Characteristic Evaluation of Gas Chromatography with Different Detectors for Accurate Determination of Sulfur Hexafluoride.

Sulfur hexafluoride (SF), which survives in the atmosphere for an extremely long period of time, is the most potent greenhouse gas regulated under the Kyoto Protocol. So, the accurate monitoring of atmospheric SF plays an important role in the study of the control policies for reducing greenhouse gas emissions. The instruments for SF measurement are typically calibrated using certified reference materials.

Determination of A1 and A2 β-Casein in Milk Using Characteristic Thermolytic Peptides via Liquid Chromatography-Mass Spectrometry.

β-casein, a protein in milk and dairy products, has two main variant forms termed as A1 and A2. A1 β-casein may have adverse effects on humans. The fact that there is only one amino acid variation at the 67th position between A1 and A2 β-casein makes it difficult to distinguish between them.

Recent Developments in the Determination of PM Chemical Composition.

Fine particulate matter (named PM) has become a prominent and dangerous form of air pollution. The chemical composition of PM mainly includes inorganic elements, water soluble ions, elemental carbon (EC), organic carbon (OC), and organic compounds. The detection method for inorganic elements mainly includes X ray fluorescence, inductively coupled plasma-atomic emission spectrometry, and inductively coupled plasma mass spectrometry.

Deficiency of ER Ca sensor STIM1 in AgRP neurons confers protection against dietary obesity.

Store-operated calcium entry (SOCE) is pivotal in maintaining intracellular Ca level and cell function; however, its role in obesity development remains largely unknown. Here, we show that the stromal interaction molecule 1 (Stim1), an endoplasmic reticulum (ER) Ca sensor for SOCE, is critically involved in obesity development. Pharmacological blockade of SOCE in the brain, or disruption of Stim1 in hypothalamic agouti-related peptide (AgRP)-producing neurons (ASKO), significantly ameliorates dietary obesity and its associated metabolic disorders.

Hypothalamic extended synaptotagmin-3 contributes to the development of dietary obesity and related metabolic disorders.

The C domain containing protein extended synaptotagmin (E-Syt) plays important roles in both lipid homeostasis and the intracellular signaling; however, its role in physiology remains largely unknown. Here, we show that hypothalamic E-Syt3 plays a critical role in diet-induced obesity (DIO). E-Syt3 is characteristically expressed in the hypothalamic nuclei.

Reversal of prolonged obesity-associated cerebrovascular dysfunction by inhibiting microglial Tak1.

Prolonged obesity is associated with cerebrovascular dysfunction; however, the underlying mechanisms remain largely unclear. In the present study, using a prolonged obesity mouse model that suffers from basilar artery (BA) abnormalities, we find that microglial transforming growth factor β-activated kinase 1 (Tak1) is over-activated in the brainstem. Both pharmacological inhibition primarily in the brainstem and genetic microglia-selective deletion of Tak1 ameliorated BA vascular dysfunction.

Caffeine inhibits hypothalamic AR to excite oxytocin neuron and ameliorate dietary obesity in mice.

Caffeine, an antagonist of the adenosine receptor AR, is used as a dietary supplement to reduce body weight, although the underlying mechanism is unclear. Here, we report that adenosine level in the cerebrospinal fluid, and hypothalamic expression of AR, are increased in the diet-induced obesity (DIO) mouse. We find that mice with overexpression of AR in the neurons of paraventricular nucleus (PVN) of the hypothalamus are hyperphagic, have glucose intolerance and high body weight.

Quantitative detection of nitric oxide in exhaled human breath by extractive electrospray ionization mass spectrometry.

Exhaled nitric oxide (eNO) is a useful biomarker of various physiological conditions, including asthma and other pulmonary diseases. Herein a fast and sensitive analytical method has been developed for the quantitative detection of eNO based on extractive electrospray ionization mass spectrometry (EESI-MS). Exhaled NO molecules selectively reacted with 2-phenyl-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO) reagent, and eNO concentration was derived based on the EESI-MS response of 1-oxyl-2-phenyl-4, 4, 5, 5-tetramethylimidazoline (PTI) product.

Facilitated diffusion of acetonitrile revealed by quantitative breath analysis using extractive electrospray ionization mass spectrometry.

By using silver cations (Ag⁺) as the ionic reagent in reactive extractive electrospray ionization mass spectrometry (EESI-MS), the concentrations of acetonitrile in exhaled breath samples from the volunteers including active smokers, passive smokers, and non-smokers were quantitatively measured in vivo, without any sample pretreatment. A limit of detection (LOD) and relative standard deviation (RSD) were 0.16 ng/L and 3.

A highly anti-selective asymmetric Henry reaction catalyzed by a chiral copper complex: applications to the syntheses of (+)-spisulosine and a pyrroloisoquinoline derivative.

A highly anti-selective asymmetric Henry reaction has been developed, affording synthetically versatile β-nitroalcohols in a predominately anti-selective manner (mostly above 15:1) and excellent ee values (mostly above 95%). Moreover, the anti-selective Henry reaction was carried out in the presence of water for the first time with up to 99% ee. The catalytic mechanism was proposed based on the detection of the intermediates by extractive electrospray ionization mass spectrometry (EESI-MS).