Combining two-directional synthesis and tandem reactions: a short formal synthesis of halichlorine

A short and efficient synthesis of an advanced intermediate (1) in the Clive route to halichlorine has been achieved in 12 steps and 13.2% yield by a combined two-directional synthesis/tandem reaction strategy.     

Preservice Elementary Teachers' Mathematics Content Knowledge and Teacher Efficacy

The purpose of this study was to examine the relationship between mathematics content knowledge and teacher efficacy during an elementary mathematics methods course. A positive moderate relationship between content knowledge and personal teaching efficacy was found, and this relationship was stable during the course. No relationship was found between content knowledge and outcome expectancy. Written artifacts were used to understand and elaborate on these findings. Those data suggest that prior learning experiences may help explain this relationship. Additionally, they suggest that preservice teachers with different levels of content knowledge may attend to different sources of information when making efficacy judgments about teaching.     

Euphohelioscopin A Is a PKC Activator Capable of Inducing Macrophage Differentiation

To identify small molecules that selectively control hematopoietic stem cell differentiation, we performed an unbiased screen using primary human CD34(+) cells. We identified a plant-derived natural product, euphohelioscopin A, capable of selectively differentiating CD34(+) cells down the granulocyte/monocytic lineage. Euphohelioscopin A also inhibits proliferation and induces differentiation of the myeloid leukemia cell lines THP-1 and HL-60. Mechanistic studies revealed that euphohelioscopin A is an activator of protein kinase C (PKC), and that the promonocytic effects of this natural product are mediated by PKC activation. In addition to shedding insights into normal hematopoiesis, this work may ultimately facilitate the application of stem cell therapies to a host of myeloid dysfunctions.     

Fusion around the barrier for 7Li+12C

Fusion cross-sections for the ⁷Li + ¹²C reaction have been measured at energies above the Coulomb barrier by the direct detection of evaporation residues. The heavy evaporation residues with energies below 3 MeV could not be separated out from the α-particles in the spectrum and hence their contribution was estimated using statistical model calculations. The present work indicates that suppression of fusion cross-sections due to the breakup of ⁷Li may not be significant for ⁷Li + ¹²C reaction at energies around the barrier.     

An informative subtlety of itemperature-jump or coulostatic responses for surface-attached species

Theoretical relationships are developed to describe the open-circuit responses associated with the indirect laser-induced temperature-jump (ILIT) method, a method for measuring fast electron-transfer rate constants of surface-attached redox species. The analysis is also applicable to data obtained using the coulostatic charge-injection method. The unique relationship between k_m, the relaxation rate constant for the ILIT (or coulostatic) response, and E_i, the potential at which the system is initially poised, exhibits a surprising sensitivity to the values of k₀, E_i^0′ (the standard rate constant and formal potential for the redox couple), α (the transfer coefficient in the Butler–Volmer equation) and γ (a dimensionless parameter which is directly proportional to the total surface concentration of the redox moiety). ILIT data for several examples of surface-attached ferrocene moieties confirm the theoretically predicted k_m vs E_i behavior. Values of E_i^0′ and γ extracted from the ILIT data agree well with the values obtained from cyclic voltammetric data thereby confirming that the ILIT and cyclic voltammogram (CV) experiments are sampling the same ferrocene population.     

Quantitation by fast-atom bombardment/mass-analysed ion kinetic energy spectrometry: kinetic analysis of cyclic nucleotide phosphodiesterase activity

Quantitation of cyclic nucleotide phosphodiesterase activity by means of fast-atom bombardment (FAB) mass spectrometry with mass-analysed ion kinetic energy (MIKE) spectrum scanning is described. Characteristic peaks of the substrate, cyclic AMP, and product, AMP, were identified in positive-ion FAB mass spectra and MIKE scans of the protonated molecules. By spiking enzyme incubates with known quantities of cyclic AMP and AMP and measuring peak heights in the MIKE spectra of both spiked and unspiked samples, the concentrations of cyclic AMP and AMP in solution at the end of a series of enzyme incubations have been estimated. From the data obtained the Km and Vmax of the enzymes were calculated as 181 microM and 28.6 nmol/min respectively, showing excellent agreement with values of the Michaelis constant, Km = 205 microM and the maximum velocity Vmax = 33.2 nmol/min obtained by radioactive assay.     

A finite element method for the solution of two-dimensional transonic flows in cascades

Steady two-dimensional transonic flow is calculated in cascades of compressor and turbine blades using a mesh of triangular finite elements. A velocity potential is used, the equations being solved by the Newton-Raphson technique. The resulting computer program is fast, and is shown to give good accuracy. Shock waves are well represented, provided they are not too strong.     

Online immobilized metal affinity chromatography/mass spectrometric analysis of changes elicited by cCMP in the murine brain phosphoproteome

An automated online immobilized metal affinity chromatography/high‐performance liquid chromatography mass spectrometric (IMAC‐HPLC/MS/MS) method was developed to study cytidine 3′,5′‐cyclic monophosphate (cCMP)‐specific protein phosphorylation, analogous to a previously successful offline IMAC method using microvolume IMAC pipette tips. The optimized method identified murine brain phosphoproteins selectively modified by challenge with cCMP, using manual interpretation of the results to confirm both phosphorylation and selectivity of response to cCMP. A number of proteins identified by this strategy have potential roles in hyperproliferation, a previously reported response to elevated levels of cCMP. Copyright © 2008 John Wiley & Sons, Ltd.     

Quantitation by fast-atom bombardment mass spectrometry: assay of cytidine 3',5'-cyclic monophosphate-responsive protein kinase.

A protein kinase, stimulated by cytidine 3',5'-cyclic monophosphate, is conventionally assayed by monitoring the incorporation of radiolabelled phosphate from adenosine triphosphate into a histone substrate. Here the assay of the protein kinase is carried out by positive-ion fast-atom bombardment mass spectrometric analysis of the enzyme incubation mixture after the reaction has been terminated. The data so obtained show good agreement with data obtained by the conventional radiometric assay: the intrinsic advantage of the mass spectrometric assay is the capacity for multiple component monitoring; the ability of the kinase to bind competing cyclic nucleotides together with integral adenosine triphosphatase (ATPase) and phosphodiesterase activity can also be assessed.