Immune Response in Heart Transplant Patients Following COVID-19 Vaccination

Purpose

Previous studies have described poor outcomes in heart transplant patients who develop COVID-19 infection. Therefore, we sought to characterize a single center's experience with heart transplant patient outcomes during the COVID-19 pandemic and the recent role of vaccination in mitigating the risk of mortality.

Methods

From a single center, we identified all orthotopic heart transplant patients alive at the beginning of the COVID-19 pandemic in March 2020. All patients were followed from the start of the pandemic until their most recent follow up or death. Baseline comorbidities and immediate outcomes data were obtained from the Society for Thoracic Surgery (STS) Adult Cardiac Surgery Database (ACSD). Multiple logistic regression analyzed the association between vaccination status, baseline covariates, and other standard STS outcome measures. Non-parametric tests were used to compare different subgroups.

Results

We included 153 patients, of which 20.9% developed COVID-19 infection (32/153) with 40.6% (13/32) requiring hospitalization and 15.6% of those patients (5/32) dying as a direct result of COVID-19 pneumonia. Kaplan-Meier survival analysis revealed that unvaccinated patients had a significantly higher rate of all-cause mortality as compared to those patients that were fully vaccinated despite similar baseline characteristics (p < 0.001). Patients with previous COVID-19 infection in addition to vaccination had significantly higher IgG titers as compared to those only vaccinated (6568.50 AU/mL vs. 58.05 AU/mL, p = 0.002).

Conclusion

Immunization against COVID-19 is associated with a significant reduction in the mortality of heart transplant patients. IgG titers were variable among heart transplant patients who received the vaccine with the highest titers seen in those patients with a personal history of COVID-19. The implications of IgG levels are still unknown.

Temporal changes in the implementation of secondary prevention of coronary artery disease in every day practice

Funding Acknowledgements

Type of funding sources: None.

OnBehalf

-

Introduction

Patients with coronary artery disease (CAD) are at high risk of recurrent cardiovascular events and control of their risk factors is crucial.

Objectives

Comparison of risk factors control in patients with CAD in 2016–2017 and 2011–2013.

Patients and methods

Five hospitals with cardiology departments serving the city and surrounding districts participated in the study. Consecutive patients hospitalized due to an acute coronary syndrome or a myocardial revascularization procedure were interviewed 6–18 months after hospitalization. The surveys were carried out in 2011–2013 and 2016–2017.

Results

We examined 616 patients in 2011–2013 and 388 in 2016–2017 (mean age: 64.7 ± 8.8 vs. 66.4 ± 8.4, P &lt;0.01). After adjusting for covariates the proportion of patients with high blood pressure decreased by 8.9% (95% confidence intervals: -2.1% – -15.6%) and proportion of patients with high LDL cholesterol decreased by 9.5% (-2.2% – -16.7%) in 2016/2017 compared to 2011/2013, whereas the proportion of smoking patients (-0.2% [-6.0% – 5.5%]) and those with high glucose level (3.9% [-2.2% - 10.0%]) and with body mass index ≥25 kg/m2 (3.8% [-3.9% – 11.6%]) did not change significantly. The proportion of patients prescribed antiplatelets (6.5% [2.6% - 10.3%]), β-blockers (7.4% [2.2% - 12.6%]), angiotensin converting enzyme inhibitors or sartans (8.6% [2.9% – 14.3%]), calcium antagonists (8.1% [1.3 – 15.0]) and anticoagulants (5.5% [0.7% - 10.2%]) increased significantly.

Conclusions

In CAD patients, there was an increase of the proportion of patients with cardiovascular drugs prescribed and a slight improvement in the control of blood pressure and LDL cholesterol between 2011–2013 and 2016–2017. However, no significant changes were found for the other main risk factors.

Patients who do not reach treatment goal Survey Smoking, % BP not at goal, %a BP ≥140/90 mmHg, % LDL cholesterol ≥1.8 mmol/l, % HbA1c ≥7.0%b, % Fasting glucose ≥7.0 mmol/l, % BMI≥25 kg/m2, % BMI≥30 kg/m2, % 2011-2013 19.0 50.3 43.0 71.9 14.1 15.9 81.2 33.8 2016-2017 16.2 40.7 39.2 60.3 14.9 20.2 83.4 38.3 P value 0.26 &lt;0.01 0.24 &lt;0.001 0.76 0.09 0.37 0.14 Differences adjusted for age, sex, index diagnosis, duration of education, professional activity (95% confidence intervals) 2016-2017 vs 2011-2013 -0.2(-6.0 - 5.5) -8.9(-15.6 - -2.1) -6.7(-14.3 - 1.0) -9.5(-16.7 - -2.2) 2.0(-3.4 - 7.4) 3.9(-2.2 - 10.0) 3.8(-3.9 - 11.6) 1.6 (-5.8 - 9.0) Abbreviations BMI, body mass index; BP, blood pressure; LDL, low-density lipoprotein a BP goal of &lt;140/90mmHg (&lt;130/80 mmHg in diabetics) in 2011–2013 and &lt;140/90 mmHg (&lt;140/85 mmHg in diabetics) in 2016–2017 b available for 362 patients in 2011-2013 and 383 patients in 2016-2017

Evaluation of clinically relevant operating conditions for left ventricular assist device investigations

Standardized boundary conditions for flow rate and pressure difference are currently not available for the development and certification process of ventricular assist devices. Thus, interdisciplinary studies lack comparability and quantitative assessment. Universally valid boundary conditions could be used for the application of numerical and experimental investigations and the approval procedure of ventricular assist devices. In order to define such boundaries, physiological data from INCOR^® patients were evaluated. A total of 599 out of possible 627 ventricular assist device patients were analyzed regarding their cardiac demands of flow rate and pressure head. An analysis of long-term data was performed, in order to provide respective, static mean values for benchmark testing. Furthermore, the short-term data of 188 patients delivered field data-based dynamic flow and pressure curves. The results of the study revealed physiologically reasonable boundary conditions, which can be applied in numerical or experimental investigations of ventricular assist devices. For steady flow analysis, single values for flow rate (4.46 L/min) and pressure head (62 mmHg) are suggested. For the support of pulsatile and unsteady flow studies, seven typical patients and one representative dynamic curve for flow rate and pressure head are proposed.The standardized results provided in this article, can be used in favor of interdisciplinary comparability of future numerical computations or in vitro ventricular assist device tests in research, development, and approval.

P01-366-New treatment option in resistant schizophrenia in adolescence - case study

Early-onset schizophrenia has not only more severe course than in adults, it is also associated with poor response to antipsychotic treatment. There are only limited data about effectiveness, safety and tolerability of second generation antipsychotics (SGA) in children, but current recommendations suggest using atypical antipsychotics as the first line treatment.

Case study

15-year-old schoolboy admitted to psychiatric hospital after acute psychotic episode. His symptoms started 2 years ago. After a few months he was diagnosed schizophrenia paranoid type. During 2 years he has been hospitalized many times because of persistent psychotic symptoms. He was treated using: risperidon, olanzapine, amisulpride, quetiapine, ziprasidone, perfenazin. All the drugs were ineffective, all were used in full doses, given no shorter than 8 weeks. Patient did not cooperate in treatment - he spits out or has hide the tablets, has to be controlled during drug supplies. He did not responded to long-acting injections of risperidon. Finally the treatment has been changed to new form of olanzapine in extended release injections started 210 mg i.m. every 14 days increased to 300 mg after 2 weeks. After 2 months of treatment (5 injections) reduction of positive and negative symptoms of schizophrenia was observed. Patients starts to socialize, attend school. He is on the drug now, the drug is well tolerated.

Adalimumab or infliximab as monotherapy, or in combination with an immunomodulator, in the treatment of Crohn's disease

BACKGROUND

The comparative efficacy of adalimumab (ADA) and infliximab (IFX) in Crohn's disease, and the benefit of initial combotherapy with an immunomodulator, are debated.

AIM

To assess the best anti-TNF treatment regimens in Crohn's disease.

METHODS

We included 906 biologic-naïve Crohn's disease patients [median age, 31 years (24-41)] and performed a retrospective analysis of 1284 therapeutic exposures to ADA (n = 521) or IFX (n = 763) between 2006 and 2015. An immunomodulator was associated during the first 4-6 months (initial combotherapy) during 706 therapeutic exposures (55%). Median duration of anti-TNF therapy was 39 months (IQR 17-67). Primary outcomes were 6-month and 2-year response rates and drug survival. Logistic regression with propensity scoring and Cox proportional hazard analysis determined variables associated with outcomes.

RESULTS

The response rates at 6 months and 2 years were 64% and 44% on ADA mono, 86% and 70% on ADA combo, 72% and 45% on IFX mono, and 84% and 68% on IFX combotherapy, respectively. Differences between ADA and IFX were not significant, whereas combotherapy was superior to monotherapy (P < 0.001). Drug survival was longer with combotherapy vs. monotherapy [adjusted hazard ratio 2.17 (1.72-2.70)] and not significantly different between ADA and IFX. During subsequent anti-TNF exposures, IFX combotherapy fared better than other groups regarding response rates, drug survival, disease activity, hospitalisations and abdominal surgery.

CONCLUSION

In this retrospective analysis of a large tertiary centre cohort of Crohn's disease patients, ADA and IFX had similar efficacy as first line treatment, while initial combotherapy with an immunomodulator improved all outcome measures.

Application of termite nest for adsorption of Cr(VI)

This work proposes the use of tree termite nest as an adsorbent for the reduction/removal of Cr(VI) present in aqueous solution. In laboratory experiments, adsorption of Cr(VI) was sensitive to pH in the range investigated (2-5), with maximum adsorption capacity achieved at pH 2 (3.70 ± 0.04 mg g(-1), representing 93.2% removal of Cr). The termite nest was characterized by off-line pyrolysis GC/MS (py-GC/MS), infrared spectroscopy (FTIR), and electron paramagnetic resonance spectroscopy (EPR). Pyrolysis of the adsorbent produced a complex mixture of aromatic compounds, including the guaiacyl and syringilic derivatives that are characteristic of lignocellulosic materials. Infrared spectroscopy revealed deprotonation of the carboxylic acid group of the biomass with increasing pH, which was associated with a decrease in the capacity for adsorption of Cr(VI). The EPR g-factor for the termite nest samples varied between 2.0037 and 2.0038, indicating the presence of organic free radicals that were responsible for the redox reaction. A second line with g-factor values of 1.9790, only observed for the samples after contact with Cr(VI) solutions at different pH values, was assigned to Cr(III)-Cr(III) exchange coupled pairs, which explained the capacity of the adsorbent to retain a large portion of the Cr(III) ions produced after reduction of Cr(VI) to Cr(III). Fixed-bed column experiments showed that the termite nest had a maximum adsorption capacity of 18.60 mg Cr g(-1), an adsorption efficiency varying between 60.8 and 97.4%, and a desorption efficiency varying between 54.5 and 91.4%, for three successive cycles. The adsorbent presented excellent performance in the removal of chromium under acidic conditions, with the advantage that it could be regenerated and reused.

Magnetic dynamic properties of electron-doped La(0.23)Ca(0.77)MnO3 nanoparticles

Magnetic properties of basically antiferromagnetic La(0.23)Ca(0.77)MnO(3) particles with average sizes of 12 and 60 nm have been investigated in a wide range of magnetic fields and temperature. Particular attention has been paid to magnetization dynamics through measurements of the temperature dependence of ac-susceptibility at various frequencies, the temperature and field dependence of thermoremanent and isothermoremanent magnetization originating from nanoparticles shells, and the time decay of the remanent magnetization. Experimental results and their analysis reveal the major role in magnetic behaviour of investigated antiferromagnetic nanoparticles played by the glassy component, associated mainly with the formation of the collective state formed by ferromagnetic clusters in frustrated coordination at the surfaces of interacting antiferromagnetic nanoparticles. Magnetic behaviour of nanoparticles has been ascribed to a core-shell scenario. Magnetic transitions have been found to play an important role in determining the dynamic properties of the phase separated state of coexisting different magnetic phases.

Anomalous magnetic behavior of Sm0.8Ca0.2MnO3 nanoparticles

Magnetic properties of compacted Sm0.8Ca0.2MnO3 (SCMO) particles with average particle size of 23-100 nm, prepared by the glycine-nitrate method, have been investigated. It was found that the relative volume of the ferromagnetic phase decreases with decreasing particle size. Curves of field cooled and zero filed cooled magnetization (M(ZFC)) exhibit a bifurcation just below the Curie temperature (T(c) approximately 55-64 K) for all particles studied. The field dependence of M(ZFC) peak follows de Almeida-Thouless line. Both features are characteristic of spin-glasses (SG). Measurements of ac-susceptibility in the temperature range 5-300 K and the frequency range f = 10 Hz-10 kHz show a sharp peak for both real and imaginary components in the vicinity of T(c), apparently attributed to the Hopkinson effect. A second small peak is seemingly associated with antiferromagnetic or ferrimagnetic ordering. Though, for smaller particles both peaks depend on frequency, no shift to higher temperatures with increasing f, characteristic for SG systems, was observed. The dissimilarity in magnetic properties and dynamic characteristics observed for SCMO and for La0.8Ca0.2MnO3 nanoparticles is discussed, taking into account a difference in the width of the band and the strength of double exchange and interparticle interactions.

Nanometer size effect on structural and magnetic properties of La0.2Ca0.8MnO3

Structural and magnetic properties of La0.2Ca0.8MnO3 nanoparticles with average size of 15-37 nm, prepared by the glycine-nitrate method, have been studied. Synchrotron experiments performed in the temperature range of 80-300 K have shown that a structural transition from room temperature orthorhombic Pnma to monoclinic P2(1)/m space group, associated with orbital ordering, occurs below 200 K in the studied particles. This transition observed for the largest particles of 37 nm is very close to that of bulk, as seen by similar temperature variation of lattice parameters and orthorhombic strain. The transition is highly suppressed for smaller 15 nm particles. Horizontal and vertical shifts of magnetic hysteresis loops (M(Shift) and H(EB)), displayed in a field cooled process, indicate size dependent exchange bias effect. It is also shown that M(shift) and H(EB), as well as the remanent magnetization M(r) and coercive field H(c) at low temperatures, exhibit a non-monotonic size dependence for particles around 23 nm. These effects may be attributed to the changes in uncompensated spins at the surface, anisotropy or alternatively to a transition from a multi-domain to the single domain state.

Pressure-induced enhancement of the superconducting properties of single-crystalline FeTe0.5Se0.5

The pressure dependence, up to 11.3 kbar, of basic parameters of the superconducting state, such as the critical temperature (T(c)), the lower and the upper critical fields, the coherence length, the penetration depth, and their anisotropy, was determined from magnetic measurements performed for two single-crystalline samples of FeTe(0.5)Se(0.5). We have found pressure-induced enhancement of all of the superconducting state properties, which entails a growth of the density of superconducting carriers. However, we noticed a more pronounced increase in the superconducting carrier density under pressure than that in the critical temperature which may indicate an appearance of a mechanism limiting the increase of T(c) with pressure. We have observed that the critical current density increases under pressure by at least one order of magnitude.

Magnetic behaviour of interacting antiferromagnetic nanoparticles

Magnetic properties of interacting La(0.2)Ca(0.8)MnO(3) nanoparticles have been investigated. The field-induced transition from antiferromagnetic (AFM) to ferromagnetic (FM) state in the La(0.2)Ca(0.8)MnO(3) bulk has been observed at exceptionally high magnetic fields. For large particles, the field-induced transition widens while magnetization progressively decreases. In small particles the transition is almost fully suppressed. The thermoremanence and isothermoremanence curves constitute fingerprints of irreversible magnetization originating from nanoparticle shells. We have ascribed the magnetic behaviour of nanoparticles to a core-shell scenario with two main magnetic contributions; one attributed to the formation of a collective state formed by FM clusters in frustrated coordination at the surfaces of interacting AFM nanoparticles and the other associated with inner core behaviour as a two-dimensional diluted antiferromagnet.

Environmental strategies to remove volatile aromatic fractions (BTEX) from petroleum industry wastewater using biomass

This work investigates the potentials of peat and angico hardwood sawdust to remove BTEX (benzene, toluene, ethylbenzene, and isomers of xylene) from the produced water discharged into aquatic systems during petroleum extraction. Peat and angico sawdust samples were pyrolyzed at 500°C, and found to contain n-alkenes, n-alkanes and pentacyclic triterpenes (peat), and 4-methoxyphenol, 1,4-dimethoxyphenol and 1,3,4-trimethoxyphenol (angico sawdust). In batch experiments, the removal capacities using peat were 32.4%, 50.0%, 63.0%, 67.8%, and 61.8% for benzene, toluene, ethylbenzene, m,p-xylenes and o-xylene, respectively. This compared with removal capacities using angico sawdust of 20.2%, 36.4%, 52.8%, 57.8%, and 53.7% for these compounds respectively, demonstrating the superior performance of the peat.

Sedative effects of essential oils obtained from Baccharis uncinella

CONTEXT

Essential oils (EOs) have been reported to possess pharmacological properties, of which those related to the central nervous system have been especially attributed to mono- and sesquiterpenes. Baccharis uncinella DC. (Asteraceae) is used by the Laklaño Indians (Santa Catarina, Brazil) for sedative purposes. Interestingly, the species does not seem to be used medicinally elsewhere in Brazil.

OBJECTIVE

This study was designed to compare the composition and sedative properties of B. uncinella EOs obtained closer (BU-SC) and farther (BU-PR) to the Laklaño Indian Reserve.

MATERIALS AND METHODS

BU-SC and BU-PR obtained by hydrodistillation were analyzed by CG-MS. Mice treated with BU-SC and BU-PR (50 and 100 mg/kg) were evaluated regarding pentobarbital-induced sleeping time, body temperature, and locomotion.

RESULTS

BU-SC presents a higher monoterpene/sesquitherpene ratio (0.31); α-pinene (6.42%), limonene (7.21%), caryophyllene (26.13%), spathulenol (13.39%) and caryophyllene oxide (13.26%) were identified as major components. BU-PR presents a low monoterpene/sesquitepene ratio (0.004); spathulenol (32.93%), caryophyllene oxide (27.78%), viridiflorol (5.29%) and α-cadinol (2.42%) were identified as the main components. Both samples significantly (p < 0.05, ANOVA) decreased locomotion and body temperature, as well as increased sleeping time. The hypnotic activity was sensitive to the differences in monoterpene composition.

CONCLUSIONS

In comparison with a sample collected in Paraná State, B. uncinella EO collected closer to the Laklaño Indians possess a composition that better justifies the claimed sedative properties. The study confirms the value of traditional information to guide bioactivity assessment in medicinal plants, and gives notice to the ecological factors that can interfere with the conclusions of such assessments.

P01-365 Safety of second-generation antipsychotics in children-questionnaire evaluation in psychiatrists

Atypical antipsychotics are more safe than first generation drugs. But some researchers suggest that children and adolescents might be more sensitive than adults to developing antipsychotic-related adverse side effects. The standards of safety monitoring strategies do not exist in Poland.

Objective

The aim of this study was to estimate physicians awareness to side effects in youth population treated with antipsychotics.

Material

20 questionnaires filled up by polish child psychiatrists.

Method

Information from author's questionnaire concerns side effects observed in antipsychotics medicated children, psychiatrists own preferences in safety monitoring strategies were analyzed.

Results

Atypical antipsychotics are used in 25% of medicated children. Risperidon is the most popular antipsychotic in psychotic and non-psychotic indications (81%, 66%), afterwards olanzapine (54%, 30%) and quetiapine (34%, 24%). The most common indications for antipsychotics in children are: tics (55%), conduct disorders (53%) and schizophrenia (45%). Before drug initiation doctors check liver enzymes (GOT, GTP) (98%), hematology (98%), glucose level (95%), weight and height (91%), ECG (90%). The most common side effects observed are: weigh gain (63%), somnolence (59%), prolactin elevation (47%), attention deficits (43%).

Conclusion

In spite of lack of safety monitoring standards in youth population psychiatrists seem to be aware and careful in atypical neurolpetic treatment in children.

Biofuels from continuous fast pyrolysis of soybean oil: a pilot plant study

The continuous fast pyrolysis of soybean oil in a pilot plant was investigated. The experimental runs were carried out according to an experimental design alternating the temperature (from 450 to 600 degrees C) and the concentration of water (from 0% to 10%). The liquid products were analyzed by gas chromatography and by true boiling point (TPB) distillation. A simple distillation was used to obtain purified products such as gasoline and diesel. Physical-chemical analysis showed that these biofuels are similar to fossil fuels. Mass and energy balances were carried out in order to determine the vaporization enthalpy and the reaction enthalpy for each experiment. The thermal analysis showed that it is possible to use the products as an energy source for the process.

Effect of high-dose isoflavones on cognition, quality of life, androgens, and lipoprotein in post-menopausal women

CONTEXT

Recent interventional studies indicate that post-menopausal hormone replacement therapy is associated with an increased risk of cardiovascular mortality and breast cancer. Isoflavones, a class of plant estrogens, have structural similarities to estradiol. Hence, isoflavones may exert beneficial estrogenic health effects in postmenopausal women with fewer adverse effects.

OBJECTIVE

To evaluate the effect of high-dose isoflavones on self-reported quality of life (QOL), cognition, lipoproteins and androgen status in post-menopausal women.

DESIGN AND SUBJECTS

Double-blind, randomized, placebo-controlled, 12-week trial of 93 healthy, ambulatory, post-menopausal women (mean age 56 yr). The study was conducted at a tertiary care center in the United States.

INTERVENTION

Participants were randomly assigned to receive 20 g of soy protein containing 160 mg of total isoflavones vs taste-matched placebo (20 g whole milk protein). Both soy and the placebo were provided in the form of a powder to be mixed with beverages.

MAIN OUTCOME MEASURES

QOL was judged by the Menopause-specific Quality of Life (MENQOL) questionnaire while cognitive function was assessed with standard instruments. Total, free, and bioavailable testosterone, gonadotropins, SHBG, and fasting lipids were measured.

RESULTS

Eighty-four women (90%) completed the study (active=38, placebo=46). There was a significant improvement in all 4 QOL subscales (vasomotor, psychosexual, physical, and sexual) among the women taking isoflavones, while no changes were seen in the placebo group. No significant changes in cognition, serum androgens or plasma lipids were seen within any of the groups. However, at the end of the study, a group-by-time interaction was observed such that total testosterone and HDL levels were significantly lower in the isoflavones compared to placebo groups.

CONCLUSION

High-dose isoflavones is associated with improved QOL among women who have become menopausal recently. Hence, the timing of isoflavone supplementation with regards to the onset of menopause appears to be important. The use of isoflavones, as an alternative to estrogen therapy, may be potentially useful and seemingly safe in this group of women who are looking for relief from menopausal symptoms.

Temperature and field dependence of the anisotropy of MgB2

The anisotropy gamma of the superconducting state of high quality single crystals of MgB2 was determined, using torque magnetometry with two different methods. The anisotropy of the upper critical field was found to be temperature dependent, decreasing from gamma approximately 6 at 15 K to 2.8 at 35 K. Reversible torque data near T(c) reveal a field dependent anisotropy, increasing nearly linearly from gamma approximately equal to 2 in zero field to 3.7 in 10 kOe. The unusual temperature dependence is a true bulk property and can be explained by nonlocal effects of anisotropic pairing and/or the k--> dependence of the effective mass tensor.

Comparison of the systemic effects of fluticasone propionate and budesonide given by dry powder inhaler in healthy and asthmatic subjects

BACKGROUND

The potential for long term adverse effects from inhaled corticosteroids relates to their systemic absorption, usually assessed from proxy markers in short term studies. When fluticasone propionate and budesonide have been compared in this way the results have been inconsistent. To determine whether this is because of the subjects studied or the sensitivity of the systemic marker used, we have compared the effects of fluticasone propionate and budesonide in healthy and asthmatic subjects and investigated the effect of treatment on three systemic markers.

METHODS

Forty six healthy subjects were randomised to receive inhaled fluticasone propionate 1500 microg/day (via an Accuhaler), budesonide 1600 microg/day (via a Turbuhaler), or placebo; 31 subjects with moderately severe asthma were randomised to receive the same doses of fluticasone propionate or budesonide but not placebo. Systemic effects in healthy and asthmatic subjects were compared after 7 days. Treatment was continued for another 21 days in the subjects with asthma when systemic effects and asthma control were assessed.

RESULTS

At baseline healthy subjects had higher urinary levels of total cortisol metabolites (TCM) than subjects with asthma. After 7 days of treatment with fluticasone propionate urinary TCM levels in the healthy subjects were significantly lower than in the subjects with asthma (mean difference between groups 1663 microg/day, 95% CI 328 to 2938). This was not the case with budesonide, however, where urinary TCM levels in the healthy subjects remained above those in the asthmatic subjects (mean difference between groups 1210 microg/day, 95% CI -484 to 2904). Urinary TCM levels were considerably more sensitive to the effects of inhaled corticosteroids than morning serum cortisol or osteocalcin concentrations. Only budesonide reduced the serum level of osteocalcin.

CONCLUSIONS

When given by dry powder inhaler for 7 days, fluticasone propionate 1500 microg/day has a greater effect on the hypothalamic-pituitary-adrenal axis in healthy subjects than in subjects with asthma, but this is not the case for budesonide 1600 microg/day. These findings, together with the differences in sensitivity between systemic markers, explain many of the discrepancies in the literature.

Age effects on executive ability

Heterogeneity of executive tasks has made it difficult to determine whether there are age-related declines in executive functioning. To address this issue, 112 individuals, 20-79 years old, took the California Trail Making Test (CTMT) and the California Stroop Test (CST), subtests of the Delis-Kaplan Executive Function Scale (D. C. Delis, E. Kaplan, & J. H. Kramer, in press) that include measurement of component skills embedded in the executive function tasks. Multiple regression analyses revealed that after controlling for component skills, age had a significant effect on the executive requirement of the CST, namely speed on the interference condition. Age did not affect switching performance on the letter-number condition of the CTMT. Additional analyses revealed that age was significantly associated with commission of certain types of errors. This study confirms the importance of partialing out components in the assessment of multidimensional cognitive tasks, particularly when making age comparisons. It also emphasizes specificity over generalizability when examining the impact of age on cognition.

Age effects on executive ability

Heterogeneity of executive tasks has made it difficult to determine whether there are age-related declines in executive functioning. To address this issue, 112 individuals, 20-79 years old, took the California Trail Making Test (CTMT) and the California Stroop Test (CST), subtests of the Delis-Kaplan Executive Function Scale (D. C. Delis, E. Kaplan, & J. H. Kramer, in press) that include measurement of component skills embedded in the executive function tasks. Multiple regression analyses revealed that after controlling for component skills, age had a significant effect on the executive requirement of the CST, namely speed on the interference condition. Age did not affect switching performance on the letter-number condition of the CTMT. Additional analyses revealed that age was significantly associated with commission of certain types of errors. This study confirms the importance of partialing out components in the assessment of multidimensional cognitive tasks, particularly when making age comparisons. It also emphasizes specificity over generalizability when examining the impact of age on cognition.

The effect of the nitric oxide synthase inhibitor, L-NMMA, on sodium metabisulphite-induced bronchoconstriction and refractoriness in asthma

Refractoriness to indirect bronchoconstrictor stimuli, is a feature of asthma but the mechanism is poorly understood. This study tested the hypothesis that endogenous nitric oxide (NO) produced during a first bronchoconstrictor challenge protects against subsequent challenge and therefore has a role in the refractory process. The effect of an NO synthase inhibitor, N(G)-mono-methyl-L-arginine (L-NMMA), on refractoriness to sodium metabisulphite (MBS) was investigated in 20 subjects with mild asthma. On visit one, the dose of MBS which caused a 20% fall in forced expiratory volume in one second (FEV1) (PD20) was determined. On visit two, the refractory index (RI) to MBS was determined by challenging the subjects twice with their PD20 of MBS, the second challenge proceeding after recovery from the first. Those showing a refractory index of approximately 30% (10 subjects) inhaled either L-NMMA or placebo followed 5 min later by two challenges with their PD20 of MBS in a double-blind cross over study at two further visits. The dose of L-NMMA used was shown to reduce exhaled NO for a duration sufficient to cover the second MBS challenge However, no significant difference was found between L-NMMA and placebo in maximum fall in FEV1% and area under the curve (AUC) during first or second MBS challenges or in RI on the two study days. It is concluded that subjects with mild asthma show refractoriness to sodium metabisulphite, but that endogenous nitric oxide is unlikely to be involved either in the refractory process or in the response to sodium metabisulphite per se.

Ineffectiveness of burst suppression therapy in mitigating perioperative cerebrovascular dysfunction. Multicenter Study of Perioperative Ischemia (McSPI) Research Group

BACKGROUND

Cerebral injury is among the most common and disabling complications of open heart surgery. Attempts to provide neuroprotection have yielded conflicting results. We assessed the potential of propofol-induced burst suppression during open heart surgery to provide cerebral protection as determined by postoperative neuropsychologic function.

METHODS

Two hundred twenty-five patients undergoing valve surgery were randomized to receive either sufentanil or sufentanil plus propofol titrated to electroencephalographic burst suppression. Blinded investigators performed neurologic and neuropsychologic testing at baseline, postoperative day (POD) 1 (neurologic testing only), PODs 5-7, and PODs 50-70. Neuropsychologic tests were compared with the results of 40 nonsurgical patients matched for age and education.

RESULTS

Electroencephalographic burst suppression was successfully achieved in all 109 propofol patients. However, these patients sustained at least as many adverse neurologic outcomes as the 116 controls: POD 1, 40% versus 25%, P = 0.06; PODs 5-7, -18% versus 8%, P = 0.07; PODs 50-70, -6% versus 6%, P = 0.80. No differences in the incidence of neuropsychologic deficits were detected, with 91% of the propofol patients versus 92% of the control patients being impaired at PODs 5-7, decreasing to 52 and 47%, respectively, by PODs 50-70. No significant differences in the severity of neuropsychologic dysfunction, depression, or anxiety were noted.

CONCLUSIONS

Electroencephalographic burst suppression surgery with propofol during cardiac valve replacement did not significantly reduce the incidence or severity of neurologic or neuropsychologic dysfunction. The authors' results suggest that neither cerebral metabolic suppression nor reduction in cerebral blood flow reliably provide neuroprotection during open heart surgery. Other therapeutic approaches must be evaluated to address this important medical problem.

Comparison of three inhaled non-steroidal anti-inflammatory drugs on the airway response to sodium metabisulphite and adenosine 5'-monophosphate challenge in asthma

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) are used to assess the role of prostaglandins in asthma but their effects on bronchoconstrictor challenges have been inconsistent. The effects of three nebulised nonsteroidal anti-inflammatory drugs on the airway response to inhaled sodium metabisulphite (MBS) and adenosine 5'-monophosphate (AMP) were compared in the same asthmatic subjects to see whether contractile prostaglandins were involved in MBS or AMP induced bronchoconstriction. A possible protective effect of the osmolarity or pH of the inhaled solutions was also assessed.

METHODS

Two double blind placebo controlled studies were carried out. In study 1, 15 non-aspirin sensitive patients with mild asthma attended on four occasions and inhaled 5 ml of lysine aspirin (L-aspirin) 900 mg, indomethacin 50 mg, sodium salicylate 800 mg, or saline 20 minutes before an inhaled MBS challenge. On four further occasions 14 of the patients inhaled the same solutions followed by an inhaled AMP challenge. In study 2, 10 of the patients attended on four additional occasions and inhaled 5 ml of 0.9%, 3%, 10%, or 9.5% saline with indomethacin 50 mg 20 minutes before an inhaled MBS challenge.

RESULTS

In study 1 inhaled lysine aspirin had a similar effect on MBS and AMP induced bronchoconstriction, increasing the provocative dose causing a 20% fall in FEV1 (PD20) by 1.29 (95% CI 0.54 to 2.03) and 1.23 (95% CI 0.53 to 1.93) doubling doses, respectively. Indomethacin increased the MBS PD20 and AMP PD20 by 0.64 (95% CI -0.1 to 1.38) and 0.99 (95% CI 0.29 to 1.69) doubling doses, respectively. Sodium salicylate had no significant effect on either challenge. The two solutions causing most inhibition were the most acidic and the most alkaline. In study 2 inhaled 9.5% saline with indomethacin (osmolarity 3005 mOsm/kg) increased the MBS PD20 by 1.1 doubling doses (95% CI 0.2 to 2.0) compared with only 0.09 (95% CI -0.83 to 1.0) and 0.04 (95% CI -0.88 to 0.95) doubling doses with 3% saline (918 mOsm/kg) and 10% saline (2994 mOsm/ kg), respectively.

CONCLUSIONS

Inhaled L-aspirin and indomethacin have broadly similar protective effects against MBS and AMP induced bronchoconstriction in the doses given, although the effect of indomethacin on MBS was not quite statistically significant. The osmolarity and pH of the solutions did not appear to be important determinants of the response. The effect of L-aspirin and indomethacin is likely to be the result of cyclooxygenase inhibition reducing the production of contractile prostaglandins during MBS and AMP challenge.

Dietary sodium intake and the risk of airway hyperreactivity in a random adult population

BACKGROUND

High dietary sodium intake has been identified as a potential cause of asthma and airway hyperreactivity. This study was designed to test the hypothesis that dietary sodium intake is an independent determinant of the risk of hyperreactivity in the general population, and to assess the role of atopy in the association between these factors.

METHODS

Airway reactivity to methacholine, atopy, 24 hour urinary sodium excretion, and self-reported smoking and symptom history were measured in a random sample of 1702 adults aged 18-70 from an administrative district of Nottingham. Hyperreactivity was defined as a PD20FEV1 of 12.25 mumol or less, and atopy was defined quantitatively as the mean allergen skin weal response to Dermatophagoides pteronyssinus, cat fur, and grass pollen, and categorically as the occurrence of any allergen response 1 mm or greater than the saline control. Multiple logistic regression analysis was used to estimate the independent relative odds of hyperreactivity, atopy, or symptoms in relation to sodium excretion in all 1702 subjects, and multiple linear regression to assess the independent relation between sodium excretion and mean allergen skin weal diameter, and the PD20 value amongst hyperreactive subjects.

RESULTS

There was no relation between the relative odds of hyperreactivity to methacholine and 24 hour urinary sodium excretion, either before or after adjustment for age, smoking, allergen skin weal diameter, and sex, and similarly no relation if the analysis was restricted to men or women only. The relative odds of having at least one allergen skin test response 1 mm greater than the saline control were increased in relation to sodium excretion after adjustment for age, sex, and smoking by a ratio of 2.08 (95% CI 1.04 to 4.15) per log10 unit increase in sodium excretion, but there was no evidence of an association between sodium excretion and the occurrence of self-reported wheeze, hay fever, eczema, or asthma. There was no relation between 24 hour sodium excretion and the magnitude of the mean allergen skin weal response or the PD20 value.

CONCLUSIONS

These findings do not support the hypothesis that a high dietary sodium intake is a risk factor for airway hyperreactivity or atopic disease in the general adult population.

Dietary magnesium, lung function, wheezing, and airway hyperreactivity in a random adult population sample

Magnesium is involved in a wide range of biological activities, including some that may protect against the development of asthma and chronic airflow obstruction. We tested the hypothesis that high dietary magnesium intake is associated with better lung function, and a reduced risk of airway hyper-reactivity and wheezing in a random sample of adults. In 2633 adults aged 18-70 sampled from the electoral register of an administrative area of Nottingham, UK, we measured dietary magnesium intake by semiquantitative food-frequency questionnaire, lung function as the 1-sec forced expiratory volume (FEV1), and atopy as the mean skin-prick test response to three common environmental allergens. We measured airway reactivity to methacholine in 2415 individuals, defining hyper-reactivity as a 20% fall in FEV1 after a cumulative dose of 12.25 mumol or less. Mean (SD) daily intake of magnesium was 380 (114) mg/day. After adjusting for age, sex, and height, and for the effects of atopy and smoking, a 100 mg/day higher magnesium intake was associated with a 27.7 (95% CI, 11.9-43.5) mL higher FEV1, and a reduction in the relative odds of hyper-reactivity by a ratio of 0.82 (0.72-0.93). The same incremental difference in magnesium intake was also associated with a reduction in the odds of self-reported wheeze within the past 12 months, adjusted for age, sex, smoking, atopy, and kilojoule intake, by a ratio of 0.85 (0.76-0.95). Dietary magnesium intake is independently related to lung function and the occurrence of airway hyper-reactivity and self-reported wheezing in the general population. Low magnesium intake may therefore be involved in the aetiology of asthma and chronic obstructive airways disease.

Factors influencing the occurrence of airway hyperreactivity in the general population: the importance of atopy and airway calibre

The factors that determine the occurrence of airway hyperreactivity in the general population are not clearly understood. This study was designed to assess the independent effects of age, atopy, smoking and airway calibre. In a random sample of 2,415 adults aged 18-70 yrs we measured reactivity to methacholine as the dose provoking a 20% fall (PD20) in one-second forced expiratory volume (FEV1), atopy as the mean skin wheal response to three common environmental allergens, and airway calibre as the baseline FEV1 in absolute terms, as percent predicted (FEV1 % predicted) and as percent forced vital capacity (FEV1 % FVC). Hyperreactivity, defined as a PD20 < or = 12.25 mumol, was present in 314 (13%) of the sample, and before adjustment for FEV1 was more common in females (independent odds ratio (OR) = 2.05 (95% confidence interval 1.6-2.7)), current smokers (OR = 1.89 (1.3-2.6)), atopics (OR = 1.39 (1.3-1.5) per mm skin wheal), and in older age groups (OR for age 60-70 yrs relative to 18-29 yrs = 2.70 (1.7-4.3)). However, the odds of hyperreactivity were also strongly and independently related to absolute FEV1 (OR = 0.46 (0.27-0.77) per litre), FEV1 % predicted (OR = 0.96 (0.94-0.98) per percent), and FEV1 % FVC (OR = 0.92 (0.90-0.94) per percent; combined chi-square on 3 df = 312, p << 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Factors influencing the occurrence of airway hyperreactivity in the general population: the importance of atopy and airway calibre

The factors that determine the occurrence of airway hyperreactivity in the general population are not clearly understood. This study was designed to assess the independent effects of age, atopy, smoking and airway calibre. In a random sample of 2,415 adults aged 18-70 yrs we measured reactivity to methacholine as the dose provoking a 20% fall (PD20) in one-second forced expiratory volume (FEV1), atopy as the mean skin wheal response to three common environmental allergens, and airway calibre as the baseline FEV1 in absolute terms, as percent predicted (FEV1 % predicted) and as percent forced vital capacity (FEV1 % FVC). Hyperreactivity, defined as a PD20 < or = 12.25 mumol, was present in 314 (13%) of the sample, and before adjustment for FEV1 was more common in females (independent odds ratio (OR) = 2.05 (95% confidence interval 1.6-2.7)), current smokers (OR = 1.89 (1.3-2.6)), atopics (OR = 1.39 (1.3-1.5) per mm skin wheal), and in older age groups (OR for age 60-70 yrs relative to 18-29 yrs = 2.70 (1.7-4.3)). However, the odds of hyperreactivity were also strongly and independently related to absolute FEV1 (OR = 0.46 (0.27-0.77) per litre), FEV1 % predicted (OR = 0.96 (0.94-0.98) per percent), and FEV1 % FVC (OR = 0.92 (0.90-0.94) per percent; combined chi-square on 3 df = 312, p << 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Refractoriness to inhaled sodium metabisulphite in subjects with mild asthma

Refractoriness occurs after challenges causing mediator release in asthma, by a mechanism which may involve inhibitory prostaglandins. Bronchoconstriction due to inhaled sodium metabisulphite is thought to involve neural pathways and to be independent of mediator release; whether it shows refractoriness is uncertain. We have sought evidence of refractoriness to the bronchoconstrictor response to inhaled sodium metabisulphite in subjects with mild asthma, and have tested the hypothesis that the development of refractoriness involves inhibitory prostaglandins. Twelve subjects were challenged twice with a dose of sodium metabisulphite, previously shown to cause a 20% fall in forced expiratory volume in one second (FEV1); the second challenge proceeded after recovery from the first. The response to sodium metabisulphite was expressed as the maximum % fall in FEV1 and area under the change in FEV1 curve over 20 min (AUC). Nine subjects were studied after double-blind treatment with oral indomethacin, 50 mg t.d.s., or placebo, for 3 days. The second sodium metabisulphite challenge caused significantly less bronchoconstriction than the first (mean maximum fall in FEV1 13.1 and 24.3%, respectively). Nine subjects showed a greater than 50% reduction in the response to the second challenge (mean reduction in AUC 73.7%). In these subjects, indomethacin did not alter the response to the first sodium metabisulphite challenge, or the mean maximum fall in FEV1 in response to the second challenge (placebo 9.7%, indomethacin 11.2%), but significantly increased the AUC of the second challenge (placebo 55, indomethacin 114). The mean reduction in AUC from first to second challenge was 78% with placebo and 48% with indomethacin.(ABSTRACT TRUNCATED AT 250 WORDS)

Inhaled frusemide and exercise induced asthma: evidence of a role for inhibitory prostanoids

BACKGROUND

Inhaled frusemide protects subjects with asthma against a wide range of bronchoconstrictor challenges, including allergen, exercise and inhaled sodium metabisulphite. An investigation was designed to determine whether this protection is related to the production of inhibitory prostaglandins, such as prostaglandin E2 (PGE2), by studying the effect of the cyclooxygenase inhibitor indomethacin on the protection afforded by inhaled frusemide against exercise induced asthma.

METHODS

In a double blind crossover study 10 subjects with mild asthma were pretreated with indomethacin (50 mg thrice daily) or placebo capsules for three days; they then inhaled frusemide (40 mg) or placebo 10 minutes before an exercise test previously shown to cause a 20-30% fall in forced expiratory volume in one second (FEV1).

RESULTS

After inhalation of placebo exercise caused a similar maximum fall in FEV1 whether pretreatment was with placebo (26%) or indomethacin (25.2%). After inhalation of frusemide the maximum fall in FEV1 was reduced to 14.3% after placebo pretreatment and to 21.8% after indomethacin pretreatment; the difference between placebo and indomethacin pretreatment was significant (mean difference 7.5%, 95% limits 0.6%, 14.4%). The inhibitory effect of frusemide on the response to exercise, assessed as change in FEV1 over 30 minutes, was significantly greater with placebo (62%) than indomethacin (13%) pretreatment.

CONCLUSION

These findings support a role for inhibitory prostanoids, such as PGE2, in the beneficial effects of frusemide as a protection against exercise induced asthma.

Modification of bronchial reactivity by physiological concentrations of plasma epinephrine

Circulating epinephrine concentrations are altered in certain pathophysiological states, but whether such changes in epinephrine concentrations can alter bronchial responsiveness in subjects with asthma has not been studied. We studied 10 subjects with asthma in a double-blind crossover study on 4 nonconsecutive days. After measurement of baseline forced expiratory volume in 1 s (FEV1) and plasma epinephrine concentration, subjects were given placebo or 4, 16, or 64 ng.kg-1.min-1 epinephrine by intravenous infusion for 45 min. Blood was taken for plasma epinephrine concentration before the infusion and at 30 min, when a histamine challenge test was performed. Mean plasma epinephrine concentrations ranged from 0.37 nmol/l on placebo to 3.76 nmol/l with the 64-ng/kg infusion. FEV1 increased progressively with increasing concentrations of infused epinephrine, the mean change ranging from -0.051 on placebo to 0.331 after the highest concentration of epinephrine. The provocative dose of histamine causing a 20% fall in FEV1 increased progressively with increasing concentrations of infused epinephrine, geometric mean values ranging from 0.61 mumol with placebo to 1.7 mumol after the highest dose of epinephrine. Thus epinephrine, at physiological plasma concentrations, can modify bronchial reactivity.

Effect of inhaled budesonide on bronchial reactivity to histamine, exercise, and eucapnic dry air hyperventilation in patients with asthma

BACKGROUND

It has been suggested that inhaled corticosteroids may provide greater protection against constrictor stimuli that act indirectly such as exercise than those that act directly such as histamine.

METHODS

The effects of six weeks treatment with inhaled budesonide (800 micrograms twice daily) on bronchial reactivity to histamine, exercise, and eucapnic voluntary hyperventilation of dry air were compared in a double blind, placebo controlled, non-crossover study in 40 subjects with asthma. Change in bronchial reactivity to histamine and eucapnic hyperventilation over the six weeks was measured as change in the provocative dose of histamine or dry air causing a 20% fall in FEV1 (PD20 histamine and PV20 eucapnic hyperventilation (EVH) of dry air); this was not possible for exercise because of the development of refractoriness. To enable the change in response to all three stimuli to be compared, the response (percent fall in FEV1) to a fixed dose was measured for all three challenge tests.

RESULTS

After budesonide there was an increase in PD20 histamine from 0.48 to 2.81 mumol and in PV20 EVH from 364 to 639 litres, and a significant correlation between the changes in PD20 histamine and PV20 EVH (r = 0.63). The median percentage fall in FEV1 in response to eucapnic hyperventilation, exercise, and histamine was similar before budesonide (25.5%, 26.6%, and 24.5%); the reduction in the percentage fall in FEV1 with budesonide was also similar for the three challenges (18.9%, 17.5%, and 16.6%), and all differed significantly from the changes following placebo. There was a significant correlation between change in percentage fall in FEV1 after budesonide with the three stimuli (histamine v exercise: r = 0.48; histamine v eucapnic hyperventilation: r = 0.46; exercise v eucapnic hyperventilation: r = 0.63).

CONCLUSION

The similar magnitude of change in bronchial reactivity to all three stimuli after budesonide and the within subject correlation obtained between these changes suggest that corticosteroids act by a common mechanism to protect against eucapnic hyperventilation, exercise, and histamine.

Effect of inhaled prostaglandin E2 on bronchial reactivity to sodium metabisulphite and methacholine in patients with asthma

Inhaled frusemide protects against the bronchoconstrictor response to a wide range of stimuli that cause bronchoconstriction by indirect mechanisms. One possible explanation for this protection relates to the known ability of frusemide to enhance synthesis of prostaglandin E2 (PGE2). Studies in vitro suggest that PGE2 might protect against indirectly acting bronchoconstrictor challenges rather than those that act directly on airway smooth muscle, though little is known about the effects of PGE2 in vivo. The effect of inhaled PGE2 on the bronchoconstrictor response to inhaled sodium metabisulphite (a stimulus with an indirect action) and methacholine (which acts directly on airway smooth muscle) was studied in nine patients with asthma. Subjects were studied on four days, inhaling PGE2 (100 micrograms) or placebo in a double blind fashion followed immediately by a cumulative dose challenge with sodium metabisulphite or methacholine. The response to the constrictor stimuli was measured as the provocative dose causing a 20% fall in FEV1 (PD20). There was no significant change in FEV1 after inhaled PGE2 compared with placebo, nor any significant change in the response to methacholine; the geometric mean methacholine PD20 was 0.9 mumol after PGE2 and 0.56 mumol after placebo (mean difference 0.7 (95% confidence limits--0.1, 1.5) doubling doses). PGE2, however, protected against sodium metabisulphite, the geometric mean sodium metabisulphite PD20 being 11.8 mumol after PGE2 and 1.8 mumol after placebo (mean difference 2.5 (95% CL 1.9, 3.1) doubling doses). PGE2 conferred significantly greater protection against sodium metabisulphite than methacholine (mean difference 1.8 (95% CL 0.8, 2.8) doubling doses). This suggests that PGE2, like frusemide, has an inhibitory effect on pathways relevant to the bronchoconstriction induced by sodium metabisulphite, with little or no effect on those relevant to methacholine.

Time course of change in bronchial reactivity with an inhaled corticosteroid in asthma

The time course of change in FEV1, bronchial reactivity, and daily measures of asthma control (peak expiratory flow, symptoms, and beta 2-agonist inhaler use) was determined during 6 wk of treatment with inhaled budesonide, 800 micrograms twice a day, and for 2 wk following cessation of treatment in 40 asthmatic subjects in a double-blind, placebo-controlled, parallel group study. Histamine reactivity, expressed as the provocative dose of histamine causing a 20% fall in FEV1 (PD20), was measured at intervals during the 8 wk of the study, with more frequent measurements after the first and last dose of drug to provide a detailed profile of change at the start and end of treatment. The first dose of budesonide caused a small increase in median values of FEV1 (0.2 L) and PD20 (1.0 doubling dose of histamine), which was maximum at 6 h. There was a further increase in FEV1 and PD20 over the 6 wk in the budesonide group relative to placebo, the maximum increases (0.53 L, 3.4 doubling doses of histamine) being recorded 6 h after the last dose on Day 42. Following cessation of treatment, FEV1 and PD20 declined and PD20 returned to placebo values at 1 wk. Median PEF increased by 40 and 30 L/min in the morning and evening, respectively, with budesonide treatment. Symptom scores and beta 2-agonist inhaler use were lower in the budesonide group than the placebo group during treatment but tended to be similar (symptom scores) or higher (beta 2-agonist) in the 2 wk following cessation of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparison of the Yan and a dosimeter method for methacholine challenge in experienced and inexperienced subjects

Bronchial reactivity is being measured with increasing frequency in epidemiological studies, but there debate continues about the relative merits of the different methods used to measure reactivity, particularly for subjects with no previous experience of reactivity testing as is the case in epidemiological studies. Repeatability is likely to improve with practice, and laboratory based studies on experienced subjects may overestimate the repeatability of a test in inexperienced subjects. We have compared the repeatability of the Yan method with a dosimeter (Mefar) method of administering methacholine to 40 asthmatic subjects: 20 with experience of methacholine challenge on at least six previous occasions and 20 with no previous experience. Subjects attended the laboratory on four days within a two week period, at the same time of day. A methacholine challenge was performed on two occasions using the Yan method and on two occasions using the dosimeter. Methacholine responsiveness was measured as the provocative dose causing a 20% reduction in forced expiratory volume in one second (PD20FEV1). Geometric mean PD20FEV1 values with the Yan method were 1.14 doubling doses (DD) of methacholine higher than with the dosimeter method. In the experienced subjects, the 95% range for a single estimate was +/- 1.56 DD for the Yan method and +/- 1.37 DD for the dosimeter method. In the inexperienced subjects, the 95% ranges were +/- 2.65 and +/- 1.87 DD for the Yan and dosimeter methods, respectively. Thus, the differences in repeatability between the Yan and dosimeter methods, were small; experienced subjects gave more repeatable values than inexperienced subjects.

A comparison of the Yan and a dosimeter method for methacholine challenge in experienced and inexperienced subjects

Bronchial reactivity is being measured with increasing frequency in epidemiological studies, but there debate continues about the relative merits of the different methods used to measure reactivity, particularly for subjects with no previous experience of reactivity testing as is the case in epidemiological studies. Repeatability is likely to improve with practice, and laboratory based studies on experienced subjects may overestimate the repeatability of a test in inexperienced subjects. We have compared the repeatability of the Yan method with a dosimeter (Mefar) method of administering methacholine to 40 asthmatic subjects: 20 with experience of methacholine challenge on at least six previous occasions and 20 with no previous experience. Subjects attended the laboratory on four days within a two week period, at the same time of day. A methacholine challenge was performed on two occasions using the Yan method and on two occasions using the dosimeter. Methacholine responsiveness was measured as the provocative dose causing a 20% reduction in forced expiratory volume in one second (PD20FEV1). Geometric mean PD20FEV1 values with the Yan method were 1.14 doubling doses (DD) of methacholine higher than with the dosimeter method. In the experienced subjects, the 95% range for a single estimate was +/- 1.56 DD for the Yan method and +/- 1.37 DD for the dosimeter method. In the inexperienced subjects, the 95% ranges were +/- 2.65 and +/- 1.87 DD for the Yan and dosimeter methods, respectively. Thus, the differences in repeatability between the Yan and dosimeter methods, were small; experienced subjects gave more repeatable values than inexperienced subjects.

Alterations in brain phosphate metabolite concentrations in patients with human immunodeficiency virus infection

Human immunodeficiency virus (HIV)-infected individuals often demonstrate neuropsychiatric impairment; however, it is unclear how brain metabolism may be altered in such patients. We used in vivo phosphorus 31 magnetic resonance spectroscopy to noninvasively assess brain energy and phospholipid metabolism by measuring brain concentrations of adenosine triphosphate (ATP), phosphocreatine (PCr), and inorganic phosphate (Pi), as well as phospholipid compounds and intracellular pH. In study 1, 17 HIV-seropositive men with varying degrees of neuropsychiatric impairment and six control subjects were studied. Localized spectra were obtained from a heterogeneous 5 x 5 x 5-cm volume of interest (VOI). Patients with HIV infection had a significantly lower ATP/Pi ratio and a trend for a lower PCr/Pi ratio than did the control group. In addition, the ATP/Pi and PCr/Pi ratios were both significantly negatively correlated with overall severity of neuropsychiatric impairment. In study 2, three HIV-seropositive men with neuropsychiatric impairment were compared with 11 HIV-seronegative men. Localized phosphorus 31 magnetic resonance spectra were obtained from two relatively homogeneous VOIs: (1) a predominantly white matter VOI, and (2) a predominantly subcortical gray matter VOI. The three HIV-infected patients demonstrated significantly decreased ATP and PCr concentrations in the white matter VOI. These results suggest that HIV infection of the brain may impair brain cellular oxidative metabolism and that the degree of metabolic compromise may be related to the severity of neuropsychiatric impairment.

Effect of yoga breathing exercises (pranayama) on airway reactivity in subjects with asthma

The effects of two pranayama yoga breathing exercises on airway reactivity, airway calibre, symptom scores, and medication use in patients with mild asthma were assessed in a randomised, double-blind, placebo-controlled, crossover trial. After baseline assessment over 1 week, 18 patients with mild asthma practised slow deep breathing for 15 min twice a day for two consecutive 2-week periods. During the active period, subjects were asked to breathe through a Pink City lung (PCL) exerciser--a device which imposes slowing of breathing and a 1:2 inspiration:expiration duration ratio equivalent to pranayama breathing methods; during the control period, subjects breathed through a matched placebo device. Mean forced expiratory volume in 1 s (FEV1), peak expiratory flow rate, symptom score, and inhaler use over the last 3 days of each treatment period were assessed in comparison with the baseline assessment period; all improved more with the PCL exerciser than with the placebo device, but the differences were not significant. There was a statistically significant increase in the dose of histamine needed to provoke a 20% reduction in FEV1 (PD20) during pranayama breathing but not with the placebo device. The usefulness of controlled ventilation exercises in the control of asthma should be further investigated.