Obstructive Sleep Apnea: a risk for uncontrolled and more severe asthma in adults that we should keep an eye on.

Summary: Background. Asthma control can be influenced by several factors, including obstructive sleep apnea (OSA). The literature reports variable prevalence and magnitude of OSA impact on asthma outcomes. The aim of our study is to analyze the frequency of high-risk for OSA in asthma patients and its impact on disease severity and control. Methods. We conducted a cross-sectional study at an Allergy Department with adult asthma patients recruited while undergoing routine lung function tests. Data on sex, age, body mass index, allergen sensitization, smoking habits, risk of OSA (using the Berlin questionnaire), rhinitis control (through CARAT), asthma severity (based on GINA 2023), asthma control (using the ACT), adherence to asthma treatment (through Treatment Adherence Measure) and pulmonary function test results were collected. Results. We included 216 patients, predominantly women (70.4%), with a median (P25-P75) age of 29.0 (21.0-45.0) years, of whom 28.2% were on GINA treatment levels 4-5. In 75.5% of cases asthma was controlled. High-risk for OSA was identified in 21.8% of patients. Asthma patients with high-risk for OSA were more likely to have uncontrolled [(47.8%; n = 22) vs (15.8%; n = 26); p less than 0.001] and more severe disease [(44.7%; n = 21) vs (23.7%; n = 40), p = 0.006]. In multivariable analysis, high-risk for OSA (OR 2.81 [95%CI 1.1.28-6.17], p = 0.010), sex (women) (OR 5.21 [95% CI 1.70-15.96], p = 0.004), uncontrolled rhinitis (OR 3.65 [95%CI 1.38-9.64], p = 0.009) and GINA asthma treatment steps 4-5 (OR 2.46 [95%CI 1.15-5.26], p = 0.020) were associated with uncontrolled asthma. Conclusions. It is crucial to actively investigate OSA, especially in patients with uncontrolled and more severe forms of asthma.

All-Microwave Leakage Reduction Units for Quantum Error Correction with Superconducting Transmon Qubits.

Minimizing leakage from computational states is a challenge when using many-level systems like superconducting quantum circuits as qubits. We realize and extend the quantum-hardware-efficient, all-microwave leakage reduction unit (LRU) for transmons in a circuit QED architecture proposed by Battistel et al. This LRU effectively reduces leakage in the second- and third-excited transmon states with up to 99% efficacy in 220 ns, with minimum impact on the qubit subspace. As a first application in the context of quantum error correction, we show how multiple simultaneous LRUs can reduce the error detection rate and suppress leakage buildup within 1% in data and ancilla qubits over 50 cycles of a weight-2 stabilizer measurement.

Dynamics of Nanosecond Laser Pulse Propagation and of Associated Instabilities in a Magnetized Underdense Plasma.

The propagation and energy coupling of intense laser beams in plasmas are critical issues in inertial confinement fusion. Applying magnetic fields to such a setup has been shown to enhance fuel confinement and heating. Here we report on experimental measurements demonstrating improved transmission and increased smoothing of a high-power laser beam propagating in a magnetized underdense plasma. We also measure enhanced backscattering, which our kinetic simulations show is due to magnetic confinement of hot electrons, thus leading to reduced target preheating.

Aggregation patterns of curcumin and piperine mixtures in different polar media.

This work reports a thorough molecular dynamics investigation on the aggregation patterns of curcumin and piperine in water, ethanol and a mixture of both solvents. The low solubility of curcumin in water results in a rapid formation of very stable dimers for both keto and enol tautomers. In agreement with a higher solubility, piperine molecules move closer and farther apart several times during the simulation, which indicates the formation of a less stable dimer in water. In contrast, both curcumin and piperine are soluble in ethanol and, thus, dimers can hardly be formed in this media. In comparison with a pure-water solvent, a 30 : 70 mixture of ethanol and water significantly reduces the probability of formation of most dimers of curcumin and piperine molecules. The simulations show that larger clusters may be complex structures, but the formation of stacks (in the case of piperine and enol tautomer of curcumin) and cages (when the keto tautomer of curcumin is involved) are not rare. Furthermore, it is shown that each single molecule presents a certain degree of mobility in the cluster, especially on the surface, but without leading to dissociation.

The effect of progesterone concentrations during superovulation of Holstein heifers in a randomized trial.

The aim of this study was to evaluate the effect of different progesterone (P4) concentrations during the follicular growth on the intensity of estrous expression, ovarian response to the superovulatory treatment, and embryo production and quality in superovulated heifers. A total of 63 Holstein heifers were randomly assigned into 2 experimental groups: Low P4 (n = 31) and High P4 (n = 32). Animals received a pre-synchronization protocol followed by a protocol of superovulation that included the allocated P4 treatment. Activity was monitored continuously by an automated activity monitor, and estrus characteristics (maximum intensity and duration) were recorded. Embryo collection was performed 7 d post artificial insemination (AI). Embryos were counted and graded from good or excellent (1) to degenerated (4). The outcomes of interest were: number and diameter of follicles at the time of AI, ovulation success (confirmed 7 d post-AI), time to estrus event, maximum intensity and duration of estrus, number and quality of embryos. Data were analyzed according to the type of outcome variable using logistic, linear, or Poisson regression models. A total of 105 embryos (High P4: n = 42; Low P4: n = 63) were graded for quality. Different P4 levels did not affect the maximum intensity (High P4 = 497.8 ± 23.9%; Low P4 = 542.2 ± 23.5%) or the duration (High P4 = 13.5 ± 1.5 h; Low P4 = 14.3 ± 1.4 h) of estrus. Heifers in the High P4 treatment had greater number of follicles at time of AI (High P4 = 16.6 ± 1.6 follicles; Low P4 = 13.9 ± 1.2 follicles), but with smaller diameter (High P4 = 11.3 ± 0.1 mm; Low P4 = 12.0 ± 0.1 mm) compared with Low P4. High P4 heifers tended to have better embryo quality compared with Low P4 heifers (odds ratio = 1.98; 95% CI = 0.90-4.35). High P4 heifers had less embryos than Low P4 heifers, but this was modified by the CIDR (intravaginal implant of P4) removal to estrus interval (interval 0-21 h: mean ratio = 1.15, 95% CI = 0.42-1.87; interval 22-46 h: mean ratio = 0.58, 95% CI = 0.27-0.96). Although estrous expression was not associated with embryo quality, as the duration and the maximum intensity of estrous expression increased, the number of embryos recovered 7 d post-AI increased (duration: mean ratio = 1.04; 95% CI = 1.03-1.05; maximum intensity: mean ratio = 1.50; 95% CI = 1.42-1.58). In conclusion, P4 during the follicular growth, and intensity of estrus, are playing a role in regulating the quality and the number of embryos produced by superovulated heifers. This study was supported by contributions from Resilient Dairy Genome Project and the Natural Sciences and Engineering Research Council.

Impacts of Covid-19 interventions on air quality: evidence from Brazilian metropolitan regions.

The Covid-19 pandemic has negatively disrupted the way our economy and society functions. Nonetheless, there have also been some positive externalities of the pandemic on the environment. This paper aims to evaluate the concentration of nitrogen dioxide in Brazilian metropolitan regions after the policies adopted to confront Covid-19. In terms of methodological approach, the study employs cross-sectional quantitative analyses to compare the period of 36 days, i.e., 12 March to 16 April-before (in 2019) and after (in 2020) the pandemic declaration. The data were obtained from the Sentinel 5-P low-Earth polar satellite concerning Brazilian metropolitan regions (n = 24). Thorough spatial and statistical analyses were undertaken to identify the pre- and during pandemic nitrogen dioxide concentrations. Complementarily, Spearman's correlation test was performed with variables that impact air quality. The study results a fall in nitrogen dioxide concentration levels in 21 of the 24 metropolitan regions which was observed. The Spearman's correlation coefficient between the nitrogen dioxide variation and the vehicle density was 0.485, at a significance level of 0.05. With these findings in mind, the paper advocates that while the pandemic has a significant negative consequence on the health of population globally, a series of measures that result in a new social organization directly interfere in the reduction of air pollution that contributes to the quality of the air we breathe.

Occurrence and greater intensity of estrus in recipient lactating dairy cows improve pregnancy per embryo transfer.

The aim of this study was to determine the association between occurrence and intensity of estrous expression with pregnancy success in recipient lactating dairy cows subjected to embryo transfer (ET). Two observational studies were conducted. Holstein cows were synchronized using the same timed ET protocol, based on estradiol and progesterone in both experiments. At 9 d after the end of the timed ET protocol only animals that had ovulated were implanted with a 7-d embryo [experiment 1 (Exp. 1); n = 1,401 ET events from 1,045 cows, and experiment 2 (Exp. 2); n = 1,147 ET events from 657 cows]. Embryos were produced in vivo (Exp. 1 and Exp. 2) and in vitro (only Exp. 2), then transferred to recipient cows as fresh or frozen-thawed. Pregnancy was confirmed at 29 and 58 d after the end of timed ET protocol. In Exp. 1, animals had their estrous expression monitored through a tail chalk applied on the tail head of the cows and evaluated daily for chalk removal (no estrus: 100% of chalk remaining; estrus: <50% of chalk remaining). In Exp. 2, cows were continuously monitored by a leg-mounted automated activity monitor. Estrous expression was quantified using the relative increase in physical activity at estrus in relation to the days before estrus. Estrous expression was classified as no estrus [<100% relative increase in activity (RI)], weak intensity (100-299% RI), and strong intensity (≥300% RI). Data were analyzed by analysis of variance using mixed linear regression models (GLIMMIX) in SAS (SAS Institute Inc.). A total of 65.2% (914/1,401) and 89.2% (1,019/1,142) of cows from Exp. 1 and Exp. 2, respectively, displayed estrus at the end of the ovulation synchronization protocol. In Exp. 1, cows expressing estrus before to ET had greater pregnancy per ET than those that did not [41.0 ± 2.3% (381/914) vs. 31.5 ± 2.9% (151/487), respectively]. Similarly, in Exp. 2, cows classified in the strong intensity group had greater pregnancy per ET compared with cows in the weak intensity and no estrus groups [41.3 ± 2.2% (213/571) vs. 32.7 ± 2.7% (115/353) vs. 11.3 ± 3.5% (26/218), respectively]. There was no effect of ET type on pregnancy per ET in Exp. 1. However, in Exp. 2, cows that received an in vivo-produced embryo, either fresh or frozen, had greater pregnancy per ET compared with cows that received in vitro-produced embryo. Cows receiving embryos in the early blastocyst and blastocyst stage had greater fertility compared with cows receiving embryos in the morula stage. There was an interaction between the occurrence of estrus and the stage of embryo development on pregnancy per ET, cows which displayed estrus and received a morula or early blastocyst had greater pregnancy per ET than cows that did not display estrus. In conclusion, the occurrence and the intensity of estrous expression improved pregnancy per ET in recipient lactating dairy cows and thus could be used as a tool to assist in the decision making of reproduction strategies in dairy farms.

High-Fidelity Controlled-Z Gate with Maximal Intermediate Leakage Operating at the Speed Limit in a Superconducting Quantum Processor.

Simple tuneup of fast two-qubit gates is essential for the scaling of quantum processors. We introduce the sudden variant (SNZ) of the net zero scheme realizing controlled-Z (CZ) gates by flux control of transmon frequency. SNZ CZ gates realized in a multitransmon processor operate at the speed limit of transverse coupling between computational and noncomputational states by maximizing intermediate leakage. Beyond speed, the key advantage of SNZ is tuneup simplicity, owing to the regular structure of conditional phase and leakage as a function of two control parameters. SNZ is compatible with scalable schemes for quantum error correction and adaptable to generalized conditional-phase gates useful in intermediate-scale applications.

Modeling microsolvation clusters with electronic-structure calculations guided by analytical potentials and predictive machine learning techniques.

We propose a new methodology to study, at the density functional theory (DFT) level, the clusters resulting from the microsolvation of alkali-metal ions with rare-gas atoms. The workflow begins with a global optimization search to generate a pool of low-energy minimum structures for different cluster sizes. This is achieved by employing an analytical potential energy surface (PES) and an evolutionary algorithm (EA). The next main stage of the methodology is devoted to establish an adequate DFT approach to treat the microsolvation system, through a systematic benchmark study involving several combinations of functionals and basis sets, in order to characterize the global minimum structures of the smaller clusters. In the next stage, we apply machine learning (ML) classification algorithms to predict how the low-energy minima of the analytical PES map to the DFT ones. An early and accurate detection of likely DFT local minima is extremely important to guide the choice of the most promising low-energy minima of large clusters to be re-optimized at the DFT level of theory. In this work, the methodology was applied to the Li+Krn (n = 2-14 and 16) microsolvation clusters for which the most competitive DFT approach was found to be the B3LYP-D3/aug-pcseg-1. Additionally, the ML classifier was able to accurately predict most of the solutions to be re-optimized at the DFT level of theory, thereby greatly enhancing the efficiency of the process and allowing its applicability to larger clusters.

Aggregation of coronene: the effect of carboxyl and amine functional groups.

The aggregation of coronene is relevant to understand the formation of carbon nanomaterials, including graphene quantum dots (GQDs) that show exceptional photophysical properties. This article evaluates the influence of carboxyl and amine substituting groups on the aggregation of coronene by performing a global optimization study based on a new potential energy surface. The structures of clusters with substituted coronene are similar to those formed by un-substituted monomers, that is, stacked (non-stacked) motifs are favoured for small-size (large-size) clusters. Nonetheless, the presence of carboxyl and amine groups leads to an increase of the number of local minima of comparable energy. The clusters with substituted monomers have also shown to enhance the attractive component interaction, which can be attributed to weak induction and charge transfer effects and to stronger electrostatic contributions. Moreover, the calculated height of magic-number structures of the clusters in this work is compatible with the morphology of the GQDs reported in the literature.

Factors Associated With Asthma Control in 121 Preschool Children.

BACKGROUND AND OBJECTIVES: Data on risk factors for uncontrolled asthma in preschool children are controversial. Objective: This study aims to explore the association between clinical and functional parameters and the lack of asthma control in preschool children. METHODS: Children aged 3-5 years with asthma and healthy controls were recruited. A questionnaire was used to identify potential risk factors for uncontrolled asthma, as defined by the Global INitiative for Asthma criteria. Lung function and bronchial reversibility were evaluated through impulse oscillometry and spirometry. Adjusted odds ratios were estimated based on multivariable generalized additive regression models. The discriminative ability of the models was measured by the area under the receiver operating characteristic curve (AUC). RESULTS: The study population comprised 121 children (107 with asthma and 14 healthy controls). Fifty-three patients (50%) had uncontrolled asthma. After adjustment, the variables associated with an increased risk of lack of control were as follows: "More than 3 flare-ups in the last 12 months", "Moderate to severe rhinitis", and "Relative variation in postbronchodilator FVC and FEV1". The AUC of the final models that included variation in FVC or FEV1 were 0.82 and 0.81, respectively. The R5-20, R5-20%, and AX z-score values of the healthy group were lower than those of children with asthma. CONCLUSION: In preschool children, clinical and functional parameters are associated with uncontrolled asthma. More studies are needed to confirm the usefulness of impulse oscillometry.

Lead acetate ecotoxicity in tropical soils.

Lead acetate (AcPb) is an important raw material used in chemical industries worldwide. The potential toxicity of AcPb is generally attributed to the presence of Pb. However, the effect of AcPb on the environment as a whole is still poorly known. This study aimed to evaluate AcPb toxicity on three standard species of soil invertebrates and two plant species using ecotoxicology tests. Three tropical soils (Oxisol, Inceptisol, and Tropical Artificial Soil (TAS)) were contaminated with different concentrations of AcPb and one dose of K-acetate (positive control). These soils were used in tests with Eisenia andrei (earthworm), Folsomia candida (springtail), Enchytraeus crypticus (enchytraeid), Zea mays (maize), and Phaseolus vulgaris (common bean). Dose-response curves obtained in the laboratory tests were used to estimate the EC50 values for each species. Among invertebrates, the highest sensitivity to AcPb was observed for E. crypticus in the TAS (EC50 = 29.8 mg AcPb kg-1), whereas for E. andrei and F. candida the highest sensitivity was observed in the Oxisol (EC50 = 141.9 and 1835 mg AcPb kg-1, respectively). Folsomia candida was the least sensitive invertebrate species to AcPb in all soils. Among plant species, Z. mays was less sensitive (EC50 = 1527.5 mg AcPb kg-1) than P. vulgaris (EC50 = 560.5 mg AcPb kg-1) in the Oxisol. The present study evidenced that the toxicity of AcPb should not be attributed uniquely to the presence of Pb, as the treatment containing uniquely Ac provoked the same toxicity as the highest dose of AcPb.

Cross-cultural validation of the Portuguese from Portugal version of the Test for Respiratory and Asthma Control in Kids (TRACK) questionnaire.

SUMMARY: Introduction. The Test for Respiratory and Asthma Control in Kids (TRACK) is a tool to assess asthma control in preschool children. This study aims to validate the Portuguese from Portugal version of the TRACK questionnaire. Methods. A prospective cohort study was carried out to assess their psychometric characteristics. Caregivers of 141 children under age 5 with asthma symptoms were enrolled. Results. Internal reliability was close to 0.70 (Cronbach's α). The test-retest reliability was 0.87. TRACK scores were different between well, partially, and non-controlled asthma groups (p less than 0.001). Patients rated as having better control showed an increase in TRACK scores. Conclusions. The Portuguese version of the TRACK questionnaire is accurate and reliable for monitoring asthma control. Its use may help to overcome challenges with the management of this age group.

Laser-Plasma Interaction Experiment for Solar Burst Studies.

A new experimental platform based on laser-plasma interaction is proposed to explore the fundamental processes of wave coupling at the origin of interplanetary radio emissions. It is applied to the study of electromagnetic (EM) emission at twice the plasma frequency (2ω_{p}) observed during solar bursts and thought to result from the coalescence of two Langmuir waves (LWs). In the interplanetary medium, the first LW is excited by electron beams, while the second is generated by electrostatic decay of Langmuir waves. In the present experiment, instead of an electron beam, an energetic laser propagating through a plasma excites the primary LW, with characteristics close to those at near-Earth orbit. The EM radiation at 2ω_{p} is observed at different angles. Its intensity, spectral evolution, and polarization confirm the LW-coalescence scenario.

A thermodynamic view on the microsolvation of ions by rare gas: application to Li+ with argon.

We present a thermodynamic perspective of the microsolvation of ions by rare gas atoms, which is based on parallel tempering Monte Carlo (PTMC) simulations. This allows the establishment of a clear relationship between the structure of the solvation shells and the heat capacity (CV) as a function of the number of individual solvent species. The dependence of CV on the temperature allows the identification of the internal structure rearrangements and the onset of partial or total melting of the clusters. As an application, we have employed the PTMC technique to study the thermodynamic properties of clusters resulting from the microsolvation of Li+ by argon atoms. Specifically, calculations have been carried out for the clusters Li+Arn (n = 4-18, 33, 34, and 38) by applying two different potential energy surfaces (PESs): one includes only two-body interactions, while the other also incorporates three-body contributions. Whenever possible, we compare the present thermodynamic results with global optimization studies carried out previously (F. V. Prudente, J. M. C. Marques and F. B. Pereira, Phys. Chem. Chem. Phys., 2017, 19, 25707; W. S. Jesus et al., Int. J. Quantum Chem., 2019, 119, e25860). We conclude that the melting process arises for lower temperatures when the model PES accounts for three-body interactions. Additionally, we characterize the melting processes of the first and second solvation shells. For some specific clusters, structural rearrangements of the most external argon atoms are observed at very low temperatures.

Blood or skin: what is best in predicting cow's milk allergy diagnosis?

Summary: Cut-off values for both skin prick tests (SPT) and specific IgE (sIgE) levels for predicting cow´s milk allergy (CMA) diagnosis are not universally defined. This study is a retrospective analysis of consecutive children (0-18 years-old) with suspected CMA tested with SPT and sIgE for cow's milk (CM) and its fractions between 2016-2017. CMA diagnosis was defined by a positive oral food challenge or a highly suggestive clinical history of CMA and SPT and/or sIgE positive to CM and/or its fractions. One hundred and five patients were included, 58% males with a median age of 2.5 (P25-P75:1-6) years and the diagnosis was confirmed in 83 patients (79%). The variables associated with CMA diagnosis were SPT with CM (p minor 0,05) and casein (p minor 0,05) and all sIgE to CM and its fractions (alfa Lactalbumin, beta Lactoglobulin and casein; p minor 0,05 for all). Optimal cut39 off points (Youden's index) for CMA diagnosis were, for the mean wheal diameter, to CM milk of 4.5mm and to casein of 3mm. For sIgE levels the optimal cut-off points were: for CM of 4.36 kUA/L, alfa-lactalbumin of 1.6 kUA/L, beta-lactoglobulin of 1.7 kUA/L and for casein of 2.6 kUA/L. The role of SPT and sIgE levels to cow´s mlik and its fractions is unequivocal in CMA follow-up. Moreover, sIgE levels seem to be more discriminatory than SPT.

Asthma and COPD "overlap": a treatable trait or common several treatable-traits?

Summary: In the last years, disease classification of chronic respiratory diseases (CRD) has been vivaciously discussed and new concepts have been introduced, namely asthma-chronic obstructive pulmonary disease (COPD) overlap (ACO). Controversially the GOLD consensus document of 2020 considered that we should no longer refer to ACO, as they constitute two different diseases that may share some common traits and clinical features. The treatable traits approach has numerous strengths that are applicable to several levels of health care. In this paper we review the application of the treatable traits to CRD and describe in detail the ones already identified in patients with asthma and COPD. Treatable traits in CRD can be divided in pulmonary, extra-pulmonary and behavior/lifestyle risk factors. Patients with both asthma and COPD patients have clearly recognized treatable traits in all these subtopics but it is notorious the severe and frequent exacerbations, the associated cardiovascular disease and the low health related quality of life and productivity of these patients.

Aggregation enhancement of coronene molecules by seeding with alkali-metal ions.

Microsolvation constitutes the first step in the formation of cluster structures of molecules that surround a solute in the bulk and it allows for a deep insight into the relationship between the structure of the solvation shells and other physical properties. We propose semiempirical potential energy functions that are able to describe the interaction between K+ or Cs+ with coronene. Such functions were calibrated through the comparison with accurate estimations of the interaction between the cation and the planar hydrocarbon, obtained by means of ab initio electronic-structure calculations. By employing the potential energy functions and an evolutionary algorithm (EA), we have investigated the structure and energetics of the clusters resulting from the microsolvation of either K+ or Cs+ with coronene molecules. The reliability of the results for smaller clusters was checked by performing geometry re-optimization exploiting a suitable DFT level of theory. This has allowed for the characterization of the first solvation shells of planar molecules of coronene around an alkali-metal ion. It has also been found that the presence of metal ion impurities considerably enhances the formation of small coronene clusters leading to much stronger binding energies for heterogeneous with respect to homogeneous aggregates. These clusters could represent relevant species involved in the early stages of soot nucleation.

Alternative RNA splicing of leucocyte tissue transglutaminase in coeliac disease.

Tissue transglutaminase is a ubiquitous and multifunctional protein that contributes to several processes such as apoptosis/survival, efferocytosis, inflammation and tissue repairing under physiological and pathological conditions. Several activities can be associated with well-established functional domains; in addition, four RNA alternative splice variants have been described, characterized by sequence divergences and residues deletion at the C-terminal domains. Tissue transglutaminase is recognized as the central player in the physiopathology of coeliac disease (CD) mainly through calcium-dependent enzymatic activities. It can be hypothesized that differential regulation of tissue transglutaminase splice variants expression in persons with CD contributes to pathology by altering the protein functionality. We characterized the expression pattern of RNA alternative splice variants by RT-PCR in peripheral cells from patients with CD under free gluten diet adhesion; we considered inflammatory parameters and specific antibodies as markers of the stage of disease. We found significant higher expression of both the full length and the shortest C-truncated splice variants in leucocytes from patients with CD in comparison with healthy individuals. As tissue transglutaminase expression and canonical enzymatic activity are linked to inflammation, we studied the RNA expression of inflammatory cytokines in peripheral leucocytes of persons with CD in relation with splice variants expression; interestingly, we found that recently diagnosed patients showed significant correlation between both the full length and the shortest alternative spliced variants with IL-1 expression. Our results points that regulation of alternative splicing of tissue transglutaminase could account for the complex physiopathology of CD.

Salbutamol-induced electrophysiological changes show no correlation with electrophysiological changes during hyperinsulinaemic-hypoglycaemic clamp in young people with Type 1 diabetes.

AIMS: Hypoglycaemia causes QT-interval prolongation and appears pro-arrhythmogenic. Salbutamol, a ß2 -adrenoreceptor agonist also causes QT-interval prolongation. We hypothesized that the magnitude of electrophysiological changes induced by salbutamol and hypoglycaemia might relate to each other and that salbutamol could be used as a non-invasive screening tool for predicting an individual's electrophysiological response to hypoglycaemia. METHODS: Eighteen individuals with Type 1 diabetes were administered 2.5 mg of nebulized salbutamol. Participants then underwent a hyperinsulinaemic-hypoglycaemic clamp (2.5 mmol/l for 1 h). During both experiments, heart rate and serum potassium (and catecholamines during the clamp) were measured and a high-resolution electrocardiogram (ECG) was recorded at pre-set time points. Cardiac repolarization was measured by QT-interval duration adjusted for heart rate (QTc ), T-wave amplitude (Tamp ), T-peak to T-end interval duration (Tp Tend ) and T-wave area symmetry (Tsym ). The maximum changes vs. baseline in both experiments were assessed for their linear dependence. RESULTS: Salbutamol administration caused QTc and Tp Tend prolongation and a decrease in Tamp and Tsym . Hypoglycaemia caused increased plasma catecholamines, hypokalaemia, QTc and Tp Tend prolongation, and a decrease in Tamp and Tsym . No significant correlations were found between maximum changes in QTc [r = 0.15, 95% confidence interval (95% CI) -0.341 to 0.576; P = 0.553), Tp Tend (r = 0.075, 95% CI -0.406 to 0.524; P = 0.767), Tsym (r = 0.355, 95% CI -0.132 to 0.706; P = 0.149) or Tamp (r = 0.148, 95% CI -0.347 to 0.572; P = 0.558) in either experiment. CONCLUSIONS: Both hypoglycaemia and salbutamol caused pro-arrhythmogenic electrophysiological changes in people with Type 1 diabetes but were not related in any given individual. Salbutamol does not appear useful in assessing an individual's electrophysiological response to hypoglycaemia.