Targeted Enrichment of Enzyme-Instructed Assemblies in Cancer Cell Lysosomes Turns Immunologically Cold Tumors Hot.

Lysosome-relevant cell death induced by lysosomal membrane permeabilization (LMP) has recently attracted increasing attention. However, nearly no studies show that currently available LMP inducers can evoke immunogenic cell death (ICD) or convert immunologically cold tumors to hot. Herein, we report a LMP inducer named TPE-Py-pYK(TPP)pY, which can respond to alkaline phosphatase (ALP), leading to formation of nanoassembies along with fluorescence and singlet oxygen turn-on. TPE-Py-pYK(TPP)pY tends to accumulate in ALP-overexpressed cancer cell lysosomes as well as induce LMP and rupture of lysosomal membranes to massively evoke ICD. Such LMP-induced ICD effectively converts immunologically cold tumors to hot as evidenced by abundant CD8+ and CD4+ T cells infiltration into the cold tumors. Exposure of ALP-catalyzed nanoassemblies in cancer cell lysosomes to light further intensifies the processes of LMP, ICD and cold-to-hot tumor conversion. This work thus builds a new bridge between lysosome-relevant cell death and cancer immunotherapy.

The interaction of gamma radiation with drugs used in cholinergic medications.

Purpose: Pharmacological medications can reduce the radiation damage in the organism when applied in the stage before or after exposure to radiation. Cholinergic drugs are a category of pharmaceutical agents acting on the neurotransmitter acetylcholine, the primary neurotransmitter in the parasympathetic nervous system. In this investigation, some gamma radiation interaction parameters namely mass attenuation coefficients (µρ), effective atomic number (Zeff) and electron densities (Nel) of 12 cholinergic system drugs have been calculated in the energy range 1 KeV-100 GeV. In addition, gamma-ray energy absorption (EABF) and exposure (EBF) of buildup factors have been computed using the five-parameter geometric progression (G-P) fitting formula for investigated drugs in the energy range 0.015-15 MeV, and for penetration depths up to 40 mean free path (mfp).Materials and methods: In order to perform these calculations, data obtained from WinXCom computer program were used. The computed µρ values were then used to calculate the effective atomic numbers and electron density of the investigated drugs. To compute the buildup factors, the G-P fitting parameters were determined by the method of interpolation from the equivalent atomic number, 'Zeq'Results and Conclusions: It has been concluded that effective atomic number and electron density of malathion is bigger than the other drugs and the variations in values of Zeff and Nel for all drugs depend on chemical compositions and photon energy where the K-absorption edge of elements may affect the energy dependence of Zeff and Nel. It should also be noted that the buildup of photons is less in malathion and carbachol and is more in tabun and parathion compared with other drugs. Photon interaction parameters evaluated in the present study may be beneficial in radiation dosimetry and therapy.

Rate constants for the reaction of hydroxyl and sulfate radicals with organophosphorus esters (OPEs) determined by competition method.

Advanced oxidation processes (AOPs), such as hydroxyl radical (•OH) and sulfate radical (•SO4-) mediated oxidation, are proved to be effective methods to remove the organophosphorus esters (OPEs) in wastewater effluents. However, few studies have reported about the bimolecular reaction rate constants between free radicals (•OH and •SO4-) and OPEs. This issue was solved by selecting three OPEs as model compounds, the oxidation of these OPEs in UV/H2O2 and UV/K2S2O8 process were studied. Tris(2-chloroethyl) phosphate (TCEP), tris(1-chloro-2-propyl) phosphate (TCPP), and tris(2,3-dichloropropyl) phosphate (TDCPP) can hardly be oxidized through direct irradiation methods using UV lamp, with the oxidation rate less than 30% after 7 h' irradiation. However, TCEP, TCPP, and TDCPP undergo degradation via UV/H2O2 and UV/K2S2O8 processes easily, the oxidation rates increased with increasing H2O2 and K2S2O8 dosage. The oxidation rates of three OPEs have been studied using competition experiments in the UV/H2O2 and UV/K2S2O8 processes. The bimolecular reaction rate constants of TCEP, TCPP and TDCPP with •OH were 2.50 × 1010, 3.95 × 1010 and 2.94 × 1010 respectively; while •SO4- were 3.00 × 107, 1.82 × 107 and 2.06 × 107 respectively. Results showed that the simplified kinetic model involves only steady state concentration of free radicals and the molecular reaction rate contents are available for calculating the oxidation rates of OPEs in ultrapure water.

Pore-Filled Scintillating Membrane as Sensing Matrix for α-Emitting Actinides.

Pore-filled membranes with scintillating properties have been synthesized for sensing α-emitting radionuclides. The membranes have been prepared by in situ UV-initiator-induced polymerization of monomer bis[2-(methacryloxy)ethyl] phosphate in pores of the host membranes, poly(propylene) and poly(ethersulfone). The polymerization has been carried out in the presence of scintillating molecules, 2,5-diphenyloxazole. These scintillating molecules are physically trapped in the thus formed microgel in the membrane. Much higher α-scintillation efficiency has been obtained for the (241)Am-loaded poly(ethersulfone)-based grafted membrane compared to poly(propylene)-based membrane. This was attributed to the aromatic backbone of the poly(ethersulfone) membrane. The scintillation response of poly(ethersulfone)-based membranes has been found to be linear over the range of (241)Am activity studied. The pore-filled scintillating membranes have been found to be selective toward Pu(4+) ions at higher HNO3 concentration compared to Am(3+). The analytical performance of the pore-filled scintillating membranes has been evaluated. The membranes have been found to be stable and reusable. The scintillating membrane with optimized composition has been applied for quantification of Pu in a soil sample.

Light-Cured Self-Etch Adhesives Undergo Hydroxyapatite-Triggered Self-Cure.

Light cure is a popular mode of curing for dental adhesives. However, it suffers from inadequate light delivery when the restoration site is less accessible, in which case a self-cure mechanism is desirable to salvage any compromised polymerization. We previously reported a novel self-cure system mediated by ethyl 4-(dimethylamino)-benzoate (4E) and hydroxyapatite (HAp). The present work aims to investigate if such self-cure phenomenon takes place in adhesives that underwent prior inadequate light cure and to elucidate if HAp released from the dental etching process is sufficient to trigger it. Model self-etch adhesives were formulated with various components, including bis[2-methacryloyloxy)ethyl]-phosphate (2MP) as acidic monomer and trimethylbenzoyl-diphenylphosphine oxide (TPO) as photoinitiator. In vitro evolution of degree of conversion (DC) of HAp-incorporated adhesives was monitored by infrared spectroscopy during light irradiation and dark storage. Selected adhesives were allowed to etch and extract HAp from enamel, light-cured in situ, and stored in the dark, after which Raman line mapping was used to obtain spatially resolved DC across the enamel-resin interface. Results showed that TPO+4E adhesives reached DC similar to TPO-only counterparts upon completion of light irradiation but underwent another round of initiation that boosted DC to ~100% regardless of HAp level or prior light exposure. When applied to enamel, TPO-only adhesives had ~80% DC in resin, which gradually descended to ~50% in enamel, whereas TPO+4E adhesives consistently scored ~80% DC across the enamel-resin interface. These observations suggest that polymerization of adhesives that underwent insufficient light cure is salvaged by the novel self-cure mechanism, and such salvaging effect can be triggered by HAp released from dental substrate during the etching process.

Bond strength of dental adhesive systems irradiated with ionizing radiation.

PURPOSE: The aim of the present paper was to determine the effect of different types of ionizing radiation on the bond strength of three different dentin adhesive systems. MATERIALS AND METHODS: One hundred twenty specimens of 60 human teeth (protocol number: 032/2007) sectioned mesiodistally were divided into 3 groups according to the adhesives systems used: SB (Adper Single Bond Plus), CB (Clearfil SE Bond) and AP (Adper Prompt Self-Etch). The adhesives were applied on dentin and photo-activated using LED (Lec 1000, MMoptics, 1000 mW/cm2). Customized elastomer molds (0.5 mm thickness) with three orifices of 1.2 mm diameter were placed onto the bonding areas and filled with composite resin (Filtek Z-250), which was photo-activated for 20 s. Each group was subdivided into 4 subgroups for application of the different types of ionizing radiation: ultraviolet radiation (UV), diagnostic x-ray radiation (DX), therapeutic x-ray radiation (TX) and without irradiation (control group, CG). Microshear tests were carried out (Instron, model 4411), and afterwards the modes of failure were evaluated by optical and scanning electron microscope and classified using 5 scores: adhesive failure, mixed failures with 3 significance levels, and cohesive failure. The results of the shear bond strength test were submitted to ANOVA with Tukey's test and Dunnett's test, and the data from the failure pattern evaluation were analyzed with the Mann Whitney test (p = 0.05). RESULTS: No change in bond strength of CB and AP was observed after application of the different radiation types, only SB showed increase in bond strength after UV (p = 0.0267) irradiation. The UV also changed the failure patterns of SB (p = 0.0001). CONCLUSION: The radio-induced changes did not cause degradation of the restorations, which means that they can be exposed to these types of ionizing radiation without weakening the bond strength.

Ultrasonic destruction of pesticide contaminants in slurries.

The use of high power ultrasound to destroy pesticide contaminants in sand slurries is reported. Small quantities of DDT, chlordane, atrazine, 2,4,5-T and endosulfan in solvent were added to washed, screened sand and deposited onto the sand by slow evaporation of the solvent. Fifty wt.% slurries for all five pesticides and 20 wt.% slurries of atrazine and 2,4,5-T were sonicated for periods up to 30 min and samples were withdrawn at various intervals and analysed to follow the kinetics of contaminant destruction. Seventy percent destruction of the contaminant was obtained for four of the 50 wt.% slurries with approximately 50% destruction of 2,4,5-T in 10 min of sonication whereas, in the 20 wt.% slurries of atrazine and 2,4,5-T, and 75% and 85% reduction, respectively, was obtained in 10 min. We postulate that better stirring of the slurry will improve these rates of contaminant destruction.

Photooxidation and subsequent biodegradability of recalcitrant tri-alkyl phosphates TCEP and TBP in water.

Biodegradable organic carbon (BDOC) from OH radical oxidation (UV-H2O2) of the recalcitrant industrial anti-foaming agents and flame retardants, tri-n-butyl phosphate (TBP) and tris(2-chloroethyl) phosphate (TCEP), was quantified with respect to the fraction of the TBP or TCEP photooxidized. For 50-96% contaminant oxidation via OH, BDOC was similar in solutions of either compound, and ranged from 0.25 to 0.5 mg L(-1) (TBP0 and TCEP0 = 5 mg L(-1)). In addition, for this contaminant oxidation range, complete dehalogenation of TCEP was observed, along with a significant change in pH. Oxidation of TCEP results in both H+ and Cl(-) release, while the TBP mineralization pathway results in CO2, H2O, H+, and PO4(3-). For low microg/L levels of TCEP contamination in treated surface waters, UV-H2O2 oxidation of TCEP or TBP would not be expected to impact pH or chloride concentrations, however, a portion of the TCEP or TBP oxidation products, likely in non-halogenated aldehyde form, would become an available carbon source for bacterial growth in storage, distribution, or during further physical treatment.

Polymerization stress related to radiant exposure and its effect on microleakage of composite restorations.

OBJECTIVES: Verify the influence of radiant exposure (dose) on polymerization stress and microleakage of composite restorations using two adhesive systems. METHODS: An experimental composite (1BisGMA:1TEGDMA, 75wt.% filler) was subjected to 3, 6, 12 or 24J/cm(2) under 500mW/cm(2). Stress was measured in 1-mm height specimens placed between two glass rods (Ø=5mm) attached to a testing machine. Microleakage was assessed in cylindrical restorations (Ø=5mm, h=2mm) with enamel margins, using Adper Single Bond 2 (SB) or Adper Prompt (PR). After storage, specimens were subjected to dye penetration (50% AgNO(3)) and sectioned twice, perpendicularly. Microleakage of the 8tooth/composite interfaces was recorded in millimeters. KHN was measured at both surfaces of cylindrical specimens (Ø=5mm, 1 or 2mm height). ANOVA/Tukey test were used (alpha=0.05). KHN top and bottom were compared using paired t-tests. RESULTS: Stress increased significantly with dose (3J/cm(2): 1.4+/-0.3(c); 6J/cm(2): 4.3+/-0.5(b); 12J/cm(2): 9.3+/-0.6(a); 24J/cm(2): 9.9+/-0.7(a), in MPa). For both average and maximum microleakage, interactions were not statistically significant (p>0.05). Tooth average microleakage was influenced by the adhesive system (SB

Characterization of photopolymerization of dentin adhesives as a function of light source and irradiance.

Manufacturers have attempted to address the limitations associated with dentin bonding by eliminating as many steps as possible in the bonding protocol. Theoretically, this approach increases the efficiency of the procedure and reduces technique sensitivity. These trends are reflected in the introduction of all-in one, single-step adhesive systems; the increased concentration of acidic resin monomers in these systems allows for simultaneous etching and priming of the prepared dentin surface. Ideally, the degree of monomer conversion would be high enough that the acidic reaction would be self-limiting. The purpose of this study was to investigate the effect of light irradiance and source on the photopolymerization of three commercial dental adhesives by monitoring the double bond conversion as a function of time during and after irradiation. The photopolymerization curing efficiency of the commercial adhesives investigated in this study varied as a function of light source and distance. The use of LED performed better than the halogen light in terms of polymerization rate and degree of conversion for the commercial single-step, sixth generation adhesive, Adper Prompt. In contrast, polymerization of commercial single-bottle, fifth generation adhesive, Single Bond and One-Up Bond F, was mainly a function of exposure time, irrespective of the two light units or intensities.

Incorporation of methyl group on azobenzene for the effective photo-regulation of hybridization and suppression of thermal isomerization.

We have synthesized azobenzene-tethered DNAs and have successfully photo-regulated various DNA functions. In the present study, we synthesized azobenzenes substituted with methyl group for still more effective photo-regulation of DNA hybridization. In trans-form, mono substituted azobenzene at ortho position stabilized the DNA duplex more efficiently than the other mono-substituted ones. In contrast, melting temperature (T(m)) for 2-methylazobenzene was lower in cis-form. As a result, change of T(m) (DeltaT(m)) induced by trans-cis isomerization became larger than that of unmodified azobenzene. Furthermore, di-substituted azobenzene at both ortho positions exhibited even larger DeltaT(m). Quite interestingly, thermal cis-to-trans isomerization of this azobenzene was about 10-fold slower than that of unmodified one. Thus, introduction of methyl group at 2, 6 positions raised both photo-regulatory activity and thermal stability of cis-form.

Dissociative electron attachment to phosphoric acid esters: the direct mechanism for single strand breaks in DNA.

We use dibutyl phosphate to simulate the behavior of the phosphate group in DNA towards the attack of low energy electrons. We find that the compound undergoes effective dissociative electron attachment within a low energy resonant feature at 1 eV and a further resonance peaking at 8 eV. The dissociative electron attachment (DEA) reactions are associated with the direct cleavage of the C-O and the P-O bond but also the excision of the PO-, PO3-, H2PO3- units. For the phosphate group coupled in the DNA network these reactions represent single strand breaks. We hence propose that the most direct mechanism of single strand breaks occurring in DNA at subexcitation energies (< 4 eV) is due to DEA directly to the phosphate group.

Phosphodiester and N-glycosidic bond cleavage in DNA induced by 4-15 eV electrons.

Thin molecular films of the short single strand of DNA, GCAT, were bombarded under vacuum by electrons with energies between 4 and 15 eV. Ex vacuo analysis by high-pressure liquid chromatography of the samples exposed to the electron beam revealed the formation of a multitude of products. Among these, 12 fragments of GCAT were identified by comparison with reference compounds and their yields were measured as a function of electron energy. For all energies, scission of the backbone gave nonmodified fragments containing a terminal phosphate, with negligible amounts of fragments without the phosphate group. This indicates that phosphodiester bond cleavage by 4-15 eV electrons involves cleavage of the C-O bond rather than the P-O bond. The yield functions exhibit maxima at 6 and 10-12 eV, which are interpreted as due to the formation of transient anions leading to fragmentation. Below 15 eV, these resonances dominate bond dissociation processes. All four nonmodified bases are released from the tetramer, by cleavage of the N-glycosidic bond, which occurs principally via the formation of core-excited resonances located around 6 and 10 eV. The formation of the other nonmodified products leading to cleavage of the phosphodiester bond is suggested to occur principally via two different mechanisms: (1) the formation of a core-excited resonance on the phosphate unit followed by dissociation of the transient anion and (2) dissociation of the CO bond of the phosphate group formed by resonance electron transfer from the bases. In each case, phosphodiester bond cleavage leads chiefly to the formation of stable phosphate anions and sugar radicals with minimal amounts of alkoxyl anions and phosphoryl radicals.

Evaluation of modifying the bonding protocol of a new acid-etch primer on the shear bond strength of orthodontic brackets.

The purpose of the study was to evaluate the shear bond strength of orthodontic brackets when light curing both the self-etch primer and the adhesive in one step. Fourty eight teeth were bonded with self-etch primer Angel I (3M/ESPE, St Paul, Minn) and divided into three groups. In group I (control), 16 teeth were stored in deionized water for 24 hours before debonding. In group II, 16 teeth were debonded within half-an-hour to simulate when the initial archwires were ligated. In group III, 16 additional teeth were bonded using exactly the same procedure as in groups I and II, but the light cure used for 10 seconds after applying the acid-etch primer was eliminated, and the light cure used for 20 seconds after the precoated bracket was placed over the tooth. This saved at least two minutes of the total time of the bonding procedure. The teeth in this group were also debonded within half-an-hour from the time of initial bonding. The teeth debonded after 24 hours of water storage at 37 degrees C had a mean shear bond strength of 6.0 +/- 3.5 MPa, the group that was debonded within half-an-hour of two light exposures had a mean shear bond strength of 5.9 +/- 2.7 MPa, and the mean for the group with only one light cure exposure was 4.3 +/- 2.6 MPa. Light curing the acid-etch primer together with the adhesive after placing the orthodontic bracket did not significantly diminish the shear bond strength as compared with light curing the acid-etch primer and the adhesive separately.

Enhanced strand break induction of DNA by resonant metal-innershell photoabsorption.

We determined the number of single and double strand breaks (ssb and dsb) in a DNA-chloroterpyridine platinum complex induced by resonant photoabsorption in the L(III) innershell of a platinum atom. The number of ssb and dsb were measured in supercoiled plasmids (AG30) versus the chloroterpyridine platinum concentration, i.e., the ratio of intercalated molecules to the number of phosphate sites in DNA. A significant increase in the number of ssb and dsb was observed when the DNA contained intercalated molecules. This technique is an efficient way to induce ssb and dsb triggered by the atomic Auger effect.

Interaction of cytochrome c with liposomes: covalent labeling of externally bound protein by the fluorescent probe, azidonaphthalenedisulfonic acid, enclosed in the inner aqueous compartment of unilamellar vesicles.

The photoreactive fluorescent probe, 3-azidonaphthalene-2,7-disulfonic acid (ANDS) was encapsulated in the inner aqueous compartment of small unilamellar liposomes, prepared from egg phosphatidylcholine (PC) +/- 20 mol% dihexadecylphosphate (DHP). After adding cytochrome c externally to a suspension of these vesicles, the probe was activated by ultraviolet irradiation, and the protein was separated from the lipids. When negatively charged (egg PC/DHP) vesicles at low ionic strength were used, which form an electrostatic complex with cytochrome c, the protein was labeled by ANDS. This process depended on irradiation time, and was inhibited by increasing the ionic strength of the medium. Labeling was not observed with isoelectric (egg PC) vesicles. These observations suggest that electrostatic binding of cytochrome c to the bilayer is accompanied by intramembrane penetration to such a depth that the protein can communicate with the inner membrane-water interface.