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One century ago, the German chemist and botanist Wilhelm Pfeffer (1845–1920) died, shortly after finishing his last lecture at the University of Leipzig. Pfeffer was, together with Julius Sachs (1832–1897), the founder of modern plant physiology. In contrast to Sachs, Pfeffer’s work was exclusively based on the principles of physics and chemistry, so that with his publications, notably the ca. 1.600 pages-long Handbuch der Pflanzenphysiologie (2. ed., Vol. I/II; 1897/1904), experimental plant research was founded. Here we summarize Pfeffer’s life and work with special emphasis on his experiments on osmosis, plant growth in light vs. darkness, gravitropism, cell physiology, photosynthesis and leaf movements. We document that Pfeffer was the first to construct/establish constant temperature rooms (growth chambers) for seed plants. Moreover, he pioneered in outlining the carbon-cycle in the biosphere, and described the effect of carbon dioxide (CO2)-enhancement on assimilation and plant productivity. Wilhelm Pfeffer pointed out that, at ca. 0.03 vol% CO2 (in 1900), photosynthesis is sub-optimal. Accordingly, due to human activities, anthropogenic CO2 released into the atmosphere promotes plant growth and crop yield. We have reproduced Pfeffer’s classical experiments on the role of CO2 with respect to plant development, and document that exhaled air of a human (ca. 4 vol% CO2) strongly promotes growth. We conclude that Pfeffer not only acted as a key figure in the establishment of experimental plant physiology. He was also the discoverer of the phenomenon of CO2-mediated global greening and promotion of crop productivity, today known as the “CO2-fertilization-effect”. These topics are discussed with reference to climate change and the most recent findings in this area of applied plant research.

The prevalence of asthma is considerably high among women of childbearing age. Most asthmatic women also often have other atopic disorders. Therefore, the differentiation between patients with atopic diseases without asthma and asthmatics with coexisting diseases is essential to avoid underdiagnosis of asthma and to design strategies to reduce symptom severity and improve quality of life of patients. Hence, we aimed for the first time to conduct an analysis of volatile organic compounds in exhaled breath of women of childbearing age as a new approach to discriminate between asthmatics with other coexisting atopic diseases and non-asthmatics (with or without atopic diseases), which could be a helpful tool for more accurate asthma detection and monitoring using a noninvasive technique in the near future. In this study, exhaled air samples of 336 women (training set (n = 211) and validation set (n = 125)) were collected and analyzed by thermal desorption coupled with gas chromatography-mass spectrometry. ASCA (ANOVA (analysis of variance) simultaneous component analysis) and LASSO + LS (least absolute shrinkage and selection operator + logistic regression) were employed for data analysis. Fifteen statistically significant models (p-value

Introduction At present, there are few methods available for monitoring respiratory diseases affecting distal airways. Bronchoscopy is the golden standard for sampling the lower airways. The recently developed method for collecting non-volatile material from exhaled air – PExA (Particles in Exhaled air) is a promising new tool, but no direct comparison between the two methods has yet been performed. The aim of the present study was to compare sampling using PExA with bronchial wash (BW) representing the larger more proximal airways and broncho-alveolar lavage (BAL) representing the distal airways. Methods 15 healthy non-smoking subjects (7 female/8 male), age 28 ± 4 years, with normal lung function were included in the study. PExA-sampling (2 × 250 ng particles) and bronchoscopy with BW (2 × 20 ml) and BAL (3 × 60 ml sterile saline) was performed. Albumin and Surfactant Protein A (SP-A) were analyzed with ELISA, and analyses of correlation were performed. Results A significant association was found between BAL-fluid albumin and PExA-albumin (rs:0.65 p = 0.01). There was also an association between SP-A in PExA and BAL, when corrected for albumin concentration (rs:0.61, p = 0.015). When correlating concentrations of albumin and SP-A in bronchial wash and PExA respectively, no associations were found. Conclusions This is the first direct comparison between the bronchoscopy-based BW/BAL-fluids and material collected using the PExA methodology. Both albumin and albumin-corrected SP-A concentrations were significantly associated between BAL and PExA, however, no such association was found in either marker between BW and PExA. These results indicate that the PExA method samples the distal airways. PExA is thus considered a new promising non-invasive assessment for monitoring of the distal airways.

As a part of development of medicine for extreme situations, we determined, for the first time, the protein composition of the exhaled breath condensate (EBC) of cosmonauts before and after long-lasting orbital flights on the International Space Station (ISS). The analysis was performed by electrospray ionization ion cyclotron resonance mass spectrometry. The pattern of variation of the protein composition of the exhaled air during preflight preparation, at the time of landing, and seven days after landing was elucidated. Forty-four proteins, which appeared in the exhaled breath condensate of the cosmonauts after a long orbital flight and landing and were absent before the flight, were detected. These proteins included the immune response proteins, indicating cell and blood vessel damage. In some cases, a temporary appearance of cancer markers was noted.

Accurate diagnosis of different bronchopulmonary diseases is important in clinical practice. This study involved 20 healthy volunteers and 77 patients with bronchopulmonary diseases, including chronic obstructive pulmonary disease (COPD), bronchial asthma, pulmonary tuberculosis, and community-acquired pneumonia. The absorption spectrum of exhaled air samples was recorded on an intra-cavity photo-acoustic gas analyzer (ILPA-1, Special Technologies, Ltd., Russia) with photo-acoustic detectors and CO2 laser with a tuning range from 9.2 to 10.8 μm. In conclusion, analysis of the Mahalanobis distance-based absorption spectral profiles of breath air from bronchopulmonary patients and healthy volunteers allows the formulation of a preliminary diagnosis.

Early diagnosis of liver cirrhosis may prevent progression and development of complications. Liver biopsy is the current standard, but is invasive and associated with morbidity. We aimed to identify exhaled volatiles within a heterogeneous group of chronic liver disease (CLD) patients that discriminates those with compensated cirrhosis (CIR) from those without cirrhosis and compare this with serological markers. Breath samples were collected from 87 CLD and 34 CIR patients. Volatiles in exhaled air were measured by gas chromatography mass spectrometry. Discriminant Analysis was performed to identify the optimal panel of serological markers and VOCs for classifying our patients using a random training set of 27 CIR and 27 CLD patients. Two randomly selected independent internal validation sets and permutation test were used to validate the model. 5 serological markers were found to distinguish CIR and CLD patients with a sensitivity of 0.71 and specificity of 0.84. A set of 11 volatiles discriminated CIR from CLD patients with sensitivity of 0.83 and specificity of 0.87. Combining both did not further improve accuracy. A specific exhaled volatile profile can predict the presence of compensated cirrhosis among CLD patients with a higher accuracy than serological markers and can aid in reducing liver biopsies.

Detection of special disease markers in exhaled breath is a method becoming more and more relevant in medical diagnostic. The test environment plays a big role in the analysis of exhaled air when using ion mobility spectrometry (IMS). Environmental contaminants appear also in exhaled air of test persons, potentially even in other forms then in the ambient air. Different ways to deal with these environmental factors will be discussed and our method of choice will be presented. It was possible to identify specific fingerprints for dedicated features of probands as well as for specific environmental pollution. By using statistical evaluation it was also possible to identify characteristic features of probands notwithstanding the environmental burden for correct assignment into specific groups, reaching correct classification rates above 0.85.

Purpose A considerable amount of radioiodine is exhaled after radioiodine therapy leading to unwanted radiation exposure through inhalation. This study focused on the concentration of radioactivity exhaled and its chemical nature.

Helicobacter pylori diagnosis is fundamental in the management of gastrointestinal pathologies, whose current clinical guidelines support a non-invasive 'test-and-treat' strategy. As such, the present work reports the basis of a new, low-cost, specific breath test based on the detection of volatile carboxylic acids resulting from the hydrolysis of short-chain aliphatic amides by H. pylori amidases. Propionamide and butyramide, which are metabolized by amidases to propionic and butyric acids, were elected for this study. Conditions for the extraction of these acids from a vapour phase were optimized concerning the use of solid-phase microextraction (SPME) followed by gas chromatography-quadrupole mass spectrometry (GC-qMS) analysis. SPME-GC-qMS was then used to detect the acids released into a vapour phase upon incubation of a H. pylori reference strain J99 or a clinical specimen with the amides. These experiments have demonstrated that the administration of less than 9 mg of propionamide and/or butyramide to H. pylori cultures, in loads recognized to cause infection (10(6)-10(9) cells), resulted in the formation of detectable and/or quantifiable amounts of propionic and/or butyric acids after 30 min incubation. As such, propionic and butyric acids can be used as biomarkers for H. pylori upon incubation with the corresponding amides. SPME-GC-qMS was also used to verify the hepatic stability of the acids. These experiments were conducted in mouse liver cells and revealed no signs of metabolization that could compromise their bioavailability in future in vivo assays. Moreover, SPME-GC-qMS permitted the detection of both acids in amounts as low as 0.8 μg in systems mimicking exhaled breath, demonstrating the sensitivity of the method for these compounds.

Portovelo is one of the oldest gold mining towns in Ecuador. Artisanal gold mining still uses mercury in the process of gold recovery. In this study, mercury concentrations in the air of Portovelo were evaluated. High mercury levels in the ambient were found in El Pache sector, where most gold mining processing plants are located. These varied between 2,356.7 ± 1,807.6 and 3,699.5 ± 1,225.3 ng/m 3 during the rainy and dry seasons, respectively. Lower levels were detected in the urban (central) area of Portovelo, with 214.6 ± 43.7 ng/m 3 in the rainy season and 574.2 ± 72.8 ng/m 3 in the dry season, exceeding the Agency for Toxic Substances and Disease Registry minimum risk level of 200 ng/m 3 . Average mer- cury concentrations in exhaled air from miners, measured before and after amalgam burning ranged between 179-1,352 and 2,007-3,389 ng/m 3 , respectively. These data suggest Portovelo air is polluted with mercury and humans are being dangerously exposed. Therefore, strong actions must be undertaken to protect human and envi- ronmental health, including changing gold recovery systems.

In cystic fibrosis (CF) lung disease, exhaled nitric oxide (FeNO) is not raised, but rather is normal or even decreased when measured at a single expiratory flow. FeNO measurements at several flow rates allow differentiation between alveolar and bronchial nitric oxide (NO) production. Extended FeNO measurements therefore should be useful to localize the FeNO deficit in CF airways. FeNO was measured in stable CF adults with moderate lung disease and in healthy controls. Bronchial NO fluxes (J(NO,Br)) and alveolar NO concentrations (C(Alv)) were calculated from FeNO measurements at flow rates of 100, 150 and 200 ml/s using a method previously described. Thirty-two adults were included in the study, 12 of whom had CF. CF adults had significantly lower FeNO values at all flow rates. The median J(NO,Br) was significantly lower in CF adults than in healthy controls [0.31 nl/s (range = 0.11-0.63) vs. 0.70 nl/s (0.27-3.52); P < 0.001], while the median C(Alv) was similar in both groups [1.7 ppb (0.3-3.9) vs. 1.2 (0.1-5.2)]. Pulmonary NO exchange did not differ significantly between subgroups of CF patients with and without chronic Pseudomonas aeruginosa infection. No significant correlation was detectable between FEV(1)/VC and J(NO,Br) and C(Alv), respectively. Extended FeNO measurements can separate alveolar and bronchial NO outputs in CF adults. The lower FeNO in adults with moderate to severe CF lung disease is likely to be the result of lower bronchial NO output.

Exhaled air contains many volatile organic compounds (VOCs) produced during human metabolic processes, in both healthy and pathological conditions. Analysis of breath allows studying the modifications of the profile of the exhaled VOCs due to different disease states, including chronic obstructive pulmonary disease (COPD). The early diagnosis of COPD is complicated and the identification of specific metabolic profiles of exhaled air may provide useful indication to better identify the disease. The aim of our study was to characterize the specific exhaled VOCs by means of the electronic nose and by solid phase micro-extraction associated to gas chromatography–mass spectrometry (SPME GC-MS). Exhaled air was collected and measured in 34 subjects, 7 healthy and 27 former smokers affected by COPD (GOLD 1–4). The signals of the electronic nose sensors were higher in COPD patients with respect to controls, and allowed to accurately classify the studied subjects in healthy or COPD. GC-MS analysis identified 37 VOCs, nine of which were significantly correlated with COPD. In particular the concentration of two of these were positively correlated whereas seven were negatively correlated with COPD. The partial least squares discriminant analysis (PLS-DA) carried out with these nine VOCs produced a significant predictive model of disease. This study shows that COPD patients exhibit qualitative and quantitative differences in the chemical compositions of exhale. These differences are detectable both by the GC-MS and the six-sensor e-nose. The use of electronic nose may represent a suitable, non-invasive diagnostic tool for characterization of COPD.

The metabolic costs of flight at a natural range of speeds were investigated in Rose Coloured Starlings (Sturnus roseus, Linnaeus) using doubly labelled water. Eight birds flew repeatedly and unrestrained for bouts of 6 h at speeds from 9 to 14 m s-1 in a low-turbulence wind tunnel, corresponding to travel distances between 200 and 300 km, respectively. This represents the widest speed range where we could obtain voluntarily sustained flights. From a subset of these flights, data on the wing beat frequency (WBF) and intermittent flight behaviour were obtained. Over the range of speeds that were tested, flight costs did not change with velocity and were on an average 8.17±0.64 W or 114 W kg-1. Body mass was the only parameter with a significant (positive) effect on flight costs, which can be described as EEf=0.741 M 0.554. WBF changed slightly with speed, but correlated better with body mass. Birds showed both types of intermittent flight, undulating and bounding, but their frequencies did not systematically change with flight speed. [KEYWORDS: Endurance flight ; Power curve ; DLW ; Energy metabolism ; Wing beat frequency]

A new rapid technique is presented for determination of the dose of mercury inhaled; it is based on direct measurement of the concentration of mercury in exhaled air by use of a Zeeman mercury spectrometer RA-915+. It has been demonstrated experimentally that the dose received during short-term exposure to mercury vapor is determined more reliably by this method rather than by conventional techniques based on measurement of the mercury content in blood or urine.

Endogenously produced nitric oxide (NO) is detectable in the exhaled air of resting humans, and the amount of exhaled NO increases during exercise. It is believed that NO is likely to have an important role in the normal physiological response to exercise. Despite accumulating evidence of exhaled NO during exercise, the effects and relevance of NO to exercise are not yet completely understood. Scientific debate surrounds the site of NO production and the stimuli for production. Resolution of these controversial issues will explain the significance of exhaled NO during exercise.

In the presence of carbon dioxide absorbents, sevoflurane is degraded to CF2=C(CF3)OCH2F, an olefin compound A. There remains some concern of the hepatic and renal toxicity that compound A poses when using low-flow anaesthetic techniques. We investigated a device to decrease the concentration of compound A products by decreasing the temperature of exhaled air and soda lime in semi-closed low-flow anaesthesia technique in surgical patients. Ten patients, ASA 1 or 2, were studied. Five received anaesthesia using a cooling circuit, that consisting of an anaesthetic circuit and an intercooler device interposed in the expiratory tube. The intercooler was dipped in an iced water tank. Anaesthesia was given through this circuit from induction to emergence. Another five patients received anaesthesia without cooling. Anaesthesia was maintained with sevoflurane and O2 50%/N2O during four to six hours of operation. A fixed concentration of sevoflurane 2% at a total flow of 1 L·min−1 was administered. Gas samples were taken every hour and compound A was quantitated by gas chromatography. The temperatures of canister, circuit and body were measured every hour. The device effectively lowered the temperatures [24 ± 3.4 to 5 ± 1,3°C] and the concentrations of compound A [27.1 ± 3.8 ppm to 16.3 ± 2.08 ppm,P < 0.05] in the circuit. The body temperatures were not lowered. Compound A concentrations were reduced by cooling the anaesthetic circuit in clinical settings. En presence d’absorbants du gaz carbonique, le sevoflurane se degrade en CF2=C(CF3)OCH2F, un compose olefine A. Ce qui nous fait toujours craindre une certaine toxicite hepatique et renale possible lors de l’emploi de techniques anesthesiques a debit lent. Nous avons fait l’essai d’un dispositif qui diminuerait la concentration du compose A en abaissant la temperature de l’air expire et de la chaux sodee dans un circuit anesthesique semi-ferme a debit lent. Dix patients, ASA I ou II, ont ete etudies. Cinq d’entre eux ont recu une anesthesie avec l’emploi d’un appareil refroidisseur interpose sur le tube d’expiration du circuit d’anesthesie. Le refroidisseur etait plonge dans un reservoir d’eau glacee. L’anesthesie a ete administree par ce circuit depuis l’induction jusqu’au reveil. Les cinq autres patients ont recu une anesthesie sans refroidissement. Lanesthesie a ete maintenue avec du sevoflurane et un melange d’O2 et de N2O a 50 % pendant les quatre a six heures de l’intervention. Une concentration fixe de 2 % de sevoflurane a un debit total de 1 L·min−1 a ete administree. Des echantillons de sang ont ete preleves a chaque heure et le compose A a ete mesure par Chromatographie en phase gazeuse. Les temperatures de la chaux, du circuit et du corps ont ete mesurees a chaque heure. Le dispositif a efficacement reduit les temperatures [de 24 ± 3,4 a 5 ± 1,3°C] et les concentrations du compose A [de 27,1 ± 3,8 ppm a 16,3 ± 2,08 ppm,P < 0,05] dans le circuit. La temperature du corps n’a pas baisse. Les concentrations de compose A ont ete reduites par le refroidissement du circuit anesthesique en pratique clinique.

The pulmonary elimination after intraperitoneal administration at three different doses (50, 100, and 500 mg/kg) of methyl tertiary-butyl ether (MTBE) was studied using mice. There were two exponential curves with an initial rapid decrease of the elimination ratio followed by a slow decrease at the doses of 100 mg/kg and 500 mg/kg. The calculated half-lives of the two elimination curves obtained by the least squares method were approximately 45 min and 80 min. The pulmonary elimination ratios at the three different doses were from 23.2% to 69.0%. Most of the excreted MTBE was eliminated within 3 h. It is suggested in this paper that MTBE in exhaled air can be used as a biological exposure index for the exposure assessment of MTBE.

Background The 13C-urea breath test (UBT) is performed in adults and children with epigastric pain for non-invasively diagnosing a suspected H. pylori infection. Criteria for UBT interpretation have not been generally agreed on and test reliability has not been established in children of different ages. This study aimed at identifying reliable UBT thresholds in children by using 251 UBTs in conjunction with reference histology and by analyzing 1232 UBTs. Methods At baseline and 30 and 60 minutes after the administration of 75 mg 13C-urea to children and adolescents (0.25 to 18 years of age), the differences (Δ) of 13CO2/12CO2 ratio in exhaled air (δ) were determined by mass spectrometry. UBT Δδ value thresholds were calculated in random subgroups and evaluated in complementary subgroups using logistic regressions on reference histology or bimodal distribution analyses of Δδ values from UBTs alone. Results Δδ values were higher (median, 15.4‰) in positive (133/251, 53 %) than in negative histology (2.4‰). At 30 minutes, the calculated cut-off was 5.3‰ (mean regression determination R2 = 0.91), and sensitivity (0.95), specificity (0.97), positive (0.97) and negative predictive values (0.95) were higher than at 60 minutes (threshold 6.8‰, R2 = 0.85). Similar thresholds resulted from UBTs analysis (5.8‰ and 6.2‰) when sensitivity and specificity were maximized (concordance probabilities, 0.99 and 0.99). There was no systematic age effect. Conclusions In children, 13C UBT cut-offs were obtained and specially validated, entailing high accuracy of non-invasively testing for gastric H. pylori infection.

A relationship between the oxygen metabolism of circulating neutrophils and the intensity of lipid peroxidation in exhaled air condensate was studied in chronic bronchitis, ischemic heart disease, and in their combination. An increase in the functional reserve of neutrophils caused by ischemic heart disease promotes the realization of the bio-oxidant potential of these cells in the bronchoalveolar system and intensifies local processes of lipid peroxidation.

The content of products of lipid peroxidation and antioxidative activity were measured in exhaled air condensate and blood sera of patients with chronic bronchitis. Exacerbation of purulent bronchitis was found to be associated with an increase of heptane-soluble products of lipid peroxidation in serum and condensate, which was not observed in patients with catarrhal bronchitis. In catarrhal bronchitis, the content of heptane-soluble products is increased only in the serum; antioxidative activity increased in exhaled air condensate in catarrhal bronchitis and decreased in serum and condensate in purulent bronchitis.

Shared Beds Increase Potential for Rebreathing Exhaled Air in Sleep Microenvironments Used by Infants at High Risk for SIDS ♦ 1956

A gas chromatographic method for simultaneous determination of trichloroethylene (TRI), trichloroethanol (TCE) and trichloroacetic acid (TCA) in blood and TRI, TCE in exhaled air is described. The determination in blood is based on the relative volatility of TRI, TCE and TCA methylester, which offers the possibility of headspace analysis. The gaschromatograph is equipped with an electron capture detector.

Four male volunteers inhaled for 4 h 70 and 140 ppm trichloroethylene (TRI) at rest and also at rest combined with exercise. To estimate the amount retained in the body (dose), minute volume and concentration in exhaled air were determined. Concentrations of TRI, trichloroethanol (TCE) and trichloroacetic acid (TCA) were determined in blood. Exhaled air was analysed for TRI and TCE; urine for TCE and TCA.

We have developed a noninvasive test of gastric acid secretion for use in infants and young children. It is based on the reaction of ingested magnesium metal with gastric acid to produce hydrogen gas, which is excreted in exhaled air and belches. This test was compared to the standard intubation test by performing both, on different days, in 20 children (5-37 months of age) without known gastric disease. The results of the two tests compared well: correlation coefficients were 0.78, 0.75, or 0.72 when exhaled air was collected for a total of 56, 81, or 31 min, respectively. Because the test is noninvasive, it should be more acceptable to children and their parents than the intubation test and thus could be used to conduct studies which are currently impractical.

The results of single exposure studies with exposure to trichloroethylene, TRI, (Monster et al., 1976), to 1,1,1-trichloroethane, MC, (Monster et al., 1979b) and to tetrachloroethylene, PERC, (Monster et al., 1979c) were used to study the precision in estimating the individual uptake from measured biological parameters after exposure. With simple linear and multiple linear regression analysis the individual uptake of TRI, MC and PERC was estimated from the concentrations of solvents and metabolites in biological media (blood, urine, exhaled air) at 2 h and at 20 h after exposure. The best results are obtained by estimation from the concentrations in blood, particularly of the solvents themselves. Including results of simultaneously measured concentrations in exhaled air or urine did not improve the estimate.

Exhaled air was analyzed for tetrachloroethene (PER) in teachers and 4-5-year-old pupils of a kindergarten situated near a factory, and in residents of an old folks ' home situated near a former chemical waste dump. The PER concentrations were higher in the exhaled air of children living near the factory (mean 24 micrograms/m3, n = 6) than in control children (mean 2.8 micrograms/m3, n = 11). In the old folks ' home, the PER concentrations in the exhaled air of people living on the first floor were higher (mean 7.8 micrograms/m3, n = 10) than in the exhaled air of the people living on the second floor and higher (mean 1.8 micrograms/m3, n = 19). From the results of this study, it is clear that in environmental exposure to tetrachloroethene, biological monitoring of exhaled air is a simple, efficient, effective and convenient method of assessing total ambient exposure of both young and aged subjects.

Five male volunteers inhaled 70 ppm trichloroethylene (TRI) for 4 h on 5 consecutive days. TRI, trichloroethanol (TCE) and trichloroacetic acid (TCA) were measured, as far as present in exhaled air, blood, and urine. The uptake was 6.6 ± 0.4 mg/kg lean body mass in 4 h. The concentration of TRI in blood and exhaled air at 18 h after the 5th exposure was twice as high as at 18 h after the 1st exposure. The amount of TCE excreted per 24 h reached a level during the last exposure days, a diurnal rythm was evident. TCA in blood and urine increased during exposure days. Total recovery of the amount absorbed of TRI was 78%, 11% as TRI excreted unchanged by the lung, 43% as WE and 24% as TCA excreted in urine. Amounts of WE and TCE+TCA excreted in urine were related to lean body mass. Because of its small interindividual variation TCA in blood seems to be the most promising parameter for biological monitoring in repeated exposure.

By using a continuous infra-red monitoring technique, it could be shown that in 42 patients undergoing TEP surgery methylmethacrylate is excreted through the lungs. The amount of monomer eliminated in the exhaled air is less following acetabulum implantation than following femoral shaft implantation. The concentration of monomer in the exhaled air is strongly influenced by measures such as femoral shaft drainage, washing the implantation site with icewater and lengthening the cement mixing time which reduce the transfer of the monomer. Pulmonary elimination of MMA-monomer takes 20 min and is very fast.

A special purpose analog computer which automatically plots the alveolar ventilation-alveolar PCo 2 response curve is described. The two inputs to the computer are a differential strain-gauge manometer output voltage which is proportional to the expiratory air flow in the rebreathing system and an infra-red carbon dioxide gas analyser output voltage corresponding to the carbon dioxide concentration in exhaled air. During each respiratory cycle, voltages representing the end-expiratory (alveolar) carbon dioxide and alveolar ventilation for the preceding cycle are fed to the X- and Y-axes respectively of an X-Y plotter. A typical response curve before and after 10 mg morphine is shown.

1)Indoor concentration is less than outdoor concentration when precautions are taken to prevent indoor contamination of the air; 2) Nuclei are not produced by breathing. The nucleus content of exhaled air is less than that of the inhaled air; the loss appears to be mainly a diffusion loss; 3) Occupancy does not produce any detectable change in nucleus content; 4) A hypothesis is advanced to explain how occupancy might cause a slight decrease in small ion content without causing any increase in nucleus content.

Nach Behandlung mit Endoxan last sich bei Ratten ein fluchtiges Alkylans in der Ausatmungsluft nachweisen. Dieses wird auch nach Gaben von NH-Lost von den Tieren abgeatmet und konnte als N-2-Chlorathyl-aziridin identifiziert werden. Die ausgeatmeten Mengen betragen nach Endoxan-Gabe innerhalb von 8 Std etwa 1 Mol-% und sind dosisabhangig. Die Abgabe uber die Zeit verlauft mehr protrahiert als nach Gaben von NH-Lost, und insgesamt wird ein Mehrfaches abgeatmet, wenn man von den NH-Lost-Anteilen ausgeht, die nicht in der Bindung an unverandertes Endoxan bzw. seine Metabolite mit Harn und Faeces ausgeschieden werden. Die Abatmung des Alkylans wird als ein Entgiftungsmechanismus angesprochen, aus dessen Kenntnis sich weitere Einblicke in die komplizierten Verhaltnisse des Wirkungsmechanismus und der Pharmakodynamik des Endoxans gewinnen lassen.

Mit einer einfachen und empfindlichen Methode wurde Ammoniak in der Ausatmungsluft von Gesunden und Kranken gemessen. Die Meswerte streuen erheblich, bei Gesunden ±62%. Bei Patienten kann aus dem Atemammoiak weder auf den Blutammoniak zuruckgeschlossen werden, noch lassen sich bei uramischen Zustanden differentialdiagnostisch zuverlassige Hinweise erhalten.

DURING the past 25 years, six independent groups of workers have measured the decrease in concentration of particles in exhaled air during steady breathing, while their subjects inhaled various aerosols, and have expressed their findings as a relationship between particle size and lung deposition. These results fall into two ranges, three of the groups of workers obtaining much higher values for deposition than the other three for particles between 0.5 and 6µ diameter. The difference cannot be explained by the nature of the particles or the method of breathing1.

IN a recent communication, Davies and Muir1 pointed out that the experimental results from six independent studies of the retention of particles in the human respiratory system fall into two groups, the results of one group indicating higher values for the deposition than the other. They have attempted to explain this difference by suggesting that in two of these investigations2,3 errors were introduced by the experimental method, whereby the exhaled air was sampled continuously, including during the inhalation period. They said that there was an inaccuracy because the last part of the exhaled air, which had penetrated deeper into the lungs, contained fewer particles than the average. This may be so, but Davies and Muir give a false estimate of the magnitude of the error and do not account for the difference between the two groups of results.

THERE has long been a need for a rapid method for the quantitative determination of acetone in the blood and in the exhaled breath of the patient with diabetes mellitus. Since these concentrations are a direct reflexion of the diabetic state, precise acetone measurements would provide the physician with more accurate data with which to evaluate his diabetic patient. To be clinically practical, this analytical method should be specific, sensitive and rapid. An extension of an infra-red method previously reported1 provides the basis for this preliminary report on the analysis of actone in blood and in the expired air.