Promotion of photodynamic therapy-induced apoptosis by the mitochondrial protein Smac/DIABLO: dependence on Bax

Photodynamic therapy (PDT) using the second-generation photosensitizer phthalocyanine (Pc) 4 causes mitochondrial damage and induces apoptosis through the release of cytochrome c to the cytosol. Another protein of the mitochondrial intermembrane space, Smac/DIABLO (second mitochondria-derived activator of caspase/direct inhibitor of apoptosis-binding protein with low pI), is also released to the cytosol in response to apoptotic stimuli and promotes caspase activation by binding IAP. To investigate the possible role of Smac/DIABLO in apoptosis induced by Pc 4-PDT, we transfected Smac/DIABLO (tagged at its C-terminus with green fluorescent protein [GFP]) into MCF-7c3 cells (human breast cancer MCF-7 cells stably transfected with procaspase-3) and DU-145 cells (human prostate cancer cells that express no Bax because of a frameshift insertion mutation). Confocal microscopy showed that recombinant Smac/DIABLO, like cytochrome c, localized to mitochondria and colocalized with MitoTracker Red. Three hours after exposure of MCF-7c3 cells to PDT (200 nM Pc 4 and 150 mJ/cm2 red light), Smac/DIABLO-GFP, as well as cytochrome c, was found largely in the cytosol. In contrast, for DU-145 cells, both Smac/DIABLO-GFP and cytochrome c remained in the mitochondria after PDT. By staining with Hoechst 33,342, typical apoptotic nuclei were observed in MCF-7c3 cells, but not in DU-145 cells, after Pc 4-PDT. These results suggest that the release of Smac/DIABLO from mitochondria may be regulated by a Bax-mediated mechanism and that Smac/DIABLO may cooperate with the cytochrome c-dependent apoptosis pathway. In addition, in MCF-7c3 cells transfected by Smac/DIABLO-GFP, apoptosis induced by Pc 4-PDT was greater than in cells transfected with the GFP vector alone or in untransfected cells, as determined by flow cytometry. Thus, Smac/DIABLO promotes apoptosis after Pc 4-PDT in a Bax-dependent manner and may facilitate the passage of PDT-treated cells through the late steps of apoptosis.     

Studies on the Reaction of α‐Chloroformylarylhydrazine Hydrochloride with Imidazole and 1,2,4‐Triazole

α‐Imidazolformylarylhydrazine 2 and α‐[1,2,4]triazolformylarylhydrazine 3 have been synthesized through the nucleophilic substitution reaction of 1 with imidazole and 1,2,4‐triazole, respectively. 2,2′‐Diaryl‐2H,2′H‐[4,4′]bi[[1,2,4]‐triazolyl]‐3,3′‐dione 4 was obtained from the cycloaddition of α‐chloroformylarylhydrazine hydrochloride 1 with 1,2,4‐triazole at 60 °C and in absence of n‐Bu₃N. The inducing factor for cycloaddition of 1 with 1,2,4‐triazole was ascertained as hydrogen ion by the formation of 4 from the reaction of 3 with hydrochloric acid. 4 was also acquired from the reaction of 3 with 1 and this could confirm the reaction route for cycloaddition of 1 with 1,2,4‐triazole. Some acylation reagents were applied to induce the cyclization reaction of 2 and 3.1 possessing chloroformyl group could induce the cyclization of 2 to give 2‐aryl‐4‐(2‐aryl‐4‐vinyl‐semicarbazide‐4‐yl)‐2,4‐dihydro‐[1,2,4]‐triazol‐3‐one 6. 7 was obtained from the cyclization of 2 induced by some acyl chlorides. Acetic acid anhydride like acetyl chloride also could react with 2 to produce 7D . 5‐Substituted‐3‐aryl‐3H‐[1,3,4]oxadiazol‐2‐one 8 was produced from the cyclization reaction of 3 induced by some acyl chlorides or acetic acid anhydride. The 1,2,4‐triazole group of 3 played a role as a leaving group in the course of cyclization reaction. This was confirmed by the same product 8 which was acquired from the reaction of 1 , possessing a better leaving group: Cl, with some acyl chlorides or acetic acid anhydride.     

Syntheses of Mg/Al Multinuclear Bridged Complexes. (II). Reactions of Aluminumtrihalide with Dialkylaminomagnesium

Al₂X₆Mg[N(C₂H₅)₂]₂( X = Cl, Br), A1₂X₄(NR₂)₂ (R = C₂H₅, i-C₃H₇, X=Cl, Br), AlX₃HNR₂(R=i-C₃H7) were characterized by means of mass, infrared, and ¹H, ¹³C and ²⁷Al NMR spectra and elemental analyses. The crystal structures of two aluminum complexes, Al₂Cl₄[N(C₂H₅)₂]₂ and AlCl₃HN(i-C₃H₇)₂, were determined by means of single-crystal X-ray diffraction, Al₂Cl₄[N(C₂H₅)₂]₂ crystallized in space group Pmcn with unit-cell dimensions a = 10.577(2), b = 11.799(3) and c = 13.219(4) Å; structure analysis resulted in a final R = 0.043 for 999 observations. AlCl₃HN(i-C₃H₇)₂ crystallized in space group Pcab with unit-cell dimensions a = 10.545(7), b = 14.630(4) and c = 15.255(2) Å; structure analysis resulted in a final R = 0.041 for 1054 observations. The Al atoms in both structures show a tetrahedral bonding geometry with Al-N lengths in the range 1.927(3) ?1.956(4) A, and Al-Cl lengths in the range 2.092(3) ?2.128(3) Å. The four-membered ring of Al₂N₂ in Al₂Cl₄[N(C₂H₅)₂]₂ is almost planar.     

Tetrahydrofuran and 3,3-bis(chloromethyl) oxetane triblock copolymers synthesized by two-end living cationic polymerization

Triblock copolymers based on tetrahydrofuran (THF) and 3,3-bis(chloromethyl) oxetane (BCMO), BCMO-block-THF-block-BCMO and poly(BCMO-co-THF)-THF-(BCMO-co-THF), have been synthesized by two-end living cationic polymerization with a bifunctional initiator, trifluoromethanesulfonic anhydride [(CF₃SO₂)₂O]. The polymers are obtained by using the two end propagating species of poly(THF) to initiate the sequential BCMO polymerization. The resulting polymers are characterized by infrared (IR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC), confirming that the polymers are ABA-type block copolymers. The identities of the molecular weights predetermined and which determined by GPC show the success of predetermining molecular weights of the polymers and preparing well-defined polymers. The narrow polydispersities, 1.1–1.3, indicate that the chains are propagating by a living mechanism. © 1993 John Wiley & Sons, Inc.     

G3(MP2) study of the C3H6O+* isomers fragmented from 1,4-dioxane+*

The fragmentation process of ionized 1,4-dioxane and the reactions between the C3H6O+* ions, one of the major fragments, and various reactants (including acetonitrile, formaldehyde, ethylene, and propene) have been studied experimentally with mass spectrometry. In the present work, G3(MP2) calculations were carried out to investigate these processes theoretically. In agreement with experiment, isomers CH3OCHCH2+* (1) and *CH2CH2OCH2+ (2) were found to be the C3H6O+* ions fragmented from ionized 1,4-dioxane, with 2 being the major product. The mechanisms of the formation of 1 and 2 were successfully established. In addition, the characteristic reactivities, as well as the corresponding reaction mechanisms, of both isomers were rationalized with the aid of calculations. Finally, a minor reaction between isomer 2 and propene was identified, and the presence of the product of this reaction was found to be useful in explaining the aforementioned mass spectrometric data.     

Time-reversal symmetry in molecular rovibronic states and in second-order processes

A unified treatment of time-reversal symmetry is given for molecular systems. The treatment allows for interconversion of electronic, rotational, and vibrational angular momenta on equal footing because of a coherent phase choice. It also allows for correlation from a continuous group (of spherical or cylindrical symmetry) to lower point groups (such as C₃, C₄, C₆, S₄, S_g, T, etc.). General, many-electron molecular states that form time-reversal degenerate components are constructed. Attention is called to the Kramers' doublets as the special odd-electron case of such double degeneracy. Specific examples of a spiropentane and a 5-azoniaspiro(4.4) nonane with S₄ symmetry and possible time-reversal degeneracy are given. The optical rotation due to a time-odd polarizability tensor in one of the two time-degenerate components is shown to be of an opposite sign to that in the other component. The above result is from a second-order matrix element (over the polarizability tensor) and is proved to be independent of even- or odd-number of electron spins. It is shown to hold also for Kramers' doubly degenerate components. This result is contrasted with that of a first-order Jahn-Teller effect which depends on the number of electron spins.     

Radiochenical determination of technetium-99 in LLW by chelation with sodium diethyl dithiocarbamate (NaDDC) and extraction with chloroform

A radiochemical method has been developed for the determination of⁹⁹Tc in low-level radioactive, waste from nuclear facilities, using^99mTc as an internal tracer. Radioactive contaminants were removed by carrier hydroxide precipitation and chelating extraction with NaDDC/CHCl₃ system at pH 4. The final technetium was chelated with NaDDC in 3N HCl solution and extracted selectively into chloroform. The average of radiochemical recovery for various types of LLW sample is about 90%. The decontamination factors for most radioactive nuclides are higher than 10⁵. The detection limit for⁹⁹Tc in a sample of about 10 g is 0.17 pCi/g (6.5 Bq·kg^–1) for a 100-minute count.     

Studies on the polymerization mechanism of 3-nitratomethyl-3′-methyloxetane and 3-azidomethyl-3′-methyloxetane and the synthesis of their respective triblock copolymers with tetrahydrofuran

Novel energetic oxetane derivatives, 3-nitratomethyl-3′-methyloxetane (NMMO) and 3-azidomethyl-3′-methyloxetane (AMMO), were used as monomers in a triflic anhydride [(CF₃SO₂)₂O] initiating polymerization system. The “living cationic” characteristics of the polymerization were investigated and confirmed via a ¹⁹F NMR technique. This living polymerization system was, thus, utilized in the synthesis of well-defined block copolymers. Novel polymers of the A—B—A— type with various molecular weights (M?_w = 14320–40660) and low polydispersity indexes (PDI = 1.11–1.29) were obtained. Two glass transition temperatures (T_g) near the respective T_gs of the homopolymers were found in the DSC thermograms of the block copolymers. The THF/AMMO copolymers were shown to possess higher thermal stability compared to THF/NMMO copolymers from thermogravimetric analysis (TGA). © 1995 John Wiley & Sons, Inc.     

Comparing micellar electrokinetic chromatography and microemulsion electrokinetic chromatography for the analysis of preservatives in pharmaceutical and cosmetic products

In this study, separation and determination of nine preservatives ranging from hydrophilic to hydrophobic properties, which are commonly used as additives in various pharmaceutical and cosmetic products, by micellar electrokinetic chromatograpy (MEKC) and microemulsion electrokinetic chromatography (MEEKC) were compared. The effect of temperature, buffer pH, and concentration of surfactant on separation were examined. In MEKC, the separation resolution of preservatives improved markedly by changing the sodium dodecyl sulfate concentration. Temperature and pH of running buffers were used mainly to shorten the magnitude of separation time. However, in order to detect all preservatives in a single run in a MEEKC system, a microemulsion of higher pH was needed. The separation resolution was improved dramatically by changing temperature, and a higher concentration of SDS was necessary for maintaining a stable microemulsion solution, therefore the separation of the nine preservatives in MEEKC took longer than in MEKC. An optimum MEKC method for separation of the nine preservatives was obtained within 9.0 min with a running buffer of pH 9.0 containing 20 mM SDS at 25 degrees C. A separation with baseline resolution was also obtained within 16 min using a microemulsion of pH 9.5 which composed of SDS, 1-butanol, and octane, and a shorter capillary column at 34 degrees C. Finally, the developed MEKC and MEEKC methods determined successfully preservatives in various cosmetic and pharmaceutical products.     

Electron-transfer transitions during the collision of O2, N2, NO and CO with their respective ions

An improved theory of electron transfer absorption is proposed. The possibility of such absorption during the collision of ion-molecule pairs is discussed and frequencies for the O₂O₂⁺, O₂O₂^?, NONO^?, COCO⁺ and N₂N₂⁺ pairs are estimated. Oscillator strengths are also estimated for the O₂O₂⁺ pair.