The Effect of Polyamines on the Photochemical Reactivity of DNA

The effects of diaminopentane (cadaverine), diaminoethane and the polyamine, spermine, on the photoreactions of 4,5′, 8-trimethylpsoralen with DNA were studied. Near ultraviolet (UV) light (360 nm) irradiation of psoralen with DNA results in the formation of psoralen monoadducts with pyrimidine bases and DNA interstrand crosslinks. The polyamines studied reduced the rate of both photoreactions to the same extent by a factor of 1.5–2.0. The magnitude of the effect increased with polyamine concentration. Effectiveness was in the order spermine > cadaverine > diaminoethane. This is also the same order for stabilization of the DNA double-helix. Under conditions of higher DNA stability (higher ionic strength), higher polyamine concentrations were required to obtain an effect which was smaller than at low ionic strength. It is concluded that the photoreactions of psoralen with pyrimidines in DNA require some distortion of the double-helix. This distortion is made more difficult in the presence of stabilizing agents like polyamines and therefore the rate of the reaction is reduced. If crosslinking of DNA by psoralen is a two-step reaction then it must be concluded that the second step does not require further distortion. Consistently with the above, polyamines also reduced the UV-induced dimerization of thymine in DNA, although to a lesser extent.     

Polyamines Influence Mouse Sperm Channels Activity

Polyamines are ubiquitous polycationic compounds that are highly charged at physiological pH. While passing through the epididymis, sperm lose their capacity to synthesize the polyamines and, upon ejaculation, again come into contact with the polyamines contained in the seminal fluid, unleashing physiological events that improve sperm motility and capacitation. In the present work, we hypothesize about the influence of polyamines, namely, spermine, spermidine, and putrescine, on the activity of sperm channels, evaluating the intracellular concentrations of chloride [Cl⁻]i, calcium [Ca²⁺]i, sodium [Na⁺]i, potassium [K⁺]i, the membrane V_m, and pHi. The aim of this is to identify the possible regulatory mechanisms mediated by the polyamines on sperm-specific channels under capacitation and non-capacitation conditions. The results showed that the presence of polyamines did not directly influence the activity of calcium and chloride channels. However, the results suggested an interaction of polyamines with sodium and potassium channels, which may contribute to the membrane V_m during capacitation. In addition, alkalization of the pHi revealed the possible activation of sperm-specific Na⁺/H⁺ exchangers (NHEs) by the increased levels of cyclic AMP (cAMP), which were produced by soluble adenylate cyclase (sAC) and interact with the polyamines, evidence that is supported by in silico analysis.     

Properties of particulate resin‐luting agents with phosphate and carboxylic functional methacrylates as coupling agents

This study investigated properties of resin‐luting agents using silane [3‐(trimethoxysilyl)propyl methacrylate (TSPM)], phosphoric acid methacrylate (PAM) [mono/bis(methacryloyloxyethyl (di)hydrogen phosphate)], or carboxylic acid methacrylate (CAM) [mono‐2‐(methacryloyloxy)ethyl maleate] as coupling agents between the inorganic and organic phases. Ba‐B‐Al‐Si microparticles (3 μm) and SiO₂ nanoparticles (7 nm) were coated with TSPM, PAM, or CAM (control = no filler coating). A Bis‐GMA/triethyleneglycol dimethacrylate comonomer was loaded with 60% mass of inorganic fillers. The properties evaluated were degree of C?C conversion (DC), flexural strength (σ), and modulus (E_f), Knoop hardness number (KHN), and film thickness (FT). Dispersion/interaction of the particles with the resin phase was assessed by scanning electron microscopy (SEM). No significant differences in DC were observed. For σ and E_f, TSPM > CAM > Control > PAM. For KHN, TSPM > CAM > PAM = Control. For FT, TSPM < Control < CAM < PAM. The SEM analysis revealed clustering of nanoparticles for all groups and better organic–inorganic phases interaction for TSPM and CAM. The use of TSPM generated agents with improved properties as compared with the acidic methacrylates, with CAM showing better performance than PAM. The use of PAM generated agents with properties usually poorer compared with the material with no coupling agent. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Effects of alkylamines and PC on the oxidative stability of soybean oil TAG in milk casein emulsions

The effects of alkylamines and PC on the coppercatalyzed oxidation of soybean oil TAG were studied in milk casein emulsions. Stearylamine showed an antioxidant effect in casein emulsions in the presence of PC, whereas dicetylphosphate acted as a prooxidant. The antioxidant or prooxidant effect could be explained by the electrostatic repulsion or attraction between positively charged stearylamine or negatively charged dicetylphosophate and positively charged copper ion at the interface, respectively. On the other hand, these effects were not observed in the absence of PC, suggesting the importance of PC for charged components to show their activities at the interface. Other types of alkylamines—spermine, spermidine, and putrescine—also inhibited the oxidation of soybean oil TAG emulsified with casein in the presence of PC. The antioxidant effects of these natural polyamines were higher than that of stearylamine. PC molecular species also affected soybean oil TAG oxidation in emulsion. The oxidative stability of soybean oil TAG increased in the emulsion with PC containing oleic acid.     

Polyamine Metabolism under Different Light Regimes in Wheat

Although the relationship between polyamines and photosynthesis has been investigated at several levels, the main aim of this experiment was to test light-intensity-dependent influence of polyamine metabolism with or without exogenous polyamines. First, the effect of the duration of the daily illumination, then the effects of different light intensities (50, 250, and 500 μmol m^–2 s^–1) on the polyamine metabolism at metabolite and gene expression levels were investigated. In the second experiment, polyamine treatments, namely putrescine, spermidine and spermine, were also applied. The different light quantities induced different changes in the polyamine metabolism. In the leaves, light distinctly induced the putrescine level and reduced the 1,3-diaminopropane content. Leaves and roots responded differently to the polyamine treatments. Polyamines improved photosynthesis under lower light conditions. Exogenous polyamine treatments influenced the polyamine metabolism differently under individual light regimes. The fine-tuning of the synthesis, back-conversion and terminal catabolism could be responsible for the observed different polyamine metabolism-modulating strategies, leading to successful adaptation to different light conditions.     

Polyamine Profiles Of Healthy and Parasite-Infected Vaccinium Myrtillus Plants Under Nitrogen Enrichment

Addition of nitrogen (N) to the field layer of boreal forests has been shown to increase the occurrence of the parasitic fungus Valdensia heterodoxa on Vaccinium myrtillus plants. We investigated whether N addition to soil alters the levels of polyamines in V. myrtillus shoots, and discuss here whether such changes could promote the spread of the parasitic fungus on V. myrtillus. Using HPLC, we analyzed the concentrations of free and conjugated polyamines in healthy and naturally V. heterodoxa-infected V. myrtillus plants, which had received a moderate or high dose of N fertilizer, or no additional N. Fertilization with N increased the concentrations of free diamines (putrescine and diaminopropane), but had no significant effect on conjugated amines. Thus, N-induced changes in the constitutive levels of soluble conjugated amines do not seem to explain the increased parasite susceptibility of V. myrtillus under N enrichment. Generally, the concentrations of free diamines and insoluble conjugated putrescine were higher in diseased than in healthy shoots, suggesting parasite-induced accumulation of diamines. Free spermine seemed to accumulate in unfertilized, diseased plants, but in fertilized plants this induction was dampened, suggesting that N-induced alterations in spermine metabolism may promote the spread of parasites on V. myrtillus under N-enrichment.     

聚胺与鲑鱼精DNA相互作用中的盐效应

通过浊度、紫外吸收和Zeta电位测定,研究了盐对聚胺与鲑鱼精DNA相互作用的影响。结果表明,加入盐产生屏蔽效应,使体系Zeta电位下降,当c(NaC l)=5 mmol/L时,SPM-DNA体系Zeta电位由0 mV降至-4mV,SPD-DNA体系电位由-2.5 mV降至-4 mV。浊度和紫外吸收结果证明了盐屏蔽效应的存在,并随盐浓度的升高,屏蔽效应增大,且Ca2+、Mg2+的屏蔽作用大于K+、Na+。pH的升高使聚胺-DNA的相互作用减弱。     

Particle Associated Polycyclic Aromatic Hydrocarbons (PAHS) in Urban Air of Agra

Total Suspended Particulate Matter (TSPM) samples were collected at Nunhai Agra from April to September 2006. The concentrations of 16 PAHs in aerosols were quantified. The dominated predominant PAHs in TSPM include high molecular weight (HMW) congeners BghiP, DbA, IP and BaP. Nap and Acy were not detected in any of the samples. The sum of 14 priority PAHs ranged from 150 to 480 ng m^?3 with a mean value of 269 ± 121 ng m^?3. The Results indicated that PAH concentrations at Nunhai were higher than in other industrial sites, but are comparable to those measured in several urban Chinese cities, however, and less than the industrial locations of China. Higher HMW PAH concentration were attributable to higher rates of emissions as well as or greater scavenging and adsorption of vapor phase PAH on available TSPM. Potential sources of PAHs in aerosols were identified using the diagnostic ratios between PAHs. Vehicular emissions were the main contributors of particulate-associated PAHs, with minor contribution from stationary combustion sources may also contribute to the particulate PAHs. PAHs in aerosols were predominantly from gasoline and diesel engines.     

Oleic Acid Attenuates trans-10,cis-12 Conjugated Linoleic Acid-Mediated Inflammatory Gene Expression in Human Adipocytes

The weight loss supplement conjugated linoleic acid (CLA) consists of an equal mixture of trans-10,cis-12 (10,12) and cis-9,trans-11 (9,11) isomers. However, high levels of mixed CLA isomers, or the 10,12 isomer, causes chronic inflammation, lipodystrophy, or insulin resistance. We previously demonstrated that 10,12 CLA decreases de novo lipid synthesis along with the abundance and activity of stearoyl-CoA desaturase (SCD)-1, a δ-9 desaturase essential for the synthesis of monounsaturated fatty acids (MUFA). Thus, we hypothesized that the 10,12 CLA-mediated decrease in SCD-1, with the subsequent decrease in MUFA, was responsible for the observed effects. To test this hypothesis, 10,12 CLA-treated human adipocytes were supplemented with oleic acid for 12?h to 7?days, and inflammatory gene expression, insulin-stimulated glucose uptake, and lipid content were measured. Oleic acid reduced inflammatory gene expression in a dose-dependent manner, and restored the lipid content of 10,12 CLA-treated adipocytes without improving insulin-stimulated glucose uptake. In contrast, supplementation with stearic acid, a substrate for SCD-1, or 9,11 CLA did not prevent inflammatory gene expression by 10,12 CLA. Notably, 10,12 CLA impacted the expression of several G-protein coupled receptors that was attenuated by oleic acid. Collectively, these data show that oleic acid attenuates 10,12 CLA-induced inflammatory gene expression and lipid content, possibly by alleviating cell stress caused by the inhibition of MUFA needed for phospholipid and neutral lipid synthesis.     

Corrosion inhibition of mild steel in acidic media by Basic yellow 13 dye

The inhibition performance of Basic yellow 13 dye on mild-steel corrosion in hydrochloric acid solution was studied at 25 °C using weight loss and electrochemical techniques. The effect of inhibitor concentration on inhibition efficiency has been studied. Inhibition efficiency increased with increase of Basic yellow 13 concentration. The results showed that this inhibitor had good corrosion inhibition even at low concentrations (95% for 0.005 M Basic yellow 13) and its adsorption on mild-steel surface obeys Langmuir isotherm. ΔG _ads was calculated and its negative value indicated spontaneous adsorption of the Basic yellow 13 molecules on the mild-steel surface and strong interaction between inhibitor molecules and metal surface. The value of ΔG _ads was less than 40 kJmol⁻¹, indicating electrostatic interaction between the charged inhibitor molecules and the charged metal surface, i.e., physical adsorption.     

Structurally Diverse Polyamines: Solid‐Phase Synthesis and Interaction with DNA

A versatile solid‐phase approach based on peptide chemistry was used to construct four classes of structurally diverse polyamines with modified backbones: linear, partially constrained, branched, and cyclic. Their effects on DNA duplex stability and structure were examined. The polyamines showed distinct activities, thus highlighting the importance of polyamine backbone structure. Interestingly, the rank order of polyamine ability for DNA compaction was different to that for their effects on circular dichroism and melting temperature, thus indicating that these polyamines have distinct effects on secondary and higher‐order structures of DNA.     

Functionalized graphene oxide mediated nucleic acid delivery

We report a simple preparation of linear polyethylenimine-grafted graphene oxide (LP-GO) conjugates and their efficacy to transfer nucleic acids into the mammalian cells. Graphene oxide (GO), with epoxy functions on its surface, was reacted with different amounts of linear polyethylenimine (lPEI), a non-toxic polymer, to obtain three different positively charged LP-GO conjugates (LP-GO-1 to LP-GO-3), capable of interacting with negatively charged nucleic acids (gel retardation assay) and transporting them efficiently into the cells. The results show that these conjugates not only exhibited considerably higher transfection efficiency but also possessed even better cell viability than lPEI. LP-GO-2, the best system in terms of transfection efficiency, showed improved buffering capacity compared to lPEI and provided sufficient stability to bound DNA against DNase I. Further, LP-GO-2 was used for the sequential delivery of GFP specific siRNA, which resulted in ∼70% suppression of the target gene expression. Intracellular trafficking using fluorescence microscopy revealed that LP-GO-2 conjugate delivered pDNA in the nucleus within 1 h of exposure. The results indicate the prospect of using these conjugates as efficient carriers of nucleic acids for future gene therapy applications.     

CsCDPK6, a CsSAMS1-Interacting Protein,Affects Polyamine/Ethylene Biosynthesis in Cucumber and Enhances Salt Tolerance by Overexpression in Tobacco

S-adenosylmethionine synthetase (SAMS) plays a crucial role in regulating stress responses. In a recent study, we found that overexpression of the cucumber gene CsSAMS1 in tobacco can affect the production of polyamines and ethylene, as well as enhancing the salt stress tolerance of tobacco, but the exact underlying mechanisms are elusive. The calcium-dependent protein kinase (CDPK) family is ubiquitous in plants and performs different biological functions in plant development and response to abiotic stress. We used a yeast two-hybrid system to detect whether the protein CDPK6 could interact with SAMS1 and verified their interaction by bimolecular fluorescence complementation (BiFC) and co-immunoprecipitation (Co-IP) assays. To further explore the function of cucumber CDPK6, we isolated and characterized CsCDPK6 in cucumber. CsCDPK6 is a membrane protein that is highly expressed under various abiotic stresses, including salt stress. It was also observed that ectopic overexpression of CsCDPK6 in tobacco enhanced salt tolerance. Under salt stress, CsCDPK6-overexpressing lines enhanced the survival rate and reduced stomatal apertures in comparison to wild-type (WT) lines, as well as lowering malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) contents and causing less relative electrolyte leakage. Moreover, repression of CsCDPK6 expression by virus-induced gene silencing (VIGS) in cucumber seedling cotyledons under salt stress increased ethylene production and promoted the transformation from putrescine (Put) to spermidine (Spd) and spermine (Spm). These findings shed light on the interaction of CsSAMS1 and CsCDPK6, which functions positively to regulate salt stress in plants.     

The Emerging Clinical Role of Spermine in Prostate Cancer

Spermine, a member of polyamines, exists in all organisms and is essential for normal cell growth and function. It is highly expressed in the prostate compared with other organs and is detectable in urine, tissue, expressed prostatic secretions, and erythrocyte. A significant reduction of spermine level was observed in prostate cancer (PCa) tissue compared with benign prostate tissue, and the level of urinary spermine was also significantly lower in men with PCa. Decreased spermine level may be used as an indicator of malignant phenotype transformation from normal to malignant tissue in prostate. Studies targeting polyamines and key rate-limiting enzymes associated with spermine metabolism as a tool for PCa therapy and chemoprevention have been conducted with various polyamine biosynthesis inhibitors and polyamine analogues. The mechanism between spermine and PCa development are possibly related to the regulation of polyamine metabolism, cancer-driving pathways, oxidative stress, anticancer immunosurveillance, and apoptosis regulation. Although the specific mechanism of spermine in PCa development is still unclear, ongoing research in spermine metabolism and its association with PCa pathophysiology opens up new opportunities in the diagnostic and therapeutic roles of spermine in PCa management.     

Novel Antitumor L‐Arabinose Derivative of Indolocarbazole with High Affinity to DNA

Novel indolocarbazole derivative 12‐(α‐L ‐arabinopyranosyl)indolo[2,3‐α]pyrrolo[3,4‐c]carbazole‐5,7‐dione (AIC) demonstrated high potency (at submicromolar concentrations) against the NCI panel of human tumor cell lines and transplanted tumors in vivo. In search of tentative targets for AIC, we found that the drug formed high affinity intercalative complexes with d(AT)₂₀, d(GC)₂₀ and calf thymus DNA (binding constants (1.6×10⁶) M ^?1≤K_a≤(3.3×10⁶) M ^?1). The drug intercalated preferentially into GC pairs of the duplex. Importantly, the concentrations at which AIC formed the intercalative complexes with DNA (C≤1 μM ) were identical to the concentrations that triggered p53‐dependent gene reporter transactivation, the replication block, the inhibition of topoisomerase I‐mediated DNA relaxation and death of HCT116 human colon carcinoma cells. We conclude that the formation of high affinity intercalative complexes with DNA is an important factor for anticancer efficacy of AIC.     

A kinetic study on bulk thermal polymerization of styrene

The kinetics of bulk thermal polymerization of styrene over the range of 100–200 °C has been studied based on three stage polymerization model (TSPM) in this paper. TSPM plots showed that the whole polymerization course only exhibits two stages, low conversion stage and gel effect stage, which is consistent with TSPM as the reaction temperature is higher than the glass transition temperature of polystyrene. It was found that the critical conversion, x₁, for the transition from low conversion stage to gel effect stage is independent of the reaction temperature and approximately equal to 0.5. In addition, the apparent reaction rate constants obtained from TSPM plots could be correlated to temperature by Arrhenius equation. Expressions predicting number-average molecular weight were also derived according to TSPM. Using the expressions to treat experimental data available in the literature, it was found that number-average molecular weight is independent of the conversion and relative to the reaction temperature at low conversion stage. However, it varies with the conversions at gel effect stage and the variations are more obvious as the reaction temperature rises.     

Mixed micelles of some anionic-anionic, cationic-cationic, and ionic-nonionic surfactants in aqueous media

Critical micelle concentrations (CMC) were obtained from tensiometric studies on several binary surfactant mixtures (anionic-anionic, cationic-cationic, anionic-nonionic, and cationic-nonionic) in water at different mole fractions (0–1). The composition of mixed micelles and the interaction parameter β, evaluated from the CMC data for different systems using Rubingh's theory, are discussed. Marked interaction is observed for ionic-nonionic systems, whereas it is weak in the case of similarly charged surfactants. The influence of counterion valence in the formation of mixed micelles was investigated, and results suggest that in similarly charged surfactant mixtures, the degree of counterion binding does have a major role in deciding the extent of interactions. Salt addition reveals a weakening of interactions in ionic-nonionic systems, and this is attributed to head group charge neutralization and dehydration of the ethylene oxide units of the nonionic surfactants. Cloud point and viscosity data on these systems support the observation.     

Surface charge of gold nanoparticles mediates mechanism of toxicity

Recently gold nanoparticles (Au NPs) have shown promising biological and military applications due to their unique electronic and optical properties. However, little is known about their biocompatibility in the event that they come into contact with a biological system. In the present study, we have investigated whether modulating the surface charge of 1.5 nm Au NPs induced changes in cellular morphology, mitochondrial function, mitochondrial membrane potential (MMP), intracellular calcium levels, DNA damage-related gene expression, and of p53 and caspase-3 expression levels after exposure in a human keratinocyte cell line (HaCaT). The evaluation of three different Au NPs (positively charged, neutral, and negatively charged) showed that cell morphology was disrupted by all three NPs and that they demonstrated a dose-dependent toxicity; the charged Au NPs displayed toxicity as low as 10 μg ml(-1) and the neutral at 25 μg ml(-1). Furthermore, there was significant mitochondrial stress (decreases in MMP and intracellular Ca2+ levels) following exposure to the charged Au NPs, but not the neutral Au NPs. In addition to the differences observed in the MMP and Ca2+ levels, up or down regulation of DNA damage related gene expression suggested a differential cell death mechanism based on whether or not the Au NPs were charged or neutral. Additionally, increased nuclear localization of p53 and caspase-3 expression was observed in cells exposed to the charged Au NPs, while the neutral Au NPs caused an increase in both nuclear and cytoplasmic p53 expression. In conclusion, these results indicate that surface charge is a major determinant of how Au NPs impact cellular processes, with the charged NPs inducing cell death through apoptosis and neutral NPs leading to necrosis.     

The role of endogenous amphiphiles on the stability of virgin olive oil-in-water emulsions

Stable virgin olive oil-in-water emulsions were prepared using total endogenous surface-active components derived from oil as emulsifying agents, and the interfacial properties of the emulsion droplets were examined. The amount of oil extracted into the aqueous buffer increased with buffer pH, with the most stable emulsions being formed at pH 7.5. Light microscopy of the emulsions revealed the presence of spherical droplets with diameters ranging from 1.5 to 3 μm. Their surface was negatively charged at pH 7.5, as confirmed by the effect of ions and polycations. Potassium chloride, Ca²⁺, and spermine induced rapid aggregation (as monitored by the turbidity change and by light microscopy), showing their maximal effect at 1 M, 4 mM, and 60 μM, respectively. Papain treatment of the emulsion particles rapidly induced particle aggregation, suggesting the destruction of stabilizing structural olive oil proteins. Unlike papain, treatment with phospholipase C did not result in an appreciable turbidity change. Treatment with soybean lipoxygenase slightly increased the turbidity of the emulsion. The interaction of linoleate-Tween 20 mixed micelles with emulsion droplets produced turbidity, which was maximal at a neutral pH, whereas interaction with proteolyzed and lipoxygenase-treated droplets induced both a significant increase in turbidity and a red shift to a different absorption maximum of the system as compared with those of the untreated emulsion.     

Specific Inhibitors of the Breast Cancer Resistance Protein (BCRP)

A new class of specific breast cancer resistance protein (BCRP) inhibitors was identified, showing no inhibition of the ATP binding cassette (ABC) transporters P‐gp and MRP1. Some of these modulators inhibit BCRP with high potency; they are only slightly less potent than Ko143 and could serve as promising lead structures for the design of novel effective BCRP inhibitors. These inhibitors are structurally related to tariquidar (XR9576) and belong to a library of multidrug‐resistance modulators synthesized by our research group. The absence of the tetrahydroisoquinoline substructure appears to play a crucial role for specificity; we found that the presence of this substructure is not essential for interaction with BCRP. To determine the type of interaction between pheophorbide A and compounds with and without the tetrahydroisoquinoline substructure, various substrate pheophorbide A concentrations were used in enzyme kinetics assays. The resulting data show that these compounds share a noncompetitive‐type interaction with pheophorbide A. Experiments with imatinib and pheophorbide A revealed a mixed‐type interaction. The combination of imatinib and compounds with and without the tetrahydroisoquinoline substructure resulted in a positive cooperative effect, indicating that imatinib engages a binding site distinct from that of the new compounds on one side and distinct from that of pheophorbide A on the other side as well. The results of this study suggest that the category of BCRP‐specific inhibitors, which includes only fumitremorgin C, Ko143 and analogues, and novobiocin needs to be extended by this new class of inhibitors, which possess three key characteristics: specificity, potency, and low toxicity.