Photosensitivity and heat resistance conferred by BrdU incorporation upon a thymidine kinase-deficient mouse cell line with persistent mitochondrial enzyme activity

The selective incorporation of 5-bromodeoxyuridine (BrdU) into mitochondrial DNA (mit-DNA) in the LM(TK-) ClID cell line, a thymidine kinase-deficient derivative of L fibroblasts with persistent mitochondrial enzyme activity, has been utilized to specifically damage mit-DNA by 'visible' light irradiation. ('Visible light' indicates the source of light used, although the components most active photochemically on BrdU-substituted DNA are in the near-visible range, 300-340 nm.) (Szybalski & Opara-Kubinski, 1965). LM(TK-) Cl ID cells, which had been grown in the presence of 30 mug/ml BrdU, were irradiated with 'visible' light. Analysis of the pre-existing mit-DNA in these cells, which had been long-term labelled with [5-3H]deoxycytidine, showed a progressive decrease, with increasing duration of irradiation, in the proportion of the closed-circular form and an increase in that of the open-circular form of mit-DNA, with the subsequent appearance of fragments of this DNA. Furthermore, there was a decrease during irradiation in the total amount of mit-DNA, which became about 35% of the non-irradiated control after 65 h irradiation. On the other hand, irradiation with 'visible' light failed to cause any quantitative or qualitative change, with respect to the non-irradiated control, in mit-DNA from cells grown in the absence of BrdU and long-term labelled with [Me-3h]thymidine. An analysis of the incorporation of [5-3H]deoxycytidine into mit-DNA of BrdU-grown cells, during a 3-h exposure of the cells to the precursor following irradiation, showed a fairly rapid decline of mit-DNA labelling; this became about 50% of the non-irradiated control after 12 h irradiation, decreasing to about 25% in the next 48 h. By contrast, no effect of irradiation was observed on the subsequent pulse-labelling of mit-DNA with [Me-3H]thymidine in cells grown in the absence of BrdU. Furthermore, no change in the size of the extracted nuclear DNA was found in irradiated BrdU-grown cells. The progressive and selective damage and destruction of mit-DNA during irradiation with 'visible' light of Cl ID cells correlate fairly well with the kinetics of loss of cell viability occurring under the same conditions, as described in the accompanying paper, strongly suggesting a link between the two phenomena

State Prescription Drug Price Web Sites: How Useful to Consumers?

Compares ten sites and identifies key limitations due to data omissions, gaps between insured and uninsured consumers, and varied program implementation. Presents alternative policy options such as requiring price lists from pharmacies

Synthesis and control of generalised dynamically substructured systems

The experimental technique for testing engineering systems via the method of dynamic substructuring is receiving significant global interest, for example in the fields of large-scale structural, aerospace, and automotive system testing. Dynamically substructured systems (DSSs) enable full-size, critical components of a complete system to be physically tested in real-time, within a laboratory environment, while the remainder of the system is modelled numerically. The intention is that the combined physical-numerical DSS behaves as if it were the complete (or emulated) system.In an ideal mechanical DSS, for example, perfect synchronization of displacements and forces at the interfaces between the numerical and physical components (or substructures) is required. Hence, a key design feature of successful DSS systems is the high fidelity of the control action. Equally, a DSS controller must be able to cope with non-linear, time-varying, and uncertain parameters within the physical substructure dynamics.The main purpose of this paper is to present a generalized DSS framework, together with associated linear and adaptive control strategies, that are specifically tailored to achieve high synchronization performance. The initial studies of this problem, as described in an earlier paper by Stoten and Hyde, are therefore continued by generalizing both the DSS dynamics and the control strategies to include (a) a number of newly defined modes of operation and (b) multivariable dynamics. In addition, comparative implementation and simulation studies are included, based upon the DSS testing of a mechanical system (a planar quasi-motorcycle rig), which was specifically designed to highlight the main features of this research. The comparative studies show that excellent DSS control can be achieved, especially with the addition of an adaptive component to the controller, despite significant changes to the physical substructure dynamics

Circumventing embryonic lethality with Lcmt1 deficiency: generation of hypomorphic Lcmt1 mice with reduced protein phosphatase 2A methyltransferase expression and defects in insulin signaling.

Protein phosphatase 2A (PP2A), the major serine/threonine phosphatase in eukaryotic cells, is a heterotrimeric protein composed of structural, catalytic, and targeting subunits. PP2A assembly is governed by a variety of mechanisms, one of which is carboxyl-terminal methylation of the catalytic subunit by the leucine carboxyl methyltransferase LCMT1. PP2A is nearly stoichiometrically methylated in the cytosol, and although some PP2A targeting subunits bind independently of methylation, this modification is required for the binding of others. To examine the role of this methylation reaction in mammalian tissues, we generated a mouse harboring a gene-trap cassette within intron 1 of Lcmt1. Due to splicing around the insertion, Lcmt1 transcript and LCMT1 protein levels were reduced but not eliminated. LCMT1 activity and methylation of PP2A were reduced in a coordinate fashion, suggesting that LCMT1 is the only PP2A methyltransferase. These mice exhibited an insulin-resistance phenotype, indicating a role for this methyltransferase in signaling in insulin-sensitive tissues. Tissues from these animals will be vital for the in vivo identification of methylation-sensitive substrates of PP2A and how they respond to differing physiological conditions

Game Based Learning for Safety and Security Education

Safety and security education are important part of technology related education, because of recent number of increase in safety and security related incidents. Game based learning is an emerging and rapidly advancing forms of computer-assisted instruction. Game based learning for safety and security education enables students to learn concepts and skills without the risk of physical injury and security breach. In this paper, a pedestal grinder safety game and physical security game have been developed using industrial standard modeling and game development software. The average score of the knowledge test of grinder safety game was 82%, which is higher than traditional lecture only instruction method. In addition, the survey of physical security game shows 84% average satisfaction ratio from high school students who played the game during the summer camp. The results of these studies indicated that game based learning method can enhance students' learning without potential harm to the students

Differential-geometric approach to the integrability of hydrodynamic chains: the Haantjes tensor

The integrability of an m-component system of hydrodynamic type, u_t=V(u)u_x, by the generalized hodograph method requires the diagonalizability of the mxm matrix V(u). This condition is known to be equivalent to the vanishing of the corresponding Haantjes tensor. We generalize this approach to hydrodynamic chains -- infinite-component systems of hydrodynamic type for which the infinite matrix V(u) is `sufficiently sparse'. For such systems the Haantjes tensor is well-defined, and the calculation of its components involves finite summations only. We illustrate our approach by classifying broad classes of conservative and Hamiltonian hydrodynamic chains with the zero Haantjes tensor. We prove that the vanishing of the Haantjes tensor is a necessary condition for a hydrodynamic chain to possess an infinity of semi-Hamiltonian hydrodynamic reductions, thus providing an easy-to-verify necessary condition for the integrability.Comment: 36 pages, the classification results and proofs are refined. A section on generating functions is adde