Synthesis and analgesic activity of new α-truxillic acid derivatives with monoterpenoid fragments

Novel derivatives of α-truxillic acid with a camphor framework were synthesized and evaluated for their in vivo analgesic activity. α-Truxillic acid derivatives were prepared via solvent-free photocatalyzed [2+2] cyclodimerization of (E)-cinnamic acid. Target compounds were obtained through the substitution of –Cl or –OH groups in α-truxillic acid. The chemical structures of the synthesized compounds were elucidated by ¹H, ¹³C-NMR, and mass spectrometry. Their analgesic activities were evaluated by the acetic acid-induced writhing test and the hot plate method. Compounds 7b and 7f containing the cyclobutane unit and natural fragments at 10 mg/kg exhibited analgesic activity in the acetic acid-induced writhing test, while α-truxillic acid (10 mg/kg, per os) did not show analgesic activity in the test. Intermediate 2 caused a decrease in the writhing with pain inhibition of 28 %. In the hot plate test, borneol showed high analgesic activity with pain inhibition of 60 %.     

The growth speed of microtubules with XMAP215-coated beads coupled to their ends is increased by tensile force

The generation of pulling and pushing forces is one of the important functions of microtubules, which are dynamic and polarized structures. The ends of dynamic microtubules are able to form relatively stable links to cellular structures, so that when a microtubule grows it can exert a pushing force and when it shrinks it can exert a pulling force. Microtubule growth and shrinkage are tightly regulated by microtubule-associated proteins (MAPs) that bind to microtubule ends. Given their localization, MAPs may be exposed to compressive and tensile forces. The effect of such forces on MAP function, however, is poorly understood. Here we show that beads coated with the microtubule polymerizing protein XMAP215, the Xenopus homolog of Dis1 and chTOG, are able to link stably to the plus ends of microtubules, even when the ends are growing or shrinking; at growing ends, the beads increase the polymerization rate. Using optical tweezers, we found that tensile force further increased the microtubule polymerization rate. These results show that physical forces can regulate the activity of MAPs. Furthermore, our results show that XMAP215 can be used as a handle to sense and mechanically manipulate the dynamics of the microtubule tip.     

Caulobacter chromosome segregation is an ordered multistep process

Despite its fundamental nature, bacterial chromosome segregation remains poorly understood. Viewing segregation as a single process caused multiple proposed mechanisms to appear in conflict and failed to explain how asymmetrically dividing bacteria break symmetry to move only one of their chromosomes. Here, we demonstrate that the ParA ATPase extends from one cell pole and pulls the chromosome by retracting upon association with the ParB DNA-binding protein. Surprisingly, ParA disruption has a specific effect on chromosome segregation that only perturbs the latter stages of this process. Using quantitative high-resolution imaging, we demonstrate that this specificity results from the multistep nature of chromosome translocation. We propose that Caulobacter chromosome segregation follows an ordered pathway of events with distinct functions and mechanisms. Initiation releases polar tethering of the origin of replication, distinction spatially differentiates the two chromosomes, and commitment irreversibly translocates the distal centromeric locus. Thus, much as eukaryotic mitosis involves a sequence of distinct subprocesses, Caulobacter cells also segregate their chromosomes through an orchestrated series of steps. We discuss how the multistep view of bacterial chromosome segregation can help to explain and reconcile outstanding puzzles and frame future investigation.     

Apoptin enhances the oncolytic properties of vaccinia virus and modifies mechanisms of tumor regression

A recombinant vaccinia virus VVdGF-ApoS24/2 expressing apoptin selectively kills human cancer cells in vitro [Kochneva et al., 2013]. We compared the oncolytic activity of this recombinant with that of the parental strain L-IVP using a model of human A431 carcinoma xenografts in nude mice. Single intratumoral injections (2×10⁷ PFU/mouse) of the viruses produced a dramatic decrease in tumor volumes, which was higher after injection of apoptin-producing virus. The tumor dried out after the injection of recombinant while injection of L-IVP strain resulted in formation of cavities filled with cell debris and liquid. Both viruses rapidly spread in xenografts and replicate exclusively in tumor cells causing their destruction within 8 days. Both viruses induced insignificant level of apoptosis in tumors. Unlike the previously described nuclear localization of apoptin in cancer cells the apoptin produced by recombinant virus was localized to the cytoplasm. The apoptin did not induce a typical apoptosis, but it rather influenced pathway of cell death and thereby caused tumor shrinkage. The replacement of destroyed cells by filamentous material is the main feature of tumor regression caused by the VVdGF-ApoS24/2 virus. The study points the presence of complicated mechanisms of apoptin effects at the background of vaccinia virus replication.     

The dependence of preferred competitive racing distance on muscle fibre type composition and ACTN3 genotype in speed skaters

It is generally accepted that muscle fibre composition may influence physical performance. The α-actinin-3 (ACTN3) gene R577X polymorphism is suspected to be one of the contributing gene variations in the determination of muscle fibre type composition and athletic status. In the present study, we examined the dependence of average preferred racing distance (PRD) on muscle fibre type composition of the vastus lateralis muscle in 34 subelite Russian speed skaters (20 men and 14 women) who competed in races of different length (500-10,000 m). We also investigated the association between the ACTN3?polymorphism and muscle fibre characteristics in 94 subjects (60 physically active healthy men and 34 speed skaters), as well as the relationship between PRD and?ACTN3?genotype in 115 subelite and elite speed skaters. In addition, ACTN3 genotype and allele frequencies of the 115 speed skaters were compared with 1301 control subjects. The ACTN3 XX genotype frequency was significantly lower in sprinters (n = 39) compared with control subjects (2.6 versus 14.5%; P = 0.034). We observed a positive relationship between PRD and the proportion of slow-twitch muscle fibres that was close to linear, but better fitted a logarithmic curve (r = 0.593, P < 0.0005). The?ACTN3?R577X polymorphism was associated with muscle fibre composition (slow-twitch fibres: RR genotype, 51.7 (12.8)%; RX, 57.4 (13.2)%; XX 61.5 (16.3)%; = 0.215; P = 0.049) in the overall muscle biopsy group, and with PRD of all athletes ( = 0.24, P = 0.010), indicating thatACTN3 XX genotype carriers exhibit a higher proportion of slow-twitch fibres and prefer to skate long-distance races. However, the majority of the association between muscle fibre type and PRD was independent of?ACTN3?genotype. In conclusion, the?ACTN3?R577X polymorphism is associated with preferred racing distance in speed skaters and muscle fibre type composition. Thus, it is probably partly via associations with fibre type that the R577X polymorphism contributes to a small but perhaps important component of the ability to perform at a high level in speed skating.     

Preparation of high specific activity tritium‐labelled leukotriene B4 suitable for radioligand binding assay

We describe a method of preparation of high specific activity tritium‐labelled leukotriene (LT) B₄ from [5,6,8,9,11,12,14,15‐³H] arachidonic acid (AA; 6.66 TBq/mmol) utilizing a LTB₄‐synthesizing enzyme system from rat basophilic leukemia (RBL‐1) cells. It was shown that both cyclooxygenase inhibitor indomethacin and adenosine 5′‐triphosphate induced [³H] AA transformation to [³H] LTB₄. In optimized conditions up to 15% of total radioactivity of the incubation mixture was present in [³H] LTB₄. A separation of [³H] LTB₄ from other labelled C_20:4 products was achieved by a three‐step reverse phase‐high‐performance liquid chromatography in methanol‐ and acetonitrile‐based solvent systems. [³H] LTB₄ was confirmed to be identical to the naturally occurring LTB₄ by a radioligand binding assay using a culture of HF1 cells that express a BLT₁ receptor. Copyright © 2008 John Wiley & Sons, Ltd.