126) and PKA (KT5720) was necessary to block completely the excitatory effects of a ROS donor (tBOOH). A PKC inhibitor (GF109203X) had no effect. Antagonists and inhibitors alone did not affect neuronal excitability. The results suggest an important role for the novel mGluR5- IP3-ROS-ERK/PKA signaling pathway in amygdala pain mechanisms.
Cloning, pharmacological characterization, and expression analysis of Atlantic salmon (Salmo salar L.) nuclear progesterone receptor
Authors: Chen Shi X , Bogerd Jan , Andersson Eva , Almeida Fernanda F L , Taranger Geir Lasse , Schulz Rüdiger W
Published: January 2011

To better understand the role(s) of progestogens during early stages of spermatogenesis, we carried out studies on the nuclear progesterone receptor (Pgr) of the Atlantic salmon. Its open-reading frame shows the highest similarity with other piscine Pgr proteins. When expressed in mammalian cells, salmon Pgr exhibited progestogen-specific, dose-dependent induction of reporter gene expression, with 17α,20β-dihydroxy-4-pregnen-3-one (DHP) showing the highest potency. We then analyzed testicular pgr mRNA and DHP plasma levels in animals during the onset of spermatogenesis, which were exposed to natural light or to constant light, to induce significant differences in testis growth. Grouping of the animals according to their progress through spermatogenesis showed that testicular pgr mRNA levels as well as DHP plasma levels first increased when germ cells had reached the stage of late type B spermatogonia and further increased when entered meiosis, i.e. when spermatocytes were present. However, in situ hybridization studies revealed that pgr mRNA expression was restricted to Sertoli cells, with a strong signal in Sertoli cells contacting type A/early type B spermatogonia, while Sertoli cells contacting larger germ cell clones with further differentiated stages (e.g. late type B spermatogonia) were less intensely/not stained. We conclude that the increase in pgr mRNA levels per pair of testis reflects, at least in part, the increased number of Sertoli cells enveloping type A and early type B spermatogonia. We propose that Sertoli cell-expressed Pgr may mediate DHP-stimulated early steps in spermatogenesis in Atlantic salmon, such as an increase in the number of new spermatogonial cysts.
Calcein Mark Retention in Chinook Salmon and Steelhead Fry in Artificial and Natural Rearing Environments
Authors: Hill Megan S. , Quesada Cory J.
Published: January 2011

Hatchery Chinook salmon Oncorhynchus tshawytscha and steelhead O. mykiss fry were marked with calcein dye to determine its efficacy for identifying fish after release into the stream environment. The effects of the dye treatment on growth and survival of marked fish and the retention of the marks over time were evaluated in the presence and absence of sunlight. Minimal differences in growth were observed between marked and unmarked Chinook salmon, and there was no difference in the total length of marked and unmarked steelhead at the conclusion of the study. Calcein marking had no effect on survival of Chinook salmon or steelhead fry during the 8-week experiment. The calcein mark rapidly lost its intensity over time in Chinook salmon and steelhead. Steelhead fry were marked and reared in three light treatments to directly evaluate whether sunlight exposure affected calcein retention. After 28 d, steelhead exposed to sunlight had no visible calcein marks, whereas those held in covered tanks had 100% mark retention. Chinook salmon fry were monitored in stream habitats after release into the stream environment. No marks were visible 8 months after release. These observations demonstrate reduced calcein mark retention in fish exposed to natural sunlight. Calcein mark retention differed between Chinook salmon and steelhead. Because externally visible calcein marks have a finite life span in the presence of sunlight, calcein use in long-term fish-marking projects will be limited.
Evaluation of Calcein as a Mass Mark for Rainbow Trout Raised in Outdoor Hatchery Raceways
Authors: Elle F. Steven , Koenig Martin K. , Meyer Kevin A.
Published: January 2011

Mass marks are useful for evaluating releases of hatchery fishes for management and research purposes. Calcein is a chemical that shows potential for producing a cost-effective batch mark that can be easily applied to large numbers of small fish and can be detected externally by nonlethal means. However, calcein shows some drawbacks related to mark deterioration when exposed to direct sunlight. We evaluated calcein mark retention over time in rainbow trout Oncorhynchus mykiss by using both external (head, fins) and internal structures (otoliths), and we compared mark retention between fish reared in normal outdoor raceways under ambient light conditions and those reared indoors in shaded circular tanks. Calcein marks on rainbow trout that were marked as fry and reared in outdoor raceways deteriorated significantly within 8 d of marking and remained at low or undetectable levels throughout the study. Mark quality was much better for rainbow trout reared indoors but still degraded over the 7-month evaluation period. Calcein marks were visible over the entire study period for otoliths of fish reared both indoors and outdoors, with better results being obtained for fish reared indoors. While calcein shows potential for generating a successful nonlethal batch mark, it may have limited use in situations where fish are exposed to sunlight, which can degrade the external mark. Marks in otoliths were retained well but required time-consuming processing and lethal sampling. For use of otolith marks, we recommend combining calcein with some other external mark (e.g., adipose fin clip) to aid in identifying chemically marked individuals.