AbstractChiral spiroketals (II), (VI) and (IX) are synthesized based on remote asymmetric induction.

A novel and rapid approach to chiral mono- or di-substituted spiroketals based on remote asymmetric induction by intramolecular iodoetherification of ene or diene ketals has been developed. This strategy concisely offers 5,5- and 5,6-spiroketals including the natural insect pheromone of the wasp.

We investigated the mechanisms by which radiofrequency (RF) fields exert their activity, and the changes in both cell proliferation and the gene expression profile in the human cell lines. A172 (glioblastoma). H4 (neuroglioma), and IMR-90 (fibroblasts from normal fetal lung) following exposure to 2.1425 GHz continuous wave (CW) and Wideband Code Division Multiple Access (W-CDMA) RF fields at three field levels. During the incubation phase. cells were exposed at the specific absorption rates (SARs) of 80, 250, or 800 mW/kg with both CW and W-CDMA RF fields for up to 96 h. Heat shock treatment was used as the positive control No significant differences in cell growth or viability were observed between any test group exposed to W-CDMA or CW radiation and the sham-exposed negative controls Using the Affymetrix Human Genome Array, only a very small (< 1%) number of available genes (ca 16,000 to 19,000) exhibited altered expression in each experiment The results confirm that low-level exposure to 2 1425 GHz CW and W-CDMA RF fields for up to 96 h did not act as an acute cytotoxicant in either cell proliferation or the gene expression profile These results suggest that RF exposure up to the limit of whole-body average SAR levels as specified in the ICNIRP guidelines is unlikely to elicit a general stress response in the tested cell lines under these conditions.

Given the widespread use of the cellular phone today, investigation of potential biological effects of radiofrequency (RF) fields has become increasingly important. In particular, much research has been conducted on RF effects on brain function. To examine any biological effects on the central nervous system (CNS) induced by 1950 MHz modulation signals, which are controlled by the International Mobile Telecommunication-2000 (IMT-2000) cellular system, we investigated the effect of RF fields on microglial cells in the brain. We assessed functional changes in microglial cells by examining changes in immune reaction-related molecule expression and cytokine production after exposure to a 1950 MHz Wideband Code Division Multiple Access (W-CDMA) RF field, at specific absorption rates (SARs) of 0.2, 0.8, and 2.0 W/kg. Primary microglial cell cultures prepared from neonatal rats were subjected to an RF or sham field for 2 h. Assay samples obtained 24 and 72 h after exposure were processed in a blind manner. Results showed that the percentage of cells positive for major histocompatibility complex (MHC) class II, which is the most common marker for activated microglial cells, was similar between cells exposed to W-CDMA radiation and sham-exposed controls. No statistically significant differences were observed between any of the RF field exposure groups and the sham-exposed controls in percentage of MHC class II positive cells. Further, no remarkable differences in the production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) were observed between the test groups exposed to W-CDMA signal and the sham-exposed negative controls. These findings suggest that exposure to RF fields up to 2 W/kg does not activate microglial cells in vitro.

A novel double intramolecular iodoetherification of σ-symmetric diene acetals from (R,R)-hydrobenzoin occurred in highly diastereoselective manners to give tetrahydrofuran moieties with multiple chiral centers in a one-pot operation. The chemoselective discrimination of the two iodomethyl functions in the products was attained in various reactions. The reaction was applied to the concise asymmetric syntheses of rubrenolide and rubrynolide, in which the unit from the chiral auxiliary worked as a template to achieve the chemoselectivity and as the protecting group of the hydroxyl function.

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Cerium ammonium nitrate (CAN) removed hydroxyethyl units from 2-hydroxyethyl ethers and 2-hydroxyethyl amines to produce alcohols and amines in good yields. Especially, removal of the 2-hydroxyethyl ethers from C-2-symmetric diols, chiral 2,3-butanediol and chiral hydrobenzoin, was very useful for asymmetric syntheses using C-2-symmetric diols. The reactions using dual abilities of CAN, i.e., the ability for removal of the 2-hydroxyethyl unit and the ability for acetal hydrolysis by a single electron transfer, were also achieved Successfully. The reaction conditions were very mild and efficient, and many functional groups, which can be affected under normal conditions, were unaffected during the reaction. (c) 2006 Published by Elsevier Ltd.

We previously reported that overexpressing connexin 26 (Cx26) enhances the spontaneous metastasis of mouse BL6 melanoma cells. In contrast, daily intraperitoneal injections of an oleamide derivative named MI‐18 potently inhibits the spontaneous metastasis of BL6 cells. In the present study, we chemically synthesized a novel oleamide derivative named MI‐22 and found that it also efficiently suppressed the spontaneous metastasis of BL6 cells. Both MI‐18 and MI‐22 inhibited the gap junction‐mediated intercellular communications (GJIC) that are formed between HeLa cells by the ectopic expression of the hCx26 and hCx32 human connexin subtypes; however, they had no effect on GJIC mediated by hCx40, hCx43 or hCx45. Fluorescently labeled MI‐18 primarily localized not only at plasma membrane but also at Golgi/endosome. This suggests that this oleamide derivative may also act on the Cx26 molecules that accumulate in the Golgi/endosome because of their overexpression. Notably, neither derivative had a cytotoxic effect on HeLa cells when they were added into the tissue culture medium. Taken together, we propose that the MI‐18 and MI‐22 oleamide derivatives may serve as prototypes for novel and clinically important anticancer drugs. © 2007 Wiley‐Liss, Inc.

To examine the biological effects of radio frequency (RF) electromagnetic fields in vitro, we have examined the fundamental cellular responses, such as cell growth, survival, and cell cycle distribution, following exposure to a wide range of specific absorption rates (SAR). Furthermore, we compared the effects of continuous and intermittent exposure at high SARs. An RF electromagnetic field exposure unit operating at a frequency of 2.45 GHz was used to expose cells to SARs from 0.05 to 1500 W/kg. When cells were exposed to a continuous RF field at SARs from 0.05 to 100 W/kg for 2 h, cellular growth rate, survival, and cell cycle distribution were not affected. At 200 W/kg, the cell growth rate was suppressed and cell survival decreased. When the cells were exposed to an intermittent RF field at 300 W/kg(pk), 900 W/kg(pk) and 1500 W/kg(pk) (100 W/kg(mean)), no significant differences were observed between these conditions and intermittent wave exposure at 100 W/kg. When cells were exposed to a SAR of 50 W/kg for 2 h, the temperature of the medium around cells rose to 39.1 degrees C, 100 W/kg exposure increased the temperature to 41.0 degrees C, and 200 W/kg exposure increased the temperature to 44.1 degrees C. Exposure to RF radiation results in heating of the medium, and the thermal effect depends on the mean SAR. Hence, these results suggest that the proliferation disorder is caused by the thermal effect.

The reaction of cyclohexa-2,5-dienyl-1-methylaldehyde and optically pure 1,2-diaryl-1,2-diamine followed by intramolecular bromo-amination produced a one-pot discrimination of two olefins in the cyclohexane system, which was used for the asymmetric synthesis of (-)-gamma-lycorane.

Tetrahydrofuran-Einheiten mit mehreren Chiralitätszentren entstehen hoch diastereoselektiv bei der im Schema gezeigten Eintopfreaktion aus σ-symmetrischen Dienacetalen. Die Nüzlichkeit des Verfahrens belegt die ebenfalls beschriebene kurze asymmetrische Synthese von (+)-Rubrenolid. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2001/2005/z461584_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

CAN is a good reagent for the transformation of 2-hydroxyethyl ether units to alcohols. Significantly, many functional groups can tolerate the reaction conditions, although they do not survive under many previously reported removal conditions. The reaction mechanism is clarified.

To investigate the induction of chromosomal aberrations in mouse m5S cells after exposure to high-frequency electromagnetic fields (HFEMFs) at 2.45 GHz, cells were exposed for 2 h at average specific absorption rates (SARs) of 5, 10, 20, 50 and 100 W/kg with continuous wave-form (CW), or at a mean SAR of 100 W/kg (with a maximum of 900 W/kg) with pulse wave-form (PW). The effects of HFEMF exposure were compared with those in sham-exposed controls and with mitomycin C (MMC) or X-ray treatment as positive controls. We examined all structural, chromatid-type and chromosome-type changes after HFEMF exposures and treatments with MMC and X-rays. No significant differences were observed following exposure to HFEMFs at SARs from 5 to 100 W/kg CW and at a mean SAR of 100 W/kg PW (a maximum SAR of 900 W/kg) compared with sham-exposed controls, whereas treatments with MMC and X-rays increased the frequency of chromatid-type and chromosome-type aberrations. In summary, HFEMF exposures at 2.45 GHz for 2 h with up to 100 W/kg SAR CW and an average 100 W/kg PW (a maximum SAR of 900 W/kg) do not induce chromosomal aberrations in m5S cells. Furthermore, there was no difference between exposures to CW and PW HFEMFs.

We investigated the effects of 6- and 10-T static magnetic fields (SMFs) on the expression of protooncogenes using Western blot immunohybridization methods. We used a SMF exposure system, which can expose cells to a spatially inhomogeneous 6 T with a strong magnetic field (MF) gradient (41.7 T/m) and a spatially homogeneous 10 T of the highest magnetic flux density in this experiment. HL-60 cells exposed to either 6- or 10-T SMF for periods of 1 to 48 h did not exhibit remarkable differences in levels of c-Myc and c-Fos protein expression, as compared with sham-exposed cells. In contrast, c-Jun protein expression increased in HL-60 cells after exposure to 6-T SMF for 24, 36, 48, and 72 h. These results suggest that a homogeneous 10-T SMF does not alter the expression of the c-jun, c-fos, and c-myc protooncogenes. However, our observation that exposure to a strong MF gradient induced c-Jun expression suggests that a strong MF gradient may have significant biological effects, particularly regarding processes related to an elevation of c-jun gene expression.