[Density functional theory calculation of SERS spectra of trans-1,2-bis(4-pyridyl)-ethylene on silver].

It has been found that trans-1, 2-bis(4-pyridyl)-ethylene has the best SERS signal and can be employed as a kind of self-assembly ? Im for the exploration of the SERS-active on the silver foil substrate. The shifts in the experiment surface enhanced Raman scattering of trans-1,2-bis(4-pyridyl)-ethylene were simulated by density functional theory calculation with the BP86, BPw91, B3LYP method. The basis set of 6-31++G(d,p) and Lan12dz was used by H, C, N atoms and Ag atom for the t-BPE-Ag complex. The Raman spectra and surface enhanced Raman scattering of trans-1, 2-bis (4-pyridyl)-ethylene were assigned by the calculated results of potential energy distribution The density functional theory calculated results explain that the angles between pyridyl rings for t-BPE-Ag complex holding 0o. Thus, the calculated Raman spectra of trans-1, 2-bis(4-pyridyl)-ethylene and Ag complex accord with observed SERS results of t-BPE. The energy level space between the high occupied molecular orbital and lowest unoccupied molecular orbital is estimated to arise between 415 and 912 nm for trans-1,2-bis(4-pyridyl)-ethylene and Ag complex.

Subcellular localization of sigma-2 receptors in breast cancer cells using two-photon and confocal microscopy.

Sigma-2 receptor agonists have been shown to induce cell death via caspase-dependent and caspase-independent pathways. Unfortunately, there is little information regarding the molecular function of sigma-2 receptors that can explain these results. In this study, two fluorescent probes, SW107 and K05-138, were used to study the subcellular localization of sigma-2 receptors by two-photon and confocal microscopy. The results indicate that sigma-2 receptors colocalize with fluorescent markers of mitochondria, lysosomes, endoplasmic reticulum, and the plasma membrane in both EMT-6 mouse and MDA-MB-435 human breast cancer cells. The fluorescent probe, K05-138, was internalized rapidly, reaching a plateau of fluorescent intensity at 5 min. The internalization of K05-138 was reduced approximately 40% by phenylarsine oxide, an inhibitor of endocytosis. These data suggest that sigma-2 ligands are internalized, in part, by an endocytotic pathway. The localization of sigma-2 receptors in several organelles known to have a role in both caspase-dependent and caspase-independent pathways of cell death supports the conclusions of previous studies suggesting that sigma-2 receptor ligands should be evaluated as potential cancer chemotherapeutic agents.

SPECT imaging of herpes simplex virus type1 thymidine kinase gene expression by [(123)I]FIAU(1).

RATIONALE AND OBJECTIVES: Introduction of suicide genes, such as herpes simplex virus type1 thymidine kinase (HSV1-tk), in tumor cells has provided a useful method for tumor gene therapy. Several L-nucleosides, such as Lamivudine (3TC) and Clevudine (L-FMAU), have been successfully tested as high-potency antiviral agents. To investigate the potential differences between D- and L-isomers of nucleosides, [(125/123)I]-2'-fluoro-2'-deoxy-1beta-D/L-arabino-furanosy-5-iodo-uracil (D/L-FIAU) have been synthesized and evaluated as potential SPECT agents for imaging HSV1-tk gene expression. MATERIALS AND METHODS: [(125/123)I]D- and L-FIAU were prepared by iododestannylation of the respective tin precursors with (125/123)I-sodium iodide. In vitro cell uptake studies were performed by incubation of [(125)I]D- and L-FIAU in RG2 cells expressing HSV1-tk (RG2TK+). In vivo studies including biodistribution and SPECT were performed in RG2TK+ and RG2TK- tumor-bearing nude mice using [(123)I]D- and L-FIAU. RESULTS: Cell uptake and biodistribution studies indicated that [(125/123)I]L-FIAU did not show any high accumulation (sensitivity) or uptake ratios (selectivity) in HSV1-TK-positive (RG2TK+) tumors as compared to control tumors. In contrast, [(125/123)I]D-FIAU displayed both sensitivity and selectivity to RG2TK+ tumors. The selective in vivo accumulation of [(123)I]D-FIAU increased with time and the tumor uptake ratios (RG2TK+/RG2TK-) for 2, 4, and 24 hours averaged 6.2, 22.7, and 58.8, respectively. High-resolution SPECT of four nude tumor-bearing mice demonstrated a very high uptake of [(123)I]D-FIAU in the RG2TK+ tumor, while no significant tracer accumulation was observed in the RG2TK- tumor and other organs. CONCLUSION: The data suggest that only the D-isomer of [(123)I]FIAU is useful for imaging HSV1-tk gene expression in mice by high-resolution SPECT imaging.

Selective binding of 2-[125I]iodo-nisoxetine to norepinephrine transporters in the brain.

A radioiodinated ligand, (R)-N-methyl-(2-[(125)I]iodo-phenoxy)-3-phenylpropylamine, [(125)I]2-INXT, targeting norepinephrine transporters (NET), was successfully prepared. A no-carrier-added product, [(125)I]2-INXT, displayed a saturable binding with a high affinity (K(d)=0.06 nM) in the homogenates prepared from rat cortical tissues as well as from LLC-PK(1) cells expressing NET. A relatively low number of binding sties (B(max)=55 fmol/mg protein) measured with [(125)I]2-INXT in rat cortical homogenates is consistent with the value reported for a known NET ligand, [(3)H]nisoxetine. Competition studies with various compounds on [(125)I]2-INXT binding clearly confirmed the pharmacological specificity and selectivity for NET binding sites. Following a tail-vein injection of [(125)I]2-INXT in rats, a good initial brain uptake was observed (0.56% dose at 2 min) followed by a slow washout from the brain (0.2% remained at 3 hours post-injection). The hypothalamus (a NET-rich region) to striatum (a region devoid of NET) ratio was 1.5 at 3 hours post-i.v. injection. Pretreatment of rats with nisoxetine significantly inhibited the uptake of [(125)I]2-INXT (70-100% inhibition) in locus coeruleus, hypothalamus and raphe nuclei, regions known to have a high density of NET; whereas escitalopram, a serotonin transporter ligand, did not show a similar effect. Ex vivo autoradiography of rat brain sections of [(125)I]2-INXT (at 3 hours after an i.v. injection) displayed an excellent regional brain localization pattern corroborated to the specific NET distribution in the brain. The specific brain localization was significantly reduced by a dose of nisoxetine pretreatment. Taken together, the data suggest that [(123)I]2-INXT may be useful for mapping NET binding sites in the brain.

A comparison of amyloid fibrillogenesis using the novel fluorescent compound K114.

Proteinaceous inclusions with amyloidogenic properties are a common link between many neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Histological and in vitro studies of amyloid fibrils have advanced the understanding of protein aggregation, and provided important insights into pathogenic mechanisms of these neurodegenerative brain amyloidoses. The classical amyloid dyes Congo Red (CR) and thioflavin T and S, have been used extensively to detect amyloid inclusions in situ. These dyes have also been utilized to monitor the maturation of amyloid fibrils assembled from monomer subunits in vitro. Recently, the compound (trans,trans)-1-bromo-2,5-bis-(3- hydroxycarbonyl-4-hydroxy)styrylbenzene (BSB), derived from the structure of CR, was shown to bind to a wide range of amyloid inclusions in situ. More importantly it was also used to label brain amyloids in live animals. Herein, we show that an analogue of BSB, (trans,trans)-1-bromo-2,5-bis-(4-hydroxy)styrylbenzene (K114), recognizes amyloid lesions, and has distinctive properties which allowed the quantitative monitoring of the formation of amyloid fibrils assembled from the amyloid-beta peptide, alpha-synuclein, and tau.