No-carrier-added radiohalogenations utilizing organoboranes: The synthesis of iodine-123 labeled curcumin

The use of organoborane intermediates for radiohalogenations is briefly reviewed. The synthesis of an iodine-123 labeled curcumin derivative using a newly developed radio-iodination technique is reported.     

Tamoxifen subcellular localization; observation of cell-specific cytotoxicity enhancement by inhibition of mitochondrial ETC complexes I and III

Recently, a nongenomic cytotoxic component of the chemotherapeutic agent tamoxifen (TAM) has been identified that predominantly triggers mitochondrial events. The present study delineates the intracellular fate of TAM and studies its interaction with a spectrum of cell homeostasis modulators primarily relevant to mitochondria. The subcellular localization of TAM was assessed by confocal fluorescence microscopy. The effect of the modulators on TAM cytotoxicity was assessed by standard MTT assays. Our findings show that in estrogen receptor positive MCF7 breast adenocarcinoma cells and DU145 human prostate cancer cells, TAM largely accumulates in the mitochondria and endoplasmic reticulum, but not lysosomes. Our results further demonstrate that in MCF7, but not in DU145 cells, mitochondrial electron transport chain complex I and III inhibitors exacerbate TAM toxicity with an order of potency of myxothiazol ≥ stigmatellin > rotenone > antimycin A, suggesting a cell-specific cytotoxic interplay between mitochondrial complex I and III function and TAM action.     

Local radiolytic effectiveness of Auger electrons of iodine-125 in benzene-iodine solutions

The gas-chromatographic analysis of benzene-iodine solutions containing molecular iodine-125 after various storage times showed that no radiolytic products appeared while some products such as benzene, iodobenzene, biphenyl, and iodobiphenyl, were detected under the same analytical conditions in our recent studies concerning the reactions of iodine atoms activated by L shell photoelectric ionization in benzene-iodine solutions, and the self-radiolysis of iodobenzene labelled with iodine-125¹⁵. On the other hand, our theoretical calculations showed that if iodine molecules were uniformly distributed in benzene, iodobenzene should be detected as a radiolytic product due to the local absorption of Auger electrons of iodine-125. The absence of any radiolytic product clearly demonstrated that iodine aggregates have an important role in the absorption of Auger electrons of iodine-125 in benzene-iodine solutions. In addition, theoretical calculations showed that if the iodine aggregation is taken into account the experimental result agrees well with theoretical calculations.     

Studies on the subcellular localization of the porphycene CPO

This study was designed to provide more detailed information on the subcellular sites of binding of the porphycene, termed 9-capronyloxytetrakis (methoxyethyl) porphycene (CPO), with a fluorescence resonance energy transfer (FRET) technique. The proximity of CPO to two fluorescent probes was determined: nonyl acridine orange (NAO), a dye with specific affinity for the mitochondrial lipid cardiolipin, and dihexa-oxacarbocyanine iodide (DiOC6), an agent that labels the endoplasmic reticulum (ER). FRET spectra indicated energy transfer between DiOC6 and CPO but no significant transfer between NAO and CPO. These results confirm data obtained by fluorescence microscopy, suggesting a similar pattern of subcellular localization by CPO and DiOC6 but not by CPO and NAO. However, when cells containing CPO were irradiated and then loaded with NAO, FRET between the two fluorophores was observed. Hence, a relocalization of CPO can occur during irradiation. These data provide an explanation for recent studies on CPO-catalyzed photodamage to both ER and mitochondrial Bcl-2.     

Preparation of125I labeled testosterone derivatives for use in radioimmunoassays

A study for separation and sequential recovery of uranium and plutonium from nitric acid solutions by extraction chromatography using tributyl phosphate (TBP)/Amberlite XAD7 as stationary phase is presented. Distribution ratios of actinides, lanthanides and fission products were obtained. The column capacity was investigated and actinides retention conditions were established. Finally, U-Pu sequential separation was studied as well as the U and Pu recovery yields from nitric solutions containing Am/fission products were determined.     

Improved iodine-125 removal in anionic form of iodate by column method using laterite soil

Soil column experiments have been conducted to treat liquid wastes from hospitals containing¹²⁵I. Three sorbent samples of laterite clay materials with different contents of iron oxides (goethite, -FeOOH) and hydroxides were used to sorb anionic iodate. Post-treatment on effluent wastes with sodium hypochlorite (redox reagent) oxidized the iodide to the desirable iodate ion. Effluent pH after treatment ranges between 4.8 to 5.8, which does not vary much from the initial effluent pH of 4.5 before treatment. Results show that 90 to 97% sorption of iodine radionuclides with a decontamination factor ranges between 10–32 was obtained after the first two hours of experiments. Concentration has decreased from the initial 10 Bq/ml to concentration ranges of 0.3 to 0.9 Bq/ml. Batch experiments conducted using different sorbent masses of soils, show that there was a drop in sorption as the mass of soils fell below approximately 0 to 0.25 g. The sorption remains constant with the soil mass above 0.25 g. Another batch experiment using a different concentration shows that the adsorption capacity of the laterite soil was 1.1 Ci/g. The adsorption is about 96% with a distribution coefficient of 1170.     

Tissue-specific expression and subcellular localization of ALADIN, the absence of which causes human triple A syndrome

Triple A syndrome is a rare genetic disorder caused by mutations in the achalasia-addisonianism-alacrima syndrome (AAAS) gene which encodes a tryptophan aspartic acid (WD) repeat-containing protein named alacrima-achalasia-adrenal insufficiency neurologic disorder (ALADIN). Northern blot analysis shows that the 2.1 kb AAAS mRNA is expressed in various tissues with stronger expression in testis and pancreas. We show that human ALADIN is a protein with an apparent molecular weight of 60 kDa, and expressed in the adrenal gland, pituitary gland and pancreas. Furthermore, biochemical analysis using anti-ALADIN antibody supports the previous finding of the localization of ALADIN in the nuclear membrane. The mutations S544G and S544X show that alteration of S544 residue affects correct targeting of ALADIN to the nuclear membrane.     

Photodynamic effects of mTHPC on human colon adenocarcinoma cells: photocytotoxicity,subcellular localization and apoptosis

The photodynamic properties of meta-tetra(hydroxyphenyl)chlorin (mTHPC), a promising second-generation photosensitizer, were investigated using a human colon adenocarcinoma cell line (Colo 201 cells). The study on photocytotoxicity using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction assay showed that mTHPC was an effective photosensitizer on Colo 201 cells. The photocytotoxicity of mTHPC showed both drug and light dose-dependent characteristics. To reach LD50, namely, the dose at which 50% of the cells were killed, only 0.45+/-0.15 microg/mL of mTHPC and 3 J/cm2 of light dose were required. The presence of 10% fetal calf serum in culture medium significantly decreased the incorporation of mTHPC into cells and resulted in the reduction of photodynamic efficacy. Using confocal laser scanning microscopy, mTHPC was first shown to localize in lysosomes rather than in mitochondria. Furthermore, nuclear stainings demonstrated that photodynamic therapy with mTHPC induced apoptosis in Colo 201 cells.     

Preparation and characterization of125I labeled progesterone derivatives for the development of a radioimmunoassay for progesterone

Preparation and purification of radioiodinated progesterone derivatives for the development of a radioimmunoassay of progesterone is described. We have standardized two procedures for preparing radioiodinated progesterone conjugate. In the first procedure¹²⁵I labeled histamine was conjugated to progesterone 11 hemisuccinate by the mixed anhydride method. In the secod procedure, tyrosyl methyl ester was conjugated to progesterone 11 hemisuccinate and iodination of the conjugate was carried out. Purification of the iodinated products was carried out by solvent extraction and thin layer chromatography techniques. The radiochemical purity of the tracers prepared by both methods were more than 95%. Labeled progesterone derivatives prepared were used for developing a radioimmunoassay procedure. The non-specific binding of the tracer was about 2–3%, while up to 80% binding could be obtained in the presence of excess antibody. The radioiodinated tracer could be used up to four months in the assay.     

Occurrence,evolution and degradation of heavy haze events in Beijing traced by iodine-127 and iodine-129 in aerosols

Heavy haze events have become a serious environment and health problem in China and many developing countries, especially in big cities, like Beijing. However, the factors and processes triggered the formation of secondary particles from the gaseous pollutants are still not clear, and the processes driving evolution and degradation of heavy haze events are not well understood. Iodine isotopes (¹²⁷I and ¹²⁹I) as tracers were analyzed in time series aerosol samples collected from Beijing. It was observed that the ¹²⁷I concentrations in aerosols peaked during the heavy haze events. The conversion of gaseous iodine to particular iodine oxides through photochemical reactions provides primary nuclei in nucleation and formation of secondary air particles, which was strengthened as the external iodine input from the fossil fuel burning in the south/southeast industrial cities and consequentially induced heavy haze events. Anthropogenic ¹²⁹I concentrations peaked during clean air conditions and showed high levels in spring and later autumn compared to that in summer. ¹²⁹I originated from the direct air discharges and re-emissions from contaminated seawaters by the European nuclear fuel reprocessing plants was transported to Beijing by the interaction of Westerlies and East Asian winter monsoon. Three types of mechanisms were found in the formation and evolution of heavy haze events in Beijing by the variation of ¹²⁷I and ¹²⁹I, i.e., iodine oxides intermediated secondary air particles, dust storm and mixed mode by both secondary air particles and dust storm induced processes.     

Neutron activation analysis of iodine-129 and iodine-127 in environmental samples

The possibilities of reactor induced (n, p) reactions as a tool for neutron activation analysis of titanium in geological samples are discussed. The interference of calcium and scandium is experimentally evaluated. Results for Ti, Ca and Sc in GSP-1 and PCC-1 standard rocks are presented. On the basis of the experimental values, it is concluded that the⁴⁷Ti(n, p)⁴⁷Sc reaction is the most favourable for titanium determination.     

Encapsulation of p-THPP into nanoparticles: cellular uptake,subcellular localization and effect of serum on photodynamic activity

The cellular uptake, localization and efflux of meso-tetra-(4-hydroxyphenyl)porphyrin (p-THPP)-loaded nanoparticles have been studied in EMT-6 tumor cells. The effect of blood serum on photocytotoxicity has also been evaluated. Sub-130 nm nanoparticles based on poly(D,L-lactide-co-glycolide) (PLGA) (50:50 PLGA and 75:25 PLGA) and poly(D,L-lactide) (PLA) have been examined in comparison with free p-THPP. For all formulations tested, uptake of photosensitizer into cells was dependent on concentration, time and temperature. All nanoparticulate formulations accumulated within the cells to a greater extent relative to free drug. Indeed, the fluorescence intensities measured on EMT-6 cells treated with p-THPP-loaded nanoparticulate formulations were at least two-fold higher than those obtained with free dye. Furthermore, the highest accumulation level was found with PLGA nanoparticles. Fluorescence microscopy revealed that endocytosis is a major intracellular sequestration mechanism of these p-THPP formulations and that these were localized into early and late endosomes. The efflux study performed on both nonirradiated and irradiated cells indicated that free and p-THPP-loaded nanoparticles gradually escaped from EMT-6 cells as a function of time. This was more pronounced when cells were treated with nanoparticles and irradiated, reflecting important photodamage. It was also found that regardless of the nanoparticulate formulations tested, p-THPP photocytotoxicity was influenced by the concentration of the serum.     

Cellular uptake and subcellular localization of highly luminescent silica-coated CdSe quantum dots--in vitro and in vivo

With excellent optical properties, quantum dots (QDs) have been made as attractive molecular probes for labeling cells in biological research. The purpose of the present work is to explore the possible role of silica-coated cadmium selenide (CdSe) QDs in the in vitro and in vivo cellular uptake and their subcellular localization. The in vitro uptake characteristics of silica-coated CdSe QDs were performed in cultured New Zealand rabbit adipose tissue-derived mesenchymal stem cells (RADMSCs) and Human cervical cancer cells (HeLa) using fluorescence microscopy after staining with 4,6-diamidino-2-phenylindole (DAPI). The in vitro results showed that the silica-coated CdSe QDs were efficiently taken up by the cells and it was localized in the intracellular vesicles giving strong fluorescence from the cytoplasm and nearby nucleus. Subsequently, the in vivo localization and distribution of QDs were studied by the hematoxilin stained semithin cryosections of tissues (~15 μm thickness) under fluorescence microscopy and ultrathin sections of tissues (~100 nm thickness) under confocal laser scanning microscopy at the distribution maxima. Our in vivo results confirmed the effective cellular uptake and even distribution pattern of QDs in tissues. Overall, these in vitro and in vivo results are represented with focus on internalization, subcellular localization and distribution of the QDs, in view of their potential applications in biomedical field.     

Influence of substitutions on asymmetric dihydroxychlorins with regard to intracellular uptake, subcellular localization and photosensitization of Jurkat cells

The search for new efficient sensitizers for photodynamic therapy (PDT) points to improve photophysical properties like absorption in the red region and singlet oxygen quantum yield as well as to control the localization of the sensitizer within the tumour cell. Depending on their physicochemical properties and their uptake mechanism, sensitizers can reach different intracellular concentrations and localize in different subcellular compartments. Moreover, the preferential localization of a sensitizer in target organelles, like mitochondria or lysosomes, could determine the cell death mechanism after PDT. This study aimed to investigate the influence of substitutions on dihydroxychlorins with regard to intracellular uptake, subcellular localization and cell death pathway. Moreover, the effect of a liposome-based delivery system was tested. The intracellular uptake was found to be strictly dependent on the sensitizer molecular structure and the means of its delivery. The most polar sensitizer in this study (compound 3) had, depending on incubation time, an intracellular concentration 2-8 times higher than the unsubstituted chlorin 1. All investigated photosensitizers localize predominantly in lysosomes but after longer incubation times weak fluorescence intensity was also detected in mitochondria and Golgi apparatus. The cell death pathway was found to be influenced by the sensitizer intracellular concentration and the applied light doses. In general, the increasing amphiphilicity of the sensitizer molecules is correlated with an increased sensitizer uptake and an increased rate of necrotic cells after irradiation.     

Prediction of apoptosis protein subcellular localization via heterogeneous features and hierarchical extreme learning machine

Apoptosis is a fundamental process controlling normal tissue homeostasis by regulating a balance between cell proliferation and death. Predicting the subcellular location of apoptosis proteins is very helpful for understanding the mechanism of programmed cell death. Predicting protein subcellular localization with bioinformatic techniques provides quite a few opportunities in related fields. In this work, we propose the use of a hierarchical extreme learning machine (H-ELM) to make a classification of high-dimensional input data without demanding a dimension reduction process, which yields acceptable results. An attempt is made to extract features from different perspectives, and a feature fusion process is accomplished. Regarding the position-specific scoring matrix, the first type depicts the correlation within the sequence with the autocorrelation function for relatively random sections from the sequence; and the second type is the Kullback-Leibler (K-L) divergence of the two distributions formed by the amino acids’ constitutuent proportions. It is illustrated in an experiment with features from different sources mixed by simple concatenation yielding a poor result, but the synthetical feature fused with stochastic nonlinear embedding (t-SNE) greatly improved the classification. Finally, the highest overall accuracy of ZD98 is 87.5% by adjusting the hyper-parameters of H-ELM, and of CL317 is 92.4%.     

A comparative study on in vitro cytotoxicity,cellular uptake,localization and apoptosis-inducing mechanism of two ruthenium(II) complexes

Two ruthenium complexes [Ru(MeIm)₄(bpy)]²⁺ (Ru1, MeIm = 1-methylimidazole, bpy = 2,2′-bipyridine) and [Ru(Im)₄(bpy)]²⁺ (Ru2, Im = imidazole) with the same PF ₆ ^? counter-ion but different lipophilicities were synthesized and characterized and as potent anticancer agents. The relationships between cellular uptake, localization and molecular action mechanisms of these complexes were elucidated. The results showed that Ru1 with higher logP_o/w exhibited faster cellular uptake rates, but lower anticancer activity than Ru2. In addition, Ru1 predominantly accumulated in the mitochondria and cytoplasm, and induced G0/G1 cell cycle arrest, whereas the more hydrophilic Ru2 tended to localize and accumulate in the cell nucleus and mitochondria. Further mechanism studies indicated that Ru2 caused cell cycle arrest at S phase by regulating cell cycle related proteins and induced apoptosis in A549 cells through DNA damage, cellular ROS accumulation, activation of the caspase pathway and mitochondrial dysfunction.