Bio-gas or breath gas analysis in medical field was reviewed. In digestive diseases, breath hydrogen has successfully been measured in lactose intolerance and small bowel bacterial overgrowth. In liver diseases, breath or skin ammonia has been measured ; however, more study is needed for clinical use because ammonia does not reflect disease severity. In diabetes, acetone has been the main target for bio-gas measurement. However, there has been controversy over the usefulness of acetone, especially in type 2 diabetes. Measurement of acetone either breath or skin is useful in diabetic keto-acidosis. In respiratory diseases, breath NO in bronchial asthma has been established and used in clinics. In conclusion, bi-gas analysis is a promising field in medicine, but the basic research such as how to collect breath gas is still needed, and larger epidemiological study should be done to draw any significant conclusions.
Recent advances in instrumental chemical analysis have revealed that human body odor consists of numerous kinds of volatile organic and inorganic gases, some of which are associated with physical conditions, physiological changes, diseases, life styles and living environment. The biogas is called human skin gas. This paper aims to propose new insights in both wellness and medical researches based on human skin gas analysis by reviewing possible formation mechanisms and emission routes of the human skin gases, passive flux sampler - GC-MS methodology, and several clinical applications to healthy volunteer and hospitalized patients.
Nondigestible saccharides and dietary fibers are not hydrolyzed by any gastrointestinal enzymes, which digest carbohydrates, and reach the large intestine, where fermented by the intestinal microbes, and metabolized to short chain fatty acids (SCFAs), gases, such as carbon dioxide, methane, hydrogen, and the other metabolic products. Nonabsorbable saccharide and rare sugars are also fermented by the intestinal microbes. The SCFAs are absorbed through the absorptive epithelial cells, thereafter, converted to the available energy to the host. When the nondigestible and/or nonabsorbable saccharide are completely fermented by the intestinal microbes, 2kcal per 1g of the available energy were produced and supplied to the host. On the other hand, hydrogen gas derived from intestinal microbes are mostly absorbed through the epithelial cell, reach the lungs, and finally excreted to expiratory gas. We established the method to measure the hydrogen gas quantitatively, and clarified that the profile and amount of hydrogen excretion are indirectly responded with the digestibility and fermentability of nondigestible and/or nonabsorbable saccharide. Furthermore, we proposed the method to measure the available energy of nondigestible and/or nonabsorbable saccharide using the breath hydrogen excretion, together with serum glucose and insulin and the other indices.
We have focused on ammonia gas in particular in much biogas species, and have developed two kinds of new sensor systems to detect ammonia gas by gas sensor device using Copper Bromide (CuBr) film as sensing material.
The one is the system of sensing exhaled human breath for helping assessing of wellness states and another is the system of sensing the odor of the restroom.
By using these odor-visualization systems and integrating these systems into ICT technology, more comfortable, convenient and healthy life will be achieved.
In this study, focusing on the oxidation reactivity of glass containing CuO, the authors investigated the deodorizing function of the glass to malodorous substances sulfur-based compounds and lower fatty acids, particularly methyl mercaptan. It was confirmed the glass removes hydrogen sulfide, mercaptans and lower fatty acids by the deodorization test with the gas detection tube. Dimethyl disulfide which is an oxidation product of methyl mercaptan was identified by gas chromatography in the gas which methyl mercaptan was removed. The hydroxyl radicals generated from the glass was observed by the radical detection test using the spin-trapping method. Therefore, it is considered this radical dimerized methyl mercaptan and it lead to dimethyl disulfide formation. To compare with CuO showing the same oxidation mechanism as glass, a repeated deodorization test of methyl mercaptan was carried out and the surfaces of the glass and CuO were analyzed by X-ray photoelectron spectroscopy before and after deodorization. As a result, the glass showed higher deodorizing function durability of methyl mercaptan. Sulfur is hardly immobilized on the glass surface, however is immobilized on CuO surface, therefore it is presumed that the glass deodorizing function is more persistent than that of CuO. This study suggested that the glass containing CuO has a function of deodorizing sulfur-based compounds and lower fatty acids and that oxidation mechanism of methyl mercaptan to dimethyl disulfide is a radical reaction.