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Xenon exposure in the neonatal rat brain: effects on genes that regulate apoptosis.
No full textBACKGROUND:
In the developing rodent brain, exposure to volatile anesthetics causes widespread neuronal apoptosis in several regions of the brain. Increasing evidence points to a possible neuroprotective role for the anesthetic gas xenon, following neuronal injury. To address this gap in understanding, we explored the transcriptional consequences of xenon in the brains of postnatal day 7 (P7) rats exposed to xenon compared to those of air-breathing animals, with particular emphasis on the mRNA transcript levels of Akt and c-Jun N-terminal kinase kinase 1 (JNKK1), which are important for cell survival and the activation of extrinsic neuroapoptotic pathways, respectively.
METHODS:
P7 Sprague/Dawley rats were exposed to air (75% nitrogen, 25% oxygen) or xenon (75% xenon, 25% oxygen) for 120 min (N=6/group). Forebrains were harvested for reverse transcription polymerase chain reaction, which enabled quantification of Akt and JNKK1 mRNA transcripts. Suppression subtractive hybridization was used to explore the "genetic signature" of xenon exposure.
RESULTS:
Compared to control air-breathing animals, xenon-breathing rats exhibited a 0.7-fold decrease in Akt mRNA expression (P<0.01) and a 1.6-fold increase in JNKK1 mRNA levels (P<0.05).
CONCLUSION:
The concomitant decrease in the Akt mRNA expression level and increase in the JNKK1 mRNA transcript level provide evidence that xenon has a neuroapoptotic effect in the developing rodent forebrain. Given these results, further study into the paradoxical neuroprotective and neuroapoptotic effects of xenon is warranted
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
XENON INDUCED GENE EXPRESSION ANALYSIS IN ANIMAL MODELS
No full textXenon, a rare noble gas discovered by Ramsay and Travers in 1898, has medicinal use in radiological and perioperative clinical settings. A possible mechanism for Xenon's salubrious properties in the perioperative period (including anesthesia, analgesia and organ protection) have been attributed either to a non-competitive inhibition of NMDA receptors or to an activation of potassium channels. Interest in Xenon has evolved from the recent description of its neuroprotective properties in several models of acute neurological injury. Xenon's neuroprotective effect has been reproduced both in vitro and in vivo at sub-anaesthetic doses, suggesting that Xenon may find clinical utility for current unmet medical needs such as stroke or neonatal asphyxia. Xenon's neuroprotection is long lasting when used either as a post-injury treatment or in the setting of preconditioning. The molecular mechanisms underlying Xenon-induced neuroprotective effects have not yet been elucidated. For this reason exploring at molecular level the effects of Xenon exposure, may contribute to partially elucidate the molecular mechanisms involved in Xenon-induced neuroprotection. To gain further insight in Xenon’s salubrious effects, we decided to adopt a global approach, by isolating and cloning the mRNAs differentially expressed in rat brains after Xenon exposure compared to either air or nitrous oxide, another inhalatory anaesthetic agent that does not exhibit preconditioning or organ protective effects. This approach allowed us to identify Xenon’s “genetic signature” that has yielded possible insights into the molecular mechanisms involved in Xenon-induced neuroprotection. In order to achieve our goal we adopted the Suppression Subtractive Hybridization (SSH) method. SSH is an efficient technique, used to identify significant changes in gene expression comparing two cell populations differing for one character: in our case the Xenon treatment. The study has been performed on two paired sets (the experimental and the validation sets) of animals (7 days old, Sprague Dawley rats). Each set has been subdivided in two groups: the control group has been exposed to air (75% nitrogen and 25% oxygen), the treated one has been exposed to Xenon (75% Xenon and 25% oxygen). Under the same conditions, a third set of four animals (7 days old, Sprague Dawley rats), has been treated with nitrous-oxide (25% oxygen and 75% nitrous oxide) to
control for the anaesthetic state produced by Xenon. RNA Poly(A)+ isolated from control and
treated rat brains of the experimental set, has been used to performed SSH. Once evaluated subtraction efficiency, the secondary PCR products of the forward library were cloned and subjected to differential screening. Clones showing an on/off hybridization signal have been sequenced by the dideoxy chain terminator method and analyzed at the National Center of Biotechnology Information server (http://www.ncbi.nlm.nih.gov), at the European Bioinformatics Institute server (http://www.ebi.ac.uk) and at the Rat Genome Database (http://rgd.mcw.edu ). In this way we in silico selected the main target of our interest. Selected sequences were submitted to two steps data validation. As first step we performed a semi-quantitave RT-PCR on messenger RNAs used for library construction; as second step we performed a Relative Real-Time PCR on total RNAs obtained from the validation set. Relative Real-Time PCR data, were then statistically analyzed with REST 2005. A p value <0.05 will be considered significant. In order to verify if the Xenon induced gene transcription could be shared by other noble gases, the expression of Xenon’s induced transcripts has been further investigated by relative Real Time PCR, on total RNA isolated from another set of animals (7 days old, Sprague Dawley rats) treated with three other different noble gases: Argon (75% Argon and 25% oxygen), Krypton (75% Krypton and 25% oxygen), Neon (75% Neon and 25% oxygen) and the paired air-control cases (75% nitrogen and 25% oxygen). Next we investigated if the Xenon induced up-regulation of validated genes was followed by a parallel increase in their pair gene products. Proteins subcellular localization was analyzed by immunohistochemistry on paraffin-embedded brains of a new set of animals, treated according to the same protocol and sacrificed 24 hours after exposure. Sections will be stained with available commercial antibodies. Difference in protein-expression level was studied by Western blot technique
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Espressione genica differenziale nel Sistema Nervoso Centrale di ratti trattati con acetil-L-carnitina
No full textL’ Acetil-L-Carnitina (ALC) è una biomolecola naturale fisiologicamente presente nel Sistema Nervoso Centrale (SNC) e rappresenta l’estere di carnitina più abbondante nel tessuto cerebrale del Vertebrato.
È un composto di notevole interesse per le sue ampie applicazioni cliniche: viene infatti ampiamente utilizzato nel trattamento del dolore.
Recentemente, è stato visto esercitare un potente effetto analgesico attraverso l’up-regulation dei recettori metabotropici del glutammato, mGlu2, nel ratto.
Studi comportamentali hanno messo in evidenza un possibile ruolo dell’ALC nel miglioramento dei livelli di attenzione, di apprendimento e di memoria in ratti trattati con questa sostanza. Studi elettrofisiologici condotti su fettine di ippocampo di ratto hanno evidenziato una facilitazione delle connessioni sinaptiche tra le fibre collaterali di Schaffer e le cellule piramidali del campo CA1. Inoltre, è stato dimostrato che l’ALC esercita un potenziamento sulla Long Term Potentiation (LTP). La LTP rappresenta il modello di plasticità neuronale attività-dipendente maggiormente studiato nel SNC di Vertebrato quale modello cellulare di apprendimento e memoria.
Altri studi condotti sul modello dell’invertebrato Hirudo medicinalis hanno dimostrato che l’ALC influenza i processi di apprendimento non associativo a breve e a lungo termine, tipo disabitudine e sensitizzazione.
In particolare nel modello comportamentale dell’induzione al nuoto in
H. medicinalis, la somministrazione di ALC deprime la disabitudine e la sensitizzazione, indotte da stimolazione nocicettiva o da somministrazione di serotonina ed è di particolare rilievo che questi effetti si protraggano nel tempo (fino a 24 giorni dalla somministrazione di ALC).
Tutti questi risultati suggeriscono che l’azione dell’ALC possa esercitarsi attraverso variazioni quantitative e qualitative dell’espressione genica.
Per verificare questa ipotesi ci siamo avvalsi dell’ibridazione sottrattiva soppressiva (suppression subtractive hybridization, SSH), un efficiente metodo utilizzato per evidenziare patterns di espressione genica associati a particolari stati fisiologici o patologici, a determinati fenotipi, ad un tessuto o ad un tipo cellulare.
Questa tecnica permette, attraverso la costruzione di librerie sottrattive di cDNA, l’identificazione di geni la cui espressione può essere indotta o inibita dal trattamento in esame.
Lo studio è stato condotto su due gruppi di ratti Wistar, trattati per 21 giorni con somministrazione giornaliera intraperitoneale rispettivamente di ALC (Sigma Tau Laboratories, 100 mg/Kg), e soluzione fisiologica.
L’RNA poli(A)+ estratto dal SNC sia dei ratti di controllo che dei ratti trattati, è stato utilizzato per la costruzione delle librerie sottrattive di cDNA.
Dopo aver valutato l’efficienza della sottrazione, i cDNA sono stati clonati e sottoposti a screening.
Le sequenze dei cloni differenziali, ottenute con sequenziatore automatico, sono state analizzate mediante comparazione con le sequenze depositate nelle banche dati tramite programmi come FASTA, BLASTX e BLASTN
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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