Inert Compounds Research Articles

Rationale for further medical and health research on high-potency sweeteners.

High-potency or artificial sweeteners have historically been considered inert compounds without physiological consequences other than taste sensations. However, recent data suggest that some of these sweeteners have biological effects that may impact human health. Furthermore, there are significant gaps in our current knowledge of the pharmacokinetics of these sweeteners, their potential for “sweetener–drug interactions” and their impact on appetite and body weight regulation. Nine research needs are described that address some of the major unknown issues associated with ingestion of high-potency sweeteners.

In Vivo Monitoring of Red Cell Redox Status to Screen for Potential Hematotoxicity of Anti-Malarial Drugs

Abstract 2099Redox equilibrium is an important determinant of malaria pathology and host defensive response to malaria parasites. Many anti-malarial drugs are reported to increase oxidative stress in red cells (RBC). Drug-induced hemolysis, particularly in G6PD deficient individuals, limits the utility of approved 8-aminoquinolones such as primaquine. The search for derivatives of primaquine that maintain efficacy without RBC toxicity is hampered by lack of a predictive assay for hemolytic potential. In order to monitor in vivo RBC redox changes in response to anti-malaria drugs, we have established a transgenic mouse line specifically expressing a redox sensitive GFP (roGFP2) in RBC1. RoGFP2 is an engineered EGFP with 2 cysteines introduced at amino acid positions 147 and 2042. When oxidized, the 2 cysteines form a disulfide bond, resulting in a protein conformational change that alters the spectral properties of the GFP. By following the ratio of fluorescence emission at 520nm after excitation at 405 vs 488nm, the intracellular redox potential in live cells can be determined. Here we apply this novel mouse model to follow in vivo RBC redox status upon exposure of transgenic mice to a series of 8-AQÕs and control compounds including known hemolytic agents such as dapsone. Unlike in vitro studies, these whole animal experiments incorporate metabolic transformation of inert parent compounds, pharmacokinetics and a time-course that closely models clinical hemolytic reactions in susceptible individuals exposed to the same drugs.roGFP2 transgenic mice (N=4 per group) were given test compounds (primaquine, chloroquine, dapsone and 1161B*) by gavage 2X/day at a total dose of 50mg/Kg over a period of 5 days. Peripheral RBC were analyzed using a LSRII FACS (BD) to determine the 405/488 ratio, and thus follow the redox status as shown in the figure below. Chloroquine treatment did not cause detectable change in roGFP2 signal, in agreement with previous data that chloroquine does not induce ROS production or hematotoxicity. Treatment with 1161B induced a steady increase in roGFP2 ratio that was first evident at 3 days of treatment, while primaquine treatment has little effect. Dapsone serves as a positive control in this assay, as a known hemolytic agent requiring metabolic activation to produce a redox cycling metabolite.3 Treatment with dapsone produced a time dependent shift to a more oxidized state of roGFP2 that was first evident after 2 days of drug administration. Consistent with these results, CBCÕs obtained one week after start of treatment showed moderate and mild hemolysis in those mice receiving dapsone and 1161B, respectively.In summary, roGFP2 transgenic mice provide a promising platform for assessment of hemolytic potential of drugs—here demonstrated using dapsone and 8-aminoquinolones. While the mice used in this study were GFP transgenic on a wild-type background, studies are in progress to assess whether strains with specific RBC defects (such as G6PD hypomorphs, PRDX2 KO andSOD1 KO) are more sensitive to hemolytic insults. Preliminary studies indicate that PRDX2 and SOD1 KO mice are more sensitive to primaquine, but not chloroquine, according to the roGFP2 ratio changes. G6PD deficient animals may prove particularly useful for discriminating compounds such as primaquine that are safe for normal individuals, but cause hemolysis in the context of enzyme deficiency. [Display omitted] *1161B is the B enantiomer of an 8-aminoquinolone derivative with better efficacy and reduced hematoxicity4,5 in mice, when compared to the racemic mixture of the same compound. Disclosures:No relevant conflicts of interest to declare.

Direct observation of disulfide isomerization in a single protein

Photochemical uncaging techniques use light to release active molecules from otherwise inert compounds. Here we expand this class of techniques by demonstrating the mechanical uncaging of a reactive species within a single protein. We prove this novel technique by capturing the regiospecific reaction between a thiol and a vicinal disulfide bond. We designed a protein that includes a caged cysteine and a buried disulfide. The mechanical unfolding of this protein in the presence of an external nucleophile frees the single reactive cysteine residue, which now can cleave the target disulfide via a nucleophilic attack on either one of its two sulfur atoms. This produces two different and competing reaction pathways. We use single molecule force spectroscopy to monitor the cleavage of the disulfides, which extends the polypeptide by a magnitude unambiguously associated with each reaction pathway. This allowed us to measure, for the first time, the kinetics of disulfide bond isomerization in a protein.

Mechanistic investigation of chemical looping combustion of coal with Fe 2O 3 oxygen carrier

The reaction of three Chinese coals with Fe 2O 3 oxygen carrier (OC) was performed in a thermogravimetric analyzer (TGA), with special focuses on the effects of varying heating rate and coal rank on reactivity. Fourier transform infrared spectroscopy (FTIR) was used to in situ detect the emitted gases from TGA. Field scanning electron microscopy/energy-dispersive X-ray spectrometry (FSEM–EDX) was used to study the morphology and elemental compositions of the reaction residues collected from TGA and the related phase evaluation was further identified by X-ray diffraction (XRD). Through all these experiments, it was found that the pyrolysis of coal samples without Fe 2O 3 OC under N 2 atmosphere underwent the dehydration and the ensuing primary and secondary pyrolysis stages. The increasing heating rate shifted the characteristic temperature ( T m ) of the primary pyrolysis to a higher temperature and favored a more rapid generation of volatile matters. When the three coals reacting with Fe 2O 3 OC, TGA results demonstrated even over 200 °C, the reaction still experienced the partial pyrolysis at the relatively low temperature and the ensuing two reactions of Fe 2O 3 with the pyrolysis products at the primary and secondary stages. The coal of low rank with high volatile content should be preferred for the full conversion of coal into CO 2. Furthermore, the activation energy of Fe 2O 3 OC reacting with PDS at its primary pyrolysis stage was the largest, more than 70 kJ/mol. Finally, SEM–EDX and further XRD analysis of the residues from the reaction of PDS with Fe 2O 3 OC indicated the reduced counterpart of Fe 2O 3 was Fe 3O 4, and some inert iron compounds such as Fe 2SiO 4 and FeAl 2O 4 were also generated, which might deteriorate the reactivity of Fe 2O 3 OC.

Diels–Alder Reactions of Inert Aromatic Compounds within a Self‐Assembled Coordination Cage

A self-assembled coordination cage serves as a nanometer-sized molecular flask to promote the Diels-Alder reactions of aromatic hydrocarbons with N-cyclohexylmaleimide. The coordination cage accelerated the Diels-Alder reaction of anthracene at the electronically unfavorable, terminal benzene ring to give a compact, cavity-restrained syn-adduct. Activation-parameter measurements for the reactions revealed considerable reduction in the entropy cost, and preorganization of the substrates is a dominant factor in the enhanced reactivity. Owing to this entropy-cost reduction, otherwise-unreactive aromatic compounds, such as naphthalenes or triphenylene, also underwent Diels-Alder reactions in a regio- and stereocontrolled fashion. In the naphthalene Diels-Alder reaction, X-ray crystallographic analysis of the guest-inclusion complex clarified the reinforced orientation and proximity of the substrate pairs before the reaction. A perylene Diels-Alder adduct was stabilized inside the cage and protected from aerial oxidation.

Structure, solution chemistry, antiproliferative actions and protein binding properties of non-conventional platinum(ii) compounds with sulfur and phosphorus donors

Twelve Pt(II) complexes with cis-PtP(2)S(2) pharmacophores (where P(2) refers to two monodentate or one bidentate phosphane ligand and S(2) is a dithiolato ligand) were prepared, characterized and evaluated as potential antiproliferative agents. The various compounds were first studied from the structural point of view; afterward, their solubility properties as well as their solution behaviour were analyzed in detail. Antiproliferative properties were specifically evaluated against A2780 human ovarian carcinoma cells, either resistant or sensitive to cisplatin. For comparison purposes similar studies were carried out on four parent cis-dichloro bisphosphane Pt(II)complexes. On the whole, the cis-PtP(2)S(2) compounds displayed significant antiproliferative properties while the cis-PtP(2)Cl(2) (cis-dichloro bisphosphane Pt(II)) compounds revealed quite poor biological performances. To gain further insight into the molecular mechanisms of these bisphosphane Pt(II) compounds, the reactions of selected complexes against the model protein cytochrome c were investigated by ESI-MS and their adduct formation explored. A relevant reactivity with cyt c was obtained only for cis-PtP(2)Cl(2) compounds, whereas cis-PtP(2)S(2) compounds turned out to be nearly unreactive. The obtained results are interpreted and discussed in the frame of the current knowledge of anticancer platinum compounds and their structure-activity-relationships. The observation of appreciable antiproliferative effects for the relatively inert cis-PtP(2)S(2) compounds strongly suggests that these compounds will undergo specific activation within the cellular environment.

Ozonation as a Means to Optimize Biological Nitrogen Removal from Landfill Leachate

In this study, we investigate factors that can affect nitrification and denitrification in a moving bed biofilm system, treating partly stabilized landfill leachate. The optimization of biological treatment by means of controlled ozonation is additionally evaluated. Results obtained with a laboratory-scale, continuous-flow biofilm system suggest that nitrogen removal can be limited by the low influent biodegradable substrate concentrations, and that autotrophic nitrification can be adversely impacted by the high alkalinity buffer and ammonium/ammonia concentration. Our results suggest an optimum ozone dosage as high as 0.5 g/L O3 can be required to effectively decrease the effluent soluble COD concentration and pH profile in the aerobic reactors, improve the biodegradable COD production from inert compounds, and induce chemical nitrification in the system. The specific cost of ozonation evaluated is 0.36–0.73 euro/m3 with 911 mg/L average effluent soluble COD measured in the biofilm system.

Modified polyurethanes as a new type of thromboresistant polymers

New thromboresistant polymers are prepared via the physical modification of polyurethanes with water-soluble inert compounds. It is shown that the removal of water-soluble compounds from the polymer surface favors its self-purification without any dramatic changes in the conformation of proteins and in the structure of blood components. As a result, the time of whole-blood clotting on the polymer surface is higher by factor of 2.5–2.8 at a content of a low-molecular-mass modifier of 2 wt %.

Dioxygen activation responsible for oxidation of aliphatic and aromatic hydrocarbon compounds: current state and variants

The most significant aspect in microbial metabolisms, especially those of bacteria and archaea, is their marvelously wide acceptability of substrate electron donors and acceptors. This feature makes them to be attractive catalysts for environmental biotechnology in terms of degradation of harmful recalcitrant compounds, including hydrocarbons. Transformation of highly reduced and inert hydrocarbon compounds is with no doubt a challenging biochemical reaction for a single enzyme. However, several multi-component enzyme systems enable microorganisms to utilize hydrocarbons as carbon and energy (electron) sources. Initial biological attack to hydrocarbons is, in most cases, the hydroxylation that requires molecular dioxygen as a co-substrate. Dioxygen also contributes to the ring cleavage reaction of homo- and hetero-cyclic aromatic hydrocarbons. Although the molecular dioxygen is omnipresent and highly soluble in water, activation and splitting this triplet ground-state molecule to wed with difficult hydrocarbons need special devices. Non-heme iron, heme iron, or flavin nucleotide was designated as a major hidden dagger for this purpose.

High-Pressure Research at the Advanced Photon Source

Pressure, together with temperature, composition, or external fields, alone or in combination, can be used as principal variables in directing and controlling matter as well as for the synthesis of revolutionary new materials. The impact of extreme conditions to science, however, has been previously limited by the available vessels and probes. The last decade has witnessed a significant surge in extreme conditions science, thanks to the development of in situ synchrotron radiation (SR) probes and high-pressure (HP) instrumentation. Extreme conditions directly alter chemical, structural, mechanical, electronic, magnetic, and phonon properties of materials, revealing intriguing behaviors across boundaries between insulators and metals, ferromagnets and superconductors, ordered and disordered, and vigorously reactive and inert compounds. In Earth and planetary sciences, research from simulating experiments at high pressure and high temperature provides key information in understanding processes, dynamics, and formation of the deep interiors. For materials applications such as the search for new energy materials and superhard materials, extreme conditions remain a vast, unexplored field.

Innovative Process Saves Energy, Results in Elimination of Sludge

This article discusses issues with an effluent treatment plant (ETP) located in Kerala, India, and owned by the Indian company named Synthite Industries. Synthite's ETP uses activated sludge technology to treat production effluent, which requires substantial energy for aeration to sustain the microbial population of the system. Effluents received at the ETP vary in color, turbidity, and pH ‐ often several times in a day, and the ETP operators had to track pH values on an hourly basis and make corresponding adjustments to lime dosage. Finally, the use of lime, alum, and polyelectrolyte chemicals at the plant transformed Synthite's sludge from a purely organic waste to a substance designated as a hazardous waste. BiO‐WiSH? technology was selected to reduce operating and environmental costs of the ETP in two stages: reduce aeration and capture energy savings; and, eliminate chemical use. The article discusses the BiO‐WiSH technology that accelerates enzymatic biochemical reactions up to thousands of times faster than their normal rate. The speed of BiOWiSH is the result of a high‐speed enzyme and small‐molecule metabolite co‐factors that have been proven to accelerate the breakdown of all nonliving organic matter into its final inert compounds. Results and key success factors of the process are discussed.

Understanding the Effectiveness of Synthetic Crowding Agents

In vitro studies on the structure and stability of macromolecules are typically performed using very dilute solutions. However, the total intracellular concentration of macromolecules is very high, resulting in an in vivo environment that is significantly crowded. Prior studies have proven that the nonspecific interactions that occur between individual macromolecules and their crowded surroundings have a significant effect on biochemical rates and equilibira. In other words, the mechanisms under which a protein functions in a living cell may be quite different from the conditions under which a protein is studied by biochemist in the laboratory. To gain a better understanding of the phenomenon of macromolecular crowding, researchers have begun to utilize synthetic crowding agents such as ficoll, dextran, and PEG to recreate the in vivo environment. Experiments are conducted to understand the properties of proteins in such conditions with the belief that these synthetic crowding agents are able to adequately mimic the intracellular environment with its multiple components of lipids, carbohydrates, nucleic acids, and proteins. These crowding agents are thought to serve as inert compounds that have no interaction with the protein in question. This study has investigated the ability of synthetic crowding agents to produce a cellular environment that is similar to that of the actual cell. The thermal denaturations and NMR spectra of lysozyme and fibroblast growth factor (hFGF) were tested in the presence of various synthetic crowding agents. This was compared with the thermal denaturation and NMR spectra of these same proteins when placed in higher concentrations of themselves. The results indicate that synthetic crowding agents are not effective in mimicking the cellular environment. With these results, the understanding of protein study in the laboratory can be furthered as techniques to create a life like laboratory environment are refined.

Nonlinear classification of hERG channel inhibitory activity by unsupervised classification method

The side effects that occur in the central nervous system and circulatory system due to medicines are expected to be prevented by research and development. However, many of the compounds in medicines have the possibility of causing arrhythmia, and methods developed to detect this problem at the early stage of drug development are not always successful. In the present study, we classified drug compounds according to their activity using only structural information. To classify compounds, we used a self-organizing map (SOM), which is a nonlinear unsupervised classification method. We first analyzed a small-scale dataset, and an excellent classification result was obtained. We then applied our method to a large-scale dataset containing numerous inert compounds and were again able to classify the compounds according to their activity. Both classifications showed some compound activity, although a few differences between the two SOM maps were seen.

Relationships between chemical oxygen demand (COD) components and toxicity in a sequential anaerobic baffled reactor/aerobic completely stirred reactor system treating Kemicetine

In this study the interactions between toxicity removals and Kemicetine, COD removals, intermediate products of Kemicetine and COD components (CODs originating from slowly degradable organics, readily degradable organics, inert microbial products and from the inert compounds) were investigated in a sequential anaerobic baffled reactor (ABR)/aerobic completely stirred tank reactor (CSTR) system with a real pharmaceutical wastewater. The total COD and Kemicetine removal efficiencies were 98% and 100%, respectively, in the sequential ABR/CSTR systems. 2-Amino-1 (p-nitrophenil)-1,3 propanediol, l-p-amino phenyl, p-amino phenol and phenol were detected in the ABR as the main readily degradable inter-metabolites. In the anaerobic ABR reactor, the Kemicetin was converted to corresponding inter-metabolites and a substantial part of the COD was removed. In the aerobic CSTR reactor the inter-metabolites produced in the anaerobic reactor were completely removed and the COD remaining from the anerobic reactor was biodegraded. It was found that the COD originating from the readily degradable organics did not limit the anaerobic degradation process, while the CODs originating from the slowly degradable organics and from the inert microbial products significantly decreased the anaerobic ABR reactor performance. The acute toxicity test results indicated that the toxicity decreased from the influent to the effluent of the aerobic CSTR reactor. The ANOVA test statistics showed that there was a strong linear correlation between acute toxicity, CODs originating from the slowly degradable organics and inert microbial products. A weak correlation between acute toxicity and CODs originating from the inert compounds was detected.

Silicates characterization as potential bacteriocin-carriers

Abstract Two different silicates, zeosil and expanded perlite, were characterized as potential carriers of a bacteriocin with anti- Listeria monocytogenes activity, produced by Enterococcus faecium CRL1385. Specific surface areas showed a value significantly higher for zeosil (146 m 2 g − 1 ) than for perlite (0.65 m 2 g − 1 ). Potential zeta measurements revealed that both silicates had negatively charged surfaces between pH 2 and 11, but zeosil presented zero charge near pH 2. Fourier Transform Infrared (FTIR) spectra proved that zeosil presented more silanol groups available for bacteriocin interaction than perlite. Bacteriocins present in the cell-free supernatant (CFS) were adsorbed by both silicates. Adsorption was highest from pH 4 to 8 and, regardless of exposure time (0.5 or 4 h) and silicate concentration (1 or 4% w/v) at 25 °C. Bacteriocin adsorption onto zeosil ( ca . 99%) was higher than onto expanded perlite ( ca 80%). However, antimicrobial activity of bacteriocins adsorbed onto perlite was higher than onto zeosil. After 2 h contact between L. monocytogenes 01/155 cells and each silicate plus the bacteriocin sample, the number of Listeria viable cells decreased close to 2 and 6 log orders for zeosil and expanded perlite, respectively. Industrial relevance: One of the crucial problems in the use of bacteriocins as food biopreservatives is obtaining and purifying these antimicrobials. The process generally has a poor yield and is industrially expensive. Hence, alternative techniques to deliver bacteriocins may be a likely option to encourage their use as bioprotectors. Silicates, inert compounds of large surface area, are suggested in this work as peptide immobilizers so that they may later be used in food. These inorganic compounds have already been authorized as food-grade anticaking, clarifying or filtering agents. The results achieved so far with adsorption and anti- Listeria activity preservation of bacteriocin, once they have been immobilized onto silicates, offer a promising and simple alternative to incorporate this compound into food.

Optimization of the operations conditions in membrane bioreactors through the use of ASM3 model simulations

The aim of this work was the application of the ASM3 models simulations to obtain most favorable operations conditions in membrane bioreactors for efficient organic matter removal, sludge production reduction and oxygen transfer costs. Simulations were realized used the ASM3 model (Activated Sludge Model)(Henze et al., 2000) for three theoretical influents. The organic load rate (OLR) and the hydraulic retention time (HRT) were fixed at 1 kg COD m -3 d -1 and 0.4 d -1 respectively and the sludge retention time (SRT) was varied from 2.5 d to 67 d. The steady state values of the active biomass concentration (X BH ), the total biomass concentration (X SS ) (active biomass + inert suspended solid), and the oxygen uptake rate (OUR) were obtained for each condition. Thus the observed conversion yield was evaluated (Y OBS ). The results show that, if the SRT increases, the X BH increases until a maximal value. In the other hand, a constant increase evolution of the X SS is observed, without reach a saturation value. Therefore, the suspended solids accumulation after this maximal value are due to a dilution of the active biomass by inert compounds coming from endogenous respiration and also, inert influent. If the OLR restricted the amount of active biomass, on the contrary, high SRT induced high X SS concentration, thus generating rheological sludge properties that penalize the phenomena of mixing, oxygenation and membrane separation.

Dinuclear Zn(II) catalysts as biomimics of RNA and DNA phosphoryl transfer enzymes: changing the medium from water to alcohol provides enzyme‐like rate enhancements

AbstractPhosphodiesters are notoriously hydrolytically inert compounds that are demonstrated to have large accelerations of P‐OR cleavage promoted by transition and lanthanide metal ions in methanol and ethanol media. This review commentary describes recent findings of how a simple mononuclear and a dinuclear Zn(II) complex promote the cleavage of a series of RNA models and DNA models in alcohol media. The discussion centers on the analysis of the mechanisms of cleavage, energetics of the catalytic process, on recent findings of electrophilic assistance of leaving group departure, and the observation of a rapid hydrolytic reaction of a DNA model promoted by the dinuclear Zn(II) complex in ethanol containing less than 2% water. Copyright © 2009 John Wiley & Sons, Ltd.

Evaluation of the metabolic diversity of microbial communities in four different filter layers of a constructed wetland with vertical flow by Biolog™ analysis

The community-level substrate utilization test based on direct incubation of environmental samples in Biolog EcoPlates™ is a suitable and sensitive tool to characterize microbial communities. The aim of this study was to investigate the influence of plant roots and soil structure on the metabolic diversity of microorganisms in a constructed wetland with vertical flow. Sediment samples were taken from different filter depths representing specific filter layers. The color development representing the substrate utilization was measured with the samples over a period of 10 days. The average well color development (AWCD) for all carbon sources was calculated as an indicator of total activity and in order to compensate the influence of the inoculum's density on the color development in the plates. After transformation by dividing by the AWCD, the optical density data were analysed by principal component analysis (PCA). An analysis of the kinetic profile of the AWCD was carried out to increase the analytical power of the method. The corrected data have been successfully fit to the logistic growth equation. Three kinetic model parameters, the asymptote ( K), the exponential rate of color change ( p) and the time to the midpoint of the exponential portion of the curve ( s), were used for statistical analysis of the physiological profile of the microbial community in the different filter layers of the constructed wetland. We found out that in the upper two horizons, which were rooted most densely, mainly easily degradable materials like specific carbohydrates were utilized, while in the lower layers, where only single roots occur, more biochemically inert compounds, e.g. 2-hydroxy benzoic acid, were utilized. Furthermore it could be shown that microorganisms in the surface layer benefited from the plant litter because they can utilize decay products of these. In the lower filter layers specialists took advantage because they had to cope with the biochemically inert materials and the lower nutrient supply.

Acceleration of Norrish Type I Reaction with Molecular Oxygen and Catalytic CBr4

We report a useful method for facile synthesis of aryl carboxylic acids from aryl ketones by aerobic photooxidation using the inexpensive and easily handled CBr4 as catalyst. This procedure is applicable to inert compounds under usual photo-irradiation conditions, and appears very attractive from the view point of new method of expansion of Norrish Type I reaction.

In vitro system for studying blood, perfluorocarbons (PFC) and Sickle Cell Anemia

PFCs are inert compounds that dissolve more oxygen (O2) than plasma. A mixture of PFC and sickle cell blood could potentially hold and deliver more O2 to tissues, compensating for sickle cell red blood cell's (RBC) decreased affinity for O2. A system was developed for in vitro studies using blood mixed with PFC. The system (priming volume: 10 ml) includes a computer‐controlled pump, gas mixer, oxygenator, deoxygenator and interconnected tubing that allowed the flowing blood to be exposed to various O2 and CO2 tensions, yielding controlled levels of hemoglobin O2 saturation (SO2) and O2 partial pressures (PO2). SO2 and PO2 were measured using a blood gas analyzer and a CO‐oximeter. With the addition of 5, 10, and 20% of PFC by volume of blood, the total O2 content, O2 delivery and consumption increased linearly with the PFC concentration. The data suggest increased O2 transport by the PFC. The SO2 of blood mixed with PFC did not differ significantly from baseline. Changes in blood cell morphology can also be evaluated at each oxygenation level and PFC concentration using video‐microscopy. The percentage of RBC that sickle at a given PO2 with and without PFC will be determined. The system allows several variables to be studied using blood sampled from animals and patients.Support: Virginia Commonwealth University.