Cyclic Peroxidic Carbon Dioxide Dimer Fuels Peroxyoxalate Chemiluminescence.

Peroxyoxalate chemiluminescence is used in self-contained light sources, such as glow sticks, where oxidation of aromatic oxalate esters produces a high-energy intermediate (HEI) that excites fluorescence dyes via electron transfer chemistry, mimicking bioluminescence for efficient chemical energy-to-light conversion. The identity of the HEI and reasons for the efficiency of the peroxyoxalate reaction remain elusive. We present here unequivocal proof that the HEI of the peroxyoxalate system is a cyclic peroxidic carbon dioxide dimer, namely, 1,2-dioxetanedione.

Workshop report: Toward the development of a human whole stool reference material for metabolomic and metagenomic gut microbiome measurements.

Introduction: To date, there has been little effort to develop standards for metabolome-based gut microbiome measurements despite the significant efforts toward standard development for DNA-based microbiome measurements.

Objectives: The National Institute of Standards and Technology (NIST), The BioCollective (TBC), and the North America Branch of the International Life Sciences Institute (ILSI North America) are collaborating to extend NIST's efforts to develop a Human Whole Stool Reference Material for the purpose of method harmonization and eventual quality control.

Methods: The reference material will be rationally designed for adequate quality assurance and quality control (QA/QC) for underlying measurements in the study of the impact of diet and nutrition on functional aspects of the host gut microbiome and relationships of those functions to health.

Evaluating changes to Ralstonia pickettii in high-purity water to guide selection of potential calibration materials for online water bioburden analyzers.

Online water bioburden analyzers (OWBAs) can provide real-time feedback on viable bacteria in high-purity water (HPW) systems for pharmaceutical manufacturers. To calibrate and validate OWBAs, which detect bacteria using scattered light and bacterial autofluorescence, standards are needed that mimic the characteristics of bacteria in HPW. To guide selection of potential standards, e.

Inborn-like errors of metabolism are determinants of breast cancer risk, clinical response and survival: a study of human biochemical individuality.

Breast cancer remains a leading cause of morbidity and mortality worldwide yet methods for early detection remain elusive. We describe the discovery and validation of biochemical signatures measured by mass spectrometry, performed upon blood samples from patients and controls that accurately identify (>95%) the presence of clinical breast cancer. Targeted quantitative MS/MS conducted upon 1225 individuals, including patients with breast and other cancers, normal controls as well as individuals with a variety of metabolic disorders provide a biochemical phenotype that accurately identifies the presence of breast cancer and predicts response and survival following the administration of neoadjuvant chemotherapy.

In vitro evaluation of wound healing and antimicrobial potential of ozone therapy.

Although ozone therapy is extensively applied when wound repair and antimicrobial effect are necessary, little is known about cellular mechanisms regarding this process. Thus, this study aimed to evaluate ozone cytotoxicity in fibroblasts (L929) and keratinocytes (HaCaT) cell lines, its effects on cell migration and its antimicrobial activity. Cells were treated with ozonated phosphate-buffered saline (8, 4, 2, 1, 0.

[Telephone monitoring service for pregnant women and impact on prevalence of prematurity and associated risk factors in Piracicaba, São Paulo State, Brazil].

This study aims to assess the impact of a telephone monitoring service on prevalence of prematurity and to analyze associated risk factors using data on 2,739 pregnant women. Estimation was based on hierarchical multiple logistic regression, with p ≤ 0.05 for variables to remain in the model.

COD removal and toxicity decrease from tannery wastewater by zinc oxide-assisted photocatalysis: a case study.

This work reports the optimization of degradation conditions and toxicity decrease in the tannery wastewater, collected in the retanning and dyeing steps. This effluent was filtered, diluted in a 1:200 proportion, and investigated as a case study on a bench scale by heterogeneous photocatalysis. These conditions were attained when the suspension, containing 1 g L-1 of ZnO and effluent, was irradiated for 4h at pH 8.

Assessment of domestic landfill leachate toxicity to the Asian clam Corbicula fluminea via biomarkers.

In order to evaluate the effects of domestic landfill leachate to bivalves Corbicula fluminea, clams were exposed to different leachate concentrations (v/v): 2, 3, 6 and 10 percent, corresponding to dilutions observed along a stream that receives this effluent, or only to clean water for comparisons. After 5 and 15 days of exposure the activity of the biotransformation enzymes 7-ethoxyresorufin-O-deethylase (EROD) and glutathione S-transferase (GST), the multixenobiotic resistance mechanism (MXR) and lipid peroxidation (LPO) in gills and digestive gland and metallothionein (MT) content in gills were evaluated. Differences in biomarkers responses were observed between gills and digestive gland, except for MXR that decreased in both tissues of clams exposed to 6 percent for 5 days.

Beetroot-pigment-derived colorimetric sensor for detection of calcium dipicolinate in bacterial spores.

In this proof-of-concept study, we describe the use of the main red beet pigment betanin for the quantification of calcium dipicolinate in bacterial spores, including Bacillus anthracis. In the presence of europium(III) ions, betanin is converted to a water-soluble, non-luminescent orange 1∶1 complex with a stability constant of 1.4 × 10(5) L mol(-1).

Solvent cage effects: basis of a general mechanism for efficient chemiluminescence.

The induced decomposition of 1,2-dioxetanes results in the efficient formation of singlet-excited carbonyl compounds. This transformation has been assumed to involve two sequential electron-transfer steps, and the viscosity dependence of the chemiexcitation efficiency (solvent cage effect) has been considered as evidence for the occurrence of an intermolecular electron back-transfer, despite the very high chemiexcitation quantum yields observed. However, all other chemiluminescent reactions assumed to occur according to the entirely intermolecular mechanism, referred to as CIEEL, are inefficient, except for the peroxyoxalate system.

Geophysical technique and groundwater monitoring to detect leachate contamination in the surrounding area of a landfill--Londrina (PR--Brazil).

The aim of the present study was to define leachate plume by using two techniques: geophysical and groundwater sampling in order to evaluate groundwater contamination. After performing a topographic survey and using geophysics, the leachate plume was identified. With this data, the wells for groundwater monitoring were located.

Impact of processing method on recovery of bacteria from wipes used in biological surface sampling.

Environmental sampling for microbiological contaminants is a key component of hygiene monitoring and risk characterization practices utilized across diverse fields of application. However, confidence in surface sampling results, both in the field and in controlled laboratory studies, has been undermined by large variation in sampling performance results. Sources of variation include controlled parameters, such as sampling materials and processing methods, which often differ among studies, as well as random and systematic errors; however, the relative contributions of these factors remain unclear.

Parameters affecting spore recovery from wipes used in biological surface sampling.

The need for the precise and reliable collection of potential biothreat contaminants has motivated research in developing a better understanding of the variability in biological surface sampling methods. In this context, the objective of this work was to determine parameters affecting the efficiency of extracting Bacillus anthracis Sterne spores from commonly used wipe sampling materials and to describe performance using the interfacial energy concept. In addition, surface thermodynamics was applied to understand and predict surface sampling performance.

Quantum dot FRET-based probes in thin films grown in microfluidic channels.

This paper describes the development of new fluorescence resonance energy transfer (FRET)-based quantum dot probes for proteolytic activity. The CdSe/ZnS quantum dots are incorporated into a thin polymeric film, which is prepared by layer-by-layer deposition of alternately charged polyelectrolytes. The quantum dots, which serve as fluorescent donors, are separated from rhodamine acceptor molecules, which are covalently attached to the film surface by a varying number of polyelectrolyte layers.

Studies on the chemiexcitation step in peroxyoxalate chemiluminescence using steroid-substituted activators.

The peroxyoxalate reaction is utilized in a wide variety of analytical applications; however, its mechanism is still not very well understood, especially with respect to the excitation step, where the 'chemical energy' is transformed into 'excitation energy'. This base-catalysed reaction of activated oxalic phenyl esters with hydrogen peroxide in the presence of highly fluorescent aromatic hydrocarbons with low oxidation potentials is the only known chemiluminescence system for which exists experimental evidence for the occurrence of the intermolecular chemically initiated electron exchange luminescence (CIEEL) mechanism of proven high efficiency for excited state formation. We report here the singlet quantum yields and relative rate constants of the excitation step (k(CAT)/k(D)), obtained in the peroxyoxalate reaction, utilizing steroid-substituted oxazolinylidenes as activators.

Kinetic studies on the peroxyoxalate chemiluminescence reaction: determination of the cyclization rate constant.

Although more currently utilized as analytical tool because of its high sensitivity and good reproducibility, the mechanism of the peroxyoxalate system, a chemiluminescence reaction with quantum yields only comparable to bioluminescence systems, has been extensively studied. The light emission mechanism can be divided in the pathway before chemiexcitation, which contains the rate-limiting steps, and the fast and kinetically non-observable chemiexcitation step. In this work, we obtain information on the mechanism of the slow pathways, attribute values to several rate constants prior to chemiexcitation and suggest a mechanistic scheme that could help optimization of conditions when the peroxyoxalate reaction is used as analytical tool.

[Risk factors associated with the prevalence of arterial hypertension in adults in Bucaramanga, Colombia].

Objective: To assess the prevalence of high blood pressure (PHBP) and its association with age, sex, socioeconomic status (SES), and body mass index (BMI = kg/m2).

Material And Methods: A cross-sectional survey was carried out in 1996, in a random sample of 356 adults aged 20 and older, residents of Bucaramanga, Colombia. Weight, height, and blood pressure readings were obtained, plus data on age and gender.