Acute Hypercapnia/Ischemia Alters the Esterification of Arachidonic Acid and Docosahexaenoic Acid Epoxide Metabolites in Rat Brain Neutral Lipids.

In the brain, approximately 90% of oxylipins are esterified to lipids. However, the significance of this esterification process is not known. In the present study, we (1) validated an aminopropyl solid phase extraction (SPE) method for separating esterified lipids using 100 and 500 mg columns and (2) applied the method to quantify the distribution of esterified oxylipins within phospholipids (PL) and neutral lipids (NL) (i.e. triacylglycerol and cholesteryl ester) in rats subjected to head-focused microwave fixation (controls) or CO2 -induced hypercapnia/ischemia. We hypothesized that oxylipin esterification into these lipid pools will be altered following CO2 -induced hypercapnia/ischemia. Lipids were extracted from control (n = 8) and CO2 -asphyxiated (n = 8) rat brains and separated on aminopropyl cartridges to yield PL and NL. The separated lipid fractions were hydrolyzed, purified with hydrophobic-lipophilic-balanced SPE columns, and analyzed with ultra-high-pressure liquid chromatography coupled to tandem mass spectrometry. Method validation showed that the 500 mg (vs 100 mg) aminopropyl columns yielded acceptable separation and recovery of esterified fatty acid epoxides but not other oxylipins. Two epoxides of arachidonic acid (ARA) were significantly increased, and three epoxides of docosahexaenoic acid (DHA) were significantly decreased in brain NL of CO2 -asphyxiated rats compared to controls subjected to head-focused microwave fixation. PL-bound fatty acid epoxides were highly variable and did not differ significantly between the groups. This study demonstrates that hypercapnia/ischemia alters the concentration of ARA and DHA epoxides within NL, reflecting an active turnover process regulating brain fatty acid epoxide concentrations

Linoleic acid participates in the response to ischemic brain injury through oxidized metabolites that regulate neurotransmission.

Linoleic acid (LA; 18:2 n-6), the most abundant polyunsaturated fatty acid in the US diet, is a precursor to oxidized metabolites that have unknown roles in the brain. Here, we show that oxidized LA-derived metabolites accumulate in several rat brain regions during CO2-induced ischemia and that LA-derived 13-hydroxyoctadecadienoic acid, but not LA, increase somatic paired-pulse facilitation in rat hippocampus by 80%, suggesting bioactivity. This study provides new evidence that LA participates in the response to ischemia-induced brain injury through oxidized metabolites that regulate neurotransmission. Targeting this pathway may be therapeutically relevant for ischemia-related conditions such as stroke

Dietary Omega-3 Polyunsaturated Fatty Acid Deprivation Does Not Alter Seizure Thresholds but May Prevent the Anti-seizure Effects of Injected Docosahexaenoic Acid in Rats.

Background: Brain concentrations of omega-3 docosahexaenoic acid (DHA, 22:6n-3) have been reported to positively correlate with seizure thresholds in rodent seizure models. It is not known whether brain DHA depletion, achieved by chronic dietary omega-3 polyunsaturated fatty acid (PUFA) deficiency, lowers seizure thresholds in rats. Objective: The present study tested the hypothesis that lowering brain DHA concentration with chronic dietary n-3 PUFA deprivation in rats will reduce seizure thresholds, and that compared to injected oleic acid (OA), injected DHA will raise seizure thresholds in rats maintained on n-3 PUFA adequate and deficient diets. Methods: Rats (60 days old) were surgically implanted with electrodes in the amygdala, and subsequently randomized to the AIN-93G diet containing adequate levels of n-3 PUFA derived from soybean oil or an n-3 PUFA-deficient diet derived from coconut and safflower oil. The rats were maintained on the diets for 37 weeks. Afterdischarge seizure thresholds (ADTs) were measured every 4-6 weeks by electrically stimulating the amygdala. Between weeks 35 and 37, ADTs were assessed within 1 h of subcutaneous OA or DHA injection (600 mg/kg). Seizure thresholds were also measured in a parallel group of non-implanted rats subjected to the maximal pentylenetetrazol (PTZ, 110 mg/kg) seizure test. PUFA composition was measured in the pyriform-amygdala complex of another group of non-implanted rats sacrificed at 16 and 32 weeks. Results: Dietary n-3 PUFA deprivation did not significantly alter amygdaloid seizure thresholds or latency to PTZ-induced seizures. Acute injection of OA did not alter amygdaloid ADTs of rats on the n-3 PUFA adequate or deficient diets, whereas acute injection of DHA significantly increased amygdaloid ADTs in rats on the n-3 PUFA adequate control diet as compared to rats on the n-3 PUFA deficient diet (P < 0.05). Pyriform-amygdala DHA percent composition did not significantly differ between the groups, while n-6 docosapentaenoic acid, a marker of n-3 PUFA deficiency, was significantly increased by 2.9-fold at 32 weeks. Conclusion: Chronic dietary n-3 PUFA deficiency does not alter seizure thresholds in rats, but may prevent the anti-seizure effects of DHA

Les tiers-espaces une analyse de l'ambivalence dans La bagarre et Les pédagogues de Gérard Bessette, The apprenticeship of Duddy Kravitz et The Street de Mordecai Richler

In Critical Practice, Catherine Belsey states how traditionally, classic realism is interpreted as a genre that"presents individuals whose traits of character, understood as essential and predominantly given, constrain the choices they make" (Belsey 74). Belsey's claim is significant in that it articulates what is often the locus of tension and conflict in the genre: rigid, essentialist identitary discourse.In summarizing and considering the various identitary discourses at play within Mordecai Richler's The Apprenticeship of Duddy Kravitz and The Street and Gérard Bessette's La bagarre and Les pédagogues, the purpose of this thesis is to analyse how issues surrounding constructions of identity are dramatized in these classic realist, satirical texts in order to show how their cultural work in terms of identity can be understood as being more ambivalent than has heretofore often been thought. The thesis' theoretical focus is rooted primarily in post-colonial theory, especially the ways it interrogates representations of cultural and ethnic struggles for recognition and power that are a result of colonial and/or cultural hegemonic domination. More specifically, the thesis discusses and appropriates the theory and concepts of the post-colonial critic Homi K. Bhabha, particularly in terms of how the selected primary texts can be said to exemplify Bhabha's notions of ambivalence, hybridity and a Third Space of identity; how the narratives' main conflicts and tensions around identity can be better understood by looking at how some of the characters can be said to inhabit a Third Space. However, the thesis will also show that while Bhabha's claim that instances of ambivalence, hybridity and the Third Space in the selected texts can be said to represent" neither the one [...], nor the Other [...] but something else besides which contests the terms and the territories of both [i.e. of competing identities]," (Bhabha 41) their concomitant essentialist discourses can be said to trouble the idealism of Bhabha's faith in such notions.In short, this thesis posits that though the selected texts perform important cultural work via their complex problematizations of the ambivalence of said discourses, they also satirize and critique essentialist and ethnocentric discourses

Masculinities, Gendered Expression, and the Social, Emotional, and Academic Well-Being of High School Boys

There has been longstanding concern over the seemingly intractable problem of boys’ academic achievement. Despite extensive research, there is little consensus among researchers and educators regarding best practices and approaches in mitigating and remediating the problem. This mixed-methods study sought to illuminate the issue further by focusing on the meaningful lived experiences of six young men aged 18 to 24 who attended and graduated from a central Massachusetts public high school. The study asked participants to reflect through prompted writing upon the stresses and pressures as well as the factors and conditions that affected their abilities to manage their performativities in constructing masculine identities. Elements of interpretative phenomenological analysis (IPA) and narrative analysis were used to analyze participants’ electronically submitted written accounts, which were further contextualized by the scores of each participant’s Male Role Norms Inventory—Revised (MRNI-R). Multiple thematic consistencies emerged that indicated adolescent males are experiencing meaningful levels of stress and anxiety in the gendered expression of their social, emotional, and academic selves. Direct sources of stress and anxiety included peers, families, and teachers. Participants also noted societal endorsement and surveillance of the hegemonic masculine norm as factors affecting their ability to manage and maintain social proprioception during their high school years. The key conclusions drawn from the study indicate that adolescent males experience destabilizing anxiety as a result of sanctioning surveillance of multiple aspects of their masculinity performances by peers and adults. Perceived expectations around aggressive sexuality and emotional stoicism as well as and confusion around sufficiently “safe” academic achievement consistently caused participants to experience isolation, frustration, and anxiety. Key recommendations include changes in teacher preparation programming to accommodate extensive study of gender construction in children and adolescents to both expand the understanding of prospective teachers in dealing with a wide range of gendered expression and to minimize the adverse effects of imported gender biases. Future research should include more authentic voices of adolescent and young adult males in order to generate findings that may improve the social, emotional, and academic well-being of this demographic

N,N′-Dineopentyl­naphthalene-1,8-diamine

In the title compound, C20H30N2, all bond distances and angles fall within the usual ranges but the C(ipso)—N distances [1.391 (5) and 1.398 (4) Å] are slightly shorter than the corresponding typical average distance of 1.42 (3) Å. The N atoms may be described as pyramidal sp 3-hybridized with an N—H⋯H—N separation of 2.07 (2) Å. This is necessitated because the two C(bridgehead)—C(ipso)—N—C torsion angles [170.6 (4) and 172.6 (3)°] would require the amine H atoms to be in prohibitively close proximity if the N atoms were assumed to be sp 2-hybridized