Synthesis of (3R)-Amino-(2S)-Hydroxy Amino Acids for Inhibition of Methionine Aminopeptidase-1

(3R)-amino-(2S)-hydroxy heptanoic acid (AHHpA) was synthesized via asymmetric aminohydroxylation and coupled with di-and tripeptides to form three compounds that inhibit MetAP-1 with IC₅₀ values in the low micromolar range.     

Preparation and evaluation of unimolecular pentavalent and hexavalent antigenic constructs targeting prostate and breast cancer: a synthetic route to anticancer vaccine candidates

Several novel, fully synthetic, carbohydrate-based antitumor vaccines have been assembled. Each construct consists of multiple cancer-related antigens displayed on a single polypeptide backbone. Recent advances in synthetic methodology have allowed for the incorporation of a complex oligosaccharide terminating in a sialic acid residue (i.e., GM2) as one of the carbohydrate antigens. Details of the vaccine synthesis as well as the results of preliminary immunological investigations are described herein.     

The electrodeposition of high-density,ordered arrays of Bi1-xSbx nanowires

Here we report the synthesis of dense arrays of Bi1-xSbx nanowires with >5 x 1010 nanowires/cm2. The individual wires are crystalline, relatively homogeneous, and highly textured in a 110 direction, with diameters of 40 nm and a composition of x = 12-15 atom % Sb. By tuning the solution concentrations and controlling the growth rate by controlling the potential, the composition, crystallinity, and morphology of the nanowires can be varied.     

Instrumental neutron activation analysis,a technique for measurement of Se,Hg, Fe,Zn, K,Mn, Br,and the Hg:Se ratio in brain tissue samples with results from the Memory and Aging Project (MAP)

An INAA method for measurement of Se, Hg, Fe, Cr, Zn, Mn, K, and Br in autopsy cerebellum, anterior putamen, white matter, mid-frontal cortex, and inferior temporal lobe. Se, Hg, Fe, Cr, and Zn were measured autopsy samples collected from participants of the Memory and Aging Project. The first study examined the association between seafood consumption, brain Hg and Se, Apolipoprotein E (APOE-ε4) status, and brain neuropathology. Following the initial study, the samples were archived. A subsequent method was developed to measure Mn, K, and Br in the archived brain tissue samples.     

Characterization of a Recombinant Thermostable Dehalogenase Isolated from the Hot Spring Thermophile <Emphasis Type="Italic">Sulfolobus tokodaii</Emphasis>

A putative dehalogenase, l-HAD_ST, from the thermophile Sulfolobus tokodaii, was cloned and expressed in Escherichia coli. The recombinant enzyme catalyzes the stereospecific dehalogenation of l-2-haloacids with similar levels of activity as its homolog from mesophiles. l-HAD_ST remains fully active after being incubated for 4 h at 70 °C and tolerates extreme pH conditions ranging from 4 to 10. Furthermore, it can be purified conveniently without the usage of any chromatography method. The high expression yield and easy purification procedure make the recombinant dehalogenase an excellent candidate for biotechnological applications.     

Surface enhanced raman and resonance raman spectroscopy in a non-aqueous electrochemical environment: Tris(2,2′-bipyridine)ruthenium(II) adsorbed on silver from acetonitrile

This letter reports the first observation of both surface enhanced Raman scattering (SERS) and surface enhanced resonance Raman scattering (SERRS) from the transition metal complex tris(2,2′-bipyridine)ruthenium (II), Ru(bpy)₃²⁺, adsorbed on a silver electrode from acetonitrile (ACN). The assignment of these spectra as valid examples of SERS and SERRS in a non-aqueous environment is based on the following criteria: (1) in situ demonstration of monolayer surface coverage of Ru(bpy)₃²⁺ using double potential step chronocoulometry (DPSCC); (2) the Raman signals are most intense after surface roughening by anodization; (3) the Raman spectra are potential dependent in the non-faradaic potential region; (4) the measured enhancement factors are greater ilian 10⁶; (5) the surface spectra are frequency shifted relative to their bulk counterpart; and (6) several other molecules also exhibit non-aqueous SERS and SERRS behavior. These results are highly significant in that generality of surface enhanced Raman spectroscopy has been extended into the rich domain of nonaqueous electrochemistry.     

The anti-neoplastic activity of ethylamine-carboxyborane and triphenylphosphine-carboxyborane in L-1210 lymphoid leukemia cells

Studies on the mode of action of two boroncontaining anti-neoplastic agents, ethylamine-carboxyborane and triphenylphosphine-carboxyborane, are reported. The major site of inhibition was in the pyrimidine de nove synthetic pathway at orotidine monophosphate decarboxylase activity. Additional sites which may facilitate the inhibition of cell growth were IMP dehydrogenase, thymidine kinase, TMP kinase and TDP kinase, m-RNA, r-RNA and t-RNA polymerase activities as well as topoisomerase II activity. The reduction in enzyme activities led to sufficient reduction of d(NTP) levels to suppress DNA synthesis and cell growth. DNA strand scission was evident in the presence of drug. Multiple modes of action are common with amine-carboxyboranes. Acute toxicity studies in mice showed that both agents were safe in their therapeutic range based on organ weights, histological tissue sections, clinical chemistry values and hematopoietic parameters.     

Influence of the Sb dopant distribution on far infrared photoconductivity in Ge:Sb blocked impurity band detectors

Extended long wavelength response to 200 μm (50 cm⁻¹) has been observed in Ge:Sb blocked impurity band (BIB) detectors with N_D1×10¹⁶ cm⁻³. The cut-off wavelength increases from 150 μm (65 cm⁻¹) to 200 μm (50 cm⁻¹) with increasing bias. The responsivity at long wavelengths was lower than expected. This can be explained by considering the observed Sb diffusion profile in a transition region between the blocking layer and active layer. BIB modeling is presented which indicates that this Sb concentration profile increases the electric field in the transition region and reduces the field in the blocking layer. The depletion region consists partially of the transition region between the active and blocking layer, which could contribute to the reduced long wavelength response. The field spike at the interface is the likely cause of breakdown at a lower bias than expected.     

Comprehensive two-dimensional gas chromatography using a high-temperature phosphonium ionic liquid column

A high-temperature ionic liquid, trihexyl(tetradecyl)phosphonium bis(trifluoromethane)sulfonamide, was used as the primary column stationary phase for comprehensive two-dimensional gas chromatography (GC × GC). The ionic liquid (IL) column was coupled to a 5% diphenyl/95% dimethyl polysiloxane (HP-5) secondary column. The retention characteristics of the IL column were compared to polyethylene glycol (DB-Wax) and 50% phenyl/50% methyl polysiloxane (HP-50+). A series of homologous compounds that included hydrocarbons, oxygenated organics, and halogenated alkanes were analyzed with each column combination. This comparison showed that the ionic liquid is less polar than DB-Wax but more polar than HP-50+. The most unique feature of the IL × HP-5 column combination is that alkanes, cyclic alkanes, and alkenes eluted in a narrow band in the GC × GC chromatogram; whereas, these compounds occupied a much larger portion of the DB-Wax × HP-5 and the HP-50+ × HP-5 chromatograms. Each column combination was used to analyze diesel fuel. The IL × HP-5 chromatogram displayed narrow bands for three major compound classes in diesel fuel: saturates, monoaromatics, and diaromatics. The IL column was used at temperatures as high as 290 °C for several months without any noticeable changes in column performance.