Serine-70 is one of the critical sites for drug-induced Bcl2 phosphorylation in cancer cells

Taxoids and other microtubule-damaging drugs are known to induce Bcl2 phosphorylation at the G2-M phase of the cell cycle, with concomitant apoptosis in malignant cells derived from a variety of human malignancies, including leukemia, lymphoma, and breast and prostate cancer. We have investigated the ability of another antineoplastic drug, dolastatin 10, in inducing Bcl2 phosphorylation and apoptosis. We also investigated the effects of a phosphatase inhibitor okadaic acid in the regulation of Bcl2 phosphorylation, cell cycle arrest, and programmed cell death. Moreover, site-directed mutagenesis studies were performed to determine the specific serine residue(s) responsible for drug-induced Bcl2 phosphorylation. Our results indicate that these antimicrotubule agents or okadaic acid can induce posttranslational modification (phosphorylation) of Bcl2 protein at multiple serine residues. Interestingly, mutation of a serine residue at position 70 to alanine can significantly decrease drug-induced posttranslational modification (phosphorylation) of Bcl2 protein. Apparently, Ser70 seems to be a critical site for drug-induced posttranslational modification (phosphorylation) of the Bcl2 protein.     

Scanning electron microscopy studies of abraded rubber surfaces

The surfaces of polybutadiene rubber (BR) and styrene-butadiene rubber (SBR) subjected to different degrees of abrasion have been studied by scanning electron microscopy (SEM). In the case of SBR it has been shown that abrasion begins with marks in the direction of rotation which are followed by fine ribbing and then by the formation of coarse, angular and prominent ridges. Prolonged abrasion produces folding and cavities on the surface. This change in abrasion mechanism has been explained as a result of heat build-up and high crack growth rate in SBR which occur beyond a certain stage. These help in softening the matrix and removing the surface. On the other hand, fractured surfaces of BR show that ridges begin to form at about 250 revolutions and there is no characteristic difference between the abraded surfaces at lower or higher degrees of abrasion.     

On the Security of RSA with Primes Sharing Least-Significant Bits

We investigate the security of a variant of the RSA public-key cryptosystem called LSBS-RSA, in which the modulus primes share a large number of least-significant bits. We show that low public-exponent LSBS-RSA is inherently resistant to Partial Key Exposure (PKE) attacks in which least-significant bits of the secret exponent are revealed to the attacker, and in particular that the Boneh-Durfee-Frankel PKE attack [5] on low public-exponent RSA is less effective for LSBS-RSA systems than for standard RSA. On the other hand, we show that large public-exponent LSBS-RSA is more vulnerable to such attacks than standard RSA. An application to server-aided RSA signature generation is proposed.This is an extended version of an earlier paper presented at the Cryptographers Track RSA Conference (CT-RSA 2001), April 8-12 2001, San Francisco, USA [20].This work was done while the author was at the School of Network Computing, Monash University, Frankston, Australia.Acknowledgement The authors would like to thank the anonymous referees of CT-RSA 2001 for their helpful comments on a preliminary version [20] of some of the results in this paper.     

High-spatial resolution mass spectrometric imaging of peptide and protein distributions on a surface

For the first time macromolecular ion microscope images have been recorded using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Single-shot, mass-resolved images of the spatial distributions of intact peptide and protein ions over an area of 200 microm in diameter were obtained in less than 1 ms at a repetition rate of 12 Hz. The magnifying ion optics of the ion microscope allowed ion images to be obtained with a lateral resolution of 4 microm. These results prove the concept of high-resolution MALDI-MS imaging in microscope mode without the need for a tight laser focus and the accompanying sensitivity losses. The ion microscopy approach offers an improvement of several orders of magnitude in speed of acquisition compared to the conventional (microprobe) approach to MALDI-MS imaging.     

Fourier transform infrared-probed O(3P) microreactor: demonstration with ethylene reactions in argon matrix

To demonstrate the development of an oxygen atom microreactor in the form of liquid-helium-cooled solid argon matrix deposited on an infrared (IR) window, the oxidation of ethylene by mobile O atoms has been investigated. O atom diffusion through the argon matrix is confirmed and used to examine ethylene-oxygen atom reactions. In a bench-scale matrix isolation system probed with a Fourier transform infrared (FT-IR) spectrometer, matrices of solid Ar at 8-10 K doped with NO2 and ethylene have been prepared on a ZnSe window within an evacuated cryostat. The matrices have been photolyzed using 350-450 nm photons, and the reaction products resulting from the reaction of O(3P), one of the photolysis products of NO2, with ethylene have been identified using FT-IR and a Gaussian 98W simulation program. These products include oxirane, acetaldehyde, ethyl nitrite radical, and ketene. The temperature effect in the range of 10-30 K on the products formed has also been investigated. The reaction mechanisms are discussed and the viability of the solid Ar matrix being a low temperature microreactor to examine reaction mechanisms of mobile oxygen atoms is elaborated.     

A theoretical analysis of non-isothermal flow in wire-coating co-extrusion dies

A theoretical study of non-isothermal superimposed flow of two polymer melts in wire coating co-extrusion dies has been carried out. Numerical methods have been employed to solve the coupled momentum- and energy-balance equations. Various combinations of three polymers—namely, high density polyethylene (HDPE), polystyrene (PS) and low density polyethylene (LDPE) have been studied and least squares curve fitted quadratic polynomials have been used for constitutive equations for all three polymers in non-Newtonian high shear rate regions. A multitude of thermal and mechanical boundary conditions can be treated by this algorithm. It was found that temperature and velocity profiles in the die depend significantly on the arrangement of the polymers. Maximum temperature rise has been noted to increase sharply with wire velocity but it can be reduced by increasing the die radius. When the thickness of the outer layer is increased from zero, the shear stress at the wall undergoes a dramatic change (if the viscosities of the polymers are different) at small values of the flow rate ratio and it reaches an asymptotic value at large values of flow rate ratio. It was also found that viscosity ratio at the interface can be reduced by changing the initial temperatures of the liquids. It was observed in some cases that large errors in the calculation of rheological and thermal variables for this problem can be made if temperature rise due to viscous dissipation is not considered.     

Conjugated hydrogenation of triglyceride oil containing conjugated acid

Conjugated hydrogenation of tung oil (fatty acid composition: elaeostearic 57.0%, linoleic 25.8%, oleic 11.2% and saturated 6.0%) has been investigated to ascertain the influence of hydrogen donors, namely primary and secondary alcohols, on rate and selectivity under different operating conditions. 2-Propanol, in general, reflects faster rate and greater degree of reduction but less selectivity towards the reduction of unsaturated acids than ethanol, when tung oil is treated at 200 C, 225 C and 250 C with 2% Ni (optimum catalyst level) and theoretical as well as 100% excess of theoretical amount of the two hydrogen donors to ensure complete hydrogenation of the oil. The rate and degree of reduction with ethanol are less influenced by its amount and amount of catalyst, but with 2-propanol these depend considerably on both the amount of hydrogen donor and amount of catalyst. During conjugated hydrogenation of tung oil, deposition of gel-like mass in minor amount occurs only at the wall of the reaction vessel. This is evidently due to polymerization of the conjugated trienoic acid. Presented at the IXth ISF Congress, Rotterdam, September 1968.     

Using matrix peaks to map topography: increased mass resolution and enhanced sensitivity in chemical imaging

It is well known in secondary ion mass spectrometry (SIMS) that sample topography leads to decreased mass resolution. Specifically, the ion's time of flight is dependent on where it was generated. Here, using matrix-enhanced SIMS, it is demonstrated that, in addition to increasing the yield of intact pseudomolecular ions, the matrix allows the user to semiquantitatively record the topography of a sample. Through mapping the topography-related mass shifts of the matrix (which leads to decreased mass resolution), the analogous mass shifts of higher mass ions can be deconvoluted and higher resolution and greater sensitivity obtained. Furthermore, the semiquantitative topographical map obtained can be compared with any chemical images obtained, allowing the user to quickly ascertain whether local intensity maximums are due to topological features or represent genuine features of interest.     

Porous PZT ceramics for receiving transducers

PZT-air (porous PZT) and PZT-polymer (polymer impregnated porous PZT) piezocomposites with varying porosity/polymer volume fractions have been manufactured. The composites were characterized in terms of hydrostatic charge (d/sub h/) and voltage (g/sub h/) coefficients, permittivity, hydrostatic figure of merit (d/sub h/.g/sub h/), and absolute sensitivity (M). With decreasing PZT ceramic volume, g/sub h/ increased, and d/sub h/.g/sub h/ had a broad maximum around 80 to 90% porosity/polymer content. The absolute sensitivity was also increased. In each case, PZT-air piezocomposites performed better than PZT-polymer piezocomposites. Hydrophones constructed from piezocomposites showed slightly lower measured receiving sensitivities than calculated values for piezocomposite materials, which was due to the loading effect of the cable and the low permittivity associated with the piezocomposites.