[1-(11)C]acetate uptake is not increased in renal cell carcinoma

PURPOSE

The purpose of this study was to investigate the potential of [1-(11)C]acetate (AC) as a metabolic tracer for renal cell cancer in human subjects.

METHODS

Twenty-one patients with suspected kidney tumours were investigated with AC and dynamic PET. AC uptake was scored on a five-step scale. Tumour localisation was known from CT/MRI. Histology was available in 18/21 patients. The results in these 18 patients are reported.

RESULTS

AC uptake by the tumour was less than (n=11), equal to (n=5) or higher than (n=2) uptake in the surrounding renal parenchyma. Histological tumour types showed a typical distribution, with a predominance of clear cell carcinomas (n=14) and only a small number of papillary cell carcinomas (n=2) and oncocytomas (n=2). Only the benign oncocytomas were highly positive with AC.

CONCLUSION

In most kidney tumours the AC accumulation was not higher than in normal kidney parenchyma. Therefore, AC PET cannot be recommend for the characterisation of a renal mass.

Guanosine analog in the pyrido[2,3-d]pyrimidine ring system as a potential toll-like receptor agonist

The synthesis of a guanosine analog in the pyrido[2,3-d]pyrimidine ring system has been accomplished by glycosylation of the preformed aromatic heterocyclic base, which was prepared in 2 steps by condensation of methyl acrylate with guanidine carbonate and methyl cyanoacetate in the presence of sodium methoxide, followed by dehydrogenation. The analog was evaluated in vitro for its ability to modulate the innate immune response by acting as an agonist or as an antagonist of Toll-like receptor (TLR) signaling by measuring cytokine induction or inhibition of induction, respectively, in mouse bone marrow-derived macrophages. Despite its structural similarity to 7-thia-8-oxoguanosine, a known TLR7 agonist, the analog was found to antagonize TLR7-induced cytokine induction in this cell-based assay.

Life close to the thermodynamic limit: how methanogenic archaea conserve energy

Methane-forming archaea are strictly anaerobic, ancient microbes that are widespread in nature. These organisms are commonly found in anaerobic environments such as rumen, anaerobic sediments of rivers and lakes, hyperthermal deep sea vents and even hypersaline environments. From an evolutionary standpoint they are close to the origin of life. Common to all methanogens is the biological production of methane by a unique pathway currently only found in archaea. Methanogens can grow on only a limited number of substrates such as H(2) + CO(2), formate, methanol and other methyl group-containing substrates and some on acetate. The free energy change associated with methanogenesis from these compounds allows for the synthesis of 1 (acetate) to a maximum of only 2 mol of ATP under standard conditions while under environmental conditions less than one ATP can be synthesized. Therefore, methanogens live close to the thermodynamic limit. To cope with this problem, they have evolved elaborate mechanisms of energy conservation using both protons and sodium ions as the coupling ion in one pathway. These energy conserving mechanisms are comprised of unique enzymes, cofactors and electron carriers present only in methanogens. This review will summarize the current knowledge of energy conservation of methanogens and focus on recent insights into structure and function of ion translocating enzymes found in these organisms.

Accurate determination of human serum transferrin isoforms: Exploring metal-specific isotope dilution analysis as a quantitative proteomic tool

Carbohydrate-deficient transferrin (CDT) measurements are considered a reliable marker for chronic alcohol consumption, and its use is becoming extensive in forensic medicine. However, CDT is not a single molecular entity but refers to a group of sialic acid-deficient transferrin isoforms from mono- to trisialotransferrin. Thus, the development of methods to analyze accurately and precisely individual transferrin isoforms in biological fluids such as serum is of increasing importance. The present work illustrates the use of ICPMS isotope dilution analysis for the quantification of transferrin isoforms once saturated with iron and separated by anion exchange chromatography (Mono Q 5/50) using a mobile phase consisting of a gradient of ammonium acetate (0-250 mM) in 25 mM Tris-acetic acid (pH 6.5). Species-specific and species-unspecific spikes have been explored. In the first part of the study, the use of postcolumn addition of a solution of 200 ng mL(-1) isotopically enriched iron (57Fe, 95%) in 25 mM sodium citrate/citric acid (pH 4) permitted the quantification of individual sialoforms of transferrin (from S2 to S5) in human serum samples of healthy individuals as well as alcoholic patients. Second, the species-specific spike method was performed by synthesizing an isotopically enriched standard of saturated transferrin (saturated with 57Fe). The characterization of the spike was performed by postcolumn reverse isotope dilution analysis (this is, by postcolumn addition of a solution of 200 ng mL(-1) natural iron in sodium citrate/citric acid of pH 4). Also, the stability of the transferrin spike was tested during one week with negligible species transformation. Finally, the enriched transferrin was used to quantify the individual isoforms in the same serum samples obtaining results comparative to those of postcolumn isotope dilution and to those previously published in the literature, demonstrating the suitability of both strategies for quantitative transferrin isoform determination in real samples.

Pyridylthiazoles: highly luminescent heterocyclic compounds

Absorption, fluorescence, and fluorescence excitation spectra of two substituted [(5-methyl-2-pyridine-2'-yl-1,3-thiazole-4-yl)oxy]acetic acid and its methyl ester (2,2'-pyridylthiazoles) are studied at various pH values in aqueous solution. The acid exhibits pKa(1)=2.10+/-0.07 and pKa(2)=3.45+/-0.03, whereas the ester pKa=1.93+/-0.03. The protonation site is the pyridyl-nitrogen. When protonated, the cisoid conformer is the most stable; however, the transoid conformer is more stable in the deprotonated form. Fluorescence quantum yields close to unity are found. Large Stokes shift values are explained by the shortening of the inter-ring bond in the excited state. These compounds may be useful for metal sensing and as laser dyes.

Synthesis from caffeine of a mixed N-heterocyclic carbene-silver acetate complex active against resistant respiratory pathogens

The bis(N-heterocyclic carbene) (NHC) silver complex, 3, with a methyl carbonate anion was formed from the reaction of the iodide salt of methylated caffeine, 1, with silver (I) oxide in methanol. Attempts to crystallize this complex from a mixture of common alcohols and ethyl acetate led to the formation of an NHC-silver acetate complex, 4. The more direct synthesis of 4 was accomplished by the in-situ deprotonation of 1 by silver acetate in methanol. Complex 4 demonstrated antimicrobial activity against numerous resistant respiratory pathogens from the lungs of cystic fibrosis (CF) patients including members of the Burkholderia cepacia complex that cause a high rate of mortality in patients with cystic fibrosis (CF). Application of this NHC silver complex to primary cultures of murine respiratory epithelial cells followed by microarray analysis showed minimal gene expression changes at the concentrations effective against respiratory pathogens. Furthermore, methylated caffeine without silver showed some antibacterial and antifungal activity.

Novel selective orally active CRTH2 antagonists for allergic inflammation developed from in silico derived hits

Hits from an in silico derived focused library for CRTH2 were transformed into highly selective antagonists with favorable ADME properties. Oral administration of 4-bromo-2-(1-phenyl-1H-pyrazole-4-carbonyl)phenoxyacetic acid (19) inhibited peribronchial eosinophilia and mucus cell hyperplasia in a mouse model of allergic asthma, supporting the therapeutic potential of this novel compound class. In addition, this selective pharmacological tool compound provides further evidence for CRTH2 as a relevant therapeutic target for treatment of Th2- and eosinophil-related inflammation.

Hydride generation activity of arsenosugars and thioarsenicals

The major arsenosugar compounds have been reported to be hydride-generation-active, however to a lesser extent in comparison with the inorganic arsenicals. We report here for the first time the identity and quantity of the volatile arsenicals generated by As-sugar-SO(3), As-sugar-SO(4), dimethylarsinoyl acetic acid and dimethylarsinoyl ethanol. Only one major volatile compound was identified for all four compounds studied: dimethylarsine. This means that the As-C bond to the longer carbon chain was cleaved during the hydride-generation process. Theoretical calculations at the RHF/6-31G(d,p) ab initio level confirm that this As-C bond is much weaker than the As-CH(3) bonds. Furthermore, it was revealed that the sulphur analogue of dimethylarsinic acid (DMAS ) is hydride-generation-active at pH 7 in contrast to dimethylarsinic acid, despite the fact that arsenic is also pentavalent. This has been substantiated by the calculation of the change in susceptibility of the arsenic towards nucleophilic attack when oxygen is replaced by sulphur. Hence, DMAS can easily be mistaken for a trivalent arsenic species.

Quinoxaline−Imidazolium Receptors for Unique Sensing of Pyrophosphate and Acetate by Charge Transfer

[structure: see text] Quinoxaline derivatives (1-4) bearing two imidazolium moieties are found to strongly bind anions and show unique charge-transfer fluorescent responses to pyrophosphate and acetate, whereas they show excimer formation with other anions. Anion-binding studies are investigated with fluorescence and 1H NMR analysis, single-crystal X-ray analysis, and theoretical calculations.

Lagaspholones A and B: Two New Jatropholane-Type Diterpenes from Euphorbia lagascae

[structure: see text] Two new diterpenes, lagaspholones A (1) and B (2), have been isolated from the methanolic extract of Euphorbia lagascae, along with the known compounds (+)-dehydrovomifoliol, scopoletin, dehydrodiconiferyl diacetate, 3-indolcarbaldehyde, and 4-hydroxy-3,5-dimethoxybenzaldehyde. Their structures were elucidated by spectroscopic methods. Compounds 1 and 2 contain the rare jatropholane-type skeleton, characterized by a 5:6:7:3 fused ring system. A possible biosynthetic pathway for lagaspholones is proposed.

Grid-based molecular modeling for pharmaceutical salt screening: Case example of 3,4,6,7,8,9-hexahydro-2H-pyrimido (1,2-a) pyrimidinium acetate

The development of modeling capabilities for improving the efficiency with which solid-state pharmaceutical products can be developed is a key strategic goal for the pharmaceutical research and development sector. In this context, an important topic is the salt-selection process associated with drug-product formulation development. In this study, a systematic (grid-based) search method is used to predict the host/counter-ion binding for a simple but representative organic salt (i.e., a type I organic acid salt former having a single ionisable group): 3,4,6,7,8,9-hexahydro-2H-pyrimido (1,2-a) pyrimidinium acetate ([H2hpp][O2CCH3]). The relative disposition of the two ionic moieties in the asymmetric unit and, from this, the crystal packing in this compound are also predicted using the systematic grid-based search method linked to the known crystallographic unit cell dimensions. The overall strategy adopted encompasses three main steps: molecular pair search; optimization and clustering; and crystal lattice search and optimization. The predicted results, using this method, reveal a good agreement between the calculated crystal structure and that obtained from the Cambridge Crystallographic Structure Database (CCSD), indicating that the approach offers considerable promise for application as part of an integrated strategy for pharmaceutical salt selection.

Differential Attraction of Heliothis subflexa Males to Synthetic Pheromone Lures in Eastern US and Western Mexico

The mate attraction signal of Heliothis subflexa (Hs) females consists of a multicomponent sex pheromone blend. In this study, we assessed the intraspecific importance of three groups of compounds found in Hs pheromone glands: three acetate esters (Z7-16:OAc, Z9-16:OAc, and Z11-16:OAc), two 14-carbon aldehydes (14:Ald and Z9-14:Ald), and one 16-carbon alcohol (Z11-16:OH). Because the relative importance of pheromone components may vary in different regions, we conducted experiments in Eastern US (North Carolina) and Western Mexico (Jalisco). Our experiments in Eastern US showed that when the acetates were omitted from a 7-component blend in rubber septa, fewer males were caught in cone traps. Subsequent experiments conducted both in Eastern US and Western Mexico indicated that the addition of Z9-16:OAc alone does not increase attraction of male Hs, while Z11-16:OAc does. The Hs male response to Z7-16:OAc differed between the two regions. In Eastern US, significantly more males were attracted to a minimal three-component blend to which Z7-16:OAc was added, but this was not the case in Western Mexico. The two 14-carbon aldehydes also showed differential attraction between the two regions. 14:Ald and Z9-14:Ald appeared not to play any role in the sexual communication of Hs in Eastern US, but reduced trap catches in Western Mexico. The alcohol Z11-16:OH was tested in two concurrent dose-response studies with Hs males in Western Mexico, one using a minimal blend and one using a complete blend. The minimal three-component blend provided a more discriminating tool for delineating dose-response effects of Z11-16:OH than the seven-component blend. In the minimal blend, the optimal dose of Z11-16:OH was 1%, while in the complete blend similar numbers of males were caught when the alcohol ranged from 1 to 25%.

Catalytic combustion of ethyl acetate on supported copper oxide catalysts

Total oxidation of ethyl acetate on supported copper oxide catalysts was investigated. The catalysts have been prepared by wet impregnation method and characterized by XRD, TEM and XPS. Among the catalysts with the supports of TiO2, CeO2/TiO2 and CeO2-ZrO2/TiO2, CeO2-ZrO2 solid solutions doped TiO2 supported catalyst gives the highest catalytic activity. Catalyst with the composition of 5 wt.% CuO/10 wt.% CeO2-ZrO2-TiO2 shows the total oxidation of ethyl acetate at about 270 degrees C with the 100% CO2 selectivity. The characterization studies of supported copper oxide catalysts showed that the highly dispersed CuO is one of the active phase which contacts intimately with the support, the action of the interface between the components was not be ignored.

Amelioration of cisplatin induced nephrotoxicity in mice by an ethyl acetate extract of Lagerstroemia speciosa (L)

We studied an ethyl acetate (EtoAC) extract of leaves obtained from the medicinal and ornamental tree, Lagerstroemia speciosa L, for nephroprotective activity in cisplatin-induced acute renal injury in Balb/C mice. The EtoAC extract at dose levels of 50 and 250 mg/kg showed a dose-dependent reduction in cisplatin-induced elevations in urea and creatinine concentrations. Additionally, treatment with the EtoAC extract prevented the cisplatin-induced decline of the renal antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, and reduced glutathione. The findings suggest that the EtoAC extract from L. speciosa possesses marked nephroprotective activity and could offer a promising role in the treatment of acute renal injury caused by a nephrotoxin like cisplatin.

A Fraction ofAcorus calamus L. extract devoid ofβ-asarone Enhances adipocyte differentiation in 3T3-L1 cells

The effects of fractions partitioned from the ethanol extract of Acorus calamus L. (AC) on adipocyte differentiation were investigated using cultured mouse 3T3-L1 preadipocytes. The degree of differentiation was evaluated by measuring the cellular triglycerides and protein expression of the glucose transporter GLUT4 in 3T3-L1 cells. The ethyl acetate fraction of the AC extract (ACE) was found to enhance adipocyte differentiation as did rosiglitazone. The results of further fractionation of ACE indicated that the active fraction does not consist of beta-asarone, which is a toxic component of this plant. This finding suggests that ACE has potential insulin-sensitizing activity like rosiglitazone, and may improve type 2 diabetes.

Synthesis and evaluation of 2-(2-fluoro-4-hydroxymethyl-5-methoxy-phenoxy)acetic acid as a linker in solid-phase synthesis monitored by gel-phase19F NMR spectroscopy

Gel-phase (19)F NMR spectroscopy is a useful monitoring technique for solid-phase organic chemistry due to the high information content it delivers and swift acquisition times, using standard NMR spectrometers. This paper describes the synthesis of the novel linker 2-(2-fluoro-4-hydroxymethyl-5-methoxy-phenoxy)acetic acid in 29% yield over seven steps, using nucleophilic aromatic substitutions on 2,4,5-trifluorobenzonitrile as key steps. Following standard solid-phase synthesis a peptide could be cleaved from the linker using 20% TFA in CH(2)Cl(2) in 30 minutes, in contrast to a previously described monoalkoxy linker that requires 90% TFA in water at elevated temperature. A resin-bound peptide could be successfully glycosylated using only two equivalents of a thioglycoside donor, activated with N-iodosuccinimide and trifluoromethanesulfonic acid, and subsequent cleavage and deprotection gave the target glycopeptide. Direct glycosylation of the linker itself followed by mild acidic cleavage gave a fully protected hemiacetal for further chemical manipulation.

The effects of intramolecular H-bond formation on the stability constant and water exchange rate of the Gd(III)-diethylenetriamine-N′-(3-amino-1,1-propylenephosphonic)-N,N,N″,N″-tetraacetate complex

The binding interaction of metal chelates to biological macromolecules, though driven by properly devoted recognition synthons, may cause dramatic changes in some property associated with the coordination cage such as the thermodynamic stability or the exchange rate of the metal coordinated water. Such changes are due to electrostatic and H-bonding interactions involving atoms of the coordination cage and atoms of the biological molecule at the binding site. To mimic this type of H-bonding interactions, lanthanide(III) complexes with a DTPA-monophosphonate ligand bearing a propylamino moiety (H6NP-DTPA) were synthesized. Their thermodynamic stabilities and the exchange lifetime of the coordinated water molecule (for the Gd-complex) were compared with those of the analog complexes with DTPA and the parent DTPA-monophosphonate derivative (H6P-DTPA). It was found that the intramolecular H-bond between the epsilon-amino group and the phosphonate moiety in NP-DTPA complexes causes displacements of electric charges in their coordination cage that are markedly pH dependent. In turn, this affects the characteristic properties of the coordination cage. In particular it results in a marked elongation of the exchange lifetime of the coordinated water molecule.

Liquid chromatography/electrospray ionization mass spectrometry method for the determination of the active metabolite M-1 of suplatast tosilate in human plasma

A liquid chromatography/electrospray ionization mass spectrometry (LC/ESIMS) method for the determination of 4-(3-ethoxy-2-hydroxypropoxy) acrylanilide (M-1), the active metabolite of suplatast tosilate, in human plasma was established. Plasma samples were extracted with diethyl ether, separated on a C(18) column with a mobile phase of acetonitrile-10 mm ammonium acetate solution containing 0.1% formic acid (28:72, v/v) and detected by ESIMS. The method was linear over the concentration range 0.15-60.0 ng/mL. The lowest limit of quantification was 0.15 ng/mL. The intra- and inter-run relative standard deviations obtained from three validation runs were all less than 8.6%, and the intra- and inter-run relative errors were all less than 3.1%. The method was successfully applied for the evaluation of pharmacokinetic profiles of M-1 in healthy volunteers.

A rapid and highly sensitive method for the determination of glimepiride in human plasma by liquid chromatography–electrospray ionization tandem mass spectrometry: application to a pre-clinical pharmacokinetic study

A sensitive and specific liquid chromatography-positive electrospray ionization-tandem mass spectrometry method has been developed and validated for the determination of glimepiride (GPD) in human plasma. GPD and the internal standard (IS, glibenclamide) were extracted from a small aliquot of human plasma (200 microL) by a simple liquid-liquid extraction technique using ethyl acetate as extraction solvent. The compounds were separated on a YMC Propack, C18, 4.6x50 mm column using a mixture of ammonium acetate buffer, acetonitrile and methanol (30:60:10, v/v) as mobile phase at 0.5 mL/min on an API 4000 Sciex mass spectrometer connected to an Agilent HPLC system. Method validation and pre-clinical sample analysis was performed as per FDA guidelines and the results met the acceptance criteria. GPD and IS were detected without any interference from human plasma matrix. The method was proved to be accurate and precise at linearity range of 0.02-100.00 ng/mL with a correlation coefficient of 0.999. The method was robust with a lower limit of quantitation of 0.02 ng/mL. Intra- and inter-day accuracies for GPD were 88.60-113.50 and 96.82-103.93%, respectively. The inter-day precision was better than 12.21%. This method enabled faster and reliable determination of GPD in a pre-clinical study.

Determination of oridonin in rat plasma by reverse-phase high-performance liquid chromatography

A method for quantitative determination of oridonin in rat plasma using reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with UV spectrometry was established and the method was applied to a pharmacokinetics study of oridonin in rats. From a variety of compounds and solvents tested, ticolpidine was selected as the internal standard (IS) and ethyl acetate was found to be the best solvent for extracting oridonin from plasma samples. RP-HPLC analysis of the extracts was performed on an analytical column (DIKMA ODS, 200 mm x 4.6 mm; i.d., 5 microm) equipped with a security guard pre-column system. There was a good linearity over the range 0.05-8.0 microg/mL (r>0.99). The recoveries were about 95.0% in plasma, and the intra- and inter-day coefficients of variation were less than 9.0% in all cases. The limit of detection (LOD) was 0.025 microg/mL and the lower limit of quantification (LLOQ) was 0.05 microg/mL. The RP-HPLC method was readily applied to quantitate oridonin in rat plasma within 24 h in a pharmacokinetics study where experimental rats received a single dose of oridonin (12.5 mg/kg) and the result was presented.

[Simultaneous determination of residues of malachite green, crystal violet and their leuco metabolites in aquatic products by liquid chromatography-tandem mass spectrometry]

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of the residues of malachite green (MG), eucomalachite green (LMG), crystal violet (CV) and leucocrystal violet (LCV) in aquatic products. The target analytes were extracted from homogenized samples with a mixture of acetonitrile and ammonium acetate buffer, partitioned against methylene chloride, and purified on tandem neutral alumina and PRS solid-phase extraction (SPE) cartridges. Chromatographic separation was achieved by using a ZORBAX SB-C18 column with an isocratic mobile phase consisting of ammonium acetate (0.5 mmol/L) and acetonitrile (10: 90, v/v) without on-line post-column oxidation with PbO2 which had been widely used in the previous methods. Identification and quantification were performed using multiple reaction monitoring (MRM) with one precursor ion, and two product ions for each analyte and electrospray ionization in positive mode. The limits of detection were 0.5 ng/g. The recoveries were in the range of 77.6% - 98.1%, and the relative standard deviations were less than 8.2%. The results showed that the method is suitable for the determination of residues of MG, LMG, CV and LCV in aquatic products.

Effect of initial pH control on enhanced biological phosphorus removal from wastewater containing acetic and propionic acids

In the literature most of the studies on the effect of pH on enhanced biological phosphorous removal were conducted with the acetate wastewater, and the pH was controlled during the entire anaerobic and aerobic stages. This paper investigated the influence of anaerobic initial pH control, which will be more practical than the entire process pH control strategy, on enhanced biological phosphorus removal from wastewater containing acetic and propionic acids. Typical pH profile showed that both the initial alkaline and acidic pH tended to neutralize due to the consumption of short-chain fatty acid (SCFA) and intracellular pH regulation by polyphosphate accumulating organisms (PAOs). It was observed that the glycogen degradation and polyhydroxyalkanoates (PHA) accumulation decreased with increasing initial pH, which disagreed with previous reports. In the literature the metabolisms of both glycogen and PHA by PAOs in the acetate wastewater were independent of pH. An anaerobic mechanism model was proposed to explain the intra- and extra-cellular pH buffer nature of PAOs, and to address the reasons for increased polyphosphate degradation and decreased PHA synthesis and glycogen degradation at higher pH. The optimal initial pH for higher soluble ortho-phosphorus (SOP) removal efficiency should be controlled between 6.4 and 7.2. This pH control strategy will be easier to use in practice of wastewater treatment plant.

Desorption/ionization on porous silicon mass spectrometry (DIOS) of model cationized fatty acids

Desorption/ionization on porous silicon (DIOS) is a very useful technique in the case of small molecular weight compounds, compared to the matrix-assisted laser desorption ionization (MALDI). This is because MALDI generates matrix-related ions that overlap with the mass range of interest. The aim of our work was to investigate the suitability of the DIOS technique in the case of fatty acids in negative ion mode. The analysis of the chosen fatty acid models, nonadecanoic acid (C(19)H(38)O(2)) and heneicosanoic acid (C(21)H(42)O(2)), gave rise to the observation of the deprotonated monomeric species and selective cationized multimeric species. This cation selectivity was further elucidated by complementary studies based on the addition of various metals such as Ag(I), Zn(II), Fe(II), and also Cu(II). Specific behavior, depending upon the introduced metal, was highlighted by different redox reaction processes and also metastable decompositions (in PSD mode).

Marine cytotoxic macrolides haterumalides and biselides, and related natural products

Marine animals and plants are rich sources of bioactive natural products. Haterumalides and biselides, isolated from Okinawan marine animals, are 14-membered macrolides with strong cytotoxicity against human cancer cell lines. This review highlights the isolation, structures, bioactivities, and total synthesis of haterumalides, biselides, and related natural products.