Spectroscopic investigation of hydrogen and triple-oxygen isotopes in atmospheric water vapor and precipitation during Indian monsoon season.

Water vapor, the most important greenhouse gas in the atmosphere, has four natural stable isotopologues (HO, HO, HO and HDO), and their isotopic compositions can be used as hydrological tracers. But the underlying processes and pattern-dynamics of the isotopic compositions of atmospheric water vapor and precipitation in response to various meteorological conditions during monsoon season in a tropical hot and humid region is poorly understood. Here, we present results of H and triple-O-isotopes of water in precipitation and atmospheric water vapor during monsoon season exploiting high-resolution integrated cavity output spectroscopy technique.

Exploring Triple-Isotopic Signatures of Water in Human Exhaled Breath, Gastric Fluid, and Drinking Water Using Integrated Cavity Output Spectroscopy.

Water, the major body fluid in humans, has four main naturally occurring isotopologues, HO, HO, HO, and HHO (i.e., HDO) with different masses.

Exploring the physiological link of breath NO through nitrification and denitrification processes in human gastric juice.

Over the past several decades, it has been generally believed that microbial nitrification and denitrification are not significant processes in the human gastrointestinal tract. Moreover, the underlying physiological link between exhaled nitrous oxide (NO) and aerobic denitrification in the gastric environment is still largely unknown. In this report, we provide direct experimental evidence of the aerobic denitrification process in the human gastrointestinal tract by evaluating concentrations of dissolved NO and its precursor nitrite ([Formula: see text]) ion in the gastric juice along with exhaled NO concentration using a high-precision laser spectroscopy technique.

High-resolution spectral analysis of ammonia near 6.2 μm using a cw EC-QCL coupled with cavity ring-down spectroscopy.

We report on the development of a mid-infrared cavity ring-down spectrometer (CRDS) coupled with a continuous wave (cw) external cavity quantum cascade laser (EC-QCL), operating between 6.0 μm and 6.3 μm, for high-resolution spectroscopic studies of ammonia (NH3) which served as a bench-mark molecule in this spectral region.

Isotope-specific breath analysis to track the end-stage renal disease during hemodialysis.

The underlying mechanisms towards the progression of end-stage renal disease (ESRD) in chronic kidney disease (CKD) are poorly understood and it still remains a major clinical stumbling block for early detection of CKD. Most patients with CKD pass through ESRD with the necessity of frequent hemodialysis (HD) treatment. At present, plasma urea and creatinine levels are examined in most CKD patients to monitor their health status after dialysis.

New Strategy for in Vitro Determination of Carbonic Anhydrase Activity from Analysis of Oxygen-18 Isotopes of CO.

The oxygen-18 isotopic (O) composition in CO provides an important insight into the variation of rate in isotopic fractionation reaction regulated by carbonic anydrase (CA) metalloenzyme. This work aims to employ an O-isotope ratio-based analytical method for quantitative estimation of CA activity in erythrocytes for clinical testing purposes. Here, a new method has been developed that contains the measurements of O/O isotope ratios during oxygen-18 isotopic exchange between COO and HO of an in vitro biochemical reaction controlled by erythrocytes CA and estimation of enzymatic activity of CA from the isotopic composition of CO.

C isotopic abundances in natural nutrients: a newly formulated test meal for non-invasive diagnosis of type 2 diabetes.

A new method to replace commercially prepared C-labelled glucose with naturally available C-enriched substrates could result in promotion of the clinical applicability of the isotopic breath test for detection of type 2 diabetes (T2D). Variation of the carbon-13 isotope in human breath depends on the C enrichment in the diet taken by subjects. Here, we formulated a new test meal comprising naturally available C-enriched foods and subsequently administered it to non-diabetic control (NDC) subjects and those with T2D.

Natural O and C-urea in gastric juice: a new route for non-invasive detection of ulcers.

The C-urea breath test (C-UBT), developed a few decades ago, is widely used as a non-invasive diagnostic method to detect only the presence of the gastric pathogen Helicobacter pylori infection; however, the actual disease state, i.e. whether the person harbouring H.

Molecular hydrogen in human breath: a new strategy for selectively diagnosing peptic ulcer disease, non-ulcerous dyspepsia and Helicobacter pylori infection.

The gastric pathogen Helicobacter pylori utilizes molecular hydrogen (H2) as a respiratory substrate during colonization in the gastric mucosa. However, the link between molecular H2 and the pathogenesis of peptic-ulcer disease (PUD) and non-ulcerous dyspepsia (NUD) by the enzymatic activity of H. pylori still remains mostly unknown.

Continuous wave external-cavity quantum cascade laser-based high-resolution cavity ring-down spectrometer for ultrasensitive trace gas detection.

A high-resolution cavity ring-down spectroscopic (CRDS) system based on a continuous wave (cw) mode-hop-free (MHF) external-cavity quantum cascade laser (EC-QCL) operating at λ∼5.2  μm has been developed for ultrasensitive detection of nitric oxide (NO). We report the performance of the high-resolution EC-QCL based cw-CRDS instrument by measuring the rotationally resolved Λ-doublet e and f components of the P(7.

Mechanisms linking metabolism of Helicobacter pylori to (18)O and (13)C-isotopes of human breath CO2.

The gastric pathogen Helicobacter pylori utilize glucose during metabolism, but the underlying mechanisms linking to oxygen-18 ((18)O) and carbon-13 ((13)C)-isotopic fractionations of breath CO2 during glucose metabolism are poorly understood. Using the excretion dynamics of (18)O/(16)O and (13)C/(12)C-isotope ratios of breath CO2, we found that individuals with Helicobacter pylori infections exhibited significantly higher isotopic enrichments of (18)O in breath CO2 during the 2h-glucose metabolism regardless of the isotopic nature of the substrate, while no significant enrichments of (18)O in breath CO2 were manifested in individuals without the infections. In contrast, the (13)C-isotopic enrichments of breath CO2 were significantly higher in individuals with Helicobacter pylori compared to individuals without infections in response to (13)C-enriched glucose uptake, whereas a distinguishable change of breath (13)C/(12)C-isotope ratios was also evident when Helicobacter pylori utilize natural glucose.