Human Breath Odors and Their Use in Diagnosis

Sniffer Dogs Diagnose Lung Cancer by Recognition of Exhaled Gases: Using Breathing Target Samples to Train Dogs Has a Higher Diagnostic Rate Than Using Lung Cancer Tissue Samples or Urine Samples

INTRODUCTION

Sniffer dogs can diagnose lung cancer. However, the diagnostic yields of different samples and training methods for lung cancer remain undetermined.

OBJECTIVE

Six dogs were trained in three stages with the aim of improving the diagnostic yield of lung cancer by comparing training methods and specimens.

METHODS

The pathological tissues of 53 lung cancer patients and 6 non-lung cancer patients in the Department of Thoracic Surgery of Kaohsiung Chang Gung Hospital were collected, and the exhaled breath samples and urine samples were collected. Urine and exhaled breath samples were also collected from 20 healthy individuals. The specimens were sent to the Veterinary Department of Pingtung University of Science and Technology.

RESULTS

The dogs had a very low response rate to urine target samples in the first and second stages of training. The experimental results at the second stage of training found that after lung cancer tissue training, dogs were less likely to recognize lung cancer and healthy controls than through breath target training: the response rate to exhaled breathing target samples was about 8-55%; for urine target samples, it was only about 5-30%. When using exhaled air samples for training, the diagnosis rate of these dogs in lung cancer patients was 71.3% to 97.6% (mean 83.9%), while the false positive rate of lung cancer in the healthy group was 0.5% to 27.6% (mean 7.6%). Compared with using breathing target samples for training, the diagnosis rate of dogs trained with lung cancer tissue lung cancer was significantly lower (p < 0.05). The sensitivity and specificity of lung cancer tissue training (50.4% and 50.1%) were lower than the exhaled breath target training (91.7% and 85.1%). There is no difference in lung cancer diagnostic rate by sniff dogs among lung cancer histological types, location, and staging.

CONCLUSION

Training dogs using breathing target samples to train dogs then to recognize exhaled samples had a higher diagnostic rate than training using lung cancer tissue samples or urine samples. Dogs had a very low response rate to urine samples in our study. Six canines were trained on lung cancer tissues and breathing target samples of lung cancer patients, then the diagnostic rate of the recognition of exhaled breath of lung cancer and non-lung cancer patients were compared. When using exhaled air samples for training, the diagnosis rate of these dogs in lung cancer patients was 71.3% to 97.6% (mean 83.9%), while the false positive rate of lung cancer in the healthy group was 0.5% to 27.6% (mean 7.6%). There was a significant difference in the average diagnosis rate of individual dog and overall dogs between the lung cancer group and the healthy group (p < 0.05). When using lung cancer tissue samples for training, lung cancer diagnosis rate of these dogs among lung cancer patients was only 15.5% to 40.9% (mean 27.7%). Compared with using breathing target samples for training, the diagnosis rate of dogs trained with lung cancer tissue lung cancer was significantly lower (p < 0.05). The sensitivity and specificity of lung cancer tissue training (50.4% and 50.1%) were lower than the exhaled breath target training (91.7% and 85.1%). The diagnostic rate of lung cancer by sniffer dogs has nothing to do with the current stage of lung cancer, pathologic type, and the location of tumor mass. Even in stage IA lung cancer, well-trained dogs can have a diagnostic rate of 100%. Using sniffer dogs to screen early lung cancer may have good clinical and economic benefits.

Revisiting Standard and Novel Therapeutic Approaches in Halitosis: A Review

Halitosis, or bad breath, is an oral health problem characterized by an unpleasant malodor emanating from the oral cavity. This condition can have different origins and causes a negative burden in social interactions, communication and quality of life, and can in uncommon cases be indicative of underlying non-oral non-communicable diseases. Most cases of halitosis are due to inadequate oral hygiene, periodontitis and tongue coating, yet the remaining proportion of cases are due to ear-nose-throat-associated (10%) or gastrointestinal/endocrine (5%) disorders. For this reason, the diagnosis, treatment and clinical management of halitosis often require a multidisciplinary team approach. This comprehensive review revisits the etiology of halitosis as well as standard and novel treatment that may contribute to higher clinical success.

Volatile Organic Compounds as Potential Biomarkers for Noninvasive Disease Detection by Nanosensors: A Comprehensive Review

Biomarkers are biological molecules associated with physiological changes of the body and aids in the detecting the onset of disease in patients. There is an urgent need for self-monitoring and early detection of cardiovascular and other health complications. Several blood-based biomarkers have been well established in diagnosis and monitoring the onset of diseases. However, the detection level of biomarkers in bed-side analysis is difficult and complications arise due to the endothelial dysfunction. Currently single volatile organic compounds (VOCs) based sensors are available for the detection of human diseases and no dedicated nanosensor is available for the elderly. Moreover, accuracy of the sensors based on a single analyte is limited. Hence, breath analysis has received enormous attention in healthcare due to its relatively inexpensive, rapid, and noninvasive methods for detecting diseases. This review gives a detailed analysis of how biomarker imprinted nanosensor can be used as a noninvasive method for detecting VOC to health issues early using exhaled breath analysis.

Real-Time Sensing with Patterned Plasmonic Substrates and a Compact Imager Chip

Optical sensing is an important research field due to its proven ability to be extremely sensitive, nondestructive, and applicable to sensing a wide range of chemical, thermal, electric, or magnetic phenomena. Beyond traditional optical sensors that often rely on bulky setups, plasmonic nanostructures can offer many advantages based on their sensitivity, compact form, cost-effectiveness, multiplexing compatibility, and compatibility with many standard semiconductor nanofabrication techniques. In particular, plasmon-enhanced optical transmission through arrays of nanostructured holes has led to the development of a new generation of optical sensors. In this chapter we present a simple fabrication technique to use plasmonic nanostructures as compact sensors. We position the nanohole array, an LED illumination source, and a spacer layer directly on top of a standard complementary metal-oxide-semiconductor (CMOS) imager chip. This setup is a viable sensor platform in both liquid and gas environments. These devices could operate as low-cost sensors for environmental monitoring, security, food safety, or monitoring small-molecule binding to extract affinity information and binding constants.

Induction and inhibition of oral malodor

Volatile sulfur compounds (VSCs) such as hydrogen sulfide (H₂ S) and methyl mercaptan (CH₃ SH) are the main components of oral malodor, and are produced as the end products of the proteolytic processes of oral microorganisms. The main pathway of proteolysis is the metabolism of sulfur-containing amino acids by gram-negative anaerobic bacteria. Gram-positive bacteria may promote VSC production by gram-negative anaerobes by cleaving sugar chains from glycoproteins and thus providing proteins. A large variety of bacteria within the oral microbiota are thought to be involved in the complex phenomenon of halitosis. Oral microbiota associated with a lack of oral malodor, oral microbiota associated with severe and H₂ S-dominant oral malodor, and oral microbiota associated with severe and CH₃ SH-dominant oral malodor have been distinguished through molecular approaches using the 16S rRNA gene. Pathological halitosis may primarily be addressed through treatment of causative diseases. In all cases, plaque control is the basis of oral malodor control, and dentifrices, mouthwashes, and functional foods play a supplementary role in addition to brushing. Recently, the use of natural ingredients in products tends to be favored due to the increase in antibiotic-resistant strains and the side effects of some chemical ingredients. In addition, probiotics and vaccines are expected to offer new strategies for improving the oral conditions through mechanisms other than antibacterial agents.

Volatolomics: A broad area of experimentation

Chemical analysis (detection and monitoring) of compounds associated with the metabolic activities of an organism is at the cutting edge of science. Volatile metabolomics (volatolomics) are applied in a broad range of applications including: biomedical research (e.g. disease diagnostic tools, personalized healthcare and nutrition, etc.), toxicological analysis (e.g. exposure tool to environmental pollutants, toxic and hazardous chemical environments, industrial accidents, etc.), molecular communications, forensics, safety and security (e.g. search and rescue operations). In the present review paper, an overview of recent advances and applications of volatolomics will be given. The main focus will be on volatile organic compounds (VOCs) originating from biological secretions of various organisms (e.g. microorganisms, insects, plants, humans) and resulting fusion of chemical information. Bench-top and portable or field-deployable technologies-systems will also be presented and discussed.

Mass spectrometric techniques for the analysis of volatile organic compounds emitted from bacteria

Bacteria are the main cause of many human diseases. Typical bacterial identification methods, for example culture-based, serological and genetic methods, are time-consuming, delaying the potential for an early and accurate diagnosis and the appropriate subsequent treatment. Nevertheless, there is a stringent need for in situ tests that are rapid, noninvasive and sensitive, which will greatly facilitate timely treatment of the patients. This review article presents volatile organic metabolites emitted from various micro-organism strains responsible for common bacterial infections in humans. Additionally, the manuscript shows the application of different analytical techniques for fast bacterial identification. Details of these techniques are given, which focuses on their advantages and drawbacks in using for volatile organic components analysis.

GC-MS metabolomics-based approach for the identification of a potential VOC-biomarker panel in the urine of renal cell carcinoma patients

The analysis of volatile organic compounds (VOCs) emanating from biological samples appears as one of the most promising approaches in metabolomics for the study of diseases, namely cancer. In fact, it offers advantages, such as non‐invasiveness and robustness for high‐throughput applications. The purpose of this work was to study the urinary volatile metabolic profile of patients with renal cell carcinoma (RCC) (n = 30) and controls (n = 37) with the aim of identifying a potential specific urinary volatile pattern as a non‐invasive strategy to detect RCC. Moreover, the effect of some confounding factors such as age, gender, smoking habits and body mass index was evaluated as well as the ability of urinary VOCs to discriminate RCC subtypes and stages. A headspace solid‐phase microextraction/gas chromatography–mass spectrometry‐based method was performed, followed by multivariate data analysis. A variable selection method was applied to reduce the impact of potential redundant and noisy chromatographic variables, and all models were validated by Monte Carlo cross‐validation and permutation tests. Regarding the effect of RCC on the urine VOCs composition, a panel of 21 VOCs descriptive of RCC was defined, capable of discriminating RCC patients from controls in principal component analysis. Discriminant VOCs were further individually validated in two independent samples sets (nine RCC patients and 12 controls, seven RCC patients with diabetes mellitus type 2) by univariate statistical analysis. Two VOCs were found consistently and significantly altered between RCC and controls (2‐oxopropanal and, according to identification using NIST14, 2,5,8‐trimethyl‐1,2,3,4‐tetrahydronaphthalene‐1‐ol), strongly suggesting enhanced potential as RCC biomarkers. Gender, smoking habits and body mass index showed negligible and age‐only minimal effects on the urinary VOCs, compared to the deviations resultant from the disease. Moreover, in this cohort, the urinary volatilome did not show ability to discriminate RCC stages and histological subtypes. The results validated the value of urinary volatilome for the detection of RCC and advanced with the identification of potential RCC urinary biomarkers.

Genetic analysis of impaired trimethylamine metabolism using whole exome sequencing

Background

Trimethylaminuria (TMAU) is a genetic disorder whereby people cannot convert trimethylamine (TMA) to its oxidized form (TMAO), a process that requires the liver enzyme FMO3. Loss-of-function variants in the FMO3 gene are a known cause of TMAU. In addition to the inability to metabolize TMA precursors like choline, patients often emit a characteristic odor because while TMAO is odorless, TMA has a fishy smell. The Monell Chemical Senses Center is a research institute with a program to evaluate people with odor complaints for TMAU.

Methods

Here we evaluated ten subjects by (1) odor evaluation by a trained sensory panel, (2) analysis of their urine concentration of TMA relative to TMAO before and after choline ingestion, and (3) whole exome sequencing as well as subsequent variant analysis of all ten samples to investigate the genetics of TMAU.

Results

While all subjects reported they often emitted a fish-like odor, none had this malodor during sensory evaluation. However, all were impaired in their ability to produce >90% TMAO/TMA in their urine and thus met the criteria for TMAU. To probe for genetic causes, the exome of each subject was sequenced, and variants were filtered by genes with a known (FMO3) or expected effect on TMA metabolism function (other oxidoreductases). We filtered the remaining variants by allele frequency and predicated functional effects. We identified one subject that had a rare loss-of-function FMO3 variant and six with more common decreased-function variants. In other oxidoreductases genes, five subjects had four novel rare single-nucleotide polymorphisms as well as one rare insertion/deletion. Novel in this context means no investigators have previously linked these variants to TMAU although they are in dbSNP.

Conclusions

Thus, variants in genes other than FMO3 may cause TMAU and the genetic variants identified here serve as a starting point for future studies of impaired TMA metabolism.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-017-0369-8) contains supplementary material, which is available to authorized users.

Direct spectral imaging of plasmonic nanohole arrays for real-time sensing

Plasmon-enhanced optical transmission through arrays of nano-structured holes has led to the development of a new generation of optical sensors. In this paper, to dramatically simplify the standard optical setups of these sensors, we position the nanoholes, an LED illumination source and a spacer layer directly on top of a CMOS imager chip. Transmitted light diffracts from the nanohole array, spreading into a spectrum over the space of a millimeter to land on the imager as a full spectrum. Our chip is used as a sensor in both a liquid and a gas environment. The spectrum is monitored in real-time and the plasmon-enhanced transmission peaks shift upon exposure to different concentrations of glycerol-in-water solutions or ethanol vapors in nitrogen. While liquids provide good refractive index contrast for sensing, to enhance sensitivity to solvent vapors, we filled the nanoholes with solvatochromic dyes. This on-chip solution circumvents the bulky components (e.g. microscopes, coupling optics, and spectrometers) needed for traditional plasmonic sensing setups, uses the nanohole array as both the sensing surface and a diffraction grating, and maintains good sensitivity. Finally, we show simultaneous sensing from two side-by-side locations, demonstrating potential for multiplexing and lab on a chip integration.

Bacterial volatiles and diagnosis of respiratory infections

Breath testing has enormous potential in the medical diagnostic field. The underlying complexity and perceived availability of adequate specimens, combined with a lack of knowledge of the metabolic pathways that give rise to compounds that are sources of analytes detectable in breath, has greatly slowed development. These real obstacles have recently been largely overcome in the use of breath testing to identify patients with cystic fibrosis associated Pseudomonas aeruginosa infection and tuberculosis. This review summarizes progress made in the characterization of microbial volatiles produced by major lower respiratory tract bacterial pathogens, and their potential use as diagnostic markers in patient breath testing.

Spider monkeys (Ateles geoffroyi) are less sensitive to the odor of aliphatic ketones than to the odor of other classes of aliphatic compounds

Aliphatic ketones are widely present in body-borne and food odors of primates. Therefore, we used an operant conditioning paradigm and determined olfactory detection thresholds in four spider monkeys for a homologous series of aliphatic 2-ketones (2-butanone to 2-nonanone) and two of their isomers (3- and 4-heptanone). We found that, with the exception of the two shortest-chained ketones, all animals detected concentrations <1 ppm (parts per million), and with five odorants individual animals even reached threshold values <0.1 ppm. Further, we found a significant correlation between olfactory sensitivity of the spider monkeys and carbon chain length of the 2-ketones which can best be described as a U-shaped function. In contrast, no significant correlation was found between olfactory sensitivity and position of the functional carbonyl group. Across-odorant and across-species comparisons revealed the following: spider monkeys are significantly less sensitive to the odors of aliphatic ketones than to the odor of other classes of aliphatic compounds (1-alcohols, n-aldehydes, n-acetic esters, and n-carboxylic acids) sharing the same carbon length. Spider monkeys do not differ significantly in their olfactory sensitivity for aliphatic ketones from squirrel monkeys and pigtail macaques, but are significantly less sensitive to these odorants compared to human subjects and mice. These findings support the notion that neuroanatomical and genetic properties do not allow for reliable predictions with regard to a species' olfactory sensitivity. Further, we conclude that the frequency of occurrence of a class of odorants in a species' chemical environment does not allow for reliable predictions of the species' olfactory sensitivity.

Template fabricated plasmonic nanoholes on analyte-sensitive substrates for real-time vapor sensing

Plasmonic nanoholes on analyte-sensitive substrates are used for vapor sensing.

Silicon nanowire-based devices for gas-phase sensing

Since their introduction in 2001, SiNW-based sensor devices have attracted considerable interest as a general platform for ultra-sensitive, electrical detection of biological and chemical species. Most studies focus on detecting, sensing and monitoring analytes in aqueous solution, but the number of studies on sensing gases and vapors using SiNW-based devices is increasing. This review gives an overview of selected research papers related to the application of electrical SiNW-based devices in the gas phase that have been reported over the past 10 years. Special attention is given to surface modification strategies and the sensing principles involved. In addition, future steps and technological challenges in this field are addressed.

Halitosis: From diagnosis to management

Halitosis is formed by volatile molecules which are caused because of pathological or nonpathological reasons and it originates from an oral or a non-oral source. It is very common in general population and nearly more than 50% of the general population have halitosis. Although halitosis has multifactorial origins, the source of 90% cases is oral cavity such as poor oral hygiene, periodontal disease, tongue coat, food impaction, unclean dentures, faulty restorations, oral carcinomas, and throat infections. Halitosis affects a person's daily life negatively, most of people who complain about halitosis refer to the clinic for treatment but in some of the people who can suffer from halitosis, there is no measurable halitosis. There are several methods to determine halitosis. Halitosis can be treated if its etiology can be detected rightly. The most important issue for treatment of halitosis is detection etiology or determination its source by detailed clinical examination. Management may include simple measures such as scaling and root planning, instructions for oral hygiene, tongue cleaning, and mouth rinsing. The aim of this review was to describe the etiological factors, prevalence data, diagnosis, and the therapeutic mechanical and chemical approaches related to halitosis.

FMO3 allelic variants in Sicilian and Sardinian populations: trimethylaminuria and absence of fish-like body odor

The N-oxygenation of amines by the human flavin-containing monooxygenase (form 3) (FMO3) represents an important means for the conversion of lipophilic nucleophilic heteroatom-containing compounds into more polar and readily excreted products. In healthy individuals, virtually all Trimethylamine (TMA) are metabolized to Trimethylamine N-oxide (TMAO). Several single nucleotide polymorphisms (SNPs) of the FMO3 gene have been described and result in an enzyme with decreased or abolished functional activity for TMA N-oxygenation thus leading to TMAU, or fish-like odor syndrome. Three coding region variants, c. G472A (p.E158K) in exon 4, c. G769A (p.V257M) in exon 6, and c.A923G (p.E308G) in exon 7, are common polymorphisms identified in all population examined so far and are associated with normal or slightly reduced TMA N-oxygenation activity. However, simultaneous occurrence of 158K and 308G variants results in a more pronounced decrease in FMO3 activity. A fourth polymorphism, c. G1424A (p.G475D) in exon 9, less common in the general population, was observed in individuals suffering severe or moderate trimethylaminuria. The aim of this study was to determine the allelic and genotypic distributions of these four FMO3 variants in 528 healthy individuals collected from the Sicilian and Sardinian populations together with haplotype and linkage analyses. Finally, we present data on the genotype-phenotype correlation by ESI-MS/MS TMA/TMAO urinary determination in 158KK/308EG individuals. Variant 158K shows the same frequency in Sicilian and Sardinian populations while variant 257M was not observed in the Sardinian sampling. No significant differences were found for 308G and 475D variants among two populations. Cis-linkage between 158K and 308G was confirmed with the compound variant (158K-308G) being found in a proportion of 0.9% and 0.3% of Sicilian subjects, and 0.01% and 0.5% in Sardinian population. Urinary determination of TMA/TMAO ratio in 158KK/308EG individuals showed a considerable reduction in FMO3 activity although they do not show the classical features of trimethylaminuria as a strong body odor and breath. Our data support the conclusion that trimethylaminuria is not always accompanied by a fish-like odor, despite the coexistence in the same individual of the two variants 158K and 308G, and other factors account for the expression of that phenotype.

Microbial volatile compounds in health and disease conditions

Microbial cultures and/or microbial associated diseases often have a characteristic smell. Volatile organic compounds (VOCs) are produced by all microorganisms as part of their normal metabolism. The types and classes of VOC produced is wide, including fatty acids and their derivatives (e.g. hydrocarbons, aliphatic alcohols and ketones), aromatic compounds, nitrogen containing compounds, and volatile sulfur compounds. A diversity of ecological niches exist in the human body which can support a polymicrobial community, with the exact VOC profile of a given anatomical site being dependent on that produced by both the host component and the microbial species present. The detection of VOCs is of interest to various disciplines, hence numerous analytical approaches have been developed to accurately characterize and measure VOCs in the laboratory, often from patient derived samples. Using these technological advancements it is evident that VOCs are indicative of both health and disease states. Many of these techniques are still largely confined to the research laboratory, but it is envisaged that in future bedside 'VOC profiling' will enable rapid characterization of microbial associated disease, providing vital information to healthcare practitioners.

Halitosis: the multidisciplinary approach

Halitosis, bad breath or oral malodour are all synonyms for the same pathology. Halitosis has a large social and economic impact. For the majority of patients suffering from bad breath, it causes embarrassment and affects their social communication and life. Moreover,halitosis can be indicative of underlying diseases. Only a limited number of scientific publications were presented in this field until 1995. Ever since, a large amount of research is published, often with lack of evidence. In general, intraoral conditions, like insufficient dental hygiene, periodontitis or tongue coating are considered to be the most important cause (85%) for halitosis. Therefore, dentists and periodontologists are the first-line professionals to be confronted with this problem. They should be well aware of the origin, the detection and especially of the treatment of this pathology. In addition, ear-nose-throat-associated (10%) or gastrointestinal/endocrinological (5%) disorders may contribute to the problem. In the case of halitophobia, psychiatrical or psychological problems may be present. Bad breath needs a multidisciplinary team approach: dentists, periodontologists, specialists in family medicine, ear-nose-throat surgeons, internal medicine and psychiatry need to be updated in this field, which still is surrounded by a large taboo.Multidisciplinary bad breath clinics offer the best environment to examine and treat this pathology that affects around 25% of the whole population. This article describes the origin, detection and treatment of halitosis, regarded from the different etiological origins.

Characterization of volatile organic compounds in human leukocyte antigen heterologous expression systems: a cell's "chemical odor fingerprint"

The major histocompatibility complex (MHC), or human leukocyte antigen (HLA) gene-coding region in humans, plays a significant role in infectious disease response, autoimmunity, and cellular recognition. This super locus is essential in mate selection and kin recognition because of the organism-specific odor which can be perceived by other individuals. However, how the unique MHC genetic combination of an organism correlates with generation of the organism-specific odor is not well understood. In the present work, we have shown that human B-cells produce a set of volatile organic compounds (VOCs) that can be measured by GC-MS. More importantly, our results show that specific HLA alleles are related to production of selected VOCs, and that this leads to a cell-specific odor "fingerprint". We used a C1R HLA class I A and B locus negative cell line, along with C1R cell lines that were stably transfected with specific A and B alleles. Our work demonstrates for the first time that HLA alleles can directly influence production of specific odor compounds at the cellular level. Given that the resulting odor fingerprint depends on expression of specific HLA sequences, it may yield information on unique human scent profiles, composition of exhaled breath, as well as immune response states in future studies.

Artificial noses

The mammalian olfactory system is able to detect many more odorants than the number of receptors it has by utilizing cross-reactive odorant receptors that generate unique response patterns for each odorant. Mimicking the mammalian system, artificial noses combine cross-reactive sensor arrays with pattern recognition algorithms to create robust odor-discrimination systems. The first artificial nose reported in 1982 utilized a tin-oxide sensor array. Since then, however, a wide range of sensor technologies have been developed and commercialized. This review highlights the most commonly employed sensor types in artificial noses: electrical, gravimetric, and optical sensors. The applications of nose systems are also reviewed, covering areas such as food and beverage quality control, chemical warfare agent detection, and medical diagnostics. A brief discussion of future trends for the technology is also provided.

Halitology (breath odour: aetiopathogenesis and management)

This article reviews the aetiopathogenesis of halitosis (oral malodour) and management. Halitosis is any disagreeable breath odour. In most patients, the odour originates from the oral cavity. In some patients, it has an extra-oral aetiology and, in a few, metabolic anomalies are responsible. In other patients complaining of malodour, this is imagined rather than real. Volatile sulphur compounds (VSCs) and other elements appear largely responsible for the malodour. Predisposing factors include poor oral hygiene, hyposalivation, dental appliances, gingival and periodontal disease and mucosal disease. The first step in assessment is objective measurement to determine whether malodour is present. If present, the oral or extra-oral origin should be determined, because the latter requires medical investigation and support in therapy, as is also the case where the malodour is imagined rather than real. Oral malodour is managed largely by oral health improvement, plus use of one or more of the wide range of antimalodour therapies, and sometimes also with use of a malodour counteractive. Emergent treatments include probiotics and vaccines targeted against causal micro-organisms or their products.

Fast analytical methodology based on mass spectrometry for the determination of volatile biomarkers in saliva

We report a methodology for the rapid determination of biomarkers in saliva. The method is based on direct coupling of a headspace sampler with a mass spectrometer. The saliva samples are subjected to the headspace generation process, and the volatiles generated are introduced directly into the mass spectrometer, thereby obtaining a fingerprint of the sample analyzed. The main advantage of the proposed methodology is that no prior chromatographic separation and no sample manipulation is required. The following model compounds were studied to check the possibilities of the methodology: methyl tert-butyl ether and styrene as biomarkers of exposure and dimethyl disulfide, limonene, and 2-ethyl-1-hexanol as biomarkers of diseases. The method was applied to the determination of biomarkers in 28 saliva samples: 24 of them were from healthy volunteers, and the others were from patients with different types of illness (including different types of cancer). Additionally, a separative analysis by GC/MS was performed for confirmatory purposes, and both methods provided similar results.

Individuals reporting idiopathic malodor production: demographics and incidence of trimethylaminuria

BACKGROUND

Individuals with the metabolic disorder trimethylaminuria may sporadically produce malodors despite good hygiene. The psychosocial impact of trimethylaminuria can be considerable. However, trimethylaminuria is difficult to diagnose without specialized tests, in part because odor production is diet-dependent, and malodors may not be present during medical examinations. Thus, the prevalence and demographics of trimethylaminuria remain unclear.

METHODS

We tested 353 patients who had unexplained (idiopathic) malodor production for trimethylaminuria using a standard choline challenge. We also collected basic demographic information.

RESULTS

Approximately one third of patients (118) tested positive for trimethylaminuria. Consistent with previous reports, women, particularly African American women, were significantly overrepresented among trimethylaminuria-positive patients. Of note, the same pattern was seen among trimethylaminuria-negative patients. Also consistent with previous reports, trimethylaminuria-positive women who were still menstruating tended to produce higher levels of trimethylamine within ± 7 days of menses, although this trend was statistically marginal (P = .07).

CONCLUSION

If our patient sample is representative of patients with idiopathic malodor, demographic information (race and gender) may not be useful in a differential diagnosis of trimethylaminuria. However, undiagnosed cases of trimethylaminuria may be fairly common among patients with idiopathic malodor. If so, choline challenge testing should be indicated for all such patients because trimethylaminuria is responsive to dietary and other treatments. We speculate that testing also might reveal cases of trimethylaminuria among those diagnosed with certain psychologic disorders, including olfactory reference syndrome.

Halitosis: could it be more than mere bad breath?

Halitosis is a generic term used to describe unpleasant odor emanating from the mouth air and breath, independent of the source where the odor substances originate. It affects between 50 and 65% of the population, but despite its frequency, this problem is often unaccepted and declared as taboo. Ninety percent of patients suffering from halitosis have oral causes: a small, but important percentage, of oral malodor cases have an extra-oral etiology, very often falling into the category of "blood-borne halitosis". Several systemic diseases have been found to provoke malodor or to be a cofactor; bad breath may be an early sign of a serious local or systemic condition. A psychogenic halitosis also exists including the variant "pseudo-halitosis", when the oral malodor does not exist, but the patient believes he or she is suffering severely from it, and the halitophobia, when, instead, there is an exaggerated fear of having halitosis. The aims of this paper are to review both oral and extra-oral causes of halitosis, especially those related to underlying systemic diseases, and to provide the primary care clinician a helpful means for its diagnosis and management. In fact, it is important to determine quickly whether the odor comes from an oral cause or not: if so, it requires referral to a dentist; if not (extra-oral origin alone or combined), its management requires the treatment of the underlying causes. Extra-oral disorders can be the cause in up to 15% of cases.

Recent advances in electronic and bioelectronic noses and their biomedical applications

Significant effort has been made in the development of an artificial nose system for various applications. Advances in sensor technology have facilitated the development of high-performance electronic and bioelectronic noses. Numerous articles describe the advantages of artificial nose systems for biomedical applications. Recent advances in the development of electronic and bioelectronic noses and their biomedical applications are reviewed in this article.

Exploring airway diseases by NMR-based metabonomics: a review of application to exhaled breath condensate

There is increasing evidence that biomarkers of exhaled gases or exhaled breath condensate (EBC) may help in detecting abnormalities in respiratory diseases mirroring increased, oxidative stress, airways inflammation and endothelial dysfunction. Beside the traditional techniques to investigate biomarker profiles, "omics" sciences have raised interest in the clinical field as potentially improving disease phenotyping. In particular, metabonomics appears to be an important tool to gain qualitative and quantitative information on low-molecular weight metabolites present in cells, tissues, and fluids. Here, we review the potential use of EBC as a suitable matrix for metabonomic studies using nuclear magnetic resonance (NMR) spectroscopy. By using this approach in airway diseases, it is now possible to separate specific EBC profiles, with implication in disease phenotyping and personalized therapy.

Breath biomarkers for personalized medicine

Personalized medicine, in the near future, has the potential to revolutionize healthcare by allowing physicians to individualize therapy for patients through the early diagnosis of disease and risk assessment to optimize clinical response with minimal toxicity. The identification of biomarkers could detect, diagnose and help guide therapy to improve survival and quality of life by the early identification of responders to the drugs. Volatile organic compounds and stable isotope-labeled 13CO2 in breath can be uniquely utilized as in vivo diagnostic biomarkers of disease and/or lack of enzyme activity to aid physicians to personalize medication. Noninvasive detection of ailments and monitoring therapy by human breath analysis is an emerging field of medical diagnostics representing a rapid, economic and simple alternative to standard invasive blood analysis, endoscopy or harmful imaging techniques such as x-ray and CT scans.

Olfaction in dentistry

Practitioners of oral medicine frequently encounter patients with complaints of taste disturbance. While some such complaints represent pathological processes specific to the gustatory system, per se, this is rarely the case. Unless taste-bud mediated qualities such as sweet, sour, bitter, salty, umami, chalky, or metallic are involved, 'taste' dysfunction inevitably reflects damage to the sense of smell. Such 'taste' sensations as chicken, chocolate, coffee, raspberry, steak sauce, pizza, and hamburger are dependent upon stimulation of the olfactory receptors via the nasopharynx during deglutition. In this paper, we briefly review the anatomy, physiology, and pathophysiology of the olfactory system, along with means for clinically assessing its function. The prevalence, etiology, and nature of olfactory disorders commonly encountered in the dental clinic are addressed, along with approaches to therapy and patient management.

Enantioselective in-line and off-line CE methods for the kinetic study on cimetidine and its chiral metabolites with reference to flavin-containing monooxygenase genetic isoforms

An in-line screening and an off-line chiral CE method were developed to determine the stereoselectivity of flavin-containing monooxygenase (FMO) isoforms using cimetidine (CIM) as a substrate. The S-oxygenation of CIM was investigated using achiral chemical oxidants and (human supersomes) enzymatic metabolism procedures. In the off-line setup, the chiral selector sulfobutylether-beta-CD was chosen to separate the CIM S-oxide (CSO) metabolites. The electrophoretic migration order of CSO was confirmed to be (+) before (-) through the use of single enantiomers obtained by preparative chromatography. For the electrophoretically mediated microanalysis method, the in-line enzymatic reaction was performed in 100 mM phosphate reaction buffer (pH 8.3), whereas 50 mM phosphate buffer with 30 mM chiral selector (pH 2.5) was used as a BGE. During the screening of FMO isoenzymes by the electrophoretically mediated microanalysis method, formation of the new chiral center on the CIM sulfur was found to be stereoselective. FMO1 produces more (-)-CSO-enantiomer, while FMO3 generates mainly (+)-CSO-enantiomer. On the other hand, FMO5 shows no activity. The kinetic constants of FMO1 and FMO3 were measured by the off-line method. A K(m)=4.31 mM for the formation of the (+)-CSO-enantiomer and a K(m)=4.56 mM for the (-)-CSO-enantiomer are reported for the first time for FMO1.

Volatile compounds characteristic of sinus-related bacteria and infected sinus mucus: analysis by solid-phase microextraction and gas chromatography-mass spectrometry

Volatile compounds from human breath are a potential source of information for disease diagnosis. Breath may include volatile organic compounds (VOCs) originating in the nasal sinuses. If the sinuses are infected, disease-specific volatiles may enter exhaled air. Sinus infections are commonly caused by several known bacteria. We examined the volatiles characteristic of infectious bacteria in culture using solid-phase microextraction to collect and gas chromatography-mass spectrometry as well as gas chromatography with flame photometric detection to separate and analyze the resulting VOCs. Infected sinus mucus samples were also collected and their VOCs examined. Similar characteristic volatiles were seen from both cultures of individual "pure" bacteria and several mucus samples. However, the relative amounts of characteristic VOCs from individual bacteria differ greatly between cultures and sinus mucus. New compounds, not seen in culture were also seen in some mucus samples. Our results suggest an important role for growth substrate and environment. Our data further suggests that in some sinus mucus samples identification of bacteria-specific volatiles is possible and can suggest the identity of an infecting organism to physicians. Knowledge of these bacteria-related volatiles is necessary to create electronic nose-based, volatile-specific sensors for non-invasive examination for suspected sinus infection.