Friction Measurements on Contact Lenses in Their Operating Environment

An important issue concerning the use of soft contact lenses is comfort, which, among other factors, has been related to the level of friction between the anterior side of the lens and the inner eyelid. Although several studies have been carried out to investigate the frictional properties of contact lenses, these have not taken the physiological environment of the eye into account. In use, lenses are in contact with proteins present in tears, with corneal cells and with the palpebral conjunctiva (clear membrane on inner eyelid). The focus of this study was to establish a biologically relevant measurement protocol for the investigation of friction of contact lenses that would mimic the eye’s physiological environment. By optimizing parameters such as the composition of the friction counter surface, the lubricant solution, the normal load and the velocity, an ideal protocol and setup for microtribological testing could be established and used to perform a comparative study of various commercially available soft contact lenses.     

Sputtered Films of PdMn for Thermometry and Bolometry

Measurements of the magnetic sensitivity of thin sputtered films of PdMn alloy demonstrate the viability of this material for high resolution thermometry. The thinnest films (thickness 1.0 m) show significant domain scale noise below the Curie Temperature, T_c, while thicker films (thickness 10 m) show reliable non-hysteretic behavior throughout the temperature range of interest. The thin films show the effects of demagnetization with the field perpendicular to the surface, but a fine screen in this orientation shows good response with no evidence of saturation and a manageable degree of demagnetization.     

G. Stanley Hall's Contribution to Science, Practice and Policy: The Child Study, Parent Education, and Child Welfare Movements.

G. Stanley Hall influenced several social movements that had great implications for child wellbeing: the Child Study, Parent Education, and Child Welfare Movements. However, while Hall laid much of the foundation for the field of scientific child study and policy-relevant research, his legacy is virtually nonexistent. The current article reviews the life and contributions of G. Stanley Hall, and the dual role Hall played in history as a revered leader of the Child Study Movement and a controversial figure in the landscape of early child psychology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fast Fourier Transform simulation techniques for Coulomb gases

An improved approach to updating the electric field in simulations of Coulomb gases using the local lattice technique introduced by Maggs and Rossetto [A.C. Maggs, V. Rossetto, Phys. Rev. Lett. 88 (2002) 196402] is described and tested. Using the Fast Fourier Transform (FFT) an independent configuration of electric fields subject to Gauss' law constraint can be generated in a single update step. This FFT based method is shown to outperform previous approaches to updating the electric field in the simulation of a basic test problem in electrostatics of strongly correlated systems.     

Point-tracked quantitative analysis of left ventricular surface motion from 3-D image sequences

We propose and validate the hypothesis that we can use differential shape properties of the myocardial surfaces to recover dense field motion from standard three-dimensional (3-D) image sequences (MRI and CT). Quantitative measures of left ventricular regional function can be further inferred from the point correspondence maps. The noninvasive, algorithm-derived results are validated on two levels. First, the motion trajectories are compared to those of implanted imaging-opaque markers of a canine model in two imaging modalities, where subpixel accuracy is achieved. Second, the validity of using motion parameters (path length and thickness changes) for detecting myocardial injury area is tested by comparing algorithms derived results to postmortem analysis TTC staining of myocardial tissue, where the achieved Pearson product-moment correlation value is 0.968.     

Induction of human breast cancer cell apoptosis from G2/M preceded by stimulation into the cell cycle by Z-1,1-dichloro-2,3-diphenylcyclopropane

We have shown previously that Z-1,1-dichloro-2,3-diphenylcyclopropane (a.k.a. Analog II, A(II)) inhibits human breast cancer cell proliferation regardless of estrogen receptor status or estrogen sensitivity, and that its cellular targets include microtubules. In the present study, we investigated the apoptosis-inducing effects of A(II). MCF-7, MCF-7/LY2, and MDA-MB-231 cells all showed nuclear fragmentation in response to 100 microM A(II) when stained with Hoechst 33342 and examined by fluorescence microscopy. Pulsed field gel electrophoretic analysis showed that each of the cell lines also developed specific high molecular weight DNA fragments: a low level of 1-2 Mb fragments appeared after 6 hr, while 30-50 kb fragments accumulated subsequently. At 24 hr of drug exposure, the majority of cells became nonadherent, and the 30-50 kb fragments were restricted to detached MCF-7 and MDA-MB-231 cells. Both adherent and detached MCF-7/LY2 cells exhibited these fragments. A previous study by single-color (propidium) flow cytometry demonstrated that A(II) blocks MDA-MB-231 cells in G2/M of the cell cycle. More refined analyses in the present study showed this same result for MDA-MB-231 cells, but MCF-7 and MCF-7/LY2 cells did not reveal apparent drug-induced cell cycle block. A(II) demonstrated growth inhibitory, cell cycle-perturbing, and hypodiploidy-inducing activity against other human breast carcinoma lines, i.e. BT-20, CAMA-1, and SKBR-3, but no such actions in the non-tumorigenic, "normal" human breast epithelial line MCF-10A. Bromodeoxyuridine labeling and two-color flow cytometric analysis, however, suggested that A(II) caused stimulation into S phase, and that G2/M was the phase of the cell cycle from which cells apoptosed. A(II) caused cell rounding, detachment from the growth matrix, and nuclear shrinkage and fragmentation in parallel with biochemical changes. Cycloheximide inhibited A(II)-induced cell death, indicating that its toxicity requires de novo protein synthesis.     

Stereochemical course of enzymatic enolpyruvyl transfer and catalytic conformation of the active site revealed by the crystal structure of the fluorinated analogue of the reaction tetrahedral intermediate bound to the active site of the C115A mutant of MurA

MurA (UDP-GlcNAc enolpyruvyl transferase), the first enzyme in bacterial peptidoglycan biosynthesis, catalyzes the enolpyruvyl transfer from phosphoenolpyruvate (PEP) to the 3'-OH of UDP-GlcNAc by an addition-elimination mechanism that proceeds through a tetrahedral ketal intermediate. The crystal structure of the Cys115-to-Ala (C115A) mutant of Escherichia coli MurA complexed with a fluoro analogue of the tetrahedral intermediate revealed the absolute configuration of the adduct and the stereochemical course of the reaction. The fluorinated adduct was generated in a preincubation of wild-type MurA with (Z)-3-fluorophosphoenolpyruvate (FPEP) and UDP-GlcNAc and purified after enzyme denaturation. The fluorine substituent stabilizes the tetrahedral intermediate toward decomposition by a factor of 10(4)-10(6), facilitating manipulation of the adduct. The C115A mutant of MurA was utilized to avoid the microheterogeneity that arises in the wild-type MurA from the attack of Cys115 on C-2 of FPEP in competition with the formation of the fluorinated adduct. The crystal structure of the complex was determined to 2.8 A resolution, and the absolute configuration at C-2 of the adduct was found to be 2R. Thus, addition of the 3'-OH of UDP-GlcNAc is to the 2-si face of FPEP, corresponding to the 2-re face of PEP. Given the previous observation that, in D2O, the addition of D+ to C-3 of PEP proceeds from the 2-si face [Kim, D. H., Lees, W. J., and Walsh, C. T. (1995) J. Am. Chem. Soc. 117, 6380-6381], the addition across the double bond of PEP is anti. Also, because the overall stereochemical course has been shown to be either anti/syn or syn/anti [Lees, W. J., and Walsh, C. T. (1995) J. Am. Chem. Soc. 117, 7329-7337], it now follows that the stereochemistry of elimination of H+ from C-3 and Pi from C-2 of the tetrahedral intermediate of the reaction is syn.     

Management of recurrent meningeal hemangiopericytoma

BACKGROUND: Meningeal hemangiopericytoma is an uncommon neoplasm with a high propensity for recurrence. The purpose of this study was to analyze the efficacy of different treatment options in patients with recurrent disease. METHODS: The records of all patients with recurrent meningeal hemangiopericytoma treated at the study institution between 1976 and 1996 were reviewed. RESULTS: Thirty-four consecutive patients were studied. The mainstay of treatment was brain surgery in 21 patients (62%); the median time to recurrence from surgery was 12 months. Ten patients (29%) had 20 recurrent central nervous system (CNS) lesions treated by stereotactic radiosurgery. Of these, 3 previously nonirradiated patients (all with lesion size < 25 mm) achieved a complete response, which persisted at a median of 3 years. In 14 lesions (70%) a partial response (PR) occurred with a median duration of 12 months, whereas 3 lesions (15%) remained stable. Two patients with inoperable CNS lesions received external beam radiation therapy and both had PRs lasting 14 and 24 months, respectively. Nine patients (26%) received radiation therapy for metastatic disease. Of these, seven patients remained stable with good symptomatic relief, and two patients experienced tumor progression. Chemotherapy with doxorubicin-containing regimens was administered in 7 patients (21%); there was only 1 PR that lasted 8 months. The median survival from first recurrence was 4.6 years. CONCLUSIONS: Surgical management is important for the successful treatment of patients with recurrent meningeal hemangiopericytoma. Radiosurgery plays a definite role in the treatment of smaller recurrent CNS lesions. Radiation therapy is helpful in the management of inoperable tumors. More effective chemotherapeutic agents are needed.