ABSTRACT
INTRODUCTION: The Northern Ontario School of Medicine University seeks to address rural physician shortages in Northern Ontario. One key strategy the school employs is the use of experiential learning placements embedded throughout its undergraduate curriculum. In second year, students embark on two 4-week placements in rural and remote communities. This study sought to explore the factors that contribute to a positive learning experience from the preceptor's perspective. METHODS: Semi-structured interviews were conducted with five community preceptors who have participated in these placements. Using the information from these interviews a survey was created and sent to another 15 preceptors. Data were analyzed using qualitative methods and frequencies. RESULTS: Three key themes were identified from both the interviews and survey data: the role of early rural and remote placements; the risks of these placements; and the need for a reciprocal relationship between institutions, preceptors, and students to create a positive learning environment. CONCLUSION: Preceptors value the opportunity to teach students, but the aims of these placements are not clear and preceptors and local hospitals need more workforce resources to make these experiences positive.
Subject(s)
Preceptorship , Rural Health Services , Humans , Preceptorship/organization & administration , Rural Health Services/organization & administration , Ontario , Interviews as Topic , Education, Medical, Undergraduate/organization & administration , Students, Medical/psychology , Students, Medical/statistics & numerical data , Medically Underserved AreaABSTRACT
Introduction: Rural communities have poorer health compared to urban populations due partly to having lesser healthcare access. Rural placements during medical education can equip students with the knowledge and skills to work in rural communities, and, it is hoped, increase the supply of rural physicians. It is unclear how students gain knowledge of rural generalism during placements, and how this can be understood in terms of place-based and/or sociocultural educational theories. To gain insight into these questions we considered the experiences of pre-clerkship medical students who completed two mandatory four-week rural placements during their second year of medical school. Methods: Data was collected using semi-structured interviews or focus groups, followed by thematic analysis of the interview transcripts. Results: Rural placements allowed students to learn about rural generalism such as breadth of practice, and boundary issues. This occurred mainly by students interacting with rural physician faculty, with the effectiveness of precepting being key to students acquiring knowledge and skills and reporting a positive regard for the placement experience. Discussion: Our data show the central role of generalist physician preceptors in how and what students learn while participating in rural placements. Sociocultural learning theory best explains student learning, while place-based education theory helps inform the curriculum. Effective training and preparation of preceptors is likely key to positive student placement experiences.
Introduction: Les communautés rurales sont en moins bonne santé que les populations urbaines, en partie parce qu'elles ont moins accès aux soins de santé. Les stages de médecine en milieu rural peuvent permettre aux étudiants d'acquérir les connaissances et les compétences nécessaires pour travailler dans les communautés rurales et, on l'espère, augmenter le nombre de médecins y travaillent. On ne sait pas clairement comment les étudiants acquièrent des connaissances sur le généralisme rural au cours de leurs stages, et comment cela peut être compris en termes de théories éducatives socioculturelles et/ou basées sur le lieu de travail. Pour répondre à ces questions, nous avons étudié les expériences d'étudiants en médecine au pré-clinique qui ont effectué deux stages obligatoires de quatre semaines en milieu rural au cours de leur deuxième année d'études de médecine. Méthodes: Les données ont été recueillies au moyen d'entrevues semi-structurées ou de groupes de discussion, suivis d'une analyse thématique des transcriptions des entrevues. Résultats: Les stages en milieu rural ont permis aux étudiants de se familiariser avec le généralisme rural, notamment l'étendue de la pratique et les questions de limites. L'efficacité du préceptorat est essentielle pour que les étudiants acquièrent des connaissances et des compétences et qu'ils aient une expérience de stage positive. Discussion: Nos données témoignent du rôle central que jouent les médecins généralistes précepteurs quant au contenu et modes d'apprentissage des étudiants lorsqu'ils participent à des stages en milieu rural. La théorie de l'apprentissage socioculturel est celle qui explique le mieux l'apprentissage des étudiants, tandis que la théorie de la formation fondée sur le lieu contribue à orienter le programme d'études. Une formation et préparation efficace des précepteurs est probablement la clé d'une expérience de stage positive pour les étudiants.
Subject(s)
Students, Medical , Humans , Students, Medical/psychology , Students, Medical/statistics & numerical data , Rural Health Services , Preceptorship , Rural Population , Focus Groups , Education, Medical, Undergraduate/methods , General Practice/education , Female , Interviews as Topic , Male , LearningABSTRACT
Background: Students are selected for admission to the Northern Ontario School of Medicine University (NOSM U) MD degree program using criteria aiming to maximize access of persons thought most likely to practice in the region, including use of a geographic context score (GCS) which ranks those with lived experience in northern Ontario and/or rurality most highly. This study investigates the effect of this admissions process upon medical school academic performance. Methods: We used a retrospective cohort design combined with multiple linear regression analysis to investigate the relationship between admission scores and performance on pre-clerkship courses, and the Medical Council of Canada Qualifying Exam Part 1 (MCCQE1).The GCS did not significantly explain performance variance on any pre-clerkship course, nor on the MCCQE1, while the undergraduate Grade Point Average correlated with most assessment scores. The number of prior undergraduate biomedical courses predicted science and clinical skills performance, particularly in Year 1, but not with MCCQE1 scores. Performance on Year 2 courses, particularly foundational sciences and clinical skills, significantly predicted MCCQE1 scores. Results: Our data suggest that admission geographic context scoring is unrelated to future academic performance. Further, students with fewer prior undergraduate biomedical courses may benefit from increased support and/or a modified program during the early years.
Contexte: La sélection étudiants à l'École de médecine du Nord de l'Ontario est fondée sur des critères visant à faciliter l'admission de candidats qu'on estime susceptibles de pratiquer dans la région. Un de ces critères est le score de contexte géographique (SCG) qui classe au premier rang les personnes ayant déjà vécu dans le Nord de l'Ontario ou en milieu rural. Cette étude examine l'effet de ce processus d'admission sur les résultats académiques des étudiants en médecine. Méthodes: Nous avons utilisé un modèle de cohorte rétrospective et une analyse par régression linéaire multiple pour étudier la relation entre les scores d'admission et les résultats obtenus aux cours avant l'externat et à l'examen d'aptitude du Conseil médical du Canada (EACMC), partie 1.Le SCG n'explique pas de manière significative la variance des résultats dans les cours pré-cliniques, ni à l'EACMC1, tandis que la moyenne pondérée cumulative au premier cycle est en corrélation avec la plupart des scores d'évaluation. Le nombre de cours en sciences biomédicales suivis dans un programme de premier cycle ont permis de prédire les résultats en sciences et en compétences cliniques, en particulier en première année, mais pas les résultats à l'EACMC1. Les résultats aux cours de deuxième année, en particulier de sciences fondamentales et de compétences cliniques, ont permis de prédire de manière significative les résultats à l'EACMC1. Résultats: Nos données portent à croire que le score de contexte géographique au moment de l'admission est sans lien avec les résultats académiques subséquents. En outre, les étudiants ayant suivi moins de cours en sciences biomédicales au premier cycle pourraient bénéficier d'un soutien plus important ou d'un programme adapté au cours des premières années.
Subject(s)
Academic Performance , School Admission Criteria , Humans , Retrospective Studies , Schools, Medical , OntarioABSTRACT
BACKGROUND: Medical education can help alleviate the chronic undersupply of physicians to rural communities. Providing students with early rural clinical experiences may allow the gaining of necessary knowledge and skills to practice and live rurally, as well as the desire to do so. PURPOSE: This study aims to provide a detailed understanding of Remote and Rural Community Placements (RRCPs) which occur in the second year of a Doctor of Medicine programme. METHODOLOGY/APPROACH: Using a thematic analysis approach, we examined the experiences of students and preceptors in the RRCP. Data were collected using semi-structured interviews and focus groups. FINDINGS/CONCLUSIONS: Students valued RRCPs as a formative clinical experience and preceptors gained professionally from participating. The RRCPs enhanced students regard for, and knowledge of, rural medicine. Yet, contrary to the stated aims of the placement, students spent very little time in activities outside of the clinic, neither learning about the community nor about the life of a physician as a community member. IMPLICATIONS: Medical educators should recognise that students and preceptors will inevitably place different value on the different sociocultural and perceptual aspects of placements, namely clinical and non-clinical. As such, the curriculum should draw clearly articulated links between each.
ABSTRACT
Schizophrenia is a serious mental illness of unclear aetiology. The reduced ability of methylnicotinate to induce a topical vasodilatory response in patients with the disorder is well established. Methylnicotinate causes vasodilation via stimulating the release of prostaglandins (including prostaglandin D2) in the skin which in turn leads to relaxation of vascular smooth muscle. To determine whether the abnormality is likely to be due to decreased prostaglandin production, or a decreased effect of prostaglandins upon the vessels, topical methylnicotinate was applied to the forearms of patients with schizophrenia or healthy controls, followed by rating of the resulting erythema. The concentration of prostaglandin D2 and its metabolite 11ß-prostaglandin F2α in the blood draining the arm was also measured. Although erythema was reduced in the patient group, this was not correlated with plasma prostaglandin concentrations. This data suggests the abnormality underlying the reduced potency of methylnicotinate to produce vasodilation in the disorder occurs downstream of prostaglandin synthesis possibly within the vasculature itself.
Subject(s)
Nicotinic Acids/pharmacology , Prostaglandin D2/blood , Schizophrenia/metabolism , Vasodilator Agents/pharmacology , Adult , Case-Control Studies , Female , Humans , Male , Middle Aged , Schizophrenia/blood , Skin/drug effectsABSTRACT
Breath analysis is a form of metabolomics that utilises the identification and quantification of volatile chemicals to provide information about physiological or pathological processes occurring within the body. An inherent assumption of such analyses is that the concentration of the exhaled gases correlates with the concentration of the same gas in the tissue of interest. In this study we have investigated this assumption by quantifying some volatile compounds in peripheral venous blood headspace, and in nasal breath collected in Tedlar bags obtained at the same time from 30 healthy volunteers, prior to analysis by selected ion flow tube mass spectrometry. Some endogenous compounds were significantly correlated between blood headspace and nasal breath, such as isoprene (r p = 0.63) and acetone (r p = 0.68), however many, such as propanol (r p = -0.26) and methanol (r p = 0.23), were not. Furthermore, the relative concentrations of volatiles in blood and breath varied markedly between compounds, with some, such as isoprene and acetone, having similar concentrations in each, while others, such as acetic acid, ammonia and methanol, being significantly more abundant in breath, and others, such as methanal, being detectable only in breath. We also observed that breath propanol and acetic acid concentrations were higher in male compared to female participants, and that the blood headspace methanol concentration was negatively correlated to body mass index. No relationship between volatile concentrations and age was observed. Our data suggest that breath concentrations of volatiles do not necessarily give information about the same compound in the blood stream. This is likely due to the upper airway contributing compounds over and above that originating in the circulation. An investigation of the relationship between breath volatile concentrations and that in the tissue(s) of interest should therefore become a routine part of the development process of breath-based biomarkers.
Subject(s)
Breath Tests/methods , Exhalation , Nose/chemistry , Volatile Organic Compounds/blood , Adult , Biomarkers/analysis , Body Fluids/chemistry , Body Height , Body Mass Index , Body Weight , Female , Humans , Male , Mass Spectrometry/methods , Middle Aged , Young AdultABSTRACT
A large body of evidence suggests that dietary supplementation with omega-3 fatty acids may ameliorate depressed mood. The magnitude of the effect varies between studies, however, ranging from none at all to being of clinical significance. Given that substantial comorbidity occurs between mood and anxiety disorders, suggesting that they have one or more pathophysiological mechanisms in common, we hypothesized that omega-3 fatty acids may be acting primarily to reduce anxiety rather than depression per se, a possibility which could underlie their variable effects on mood. To test this hypothesis rats were fed for 8 weeks with diets containing one of three types of omega-3 fatty acids, alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid, as well as a low omega-3 fatty acid control diet. Although brain omega-3 fatty acid concentrations were altered by dietary supplementation with eicospentaenoic acid and docosahexaenoic acid, no significant change in anxiety related behaviors were observed compared to the control group as assessed by the elevated-plus maze test. Our data therefore do not support an anxiolytic effect of omega-3 fatty acids and suggest that any effect of these lipids on mood likely occurs by a mechanism unrelated to reducing anxiety.
Subject(s)
Anxiety/diet therapy , Docosahexaenoic Acids/administration & dosage , Eicosapentaenoic Acid/administration & dosage , alpha-Linolenic Acid/administration & dosage , Animals , Brain Chemistry , Dietary Supplements , Disease Models, Animal , Fatty Acids/analysis , Fatty Acids, Omega-3/administration & dosage , Male , Rats , Treatment OutcomeABSTRACT
The quantification of trace compounds in alcoholic beverages is a useful means to both investigate the chemical basis of beverage flavor and to facilitate quality control during the production process. One compound of interest is methanol which, due to it being toxic, must not exceed regulatory limits. The analysis of headspace gases is a desirable means to do this since it does not require direct sampling of the liquid material. One established means to conduct headspace analysis is selected ion flow tube mass spectrometry (SIFT-MS). The high concentration of ethanol present in the headspace of alcoholic drinks complicates the analysis, however, via reacting with the precursor ions central to this technique. We therefore investigated whether methanol could be quantified in the presence of a large excess of ethanol using SIFT-MS. We found that methanol reacted with ionized ethanol to generate product ions that could be used to quantify methanol concentrations and used this technique to quantify methanol in beverages containing different quantities of ethanol. We conclude that SIFT-MS can be used to quantify trace compounds in alcoholic beverages by determining the relevant reaction chemistry.
Subject(s)
Acetaldehyde/analysis , Alcoholic Beverages/analysis , Food Analysis/methods , Food Contamination/analysis , Methanol/analysis , Spectrometry, Mass, Electrospray Ionization/methods , Acetaldehyde/chemistry , Complex Mixtures/analysis , Complex Mixtures/chemistry , Methanol/chemistry , Reproducibility of Results , Sensitivity and Specificity , Specimen Handling/methodsABSTRACT
Reactive oxygen species react with unsaturated fatty acids to form a variety of metabolites including aldehydes. Many aldehydes are volatile enough to be detected in headspace gases of blood or cultured cells and in exhaled breath, in particular propanal and hexanal which are derived from omega-3 and omega-6 polyunsaturated fatty acids, respectively. Aldehydes are therefore potential non-invasive biomarkers of oxidative stress and of various diseases in which oxidative stress is thought to play a role including cancer, cardiovascular disease and diabetes. It is unclear, however, how changes in the abundance of the fatty acid precursors, for example by altered dietary intake, affect aldehyde concentrations. We therefore fed male Wistar rats diets supplemented with either palm oil or a combination of palm oil plus an n-3 fatty acid (alpha-linolenic, eicosapentaenoic, or docosahexaenoic acids) for 4 weeks. Fatty acid analysis revealed large changes in the abundance of both n-3 and n-6 fatty acids in the liver with smaller changes observed in the brain. Despite the altered fatty acid abundance, headspace concentrations of C1-C8 aldehydes, and tissue concentrations of thiobarbituric acid reactive substances, did not differ between the 4 dietary groups. Our data suggest that tissue aldehyde concentrations are independent of fatty acid abundance, and further support their use as volatile biomarkers of oxidative stress.
Subject(s)
Aldehydes/metabolism , Brain/metabolism , Fatty Acids, Omega-3/administration & dosage , Liver/metabolism , Plant Oils/administration & dosage , Aldehydes/isolation & purification , Animals , Dietary Supplements , Lipid Metabolism/drug effects , Male , Oxidative Stress/drug effects , Palm Oil , Rats , Reactive Oxygen Species/metabolism , Triglycerides/metabolismABSTRACT
Demethylation of industrial lignin has been for long coveted as a pathway to the production of an abundant natural substitute for fossil-oil derived phenol. In an attempt to possibly identify a novel Kraft lignin-demethylating enzyme, we surveyed a collection of fungi by using selected ion flow tube-mass spectrometry (SIFT-MS). This method readily identifies methanol resulting from lignin demethylation activity. Absidia cylindrospora, and unidentified Cylindrocladium sp. and Aspergillus sp. were shown to metabolize lignin via different pathways, based on the HPLC analysis of lignin fragments. Of these three, Cylindrocladium and Aspergillus were shown to retain most of the lignin intact after 3 weeks in culture, while removing about 40% of the available methoxy groups. Our results demonstrate that after optimization of culture and lignin recovery methods, biological modification of Kraft lignin may be a feasible pathway to obtaining demethylated lignin for further industrial use.
Subject(s)
Fungal Proteins/metabolism , Fungi/metabolism , Lignin/metabolism , Mass Spectrometry/methods , Chromatography, High Pressure Liquid , Methanol/analysis , Methylation , Mycology/methods , Species Specificity , UltrafiltrationABSTRACT
Ethane in human breath derives from lipid peroxidation, specifically the reaction between omega-3 fatty acids and reactive oxygen species. It has been proposed to be a non-invasive marker of oxidative stress, a deleterious process which may play an important role in the pathophysiology of several common diseases. It is unclear, however, whether ethane concentration actually correlates with systemic oxidative stress or whether it is primarily a marker of airway biochemistry. To investigate this possibility the breath ethane concentrations in 24 healthy volunteers were compared to that of a systemic measure of oxidative stress, plasma hydroperoxides, as well as to blood concentrations of the lipophilic anti-oxidant vitamin E, and the abundance of omega-3 fatty acids. Breath ethane concentrations were significantly (p < 0.05) positively correlated with blood hydroperoxide concentrations (rp = 0.60) and negatively with that of vitamin E (rp = -0.65), but were not correlated with either the total omega-3 fatty acid concentration (rp = -0.22) or that of any individual species of this fatty acid class. This data supports the hypothesis that breath ethane is a marker of systemic lipid peroxidation, as opposed to that of omega-3 fatty acid abundance.
ABSTRACT
Basil (Ocimum basilicum) is an important flavourant plant which constitutes the major ingredient of the pasta sauce 'Pesto alla Genovese'. The characteristic smell of basil stems mainly from a handful of terpenoids (methyl cinnamate, eucalyptol, linalool and estragole), the concentration of which varies according to basil cultivars. The simple and rapid analysis of the terpenoid constituents of basil would be useful as a means to optimise harvesting times and to act as a quality control process for basil-containing foodstuffs. Classical analytical techniques such as gas chromatography/mass spectrometry (GC/MS) are, however, slow, technically demanding and therefore less suitable for routine analysis. A new chemical ionisation technique which allows real-time quantification of traces gases, Selected Ion Flow Tube Mass Spectrometry (SIFT-MS), was therefore utilised to determine its usefulness for the assay of terpenoid concentrations in basil and pesto sauce headspace. Trace gas analysis was performed using the NO(+) precursor ion which minimised interference from other compounds. Character-impacting compound concentration was measured in basil headspace with good reproducibility and statistically significant differences were observed between cultivars. Quantification of linalool in pesto sauce headspace proved more difficult due to the presence of interfering compounds. This was resolved by careful selection of reaction product ions which allowed us to detect differences between various commercial brands of pesto. We conclude that SIFT-MS may be a valid tool for the fast and reproducible analysis of flavourant terpenoids in basil and basil-derived foodstuffs.
Subject(s)
Mass Spectrometry/methods , Ocimum basilicum/chemistry , Terpenes/analysis , Food Analysis , Gases/chemistry , Ocimum basilicum/classification , Plant Extracts/chemistry , Plant Leaves/chemistry , Reproducibility of ResultsABSTRACT
Orthognathic surgery is frequently accompanied by intermaxillary fixation. Intermaxillary fixation impedes the maintenance of effective oral hygiene and prolonged fixation can result in periodontal disease. A potential shorter term effect is the generation of oral malodour. It is unclear, however, as to how the production of malodorous compounds in the oral cavity is altered post-surgery. Oral air concentration of sulphur containing compounds, short chain organic acids, ammonia, isoprene and acetone were measured using selected ion flow tube-mass spectrometry in a patient who had undergone orthognathic surgery with subsequent intermaxillary fixation. Total sulphide levels rose approximately 5-fold during fixation with metal ties, with smaller increases recorded for the other compounds measured with the exception of isoprene which remained close to baseline levels. Organic acid levels declined markedly once elastic ties had replaced metal ties, with a lesser reduction being observed in sulphide levels, with both declining further after the commencement of a chlorhexidine-containing mouthwash. These data suggest that bacterial generation of a variety of malodorous compounds increases markedly following intermaxillary fixation. This single case also suggests that the use of elastic ties and effective oral hygiene techniques, including the use of chlorhexidine mouthwash, may help ameliorate such post-surgical effects.
Subject(s)
Halitosis/etiology , Jaw Fixation Techniques/adverse effects , Sulfides/analysis , Adult , Anti-Infective Agents, Local/therapeutic use , Breath Tests , Chlorhexidine/therapeutic use , Halitosis/drug therapy , Humans , Jaw Fixation Techniques/instrumentation , Male , Mandibular Advancement , Metals/adverse effects , Mouthwashes/therapeutic use , Orthognathic Surgical Procedures , Spectrometry, Mass, Secondary IonABSTRACT
The reactions of H(3) O(+) , NO(+) and O 2+ with twelve terpenoids and one terpene, all of which occur naturally in plants and which possess important smell and flavourant properties, were characterized using Selected Ion Flow Tube Mass Spectrometry (SIFT-MS). The H(3) O(+) reactions resulted primarily in the formation of the proton transfer product and occasionally in a water elimination product. The NO(+) reactions instead generated the charge transfer product or NO(+) adducts, and occasionally alkyl fragments, or resulted in hydride abstraction. Reaction with O 2+ caused a higher fragmentation of the terpenoids with the molecular ion being the minor product of most reactions. Identification and quantification of each compound in complex mixtures are probably possible in most cases using the H(3) O(+) and/or NO(+) precursors while O 2+ may be useful for isomer discrimination. Our data suggests that SIFT-MS may be a useful tool for the rapid analysis of these compounds in plants and derived foodstuffs.
Subject(s)
Mass Spectrometry/methods , Nitric Oxide/chemistry , Onium Compounds/chemistry , Oxygen/chemistry , Terpenes/chemistry , Cymenes , Mass Spectrometry/instrumentation , Monoterpenes/chemistryABSTRACT
Oxidative stress has been reported to be elevated in mental illness. Preliminary evidence suggests this phenomenon can be assessed non-invasively by determining breath levels of the omega-3 polyunsaturated fatty acid (PUFA) oxidation product ethane. This study compares alkane levels in chronic, medicated, patients with schizophrenia or bipolar disorder with those in healthy controls. Both ethane and butane levels were significantly increased in patients with schizophrenia or bipolar disorder, although elevated butane levels were likely due to increased ambient gas concentrations. Ethane levels were not correlated with symptom severity or with erythrocyte omega-3 PUFA levels. Our results support the hypothesis that oxidative stress is elevated in patients with schizophrenia and bipolar disorder leading to increased breath ethane abundance. This does not appear to be caused by increased abundance of omega-3 PUFA, but rather is likely due to enhanced oxidative damage of these lipids. As such, breath hydrocarbon analysis may represent a simple, non-invasive means to monitor the metabolic processes occurring in these disorders.
Subject(s)
Bipolar Disorder/metabolism , Butanes/analysis , Ethane/analysis , Fatty Acids, Omega-3/blood , Schizophrenia/metabolism , Bipolar Disorder/drug therapy , Breath Tests , Erythrocytes/chemistry , Erythrocytes/metabolism , Fatty Acids, Omega-3/chemistry , Fatty Acids, Omega-3/metabolism , Female , Humans , Male , Oxidation-Reduction , Oxidative Stress , Psychiatric Status Rating Scales , Schizophrenia/drug therapyABSTRACT
BACKGROUND AND AIMS: Breath diagnostics, the measurement of volatile chemicals in human breath, is currently receiving attention as a technique for the detection of disease which, being non-invasive in nature, is particularly suited to screening for pre-symptomatic disease in healthy populations. A disorder in which more effective screening would be beneficial is celiac disease (CD), an under-diagnosed autoimmune disease of the small intestine characterized by nutritional malabsorption, which presents with diverse, and sometimes serious, symptoms. We aimed to determine whether breath analyses could be used to screen for the presence of CD. METHODS: Based on our hypotheses that malabsorption of dietary carbohydrates would lead to over production of alcohol fermentation products in the large intestine, we investigated levels of alcohols in the breath of 10 patients with CD compared to that in 10 healthy controls using selected ion flow tube mass spectrometry (SIFT-MS). RESULTS: No differences were found in the breath levels of methanol, propanol, butanol, heptanol or hexanol investigated using chemical ionization of breath air with H3O+ and/or NO+ precursor ions. In one patient, diagnosed within days of our study and not currently in receipt of any therapeutic intervention, a relatively high production of three product ions was detected compared to all other study patients. CONCLUSION: Our data suggest that breath alcohol levels are unlikely to be of diagnostic use in CD, although further investigation of those recently diagnosed with the disorder may be warranted.
Subject(s)
Breath Tests , Celiac Disease/diagnosis , Exhalation , Mass Spectrometry , Adult , Aged , Alcohols/metabolism , Case-Control Studies , Celiac Disease/metabolism , Celiac Disease/physiopathology , Dietary Carbohydrates/metabolism , Female , Fermentation , Humans , Intestine, Large/metabolism , Male , Middle Aged , Pilot Projects , Predictive Value of Tests , VolatilizationABSTRACT
The reactions of H(3)O(+), NO(+), and O(2) (+) with nineteen ester compounds occurring naturally in plants, and having important flavourant properties, were examined using selected ion flow tube mass spectrometry (SIFT-MS). The H(3)O(+) reactions primarily generate [R(1)COOR(2).H](+), and may also produce [R(2)](+) fragment ions and/or fragmentation within the ester linkage. Collisional association/adduct ions, [R(1)COOR(2).NO](+), are the main products formed in the NO(+) reactions, although the carboxyl fragment ion is also detected frequently. The identification of the parent compound may be made more easily in the H(3)O(+) and NO(+) reactions. The inclusion of O(2) (+) reactions in the analysis provides additional information, which may be applied when the identity of a parent compound cannot be determined solely from the H(3)O(+) and NO(+) analysis. Consideration of the product ions generated with the three precursors suggests that SIFT-MS can differentiate between many of the esters investigated, including isomers, although the product ions generated in the reactions with some esters are too similar to allow independent quantification. Our data therefore suggest that SIFT-MS may be a useful tool to rapidly analyse and quantify flavourant esters in complex gas mixtures.
Subject(s)
Esters/chemistry , Mass Spectrometry/methods , Nitrogen Oxides/chemistry , Onium Compounds/chemistry , Oxygen/chemistry , Gases/chemistry , Kinetics , Molecular Weight , Volatile Organic Compounds/chemistryABSTRACT
Polyamines are a class of aliphatic compounds which include putrescine, cadaverine, spermine and spermidine. They are involved in a variety of cellular processes and have been implicated in a number of different pathophysiological mechanisms. Polyamines are volatile compounds having a distinctive odour normally perceived as being unpleasant. The measurement of their abundance has, however, been restricted to compounds present in the aqueous phase. Using selected ion flow tube mass spectrometry (SIFT-MS) we have shown that the polyamines react with the ions H3O+, NO+ and O2+ to form distinctive product ions allowing their levels to be quantified in the vapour phase. The low volatility of spermine did not allow extensive analysis of this compound by SIFT-MS while the adherent properties of cadaverine and putrescine required the use of PTFE transfer lines and couplers. Our data suggested the presence of cadaverine and putrescine in both oral air and the headspace of putrefying bovine muscle, while product ions corresponding to putrescine and spermidine were found in the headspace of human semen. SIFT-MS therefore appears to be a practical means of measuring vapour-phase polyamine levels, having applications in biology, medicine and dentistry, and food science.
Subject(s)
Mass Spectrometry/methods , Mouth/chemistry , Polyamines/chemistry , Animals , Breath Tests , Cattle , Humans , Male , Mass Spectrometry/instrumentation , Muscles/chemistry , Muscles/metabolism , Polyamines/metabolism , Semen/chemistry , VolatilizationABSTRACT
Anxiety disorders are a common group of psychiatric illnesses which have significant personal, family and societal costs. Current treatments have limited efficacy in many patients highlighting a need for new therapeutic approaches to be explored. Anxiety disorders exhibit marked comorbity with mood disorders suggesting the existence of mechanistic similarities. Such a notion is supported by observations that some conventional pharmacotherapies are both effective antidepressants and anxiolytics. As such, given that omega-3 PUFA supplementation may be effective in the treatment of major depressive disorder it is reasonable to propose that they may also possess anxiolytic properties. Experimental data in support of such a hypothesis is currently lacking although reduced abundance of omega-3 PUFA have been reported in patients with anxiety, while supplementation with omega-3 PUFA appears to inhibit activation of the HPA axis and can ameliorate some of the symptoms of anxiety. Clinical investigations carried out to date have, however, involved small numbers of participants. Larger trials using a variety of omega-3 PUFA species in clinically well-defined patients with anxiety will be required to demonstrate a therapeutic role for omega-3 PUFA in these disorders. Given the excellent side effect profile of omega-3 PUFA as well as their strong theoretical rationale, such future trials appear justified.