A Ring Contraction Strategy toward a Diastereoselective Total Synthesis of (+)-Bakkenolide A

A diastereoselective route to (+)-bakkenolide A is presented from the readily available optically active Wieland-Miescher ketone. This novel synthesis of this sesquiterpene lactone features the following as key stereoselective transformations: (i) the ring contraction reaction of a octalone mediated by thallium(III) nitrate (TTN); (ii) a hydrogenation to create the cis-fused junction; and (iii) the formation of the C7 quaternary center through an enolate intermediate. Furthermore, during this work, the absolute configuration of a trinorsesquiterpene isolated from Senecio Humillimus was assigned.

Ring Contraction of 1,2-Dihydronaphthalenes Promoted by Thallium(III) in Acetonitrile: A Diastereoselective Approach to Indanes

trans-1,3-Disubstituted indanes are conveniently accessed by a stereoselective ring contraction of 1,2-dihydronaphthalenes upon treatment with thallium(III) nitrate (TTN) in acetonitrile. Under these conditions, the oxidative rearrangement of either di- or trisubstituted double bonds is possible.

A Diastereoselective Total Synthesis of trans-Trikentrin A: A Ring Contraction Approach

A new route to obtain the polyalkylated indole (+/-)-trans-trikentrin A was developed. The synthesis of this natural alkaloid features a thallium(III)mediated ring contraction reaction to obtain the trans-1,3-disubstituted five-membered ring in a diastereoselective manner. Thallium(III) is chemoselective in this rearrangement, reacting with the olefin without oxidation of the indole moiety. Other key transformations are the Bartoli`s reaction to construct the heterocyclic ring and a Heck coupling to add the carbons atom that will originate the nonaromatic cycle.

On theory multiple contraction

The one which is considered the standard model of theory change was presented in [AGM85] and is known as the AGM model. In particular, that paper introduced the class of partial meet contractions. In subsequent works several alternative constructive models for that same class of functions were presented, e.g.: safe/kernel contractions ([AM85, Han94]), system of spheres-based contractions ([Gro88]) and epistemic entrenchment-based contractions ([G ar88, GM88]). Besides, several generalizations of such model were investigated. In that regard we emphasise the presentation of models which accounted for contractions by sets of sentences rather than only by a single sentence, i.e. multiple contractions. However, until now, only two of the above mentioned models have been generalized in the sense of addressing the case of contractions by sets of sentences: The partial meet multiple contractions were presented in [Han89, FH94], while the kernel multiple contractions were introduced in [FSS03]. In this thesis we propose two new constructive models of multiple contraction functions, namely the system of spheres-based and the epistemic entrenchment-based multiple contractions which generalize the models of system of spheres-based and of epistemic entrenchment-based contractions, respectively, to the case of contractions (of theories) by sets of sentences. Furthermore, analogously to what is the case in what concerns the corresponding classes of contraction functions by one single sentence, those two classes are identical and constitute a subclass of the class of partial meet multiple contractions. Additionally, and as the rst step of the procedure that is here followed to obtain an adequate de nition for the system of spheres-based multiple contractions, we present a possible worlds semantics for the partial meet multiple contractions analogous to the one proposed in [Gro88] for the partial meet contractions (by one single sentence). Finally, we present yet an axiomatic characterization for the new class(es) of multiple contraction functions that are here introduced.

The ACB technique: a biomagentic tool for monitoring gastrointestinal contraction directly from smooth muscle in dogs

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Validation of ACB in vitro and in vivo as a biomagnetic method for measuring stomach contraction

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

ACUTE EFFECT of STATIC STRETCHING on RATE of FORCE DEVELOPMENT and MAXIMAL VOLUNTARY CONTRACTION IN OLDER WOMEN

Gurjao, ALD, Goncalves, R, de Moura, RF, and Gobbi, S. Acute effect of static stretching on rate of force development and maximal voluntary contraction in older women. J Strength Cond Res 23(7): 2149-2154, 2009-The purpose of this study was to investigate, in older women, the acute effect of static stretching (SS) on both muscle activation and force output. Twenty-three older women (64.6 +/- 7.1 yr) participated in the study. The maximal voluntary contraction (MVC), rate of force development (RFD) (50, 100, 150, and 200 ms relative to onset of muscular contraction), and peak RFD (PRFD) (the steepest slope of the curve during the first 200 ms) were tested under 2 randomly separate conditions: SS and control (C). Electromyographic (EMG) activity of the vastus medialis (VM), vastus lateralis (VL), and biceps femoris (BF) muscles also was assessed. The MVC was significantly lower (p < 0.05) in the 3 trials of SS when compared with the C condition (control: 925.0 +/- 50.9 N; trial 1 : 854.3 +/- 55.3 N; trial 2 : 863.1 +/- 52.2 N; and trial 3 : 877.5 +/- 49.9 N). PRFD showed a significant decrease only for the first 2 trials of SS when compared with the C condition (control: 2672.3 +/- 259.1 N/s; trial 1 : 2296.6 +/- 300.7 N/s; and trial 2 : 2197.9 +/- 246.3 N/s). However, no difference was found for RFD (50, 100, 150, and 200 ms relative to onset of muscular contraction). The EMG activity for VM, VL, and BF was not significantly different between the C and SS conditions. In conclusion, the older women's capacity to produce muscular force decreased after their performance of SS exercises. The mechanisms responsible for this effect do not appear to be related to muscle activation. Thus, if flexibility is to be trained, it is recommended that SS does not occur just before the performance of activities that require high levels of muscular force.

THE RATE of FORCE DEVELOPMENT OBTAINED AT EARLY CONTRACTION PHASE IS NOT INFLUENCED BY ACTIVE STATIC STRETCHING

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Expression of fibroblast growth factor-8 and regulation of cognate receptors, fibroblast growth factor receptor-3c and-4, in bovine antral follicles

Paracrine cell signaling is believed to be important for ovarian follicle development, and a role for some members of the fibroblast growth factor (FGF) family has been suggested. In the present study, we tested the hypothesis that FGF-8 and its cognate receptors (FGFR3c and FGFR4) are expressed in bovine antral follicles. RT-PCR was used to analyze bovine Fgf8, Fgfr3c and Fgfr4 mRNA levels in oocytes, and granulosa and theca cells. Fgf8 expression was detected in oocytes and in granulosa and theca cells; this expression pattern differs from that reported in rodents. Granulosa and theca cells, but not oocytes, expressed Fgfr3c, and expression in granulosa cells increased significantly with follicle estradiol content, a major indicator of follicle health. Fgfr4 expression was restricted to theca cells in the follicle, and decreased significantly with increasing follicle size. To investigate the potential regulation of Fgfr3c expression in the bovine granulosa, cells were cultured in serum-free medium with FSH or IGF-I; gene expression was upregulated by FSH but not by IGF-I. The FSH-responsive and developmentally regulated patterns of Fgfr3c mRNA expression suggest that this receptor is a potential mediator of paracrine signaling to granulosa cells during antral follicle growth in cattle.