Effects of substance use screening and brief intervention on health-related quality of life

PURPOSE

Screening, brief intervention, and referral to treatment interventions have been shown to positively impact alcohol use. These programs utilize motivational interviewing techniques in an effort to reduce risky substance use among those at elevated risk of developing a disorder. However, there is a dearth of research assessing positive impacts above and beyond changes in alcohol use. This study examines potential benefits of brief interventions, utilizing motivation interviewing, on mental and physical quality of life.

METHODS

The present quasi-experimental study examined changes in health-related quality of life among individuals presenting at urban emergency departments. The analyses included the use of propensity score matching to minimize potential biases resulting from differences between groups at baseline.

RESULTS

The results indicated that the intervention group experienced significant increases in perceptions of mental health over those of the comparison group, regardless of changes in substance use.

CONCLUSIONS

These findings have implications for practice, as they suggest that brief substance abuse interventions delivered in the emergency department settings may have effects beyond those targeted by the intervention. Specifically, brief substance abuse interventions may positively impact mental health, thus enhancing the quality of life among targets of the intervention.

Commingling effect of gynoid and android fat patterns on cardiometabolic dysregulation in normal weight American adults

AIM

To determine the independent and commingling effect of android and gynoid percent fat (measured using Dual Energy X-Ray Absorptiometry) on cardiometabolic dysregulation in normal weight American adults.

METHODS

The 2005-2006 data (n=1802) from the United States National Health and Nutritional Examination Surveys (NHANES) were used in this study. Associations of android percent fat, gynoid percent fat and their joint occurrence with risks of cardiometabolic risk factors were estimated using prevalence odds ratios from logistic regression analyses.

RESULTS

Android-gynoid percent fat ratio was more highly correlated with cardiometabolic dysregulation than android percent fat, gynoid percent fat or body mass index. Commingling of android and gynoid adiposities was associated with much greater odds of cardiometabolic risk factors than either android or gynoid adiposities. Commingling of android and gynoid adiposities was associated with 1.75 (95% confidence interval (CI)=1.42-2.93), 1.48 (95% CI=1.32-1.91), 1.61 (95% CI=1.50-1.89), 3.56 (95% CI=2.91-4.11) and 1.86 (95% CI=1.49-1.96) increased odds of elevated glucose, elevated blood pressure, elevated low-density lipoprotein-cholesterol, elevated triglyceride and low high-density lipoprotein-cholesterol, respectively.

CONCLUSIONS

Normal weight subjects who present with both android and gynoid adiposities should be advised of the associated health risks. Both android and gynoid fat accumulations should be considered in developing public health strategies for reducing cardiometabolic disease risk in normal weight subjects.

Do medical courses adequately prepare interns for safe and effective prescribing in New South Wales public hospitals?

AIMS

To assess ability of interns immediately before starting clinical practice in New South Wales (NSW) teaching hospitals to prescribe medications safely and appropriately and to describe their impressions of the adequacy of their clinical pharmacology training in medical school.

METHODS

A cross-sectional study was performed on all interns (n= 191) who attended intern orientation programmes at four NSW hospitals in January 2008. A clinical case scenario that tested prescribing ability and a survey investigating impressions of clinical pharmacology training in medical school were administered to the interns in exam format. Outcome measures were: (i) ability to prescribe medications safely and appropriately for the clinical case scenario and (ii) interns' impressions of their training in clinical pharmacology at medical school.

RESULTS

No intern completed all prescribing tasks correctly. No intern charted the patient's usual medications on admission completely correctly, only six wrote an accurate discharge medication list, and none wrote both an accurate discharge medication list and a legal Schedule 8 discharge script. None of the respondents strongly agreed that they felt adequately trained to prescribe medications in their intern year and 84% would have liked to have more training in pharmacology as medical students.

CONCLUSIONS

Interns about to commence clinical practice in NSW teaching hospitals demonstrated significant deficits in prescribing of regular medications, initiation of new therapies, prescribing of discharge medications, and particularly prescribing of Schedule 8 medications. Most interns recognized these deficits and would have liked more clinical pharmacology training at medical school.

Inhibition of mast cell PGD2 release protects against mannitol-induced airway narrowing

Mannitol inhalation increases urinary excretion of 9alpha,11beta-prostaglandin F2 (a metabolite of prostaglandin D2 and marker of mast cell activation) and leukotriene E4. The present study tested the hypothesis that beta2-adrenoreceptor agonists and disodium cromoglycate (SCG) protect against mannitol-induced bronchoconstriction by inhibition of mast cell mediator release. Fourteen asthmatic subjects inhaled mannitol (mean dose 252+/-213 mg) in order to induce a fall in forced expiratory volume in one second (FEV1) of > or = 25%. The same dose was given 15 min after inhalation of formoterol fumarate (24 microg), SCG (40 mg) or placebo. Pre- and post-challenge urine samples were analysed by enzyme immunoassay for 9alpha,11beta-prostaglandin F2 and leukotriene E4. The maximum fall in FEV1 of 32+/-10% on placebo was reduced by 95% following formoterol and 63% following SCG. Following placebo, there was an increase in median urinary 9alpha,11beta-prostaglandin F2 concentration from 61 to 92 ng.mmol creatinine(-1), but no significant increase in 9alpha,11beta-prostaglandin F2 concentration in the presence of either formoterol (69 versus 67 ng.mmol creatinine(-1)) or SCG (66 versus 60 ng.mmol creatinine(-1)). The increase in urinary leukotriene E4 following placebo (from 19 to 31 ng.mmol creatinine(-1)) was unaffected by the drugs. These results support the hypothesis that the drug effect on airway response to mannitol is due to inhibition of mast cell prostaglandin D2 release.

Poor health is associated with episodic heavy alcohol use: evidence from a National Survey

OBJECTIVES

The objective of this study was to examine the relationship between self-rated health and episodic heavy drinking in a representative sample of American adults. We also sought to determine ethnic and gender differences in the association between self-rated health and episodic heavy drinking.

METHODS

Data (n=4649) from the Third US National Health and Nutrition Examination Survey were utilized for this investigation. Episodic heavy drinking was defined as the consumption of five or more and four or more alcoholic beverages on one occasion for men and women, respectively. Poor health was defined as answering fair or poor to the question: "Would you say your health in general is excellent, very good, good, fair or poor?" Odds ratio from the logistic linear regression analysis was used to estimate the risk for poor health that was associated with episodic heavy drinking. Statistical adjustments were made for age, hypertension, diabetes, current smoking, body mass index and race/ethnicity.

RESULTS

Overall, episodic heavy drinking was associated with increased odds of poor self-rated health in men and women. In men, episodic heavy drinking was independently associated with 1.28 (95% CI: 1.07-1.82) increased odds of poor health. The corresponding value in women was 1.86 (95% CI: 1.05-2.28). In men, being Black was associated with approximately two-fold (OR=1.96; 95% CI: 1.33, 2.89), and being Hispanic was associated with approximately four-fold (OR=3.59; 95% CI: 2.50, 5.14) increased odds of poor self-rated health relative to being White. The corresponding odds ratios in women were 2.97 (95% CI: 1.90, 4.64) and 5.18 (95% CI: 3.23, 8.30). Associations were greater among blacks (adjusted OR=2.41; 95% CI: 1.81-3.22) and Hispanics (adjusted OR=4.15; 95% CI: 3.12-5.52) than among whites.

CONCLUSIONS

Poor health is associated with episodic heavy alcohol consumption. Public health strategies to curb alcohol abuse may improve self-reported health status in these at-risk populations.

Effects of terbutaline in combination with mannitol on mucociliary clearance

Beta2-agonists and osmotic agents stimulate mucociliary clearance (MCC) via different mechanisms which could potentially interact. The effects of inhaling terbutaline in combination with mannitol on MCC were investigated in nine healthy (aged 19+/-1 yrs) and 11 mild (aged 21+/-4 yrs) asthmatic subjects. Using 99mTc-sulphur colloid radioaerosol and a gamma camera, MCC was studied on four separate days with each of the following interventions: 1) terbutaline or its placebo inhaled 10 min before mannitol (in random, double blind); 2) terbutaline inhaled 5 min after mannitol; and 3) terbutaline inhaled 10 min before the control for mannitol. Lung images were collected over a period of 120 min postintervention and over 150 min in total. The mannitol-induced increase in clearance was transiently inhibited by terbutaline pretreatment and transiently enhanced when terbutaline was administered after mannitol both in asthmatic and healthy subjects. The order of administration of mannitol and terbutaline did not affect the total clearance of radioactive mucus over 140 min from the start of intervention in both groups. The pathways through which terbutaline and mannitol increase mucociliary clearance may transiently interact in an inhibitory or synergistic way, depending on the order of administration. However, this did not affect the overall increase in mucociliary clearance over 140 min.

Clinical pharmacokinetics of inhaled budesonide

The corticosteroid budesonide is a 1:1 racemic mixture of 2 epimers, (22R)- and (22S)-, and is available in 3 different inhaled formulations for the management of asthma: a pressurised metered dose inhaler (pMDI), a dry powder inhaler (DPI) and a solution for nebulised therapy. Inhaled corticosteroids such as budesonide reach the systemic circulation either by direct absorption through the lungs (a route that is much more important than previously recognised) or via gastrointestinal absorption of drug that is inadvertently swallowed. Although the pharmacokinetics of budesonide have been extensively investigated following oral and intravenous administration, relatively few studies have defined the systemic disposition of budesonide after inhalation. Drug deposition in the lungs depends on the inhaler device: 15% of the metered dose of budesonide reached the lung with a pMDI compared with 32% with a breath-actuated DPI. In patients with asthma (n = 38) receiving different doses of budesonide by DPI (Turbuhaler), the pharmacokinetic parameters peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) were dose-dependent after both single dose and repeat dose (3 weeks) administration: time to Cmax (tmax) was short (0.28 to 0.40 hours) and the elimination half-life approximately 3 hours. Both AUC and Cmax were linearly related to budesonide dose. In a small group of healthy male volunteers (n = 9), the pharmacokinetics of budesonide 1,600 microg twice daily via pMDI were assessed on the fifth day of administration. Mean model-independent parameters for (22R)-budesonide were as follows: Cmax 1.8 microg/L, tmax 0.46 hours, elimination half-life 2.3 hours and oral clearance 163 L/h, and there were no enantiomer-specific differences in drug disposition. Budesonide undergoes fatty acid conjugation within the lung, but very limited pharmacokinetic data are available to define the pulmonary absorption characteristics. There is evidence from a population analysis that the pulmonary absorption of budesonide is prolonged and shows wide interindividual variation. Further pharmacokinetic studies are required to define the time-course of budesonide absorption through the lung in specific patient groups, and to investigate the effect of new inhaler devices (especially chlorofluorocarbon-free pMDIs) on the pharmacokinetic profile and systemic drug exposure.

Quantification of epimeric budesonide and fluticasone propionate in human plasma by liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry

A highly sensitive and selective liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry assay was developed and validated for simultaneous determination of epimeric budesonide (BUD) and fluticasone propionate (FP) in plasma. The drugs were isolated from human plasma using C18 solid-phase extraction cartridges, and epimeric BUD was acetylated with a mixture of 12.5% acetic anhydride and 12.5% triethylamine in acetonitrile to form the 21-acetyl derivatives following the solid-phase extraction. Deuterium-labelled BUD acetate with an isotopic purity >99% was synthesized and used as the internal standard. The assay was linear over the ranges 0.05-10.0 ng/ml for epimeric BUD, and 0.02-4.0 ng/ml for FP. The inter- and intra-day relative standard deviations were <14.3% in the assay concentration range.

Fexofenadine decreases sensitivity to and montelukast improves recovery from inhaled mannitol

We studied, separately, the effects of the histamine antagonist, fexofenadine hydrochloride, and the leukotriene antagonist, montelukast sodium, and their placebos on airway sensitivity to and recovery from inhaled mannitol in subjects with asthma. Two 180-mg doses of fexofenadine were taken over 14 h, and three 10-mg doses of montelukast over 36 h, with the last dose 5 h before challenge. Fexofenadine reduced sensitivity to mannitol and the PD(15) was (mean [95% confidence interval] 138 [95, 201]) mg versus placebo (51 [25, 106] mg) (p < 0.001). The final percent reduction in FEV(1) with fexofenadine was 20.8 +/- 5.4% and not different from placebo (20.1 +/- 5.3%) (p = 0.7); however, recovery was slower with fexofenadine compared with placebo (p < 0.001). By contrast, montelukast had no effect on sensitivity to mannitol and the PD(15) was 71 [36, 144] mg versus placebo (87 [51, 148] mg (p = 0.35). The total dose of mannitol delivered and the final percent reduction in FEV(1) with montelukast were 171 +/- 142 mg and 21 +/- 4% and for placebo were 182 +/- 144 mg and 20 +/- 5% (p = 0.35, p = 0.59, respectively). However, recovery of FEV(1) to baseline was faster with montelukast, with the area under the percent reduction FEV(1)-versus-time curve reduced (220 +/- 121% change.min) compared with placebo (513 +/- 182% change.min) (p < 0.001). We conclude that whereas histamine is important for the initial airway response, leukotrienes are important in sustaining the airway response to inhaled mannitol.

Impaired vascular responses to nitroglycerin in subjects with coronary atherosclerosis

To study smooth muscle function in atherosclerosis, we calculated dose-response curves in patients with coronary artery disease and in controls by measuring changes in brachial artery diameter after incremental sublingual doses of nitroglycerin. The doses required to produce a 50% maximal dilator response were significantly higher in patients with coronary artery disease than in controls (p <0.002), suggesting smooth muscle dysfunction in atherosclerosis.

Possible interactions between angiotensin II and insulin: effects on glucose and lipid metabolism in vivo and in vitro

Angiotensin II (ANGII) increases insulin sensitivity in diabetic and non-diabetic subjects, even at subpressor doses, and because there is 'crosstalk' between ANGII and insulin-signaling pathways the underlying mechanism may not be due solely to changes in regional blood flow. A series of experimental studies was undertaken to evaluate the effects of ANGII on glucose and lipid metabolism in vivo and in vitro. Groups of fructose-fed, insulin-resistant Sprague-Dawley (SD) rats were pre-treated with 0.3 mg/kg per day of the AT(1)-receptor antagonist L-158 809 (n=16), or vehicle (n=16), by oral gavage. This was prior to an oral glucose tolerance test (day 5) and measurement of the effects of ANGII infusion (20 ng/kg per min i.v. for 3 h) on whole-body insulin sensitivity using the insulin suppression test (day 7). The effect of ANGII infusion on total triglyceride secretion rate (TGSR) was evaluated in normal SD rats pretreated for 7 days with L-158 809 (n=12) or vehicle (n=12). AT(1)- and AT(2)- receptor mRNA expression and [(3)H]2-deoxyglucose uptake were assessed in cultured L6 myoblasts. Short-term treatment with L-158 809 had no effect on glucose tolerance or fasting triglyceride levels in fructose-fed rats. ANGII infusion had no effect on insulin sensitivity in fructose-fed rats pretreated with vehicle (steady-state plasma glucose (SSPG) values 8.1+/-1.6 vs 8. 4+/-0.4 mmol/l), but pretreatment with L-158 809 resulted in ANGII having a modest insulin antagonist effect in this insulin-resistant model (SSPG values 9.6+/-0.3 vs 7.1+/-0.6, P<0.03). ANGII infusion had no significant effect on TGSR (e.g. 24.6+/-1.4 vs 28.4+/-0.9 mg/100 g per h in vehicle-treated animals). RT-PCR analysis showed that L6 cells express both AT(1)- and AT(2)-receptor mRNA. Incubation with ANGII (10(-9) and 10(-8) M) had no significant effect on the dose-response curve for insulin-stimulated [(3)H]2-deoxyglucose uptake. For example, C(I200) values (dose of insulin required to increase glucose uptake by 200%) were 4.5 x 10(-9) M (control) vs 3.9 x 10(-9) M and 6.2 x 10(-9) M, whereas the positive control (glucagon-like peptide-1) increased insulin sensitivity. Thus, ANGII infusion may have a modest insulin antagonist effect on glucose disposal in insulin-resistant fructose-fed rats pretreated with an AT(1)-blocker, but ANGII has no effect on TGSR or in vitro glucose uptake in L6 myoblasts. These findings are relevant to recent clinical discussions about the metabolic effects of ANGII and renin-angiotensin system blockade.

Comparative kinetics of metabolism of beclomethasone propionate esters in human lung homogenates and plasma

The systemic availability of inhaled beclomethasone dipropionate (BDP) is the net result of the absorption of the glucocorticoid from the lower respiratory and gastrointestinal tracts, and metabolism in the lung, plasma, and other sites. The metabolism kinetics of BDP and its active metabolite, beclomethasone 17-monopropionate (17-BMP), in human lung 1000 x g supernatant (HLu) and human plasma (HP) at 37 degrees C were compared. The effect of MgCl(2) and/or an NADPH-generating system on the decomposition of BDP and 17-BMP in HLu was also investigated. The concentrations of BDP and its metabolites were determined by HPLC with UV detection at 242 nm. Kinetics of decomposition of BDP and 17-BMP in HLu and HP were qualitatively and quantitatively different. The decomposition of BDP in HLu involved only hydrolysis. In comparison, three reactions are involved following incubation of BDP in HP; namely, hydrolysis, transesterification, and loss of hydrogen chloride. The hydrolysis of BDP and 17-BMP in HLu seem to be inhibited appreciably by MgCl(2) with the NADPH-generating system. Effective activation of BDP in HLu, in combination with transesterification of 17-BMP in HP, might favor a high ratio of local antiinflammatory activity to systemic side effects following inhalation of BDP.

Optimizing the erythromycin breath test for use in cancer patients

The erythromycin breath test (EBT) is a putative in vivo probe for drug metabolism by cytochrome P450 3A4 (CYP3A4). Because many anticancer drugs are metabolized by this system, we sought to further develop the EBT as a tool for predicting the clearance, in cancer patients, of drugs metabolized by CYP3A4. Sixteen adult patients with incurable cancer were studied. The EBT was performed on day 1 and breath sampled after the i.v. injection of 4 microCi of 14C-erythromycin. The breath 14CO2 flux (CERt) was estimated at 11 time points over 2 h. On day 2, the EBT was repeated midway through a 10-min infusion of 100 mg of erythromycin lactobionate, and the plasma pharmacokinetics of erythromycin were determined. The infusion of 100 mg of erythromycin did not modify the EBT results significantly. The values of the conventional EBT parameter CER20 min obtained on day 1 were comparable for most subjects (0.03-0.06% dose/min), with the exception of an individual receiving the known CYP3A4 inducers dexamethasone and phenytoin who returned a value of 0.14% dose/min. There was no significant correlation between any of the conventional EBT parameters and erythromycin clearance. However, two parameters reflecting early emergence of breath radioactivity (1/TMAX and CER3 min/CERMAX) correlated significantly with erythromycin clearance (P = 0.005 and 0.006, respectively). Novel parameters derived from the EBT are significantly correlated with the clearance of erythromycin even in the presence of confounding factors, such as metastatic liver disease, altered protein binding, and comedication. These parameters may enable dose optimization of cytotoxics metabolized by CYP3A4.

Metabolism kinetics of beclomethasone propionate esters in human lung homogenates

PURPOSE

The purposes of this study were to characterize the kinetics of beclomethasone dipropionate (BDP) and its 17-monopropionate ester (17-BMP) in human lung 1000g supernatant (HLu) at 37 degrees C, and to analyze the interindividual variability in the metabolism of BDP in HLu.

METHODS

The concentrations of BDP and its metabolites were determined by HPLC with UV detection at 242 nm. Kinetics of BDP and 17-BMP decomposition were characterized by least-squares fitting of rate equations.

RESULTS

The active metabolite 17-BMP was rapidly formed following the incubation of BDP in HLu. Kinetics of BDP and 17-BMP in HLu were nonlinear owing to product inhibition and enzyme saturation. A model taking into account the product inhibition provides a kinetic basis for understanding the in vivo behavior of BDP and its metabolites in human lung. There was approximately a 3.5-fold difference in the initial half-life of BDP in HLu observed in seven subjects.

CONCLUSIONS

An effective activation of BDP was demonstrated in HLu through the rapid formation of 17-BMP. Kinetics of BDP and 17-BMP in HLu were well characterized by the nonlinear kinetic model. Interindividual difference in the initial half-life of BDP was due mainly to esterase metabolizing activity rather than binding affinity.

Pharmacokinetics of epimeric budesonide and fluticasone propionate after repeat dose inhalation--intersubject variability in systemic absorption from the lung

AIMS

Pharmacokinetic variability is likely to be a significant factor contributing to the interindividual differences in dose requirements, anti-inflammatory response and side-effects with inhaled corticosteroids (ICS), but there is limited information about the disposition of ICS during regular dosing with a pressurized metered dose inhaler (pMDI). This study uses a mixed effects modelling approach to quantify and compare the interindividual variability in pharmacokinetics of epimeric budesonide (BUD) and fluticasone propionate (FP) after repeat-dose inhalation.

METHODS

This pharmacokinetic substudy was part of a previously published open-label, randomised, placebo-controlled, 7-period crossover study to evaluate the short-term effects on plasma cortisol levels of inhaled BUD (400, 800, 1600 microg twice daily) and FP (375, 750, 1000 microg twice daily) via pMDI in a group of healthy male volunteers. On the fifth day of each high-dose treatment period (BUD 1600 microg twice daily and FP 1000 microg twice daily), venous blood samples were collected in nine subjects prior to the last dose and at 15 min, 30 min, 1, 2, 4, 6 and 8 h postdose for measurement of plasma drug concentrations to determine the pharmacokinetics of epimeric BUD and FP following inhalation. Non-compartmental analysis and a mixed effects model were used to characterize the disposition profiles.

RESULTS

Both drugs had a rapid absorption half-life (BUD 10 min vs FP 11.3 min), but quite different elimination half-lives (BUD 2.4 h vs FP 7.8 h). Although there were intraindividual differences in the handling of the 22R-and 22S-epimers of BUD, there were no consistent pharmacokinetic differences between the two enantiomers in the group as a whole. Consistent with previous reports of FP's higher volume of distribution (V) and lower systemic bioavailability (F), the V/F ratio was lower for BUD than FP (498 l vs 8100 l). The parameter with the greatest interindividual variability for both BUD and FP was the rate of systemic absorption from the lung.

CONCLUSIONS

This is the first report describing the pharmacokinetics of epimeric BUD and FP after repeat dose inhalation via pMDI. Three observations may be of clinical relevance: (1) there is considerable intersubject variability in the rate of absorption of both drugs from the lung; (2) in some individuals there was a long t(1/2),z for BUD, resulting in higher and more sustained plasma drug levels in the 4-12 h postdose period than would be predicted from single-dose pharmacokinetic data; and (3) there is evidence of diurnal variation in FP pharmacokinetics, with higher-than-expected plasma drug concentrations in the morning compared with the evening.

Differential potency of beclomethasone esters in-vitro on human T-lymphocyte cytokine production and osteoblast activity

Beclomethasone dipropionate is an inhaled corticosteroid, used for the treatment of asthma. It is metabolised to 17-beclomethasone monopropionate, which has greater affinity for corticosteroid receptors than the parent compound, and to beclomethasone. We investigated the potency of beclomethasone dipropionate, 17-beclomethasone monopropionate and beclomethasone (compared with dexamethasone as a reference steroid) in two different human cell types, peripheral blood mononuclear cells and osteoblasts. We found that beclomethasone dipropionate, 17-beclomethasone monopropionate (EC50 10(-14) M) and beclomethasone (EC50 approx. 10(-12) M) were much more potent than dexamethasone (EC50 10(-8) M) in inhibiting interleukin-5 production by peripheral blood mononuclear cells. In contrast, beclomethasone dipropionate, 17-beclomethasone monopropionate and beclomethasone were equipotent with dexamethasone (EC50 range 0.3-1.2 x 10(-9) M) in affecting several functional assays of osteoblasts (e.g. alkaline phosphatase activity and osteocalcin synthesis). These results show that the relative bioactivities of corticosteroids vary between different human cell types, and that affinities observed in receptor binding assays are not necessarily predictive of the bioactivity in cell populations, such as peripheral blood mononuclear cells and osteoblasts, which are putatively relevant to efficacy and side effects respectively.

Do subjects with asthma have greater perception of acute bronchoconstriction than smokers with airflow limitation?

OBJECTIVE

Smokers who develop chronic airflow limitation (CAL) do not usually present for medical attention until their lung disease is well advanced. In contrast, asthmatic subjects experience acute symptoms and present for care early in the course of their disease. The aim of this study was to determine whether subjects with asthma differ from smokers with CAL in their ability to perceive acute methacholine-induced bronchoconstriction.

METHODOLOGY

Thirteen subjects with diagnosed asthma and 10 current smokers with CAL, defined as forced expiratory volume in 1 s (FEV1) < 75% predicted and FEV1/forced vital capacity < 80%, with no previous diagnosis of asthma, were challenged with methacholine. Symptom severity was recorded on a Borg scale. Lung volumes were measured before challenge and after the FEV1 had fallen by 20%.

RESULTS

After methacholine falls in FEV1 were similar in the asthmatic subjects and smokers. The regression lines relating change in FEV1 to symptom score were significantly steeper in asthmatic subjects than smokers (0.13 +/- 0.04, 0.03 +/- 0.04, respectively, P < 0.01). At 20% fall in FEV1 there were no significant differences between asthmatic subjects and smokers in the magnitude of change of lung volumes.

CONCLUSIONS

In asthmatic subjects, symptoms are closely related to change in FEV1. In smokers with CAL, symptoms change little during bronchial challenge despite large changes in FEV1. The differences in perception between the two subject groups are not due to differences in acute hyperinflation during challenge. We propose that heavy smokers may adapt to poor lung function, or may have damaged sensory nerves as a result of prolonged cigarette smoking.

Tissue- and isoform-specific effects of aging in rats on protein kinase C in insulin-sensitive tissues

The mechanisms responsible for the age-related decline in insulin sensitivity have not been clearly identified, but activation of the diacylglycerol/protein kinase C (PKC) signalling pathway (often confined to individual isoforms of PKC) has recently been implicated in the pathogenesis of other insulin-resistant states in both humans and animal models. Fasting serum glucose, insulin and triacylglycerol (triglyceride) concentrations, and results of oral glucose tolerance tests, were compared in groups of 6-week-old (n=8) and 6-month-old (n=8) Sprague-Dawley rats. Insulin-responsive tissues (liver, soleus muscle and epididymal fat pad) were collected to compare levels of diacylglycerol, PKC enzyme activity and protein expression of individual PKC isoforms in cytosol and membrane fractions. The older group were heavier (556+/-14 g, compared with 188+/-7 g) and relatively insulin-resistant and hyperinsulinaemic (477+/-73 pM compared with 293+/-51 pM; P<0.05) compared with young rats; they also had greater areas under the serum glucose (old, 20. 3+/-1.1; young, 17.3+/-0.7 mmol.h(-1).l(-1)) and insulin (old, 1254+/-76; young, 721+/-113 mmol.h(-1).l(-1)) profiles following an oral glucose tolerance test, and significantly higher fasting triacylglycerol levels (old, 1.24+/-0.06 mM; young, 0.92+/-0.07 mM; P<0.01). There were no age-related differences in diacylglycerol levels or PKC activity in muscle and liver, but membrane-associated PKC activity was 2.5-fold higher in the adipose tissue of older rats (101+/-19 compared with 40+/-5 pmol.min(-1).mg(-1) protein; P<0.05) due to increased translocation of PKC-beta(I), -beta(II) and -epsilon. Thus insulin resistance due to normal aging is associated with tissue- and isoform-specific changes in diacylglycerol/PKC signalling. In contrast with diabetes and dietary-induced insulin resistance, there were no changes in diacylglycerol/PKC signalling in skeletal muscle and liver, but isoform-specific translocation and higher PKC activity in adipose tissue may blunt the insulin-mediated inhibition of lipolysis and contribute to the increased triacylglycerol levels observed in older animals.

Tissue and isoform-selective activation of protein kinase C in insulin-resistant obese Zucker rats - effects of feeding

The mechanisms of insulin resistance in the obese Zucker rat have not been clearly established but increased diacylglycerol-protein kinase C (DAG-PKC) signalling has been associated with decreased glucose utilisation in states of insulin resistance and non-insulin-dependent diabetes mellitus. The purpose of this study was to characterise tissue- and isoform-selective differences in DAG-PKC signalling in insulin-sensitive tissues from obese Zucker rats, and to assess the effects of feeding on DAG-PKC pathways. Groups of male obese (fa/fa, n=24) and lean (fa/-, n=24) Zucker rats were studied after baseline measurements of fasting serum glucose, triglycerides, insulin and oral glucose tolerance tests. Liver, epididymal fat and soleus muscle samples were obtained from fed and overnight-fasted rats for measurements of DAG, PKC activity and individual PKC isoforms in cytosol and membrane fractions. Obese rats were heavier (488+/-7 vs 315+/-9 g) with fasting hyperglycaemia (10.5+/-0.8 vs 7.7+/-0.1 mM) and hyperinsulinaemia (7167+/-363 vs 251+/-62 pM) relative to lean controls. In fasted rats, PKC activity in the membrane fraction of liver was significantly higher in the obese group (174+/-16 vs 108+/-12 pmol/min/mg protein, P<0.05) but there were no differences in muscle and fat. The fed state was associated with increased DAG levels and threefold higher PKC activity in muscle tissue of obese rats, and increased expression of the major muscle isoforms, PKC-theta and PKC-epsilon: e.g. PKC activity in the membrane fraction of muscle from obese animals was 283+/-42 (fed) vs 107+/-20 pmol/min/mg protein (fasting) compared with 197+/-27 (fed) and 154+/-21 pmol/min/mg protein (fasting) in lean rats. In conclusion, hepatic PKC activity is higher in obese rats under basal fasting conditions and feeding-induced activation of DAG-PKC signalling occurs selectively in muscle of obese (fa/fa) rats due to increased DAG-mediated activation and/or synthesis of PKC-theta and PKC-epsilon. These changes in PKC are likely to exacerbate the hyperglycaemia and hypertriglyceridaemia associated with obesity-induced diabetes.

Perception of bronchodilation in subjects with asthma and smokers with airflow limitation

Perception of the efficacy of bronchodilators in relieving airflow obstruction is a likely determinant of compliance with treatment in patients prescribed these drugs on an 'as needed' basis. This study aimed to determine whether bronchodilator-induced improvements in lung function are associated with improvements in breathing difficulty in subjects with asthma or smokers with airflow limitation. Twenty smokers with airflow limitation and 16 subjects with previously physician-diagnosed asthma received salbutamol (200 micrograms) and ipratropium bromide (80 micrograms). Spirometry and lung volumes were measured before and 40 min after bronchodilator. Subjects recorded changes in 'difficult breathing' on a visual analogue scale (VAS). After bronchodilator, forced expiratory volume in 1 s (FEV1) increased by 23.0 +/- 6.4% of baseline (mean +/- 95% CI) in smokers, and by 25.2 +/- 8.5% in the asthmatics, while VAS improved by 31 +/- 23% in smokers and 45 +/- 25% in asthmatics. However, these changes were not significantly correlated in either smokers (r = -0.04) or asthmatics (r = 0.15). In the asthmatic subjects, good perceivers (> 25% improvement in VAS) had greater improvements in lung volumes, as percentage predicted, than did poor perceivers. In the smokers, changes in lung function did not differ significantly between good and poor perceivers. Improvement in FEV1, as percentage predicted, was significantly correlated with improvement in VAS in good perceivers (asthma: r = 0.78, P < 0.01; smokers: r = 0.68, P < 0.05), but not in poor perceivers. Asthmatic subjects had good perception of improvements in lung function. However, in smokers with airflow limitation there is little correlation between improvement in lung function and sensation of breathing difficulty. In these subjects symptoms appear to be an unreliable guide for 'as needed' use of bronchodilators.

Fulminant psittacosis requiring mechanical ventilation and demonstrating serological cross-reactivity between Legionella longbeachae and Chlamydia psittaci

Chlamydia psittaci infection typically causes a mild respiratory illness in humans. Severe respiratory failure requiring mechanical ventilation or intensive care therapy is an uncommon development. The aetiological agents causing severe community acquired pneumonia often remain undetermined. Serological tests may aid in diagnosis. We present two cases of fulminant psittacosis, one demonstrating early cross-reactivity with Legionella longbeachae.

Comparative effects of anti-inflammatory corticosteroids in human bone-derived osteoblast-like cells

While effects of inhaled corticosteroids on serum markers of bone metabolism in normal and asthmatic subjects have been reported, there are little data on the direct effects of these corticosteroids on end-organs such as bone. The results presented here compare the effects of budesonide and its epimers (22S- and 22R-budesonide), fluticasone and dexamethasone on growth and differentiation of cultured human bone cells. Osteoblast-like cells were cultured from human foetal bone chips grown to confluence and used at first subculture. At concentrations of 10(-11)-10(-7) M each corticosteroid (CS) caused a dose-dependent decrease in [3H]thymidine incorporation into deoxyribonucleic acid (DNA), median effective concentration (EC50): fluticasone (0.06 nM) >22R (0.26 nM) >22S (0.4 nM) >budesonide (0.47 nM) >dexamethasone (1.5 nM). Each CS resulted in a dose-dependent increase in alkaline phosphatase activity, EC50: fluticasone (0.14 nM) >22R (0.2 nM)=22S (0.2 nM) >budesonide (0.4 nM) >dexamethasone (1.6 nM). The 1,25 dihydroxyvitamin D3 (1,25(OH)2D3)-stimulated osteocalcin production was decreased in the presence of each CS, EC50: fluticasone (0.02 nM) >22S (0.1 nM) >22R (0.2 nM) >budesonide (1.0 nM) >dexamethasone (1.8 nM). In human bone cells the potencies of fluticasone and budesonide in relation to dexamethasone are not dissimilar to those derived from human lymphocytes in vitro.

Metabolic effects of thioctic acid in rodent models of insulin resistance and diabetes

1. The antioxidant thioctic acid (TA) has been used in the treatment of diabetic neuropathy and recent studies have suggested that TA also has pancreatic and peripheral effects that improve glucose transport and metabolism. In the present study, the metabolic effects of TA were evaluated in rodent models of insulin resistance (fructose-fed Sprague-Dawley rat) and insulin deficiency (streptozotocin (STZ)-induced diabetic rat). Oral and intravenous glucose tolerance tests (OGTT and IVGTT, respectively) were performed in conscious rats after treatment with 50 mg/kg per day TA or vehicle for 5 days. 2. Fructose feeding for 7 days induced insulin resistance and impaired glucose tolerance and hypertriglycerideaemia. Treatment of fructose-fed rats with TA had no significant effect on fasting or stimulated glucose levels or on fasting triglyceride concentrations (e.g. the area under the curve for glucose (AUCglu) following OGTT was 1233 +/- 67 and 1284 +/- 59 in fructose-fed rats treated with either TA (n = 12) or vehicle (n = 12), respectively). Similarly, TA had no significant effect on IVGTT profiles in fructose-induced insulin resistance. 3. Low-dose STZ (80 mg/kg, i.p., over 2 days) induced hyperglycaemia, but TA had no significant glucose-lowering effects in STZ-diabetic rats (AUCglu (OGTT) following oral administration was 5507 +/- 27 and 5450 +/- 27 in TA (n = 12) and vehicle-treated (n = 12) rats, respectively). Nor did pretreatment with TA affect the diabetogenic response to STZ. 4. In contrast with previous in vitro studies reporting favourable metabolic effects of TA, the present study shows that after short-term oral therapy there are no significant improvements in glucose tolerance in rodent models of insulin resistance and insulin deficiency. Thioctic acid is unlikely to be of therapeutic benefit as an anti-diabetic drug in clinical practice.

The renal excretory mechanisms and the role of organic cations in modulating the renal handling of paraquat

Paraquat (PQ), a cationic herbicide, is predominantly excreted by the kidneys, but it is also nephrotoxic. It is thought to cause damage to proximal renal epithelial cells, which results in acute renal failure. The precise mechanism by which PQ is excreted by the kidney has not been fully elucidated, although current evidence indicates that it is actively secreted via a cation transport system. This review examines the renal cytotoxic effect and excretory mechanisms of PQ, and the role of organic cations in modulating the renal handling of PQ.

Smooth muscle dysfunction occurs independently of impaired endothelium-dependent dilation in adults at risk of atherosclerosis

OBJECTIVES

We sought to assess smooth muscle function in adults at risk for atherosclerosis.

BACKGROUND

Previous studies in subjects at risk for atherosclerosis have demonstrated arterial endothelial dysfunction, with reduced vasodilator responses after pharmacologic or physiologic stimulation of endothelial nitric oxide (NO). Most have also shown a slight but nonsignificant impairment of vasodilation in response to exogenous sources of NO, such as nitroglycerin (NTG). We hypothesized that NTG responses might be reduced in a large number of consecutively studied adults at risk for atherosclerosis, independent of any impaired endothelium-dependent responses, consistent with concomitant smooth muscle dysfunction.

METHODS

Using high resolution ultrasound, the dilator response of the brachial artery to 400 microg of sublingual NTG was measured in 800 asymptomatic subjects. Subjects were also assessed for a history of vascular risk factors, blood pressure, total serum cholesterol and flow-mediated endothelium-dependent dilation (EDD).

RESULTS

We studied 317 men and 483 women, 38 +/- 17 years old (mean +/- SD, range 15 to 76). The mean cholesterol level was 5.2 +/- 1.3 mmol/liter, and there were 126 smokers and ex-smokers (16 +/- 9 mean pack-years) and 105 diabetic subjects. On univariate analysis, a reduced vasodilator response to NTG was associated with high cholesterol, cigarette smoking, diabetes mellitus, increasing age, male gender, larger vessel size and reduced EDD (p < or = 0.01 for all). On multivariate analysis, diabetes, larger vessel size and reduced EDD were all independently associated with impaired NTG-related vasodilation (p < or = 0.001 for all). In the 574 nondiabetic subjects who had never smoked cigarettes, the independent relation between EDD and NTG responses was still observed (r = 0.24, p = 0.01).

CONCLUSIONS

The vasodilator response to exogenous NO is impaired in asymptomatic subjects with reduced EDD, consistent with smooth muscle dysfunction in adults at risk for atherosclerosis.

Effect of changing the fine particle mass of inhaled beclomethasone dipropionate on intrapulmonary deposition and pharmacokinetics

Reformulation of beclomethasone dipropionate (BDP) in the chlorofluorocarbon (CFC)-free propellant hydrofluoroalkane-134a (HFA) gave the opportunity to produce a solution formulation that provides a greater total mass of fine drug particles than the current CFC suspension metered dose inhaler (MDI). The HFA-BDP MDI was studied in three pharmacokinetic trials in asthmatic patients. Serum levels of BDP plus metabolites [total beclomethasone (total BOH) assay] were used to test whether the increased fine particle mass of HFA-BDP would result in improved intrapulmonary deposition and subsequent differences in serum profiles. Serum levels, maximum serum concentrations and area under the serum concentration-time curves of total BOH following both single and multiple doses of HFA-BDP were similar to those obtained with approximately twice the dose of CFC-BDP. The observed lower bioavailability of CFC-BDP compared with HFA-BDP could be explained if most of each inhaled dose from the CFC-BDP MDI was swallowed and absorbed from the gastrointestinal tract, while most of each inhaled dose from the HFA-BDP MDI was absorbed from the lungs. Deposition studies have confirmed this explanation. These results suggest that asthmatic patients can be treated with lower total daily doses of drug from HFA-BDP extrafine aerosol than from CFC-BDP.

Degradation products of beclomethasone dipropionate in human plasma

The anti-inflammatory glucocorticosteroid beclomethasone dipropionate was found previously to degrade in human plasma at 37 degrees C to yield beclomethasone 17-monopropionate, beclomethasone 21-monopropionate, and beclomethasone together with three unknown species, D-1, D-2, and D-3. In this paper, we report the isolation of D-2 and D-3 by preparative HPLC and the elucidation of their structures. Both products D-2 and D-3 exhibited UV bathochromic shifts relative to beclomethasone dipropionate of 9 nm. From the mass spectrometry and 1H-NMR data, it is concluded that D-2 and D-3 are formed from beclomethasone and beclomethasone 21-monopropionate, respectively, with the loss of hydrogen chloride and the formation of a 9,11-epoxide. Data for 1H-NMR methyl chemical shifts are used to show that the epoxide has the mechanistically more plausible 9beta,11beta configuration. Thus, D-2 is 9beta, 11beta-epoxy-16beta-methyl-1,4-pregnadiene-17alpha,21- diol-3, 20-dione, and D-3 is its corresponding 21-propanoate. The various enzyme-catalyzed and nonenzyme-catalyzed reactions involved in the degradation of beclomethasone dipropionate in human plasma are discussed. A degradation scheme is proposed.

Decomposition of beclomethasone propionate esters in human plasma

The kinetics of decomposition of beclomethasone dipropionate (BDP), the 17-monopropionate ester (17-BMP), and beclomethasone (BOH) were characterized in whole human plasma (HP), pH 7.1, and in solutions of 1% human serum albumin (HSA), pH 7.4, and 0.067 M phosphate buffer, pH 7.4 (mu = 0.17). A reversed-phase, high-performance liquid chromatography (HPLC) assay enabled simultaneous separation and quantification of beclomethasone propionate esters and six degradation products including three unidentified products, D1-D3, not previously reported. Following incubation of BDP, products were formed in the following sequence, D1, 17-BMP, beclomethasone-21-monopropionate (21-BMP), D3, BOH, and D2. Following incubation of 17-BMP, the same sequence of degradation products was formed with the exception of D1. Following incubation of BOH, only D2 was formed. The decomposition reactions of BDP, 17-BMP, and BOH in HP exhibit pseudo-first-order kinetics. However the degradation reactions of BDP in solutions of 1% HSA and phosphate buffer were found to follow pseudo-zero-order kinetics. At an initial concentration of 40 micrograms mL-1, the half-lives for BDP, 17-BMP, and BOH in HP were 10.9 +/- 0.4, 3.0 +/- 0.2 and 24.8 +/- 0.2 h, respectively.

Effects of budesonide and fluticasone on 24-hour plasma cortisol. A dose-response study

Comparison of the risk-benefit profiles of different inhaled glucocorticoids has been limited by inadequate information about the dose-response relationships for efficacy relative to side effects. Fluticasone propionate (FP) is twice as effective as budesonide (BUD), but the potency ratio of FP:BUD with respect to suppression of cortisol production is unknown. The effects of 5 d of treatment with BUD (800, 1,600, and 3,200 micrograms/d via pMDI) and FP (750, 1,500, and 2,000 micrograms/d via pMDI) on integrated area under the curve of 24-h plasma cortisol profiles (AUC24 h) were compared in a randomized, placebo-controlled, seven-period crossover study in normal male volunteers (n = 28). Plasma cortisol concentrations were measured during the last 24 h of each treatment period. Each treatment (except BUD 800 micrograms) produced significant dose-dependent reductions in AUC24 h compared with placebo; e.g., percent reductions in AUC24 h were 23, 41, and 69% for the three doses of BUD, and, correspondingly, 46, 85, and 93% for the three doses of FP. Model-derived measurements of dose potency ratios showed that FP was 2.9 times more potent than BUD in reducing AUC24 h (95% CI, 2.5 to 3.5) and 3.1 times more potent in reducing 8:00 A.M. plasma cortisol (95% CI, 2.4 to 4.0). Thus, on a microgram-for-microgram notional dose basis, the systemic effects of a given dose of FP on AUC24 h cortisol were equivalent to the effects of three times the dose of BUD.

An evaluation of two primary care interventions for alcohol abuse among Mexican-American patients

AIMS

This study examined the effects of two primary care interventions (a physician intervention and a clinic-based psychoeducational group) on drinking patterns, psychosocial problems and blood test results (MCV, GGT, SGOT and SGPT).

DESIGN

Subjects were randomized into one of four treatment groups: physician intervention, psychoeducation, both interventions, or no intervention. Follow-up data were collected at 12 and 18 months.

SETTING

Subjects were recruited from a family practice outpatient clinic managed by a public hospital.

PARTICIPANTS

Included 175 Mexican-American female and male primary care patients who screened positive for alcohol abuse or dependence. These patients were not seeking help for alcohol problems.

INTERVENTIONS

Included a brief physician intervention and a 6-week patient psychoeducational group.

MEASUREMENTS

The Diagnostic Interview Schedule assessed subjects for alcohol abuse; the Addiction Severity Index measured alcohol-related problems, including psychosocial issues.

FINDINGS

All four treatment groups demonstrated significant improvement over time, with few differences between intervention and control groups.

CONCLUSIONS

Assessment can be confounded with brief interventions; future investigators should use non-assessed control groups.

Transport of paraquat by a renal epithelial cell line, MDCK

Transport of paraquat (PQ), a herbicidal cation, was previously investigated in a proximal (LLC-PK1), renal epithelial cell line using permeable collagen-coated filters. PQ was actively transported from the basolateral side via a cation transport system by the LLC-PK1 cells. In the present study, the transport of PQ was investigated in a distal renal epithelial cell line, MDCK. PQ was predominantly transported from the basolateral to apical (B to A) side. The basolateral transport of PQ in MDCK cells was not saturable with increasing concentrations and not energy dependent. The flux and uptake of PQ was much lower in the MDCK than LLC-PK1 cells. It is concluded that MDCK, a distal renal tubular cell line, does not have an active transport system for PQ.

A sensitive method for the quantification of fluticasone propionate in human plasma by high-performance liquid chromatography/atmospheric pressure chemical ionisation mass spectrometry

A highly sensitive and selective method has been developed for the quantification of fluticasone propionate (FP) in human plasma. The drug was isolated from human plasma using C18 solid-phase extraction cartridges. The analysis was based on high-performance liquid chromatography/atmospheric pressure chemical ionisation mass spectrometry (HPLC/APCI/MS), using the 22R epimer of budesonide (BUD) acetate, synthesised using acetic anhydride, as internal standard. The mass spectrometer was operated in APCI mode with selected ions at tune masses of 473.2 and 501.2 m/z, corresponding to the MH+ of acetylated (22R)BUD and FP, respectively. The mobile phase used was a mixture of 50% ethanol in water with a flow rate of 0.45 ml min-1. The system was optimised by tuning the capillary and tube lens with a concentrated solution of FP. The recovery of FP from human plasma was 86.3%. Linearity of response was obtained over the concentration range 0.2-4.0 ng ml-1. The intra-assay and inter-assay variability were 6.3 and 2.9%, respectively. The lower limit of quantification was 0.2 ng ml-1 when a solid-phase extraction preceded the HPLC/APCI/MS.

Lack of effect of high doses of inhaled morphine on exercise endurance in chronic obstructive pulmonary disease

Systemic opiates may relieve dyspnoea and improve exercise tolerance in patients with chronic obstructive pulmonary disease (COPD). Small doses of inhaled opiates may have similar effects; however, recent studies have shown no benefit. We studied higher doses of inhaled morphine and measured systemic absorption to determine whether any beneficial actions are local or systemic. Twenty and 40 mg doses and 0.9% saline were nebulized in a randomized, double-blind study of 16 patients with stable COPD. Patients performed 6 min walk tests immediately after the nebulized test solution (Walk 1) and again 60 min later (Walk 2). Arterial oxygen saturation (Sa,O2), modified Borg dyspnoea score and cardiac frequency were recorded during each walk. There was no difference between placebo and either dose of nebulized morphine on these measurements. The higher dose of nebulized morphine achieved a higher plasma concentration. The highest plasma concentration was measured immediately after nebulization, and this decreased steadily in the hour thereafter (p<0.002). There was no correlation between the change in walk distance and the change in plasma morphine concentration after either dose of nebulized morphine. We conclude that higher doses of nebulized morphine do not improve exercise endurance or relieve dyspnoea in patients with chronic obstructive pulmonary disease, and that morphine is rapidly absorbed systemically after inhalation.

Effect of regular inhaled salbutamol on airway responsiveness and airway inflammation in rhinitic non-asthmatic subjects

BACKGROUND

Regular, inhaled beta 2 agonists may increase airway responsiveness in asthmatic subjects. The mechanism is not known but may be via an increase in airway inflammation. A study was undertaken to examine the effect of regular inhaled salbutamol on airway responsiveness to methacholine and hypertonic saline, on the maximal response plateau to methacholine, and on inflammatory cells in induced sputum in rhinitic non-asthmatic subjects.

METHODS

Thirty subjects with a baseline maximal response plateau of > 15% fall in forced expiratory volume in one second (FEV1) entered a randomised, placebo controlled, parallel trial consisting of two weeks run in, four weeks of treatment, and two weeks washout. Methacholine challenges were performed at the beginning of the run in period, before treatment, after treatment, and after washout. Hypertonic saline challenges were performed before and after treatment and induced sputum samples were collected for differential cell counting.

RESULTS

There was no change in airway responsiveness, maximal response plateau to methacholine, or in induced sputum eosinophils or mast cells. The maximum fall in FEV1 after hypertonic saline increased in the salbutamol group (median change 6.0%, interquartile range (IQR) 11.0) but did not change in the placebo group (median change 1.3%, IQR 5.5).

CONCLUSIONS

Regular inhaled salbutamol for four weeks increases airway responsiveness to hypertonic saline but does not alter airway responsiveness to methacholine or cells in induced sputum in non-asthmatic individuals with rhinitis. The relevance of these findings to asthmatic subjects has not been established.

The mechanism of excretion of paraquat in rats

Paraquat (PQ)(1,1'-dimethyl-4,4'-bipyridinium) is a toxic herbicidal cation. The renal excretory mechanisms of PQ and its interactions with organic cations and anions were investigated in anaesthetised rats. The renal clearance of PQ was studied in male Wistar rats using inulin as the marker of glomerular filtration rate. The fractional excretion of paraquat (FEpq) decreased from 2.1+/-0.01 to 1.2+/-0.03 as the plasma concentration rose from 0.4+/-0.02 to 21.2+/-1.6 microM. These results demonstrated that the excretion of PQ was greater than glomerular filtration, concentration dependent and saturable, indicating that it was secreted by an active transport system. The excretion of PQ was dependent predominantly on the glomerular filtration rate with a small secretory component (Km = 8.5+/-3.1 microM, Vmax = 114+/-19 nmol/kg per min). The clearance of PQ was not inhibited by high doses of cimetidine, or p-aminohippurate. However, quinine (P = 0.001) and N-methylnicotinamide (NMN) (P = 0.03) reduced the FEpq, suggesting that they share a similar cation transport system with PQ. In summary, PQ is actively secreted by the rat kidney via a cation transport system.

Effect of inhaled frusemide and oral indomethacin on the airway response to hypertonic saline challenge in asthmatic subjects

BACKGROUND

Inhaled frusemide inhibits airway narrowing and causes a transient increase in forced expiratory volume in one second (FEV1) during hypertonic saline challenge. This inhibitory effect could be secondary to prostaglandin release during challenge. The involvement of prostaglandins in the inhibitory action of frusemide during challenge with 4.5% NaCl was investigated by premedicating with indomethacin, a prostaglandin synthetase inhibitor.

METHODS

Fourteen asthmatic subjects (eight women) aged 26.6 (range 18-56) years participated in a double blind, placebo controlled, crossover study. The subjects attended five times and inhaled 4.5% NaCl for 0.5, 0.75, 1, 1.5, 2, 4, 8, 8, and 8 minutes, or part thereof, or until a provocative dose causing a 20% fall in FEV1 (PD20 FEV1) was recorded. Indomethacin (100 mg/day) or placebo were taken three days before all visits, except control day. The FEV1 was measured and frusemide (38.0 (6.4) mg, pH = 9) or vehicle (0.9% NaCl, pH = 9) were inhaled 10 minutes before the challenge. Bronchodilation was calculated as the percentage rise in FEV1 from the prechallenge FEV1 to the highest FEV1 recorded during the challenge.

RESULTS

Frusemide caused a fold increase in PD20 FEV1 compared with the vehicle which was similar in the presence of both indomethacin and placebo (3.7 (95% CI 2.0 to 7.3) versus 3.3 (2.0 to 5.4)). Frusemide, but not vehicle, also caused a transient percentage rise in FEV1 during challenge with 4.5% NaCl which was not blocked by indomethacin (3.6% (1.2 to 6.0)) or placebo (3.1% (1.0 to 5.2)).

CONCLUSIONS

Inhaled frusemide inhibited airway narrowing and caused a transient increase in FEV1 during challenge with 4.5% NaCl. These effects were not blocked by indomethacin, which suggests that the inhibitory action of frusemide is not secondary to prostaglandin release.

Characterisation and uptake of paraquat by rat renal proximal tubular cells in primary culture

1 Uptake of the herbicide paraquat (PQ), by rat proximal tubular cells (PTC) in primary culture grown on a collagen coated support was investigated. 2 The uptake of PQ by PTC was predominantly from the basolateral side. The basolateral uptake of PQ was saturable with time and increasing concentrations, energy dependent and could be inhibited by certain organic cations. Using Michaelis Menten kinetics, the apparent K(m) was 778 +/- 241 microM and Vmax was 0.97 +/- 0.24 pmol/microgram protein/15 min for the basolateral uptake of PQ. Cimetidine (5.7 +/- 0.4 pg/microgram protein/ 30 min, P < 0.001) was the most potent inhibitor of PQ uptake, followed by quinine (6.5 +/- 0.4 pg/microgram protein/30 min, P < 0.01) and then tetraethylammonium (8.2 +/- 0.5 pg/microgram protein/30 min, P < 0.05) when compared with control (11 +/- 1 pg/microgram protein/30 min). N-methylnicotinamide, p-aminohippurate and putrescine did not inhibit the basolateral uptake of PQ. The sodium hydrogen exchange inhibitors, amiloride and its analogue, 5-(N,N hexamethylene) amiloride (HMA) inhibited both the apical and basolateral uptake of PQ. 3 The apical uptake of PQ was not saturable with increasing concentrations and was not inhibited by 2,4-dinitrophenol, but it was reduced by cimetidine (P < 0.01), quinine (P < 0.05) and a sodium potassium ATPase inhibitor, ouabain (P < 0.01). 4 It is concluded that PQ was taken up from the basolateral side of primary cultured rat PTC by an energy dependent transport system.

Transport of paraquat in a renal epithelial cell line LLC-PK1

Transport of paraquat (PQ), a cationic herbicide, was investigated in a proximal renal epithelial cell line, LLC-PK1. Collagencoated permeable filters were used to study the direction of PQ transport. PQ was transported predominantly from the basolateral to apical (B-->A) membrane of these cells. The B-->A flux and uptake of PQ were saturable with time and increasing concentrations, energy dependent and inhibited by several cations. Quinine was the most potent inhibitor of basolateral PQ uptake, followed by cimetidine and then tetraethylammonium acetate (P < .0001). The noninhibitable basolateral uptake of PQ has an apparent K(m) of 357 microM and a Vmax of 1.47 pmol/micrograms protein/2 min. For flux studies, only quinine inhibited the B-->A flux of PQ (P = .02). Putrescine, p-aminohippurate, probenecid, N-methylnicotinamide and choline did not inhibit the flux or uptake of PQ. 5-N,N-Hexamethylene amiloride, a cationic amiloride analog and a potent inhibitor of the Na/H exchanger, significantly inhibited the uptake of PQ from either side (P < .0001). Acidic pH in the apical medium inhibited the uptake of PQ from either side. The studies demonstrated that PQ was actively transported by the LLC-PK1 cells. PQ shared a similar transport system with several cations, which appeared to have a more significant inhibition on the transcellular uptake than the flux of PQ.

Determination of epimers 22R and 22S of budesonide in human plasma by high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

A highly sensitive and selective method has been developed for the simultaneous quantification of 22R- and 22S-epimers of budesonide in human plasma. The drug was isolated from human plasma using C18 solid-phase extraction cartridges and was acetylated with a mixture of 12.5% acetic anhydride and 12.5% triethylamine in acetonitrile to form the 21-acetyl derivatives. Deuterium-labelled budesonide was synthesized and determined to have an isotopic purity > 99%. This was used as the internal standard. Epimers were quantified by automated liquid chromatography-atmospheric pressure chemical ionization mass spectrometry, operating in selected ion mode at m/z 473.2 and m/z 476.2. Linear responses were observed for both epimers over the range 0.25 to 10.0 ng/ml. The average recoveries of 22R- and 22S-epimers of budesonide from human plasma were 87.4% and 87.0%, respectively. The lower limit of quantification for each epimer was 0.25 ng/ml, corresponding to 50.0 pg of analyte on column. Within- and between-day coefficients of variation were 8.6% and 4.0%, respectively.

Mucociliary clearance during and after isocapnic hyperventilation with dry air in the presence of frusemide

We have previously shown that mucociliary clearance (MCC) decreased during and increased after isocapnic hyperventilation (ISH) with dry air, both in asthmatic and healthy subjects. Inhaled frusemide, an inhibitor of the Na+/K+/2Cl- and NaCl co-transporters on the basolateral membrane of the epithelial cell, prevents the airway narrowing provoked by ISH with dry air. The co-transport system controls epithelial cell volume and chloride secretion and, thus, frusemide has the potential to modify the rate of recovery of periciliary fluid volume during and after ISH with dry air, and hence affect MCC. Frusemide also blocks mediator release from mast cells, which may also modify the increase in MCC after ISH. Eleven asthmatic and 11 healthy subjects inhaled frusemide (35.7 +/- 0.44 mg) or its vehicle, from a Fisoneb ultrasonic nebulizer 30 min before ISH with dry air, on two separate occasions. MCC was measured using 99mTc-sulphur colloid and a gamma camera. Frusemide, compared to its vehicle, did not affect MCC during or 45 min after ISH. However, in the presence of frusemide, the onset of the increase of MCC after ISH was significantly delayed for approximately 10 min in the whole right lung (p < 0.002) and central region (p < 0.01) in the asthmatic but not in the healthy subjects. These findings could be explained by frusemide delaying the recovery of the periciliary fluid volume after ISH with dry air and/or interfering with the stimulus that causes the increase in MCC in the asthmatic subjects after ISH.

Inhalation of hypertonic saline aerosol enhances mucociliary clearance in asthmatic and healthy subjects

Hyperosmolarity of the airway surface liquid (ASL) has been proposed as the stimulus for hyperpnoea-induced asthma. We found previously that mucociliary clearance (MCC) was increased after isocapnic hyperventilation (ISH) with dry air, and we proposed that the increase related to transient hyperosmolarity of the ASL. We investigated the effect of increasing the osmolarity of the ASL on MCC, by administering an aerosol of concentrated salt solution. MCC was measured using 99mTc-sulphur colloid, gamma camera and computer analysis in 12 asthmatic and 10 healthy subjects on three separate days, involving administration of each of the following: 1) ultrasonically nebulized 14.4% saline; 2) ultrasonically nebulized 0.9% saline; and 3) no aerosol intervention (control). The (mean +/- SD) volume of nebulized 14.4% saline was 2.2 +/- 1.2 mL for asthmatics and 3.2 +/- 0.7 mL for healthy subjects. This volume was delivered over a period of 5.4 +/- 1.3 and 6.4 +/- 0.7 min for asthmatic and healthy subjects, respectively. The airway response to 14.4% saline was assessed on a separate visit and the fall in forced expiratory volume in one second (FEV1) was 22 +/- 4% in the asthmatic and 3 +/- 2% in the healthy subjects. Compared to the MCC with the 0.9% saline and control, the hypertonic aerosol increased MCC in both groups. In asthmatic subjects, MCC of the whole right lung in 1 h was 68 +/- 10% with 14.4% saline vs 44 +/- 14% with 0.9% saline and 39 +/- 13% with control. In healthy subjects, MCC of the whole right lung in 1 h was 53 +/- 12% with 14.4% saline vs 41 +/- 15% with 0.9% saline and 36 +/- 13% with control. We conclude that an increase in osmolarity of the airway surface liquid increases mucociliary clearance both in asthmatic and healthy subjects. These findings are in keeping with our previous suggestion that the increase in mucociliary clearance after isotonic hyperventilation with dry air is due to a transient hyperosmolarity of the airway surface liquid.

Gender differences in medical presentation and detection of patients with a history of alcohol abuse or dependence

Women and men with alcohol use disorders differ in many respects. A retrospective medical record review of 132 patients was performed to determine outpatient clinic utilization, presentation patterns and physician actions related to patient gender and lifetime DIS-status. Women, irrespective of DIS-status, utilized out-patient health care services more often than did DIS-positive or negative men. Of 16 specific alcohol-related complaints, gender differences were only detected for trauma. DIS-positive men were more likely to have had an alcohol history taken during the preceding 12 months than were DIS-positive women. Sedatives/minor tranquilizers were most often prescribed to DIS-positive women. This study supports the need in primary care settings for more screening to detect and diagnose alcohol-abusing patients, particularly women. Physicians should routinely screen for alcohol abuse before prescribing sedatives or minor tranquilizers.

Better medication compliance is associated with improved control of childhood asthma

Our previous studies have shown that medication compliance in children prescribed continuous treatment for asthma is poor, and that an intervention can improve the level of compliance. The present study examined the effects of an intervention on the clinical course of moderately severe asthma. At each of six clinic visits, spirometry was performed, medication compliance was assessed by questionnaire, and the physicians made an overall assessment of asthma severity (Severity Score) and provided a score for asthma control (Control of Asthma Score). Peak expiratory flow rates were measured twice daily for one month prior to each clinic visit, and the coefficient of variation (% CV) was calculated. Subjects received the intervention after at least two visits, and 53 of the 78 recruits completed the study. Following the intervention, % CV, Control of Asthma Score, Severity Score and % compliance improved, showing that better medication compliance was associated with better control of moderately severe asthma.

Psychiatric problems experienced by primary care patients who misuse alcohol

Of 1936 primary care patients screened using the alcohol portion of the Diagnostic Interview Schedule, 100 met criteria for "alcohol abuse and/or dependence." Sixty of the individuals who misused alcohol were matched to 60 who did not. All 160 patients answered questions about psychiatric symptoms and psychotropic drug use. The lifetime prevalence of depression, suicidal thoughts, suicidal attempts, violent behavior, and trouble concentrating was consistently higher for those who misused alcohol. Depression and trouble concentrating were more likely to be experienced by alcohol misusers during the past month. Gender differences were also noted for prevalence of psychiatric symptoms.

Different effects of inhaled amiloride and frusemide on airway responsiveness to dry air challenge in asthmatic subjects

Amiloride, a Na+ channel blocker, and frusemide, an inhibitor of the Na+/K+/2Cl- co-transporter on the basolateral surface of airway epithelial cells, have the potential to affect water transport across the airway epithelium. As isocapnic hyperventilation challenge (ISH) with dry air may provoke airway narrowing in asthmatic subjects by dehydrating the airways, inhaled amiloride and frusemide may reduce airway responsiveness by effecting airway hydration. Fifteen asthmatic subjects (6 females, 9 males), who had a fall in forced expiratory volume in one second (FEV1) of 20% after ISH, inhaled amiloride (11 mg), or its vehicle, from a Fisoneb ultrasonic nebulizer, within 10 min before ISH. On a separate day, eight of these subjects inhaled frusemide (38 mg), from the same Fisoneb, 10 min before ISH. After breathing, 30 l at resting ventilation, subjects breathed at 30% of their maximum voluntary ventilation (MVV i.e. predicted FEV1x35), then at 60% MVV, and finally at MVV for 3 or 4 min. FEV1 was measured 1, 3, 5, 7 and 9 min after each period, or until it was stable. Airway sensitivity was expressed as the ventilation (l-min-1) which provoked a 10, 15, 20 or 30% fall in FEV1, (PVE10, PVE15, PVE20 and PVE30, respectively). There was no significant difference in the PVE10,15,20,30 between the vehicle and amiloride treatment day; however, in the 8 subjects who inhaled frusemide, frusemide caused a significant increase in the PVE20 when compared to amiloride. In conclusion, inhaled amiloride failed to protect against ISH, whereas frusemide was effective at reducing airway responsiveness. Further studies are needed to explain the mechanism of action of frusemide.