SDS Polyacrylamide Gel Electrophoresis of Proteins

Probably the most widely used of techniques for analyzing mixtures of proteins is SDS polyacrylamide gel electrophoresis. In this technique, proteins are reacted with the anionic detergent, sodium dodecylsulfate (SDS, or sodium lauryl sulfate) to form negatively charged complexes. The amount of SDS bound by a protein, and so the charge on the complex, is roughly proportional to its size. Commonly, about 1.4 g SDS is bound per 1 g protein, although there are exceptions to this rule. The proteins are generally denatured and solubilized by their binding of SDS, and the complex forms a prolate elipsoid or rod of a length roughly proportionate to the protein's molecular weight. Thus, proteins of either acidic or basic pI form negatively charged complexes that can be separated on the bases of differences in charges and sizes by electrophoresis through a sieve-like matr ix of polyacrylamide gel.

Maternal immune stimulation reduces both placental morphologic damage and down-regulated placental growth-factor and cell cycle gene expression caused by urethane: are these events related to reduced teratogenesis?

Activation of the maternal immune system in mice decreased cleft palate caused by the chemical teratogen, urethane. Direct and indirect mechanisms for this phenomenon have been suggested, including maternal macrophages that cross the placenta to find and eliminate pre-teratogenic cells, or maternal immune proteins (cytokines) that cross placenta to alleviate or partially alleviate toxicant-mediated effects in the developing fetus. A third mechanism to explain improved fetal developmental outcome in teratogen-challenged pregnant mice might involve beneficial effects of immune stimulation on the placenta. In the present experiments, urethane treatment altered placental morphology and impaired placental function, the latter indicated by down-regulated activity of cell cycle genes and of genes encoding cytokines and growth factors. Maternal immune stimulation with either Freund's complete adjuvant (FCA) or interferon-gamma (IFNgamma) reduced morphologic damage to the placenta caused by urethane and normalized expression of several genes that were down-regulated by urethane. Urethane treatment also shifted placental cytokine gene expression toward a T cell helper 1 (Th1) profile, while immunostimulation tended to restore a Th2 profile that may be more beneficial to pregnancy and fetal development. These data suggest that the beneficial effects of maternal immune stimulation on fetal development in teratogen-exposed mice may, in part, result from improved placental structure and function.

Occurrence of seizure clusters and status epilepticus during inpatient video-EEG monitoring

OBJECTIVE

To investigate the occurrence of status epilepticus and seizure clusters, and the duration until first seizure at epilepsy monitoring units in the United States.

METHODS

The authors examined the inpatient video-EEG monitoring reports of 514 consecutive patients admitted to five comprehensive epilepsy centers during the year 2000. Time to first seizure, seizure clustering, and seizure duration were ascertained from reports and entered into a database.

RESULTS

In 169 admissions with complex partial seizures (CPSs) or secondarily generalized tonic-clonic (2GTC) seizures, there were 5 (3.0%) patients with status epilepticus, 30 (17.8%) with 4-hour seizure clusters, and 82 (48.5%) with 24-hour seizure clusters. There were no statistically significant differences between centers, except that seizure clusters were observed to be less common at the one center with a formal drug withdrawal protocol. The average time to CPS or 2GTC seizure was 2.1 days; the average number of days to nonepileptic event was 1.2 days (p = 0.001).

CONCLUSIONS

Although status epilepticus is uncommon at epilepsy monitoring units, clusters of seizures are common. Intensive monitoring with drug withdrawal must be performed in a highly supervised, hospitalized setting. Inpatient video-EEG monitoring is efficient, with recording of the first epileptic or nonepileptic events in 2 days or less.

Cocaine-like subjective effects of nicotine are not blocked by the D1 selective antagonist ecopipam (SCH 39166)

The effects of ecopipam (a D(1) selective antagonist) or triazolam pretreatment on the subjective and physiological effects of intravenously administered nicotine were examined in 10 cigarette-smoking cocaine abusers. Under double-blind, randomized conditions, subjects received oral capsule pretreatment (0, 30 or 100 mg ecopipam, or 0.25 mg/70 kg triazolam), followed 120 min later by an intravenous injection of 2 mg/70 kg nicotine or saline. Subjective ratings, heart rate and blood pressure were assessed before and repeatedly after each intravenous injection. Compared to oral placebo pretreatment, both ecopipam and triazolam pretreatment produced significant elevations in subject-reported capsule effect and observer ratings of sleepiness/sedation. Nicotine increased ratings of 'drug effect', 'rush', 'high', 'stimulated', 'liking', 'good effects' and 'bad effects', and produced modest increases in heart rate and blood pressure. Following both intra-venous saline and nicotine injection, ecopipam tended to reduce heart rate and blood pressure. Although both ecopipam and triazolam lowered several subjective ratings following intravenous saline injection, neither ecopipam nor triazolam affected nicotine subjective effects. In contrast to Romach et al. (Arch Gen Psychiatry 56: 1101-1106, 1999), who showed that pretreatment with ecopipam blocked cocaine subjective effects, the current study found no attenuation of the subjective effects of nicotine, and thus, provides no support for the hypothesis that D(1) receptors mediate the cocaine-like subjective effects of nicotine.

Systematic assessment of clinical practice guidelines for the management of chronic obstructive pulmonary disease

OBJECTIVE

To systematically evaluate the quality of the development of guidelines for the management of chronic obstructive pulmonary disease (COPD).

METHODOLOGY

MEDLINE and Excerpta Medica search for published guidelines, followed by independent evaluation by two reviewers, according to previously reported guideline development quality criteria, on a three-point scale.

RESULTS

Five national COPD guidelines and two international COPD guidelines were retrieved. Reviewers demonstrated good inter-observer agreement in assessing the 10 combined guideline development criteria for the seven guidelines [kappa = 0.66]. Guidelines were only partly multi-disciplinary with little or no consumer input, were up to 48 pages in length, and often lacked practical summaries or management flow charts which could have facilitated retrieval of key management recommendations. Almost all the papers were based upon a consensus approach, rather than evidence based, and methods of resolution of differences of opinion were not stated. Patient outcomes, ethical and medico-legal implications were not addressed and six of the guidelines were sponsored directly or indirectly by a single drug company.

CONCLUSIONS

In spite of COPD guidelines being reported by major national bodies for over a decade now, most fail to meet important criteria for high-quality guideline development, and evaluation of clinical impact remains undetermined.

Cost comparison of at-home treatment of deep venous thrombosis with low molecular weight heparin to inpatient treatment with unfractionated heparin

AIMS

Low molecular weight heparins (LMWH) permit safe and effective treatment of uncomplicated deep venous thrombosis (DVT) at home. The aim of this study was to evaluate the cost minimization, cost shifting and patient satisfaction associated with at-home DVT treatment using the LMWH enoxaparin, compared to standard inpatient care in an Australian health-care setting.

METHODS

Subjects presenting with a principal diagnosis of uncomplicated DVT to the Emergency Department at The Queen Elizabeth Hospital, Adelaide, were recruited over 1997-1999. Costs to the hospital, to Federal funding (Medicare) and to patients were tracked prospectively, and satisfaction was also measured. Subjects were matched to historical controls (1994-1997) for age, gender and level of comorbidity (same or lower) by two medical officers who were blinded to costs. Control costs were obtained using the clinical costing system Trendstar, and adjusted for consumer price index.

RESULTS

Twenty-eight subjects participated in the at-home programme. Of these, 26 were discharged without any inpatient admission (including one who agreed to self-injection) and two were admitted briefly. Audit demonstrated that only 29% of eligible subjects were managed at home. Mean (SEM) total treatment cost was $756 (76) per patient for at-home, and $2,208 (146) for controls. Minimal cost shifts to patients and to Medicare occurred, and satisfaction was high.

CONCLUSIONS

At-home treatment of uncomplicated DVT using enoxaparin in an Australian metropolitan setting provides effective cost minimization, with little cost-shifting. Our cost minimisation estimates are conservative as most at-home subjects received enoxaparin twice daily (now used once per day) and controls had at least as high comorbidity. However, uptake of the at-home programme was limited.

Catalytic mechanisms and reaction intermediates along the hydrolytic pathway of a plant beta-D-glucan glucohydrolase

BACKGROUND

Barley beta-D-glucan glucohydrolases represent family 3 glycoside hydrolases that catalyze the hydrolytic removal of nonreducing glucosyl residues from beta-D-glucans and beta-D-glucooligosaccharides. After hydrolysis is completed, glucose remains bound in the active site.

RESULTS

When conduritol B epoxide and 2', 4'-dinitrophenyl 2-deoxy-2-fluoro-beta-D-glucopyranoside are diffused into enzyme crystals, they displace the bound glucose and form covalent glycosyl-enzyme complexes through the Odelta1 of D285, which is thereby identified as the catalytic nucleophile. A nonhydrolyzable S-glycosyl analog, 4(I), 4(III), 4(V)-S-trithiocellohexaose, also diffuses into the active site, and a S-cellobioside moiety positions itself at the -1 and +1 subsites. The glycosidic S atom of the S-cellobioside moiety forms a short contact (2.75 A) with the Oepsilon2 of E491, which is likely to be the catalytic acid/base. The glucopyranosyl residues of the S-cellobioside moiety are not distorted from the low-energy 4C(1) conformation, but the glucopyranosyl ring at the +1 subsite is rotated and translated about the linkage.

CONCLUSIONS

X-ray crystallography is used to define the three key intermediates during catalysis by beta-D-glucan glucohydrolase. Before a new hydrolytic event begins, the bound product (glucose) from the previous catalytic reaction is displaced by the incoming substrate, and a new enzyme-substrate complex is formed. The second stage of the hydrolytic pathway involves glycosidic bond cleavage, which proceeds through a double-displacement reaction mechanism. The crystallographic analysis of the S-cellobioside-enzyme complex with quantum mechanical modeling suggests that the complex might mimic the oxonium intermediate rather than the enzyme-substrate complex.

Removal of fractured posts using ultrasonic vibration: an in vivo study

The purpose of this study was to determine the effectiveness of ultrasonic vibration in the removal of fractured posts from teeth under true clinical conditions. Thirty patients (16 men and 14 women with a mean age of 51 yr, SD 13.13) had ultrasonic vibration applied to the side of a fractured post fragment after creation of a small gutter around the fragment. A piezoelectric ultrasonic scaler was used to apply the vibration for two 15-s periods and then 30-s periods until the post fragment became loose. There was a significant correlation (r = 0.52, p = 0.003) between the cemented length of post fragment (mean length 3.8 mm, SD 1.39) and the time of ultrasonic vibration application (mean time 2.05 min, SD 1.62), but the correlation between post diameter and ultrasonic time did not reach statistical significance (r = 0.35, p = 0.059). The mean ultrasonic time was approximately 25% of that found in previous studies on post removal from extracted teeth probably because of suboptimal cementation of posts in the clinical situation.

Automated attention flags in chronic disease care planning

OBJECTIVES

To assess the value of computerised decision support in the management of chronic respiratory disease by comparing agreement between three respiratory specialists, general practitioners (care coordinators), and decision support software.

METHODS

Care guidelines for two chronic obstructive pulmonary disease projects of the SA HealthPlus Coordinated Care Trial were formulated. Decision support software, Care Plan On-Line (CPOL), was created to represent the intent of these guidelines via automated attention flags to appear in patients' electronic medical records. For a random sample of 20 patients with care plans, decisions about the use of nine additional services (eg, smoking cessation, pneumococcal vaccination) were compared between the respiratory specialists, the patients' GPs and the CPOL attention flags.

RESULTS

Agreement among the specialists was at the lower end of moderate (intraclass correlation coefficient [ICC], 0.48; 95% CI, 0.39-0.56), with a 20% rate of contradictory decisions. Agreement with recommendations of specialists was moderate to poor for GPs (kappa, 0.49; 95% CI, 0.33-0.66) and moderate to good for CPOL (kappa, 0.72; 95% CI, 0.55-0.90). CPOL agreement with GPs was moderate to poor (kappa, 0.41; 95% CI, 0.24-0.58). GPs were less likely than specialists or CPOL to decide in favour of an additional service (P<0.001). CPOL was 87% accurate as an indicator of specialist decisions. It gave a 16% false-positive rate according to specialist decisions, and flagged 61% of decisions where GPs said No and specialists said Yes.

CONCLUSIONS

Automated decision support may provide GPs with improved access to the intent of guidelines; however, further investigation is required.

P-glycoprotein efflux at the blood-brain barrier mediates differences in brain disposition and pharmacodynamics between two structurally related neurokinin-1 receptor antagonists

CP-122721 and CP-141938 are potent and selective neurokinin-1 (NK(1)) receptor antagonists with very different brain disposition and potency in models of centrally mediated activity. These investigations sought to determine whether differences in potency were related to differences in P-glycoprotein (P-gp) transport at the blood-brain barrier. Both compounds stimulated ATPase activity of human recombinant MDR1 with similar kinetic parameters. Cell-associated drug concentrations of CP-141938 were 9.4-fold lower in KBV1 cells expressing P-gp compared with KB3.1 control cells. In Madin-Darby canine kidney (MDCK) cells expressing human MDR1, asymmetric transport of CP-141938 was 5-fold higher than in wild-type MDCK cells, whereas no asymmetry was observed with CP-122721. In agreement with these differences in cellular transport, the differences in brain/plasma ratio between mdr1a/b(-/-) and FVB mice 1 h following a 3 mg/kg s.c. dose were 3- and 50-fold for CP-122721 and CP-141938, respectively. The effect of inhibiting P-gp efflux on the effects of these agents was evaluated using GR73632-induced foot tapping in gerbils as a model to measure centrally mediated NK(1) antagonism. When gerbils were pretreated with the P-gp inhibitor MS-073 (50 mg/kg s.c.), there was no effect on the activity of CP-122721 (0.05 mg/kg), whereas the percent reversal for CP-141938 (10 mg/kg) increased from 60 to 100%. In gerbils, the brain/plasma ratio for CP-122721 was unaffected by MS-073 pretreatment, whereas the brain/plasma ratio for CP-141938 brain concentrations increased 13-fold. This suggested that P-gp efflux influences the brain disposition and pharmacologic activity of CP-141938, but not CP-122721. Complete response curves for CP-141938 were then determined with respect to dose, and drug concentration in the plasma and brain in the presence and absence of MS-073 pretreatment. The dose and plasma concentration-response curves of CP-141938 were shifted to the left in the presence of MS-073, yet brain concentrations associated with the response were unchanged. This suggested that once in the brain the interaction of CP-141938 with the NK(1) receptor was not affected by P-gp transport. In conclusion, these studies show that brain disposition and centrally mediated in vivo activity of NK(1) antagonists can be profoundly affected by P-gp transport and that such transport should be considered during the design of new agents.

Prolonged in vivo residence times of antibody fragments associated with albumin

Antibody fragments can be expressed at a high level in microbial systems, but they may have limited therapeutic value because they are rapidly eliminated from the body. We demonstrate here that site-specific conjugation or binding of bacterially derived Fab' to the long-lived protein serum albumin allows full retention of the antibody's binding characteristics while imparting the albumin's longevity in vivo. In rats the area under the curve for Fab' conjugated to rat serum albumin was 17-fold greater than for the control of Fab' conjugated to cysteine. Again, a bispecific F(ab')(2) with specificity for rat serum albumin showed an area under the curve about 8-fold greater than did a F(ab')(2) without specificity to albumin. Genetic fusions of scFv to albumin were similarly long-lived and could be expressed in yeast to provide the basis of a cost-effective production system.

Physiological, subjective and reinforcing effects of oral and intravenous cocaine in humans

RATIONALE

There is little comparative information on the qualitative similarity, relative potency and reinforcing effects of oral cocaine versus cocaine administered via other routes.

METHODS

The present study used a within-subject, double-blind, double-dummy design to compare the physiological, subjective and reinforcing effects of placebo and oral (62.5, 125, 250 mg/70 kg) and intravenous (IV) (12.5, 25, 50 mg/70 kg) cocaine in volunteers with histories of cocaine abuse.

RESULTS

Cocaine produced dose-dependent increases on heart rate and blood pressure, with effects lasting longer after oral than IV cocaine. Subjective ratings (e.g., "rush," "drug effect," "liking") were qualitatively similar and dose-dependently increased after oral and IV administration, and the duration of effects was similar under both routes. On a money versus drug choice measure of reinforcement, the monetary amounts at which participants chose drug over money increased as a function of cocaine dose under both routes of administration. At doses that produced comparable subjective, physiological, and reinforcing effects, oral cocaine was not identified as cocaine as frequently as IV cocaine. Across measures, the data suggested that IV cocaine was approximately 10 times more potent than oral cocaine.

CONCLUSIONS

Overall, the results of this study support qualitatively similar effects of oral and IV cocaine and suggest that oral cocaine may be an effective tool for studying cocaine's effects in human laboratory studies.

Corticosteroid-Sparing Effect of Etanercept in Idiopathic Panuveitis Resistant to Immunosuppressive Therapy

Uveitis, an inflammatory eye disease with varying immunopathogenic mechanisms, may be associated with autoimmune disorders, may be secondary to infection, or may be idiopathic. Response to treatment of uveitis is inconsistent. In this report we describe an adult with idiopathic panuveitis who attempted to lower his oral corticosteroid dose from intolerable levels but was unable to do so because of the reappearance of symptoms. His 8-year course was managed with ocular and systemic corticosteroids, methotrexate, and cyclosporine, which allowed only partially successful control of his ocular inflammation. Complete control was not achieved until the addition of etanercept. With this case report we are the first to describe the complete response of idiopathic panuveitis to etanercept. Our success with this patient strongly supports the critical role of tumor necrosis factor in the immunopathogenesis of some cases of idiopathic panuveitis. Furthermore, etanercept offers a relatively nontoxic, safe option in cases of panuveitis that are unresponsive to traditional immunosuppressive therapy.

The Iowa radon lung cancer study--phase I: Residential radon gas exposure and lung cancer

Exposure to high concentrations of radon (222Rn) progeny produces lung cancer in both underground miners and experimentally-exposed laboratory animals. The goal of the study was to determine whether or not residential radon exposure exhibits a statistically significant association with lung cancer in a state with high residential radon concentrations. A population-based, case-control epidemiologic study was conducted examining the relationship between residential radon gas exposure and lung cancer in Iowa females who occupied their current home for at least 20 years. The study included 413 incident lung cancer cases and 614 age-frequency-matched controls. Participant information was obtained by a mailed-out questionnaire with face-to-face follow-up. Radon dosimetry assessment consisted of five components: (1) on-site residential assessment survey; (2) on-site radon measurements; (3) regional outdoor radon measurements; (4) assessment of subjects' exposure when in another building; and (5) linkage of historic subject mobility with residential, outdoor, and other building radon concentrations. Histologic review was performed for 96% of the cases. Approximately 60% of the basement radon concentrations and 30% of the first floor radon concentrations of study participants' homes exceeded the US Environmental Protection Agency action level of 150 Bq m(-3) (4 pCi l(-1)). Large areas of western Iowa had outdoor radon concentrations comparable to the national average indoor value of 55 Bq m(-3) (1.5 pCi l(-1)). Excess odds of 0.24 (95% CI = -0.05-0.92) and 0.49 (95% CI = 0.03-1.84) per 11 WLM(5-19) were calculated using the continuous radon exposure estimates for all cases and live cases, respectively. Slightly higher excess odds of 0.50 (95% CI = 0.004-1.80) and 0.83 (CI = 0.11-3.34) per 11 WLM(5-19) were noted for the categorical radon exposure estimates for all cases and the live cases. A positive association between cumulative radon gas exposure and lung cancer was demonstrated using both categorical and continuous analyses. The risk estimates obtained in this study indicate that cumulative radon exposure presents an important environmental health hazard.

Treatment of status epilepticus

The approach to treatment of status epilepticus has changed because of the demonstration of decreased mortality with rapid intervention, completion of a randomized, double-blind VA Cooperative study comparing first-line agents, and further understanding of the pathophysiologic changes discovered in experimental animal studies. This article reviews the treatments of generalized convulsive status epilepticus in the prehospital, emergency department, and intensive care unit settings.

Analysis of inhibitor binding in influenza virus neuraminidase

2,3-didehydro-2-deoxy-N:-acetylneuraminic acid (DANA) is a transition state analog inhibitor of influenza virus neuraminidase (NA). Replacement of the hydroxyl at the C9 position in DANA and 4-amino-DANA with an amine group, with the intention of taking advantage of an increased electrostatic interaction with a conserved acidic group in the active site to improve inhibitor binding, significantly reduces the inhibitor activity of both compounds. The three-dimensional X-ray structure of the complexes of these ligands and NA was obtained to 1.4 A resolution and showed that both ligands bind isosterically to DANA. Analysis of the geometry of the ammonium at the C4 position indicates that Glu119 may be neutral when these ligands bind. A computational analysis of the binding energies indicates that the substitution is successful in increasing the energy of interaction; however, the gains that are made are not sufficient to overcome the energy that is required to desolvate that part of the ligand that comes in contact with the protein.

The structure of the fusion glycoprotein of Newcastle disease virus suggests a novel paradigm for the molecular mechanism of membrane fusion

BACKGROUND

Membrane fusion within the Paramyxoviridae family of viruses is mediated by a surface glycoprotein termed the "F", or fusion, protein. Membrane fusion is assumed to involve a series of structural transitions of F from a metastable (prefusion) state to a highly stable (postfusion) state. No detail is available at the atomic level regarding the metastable form of these proteins or regarding the transitions accompanying fusion.

RESULTS

The three-dimensional structure of the fusion protein of Newcastle disease virus (NDV-F) has been determined. The trimeric NDV-F molecule is organized into head, neck, and stalk regions. The head is comprised of a highly twisted beta domain and an additional immunoglobulin-like beta domain. The neck is formed by the C-terminal extension of the heptad repeat region HR-A, capped by a four-helical bundle. The C terminus of HR-A is encased by a further helix HR-C and a 4-stranded beta sheet. The stalk is formed by the remaining visible portion of HR-A and by polypeptide immediately N-terminal to the C-terminal heptad repeat region HR-B. An axial channel extends through the head and neck and is fenestrated by three large radial channels located approximately at the head-neck interface.

CONCLUSION

We propose that prior to fusion activation, the hydrophobic fusion peptides in NDV-F are sequestered within the radial channels within the head, with the central HR-A coiled coil being only partly formed. Fusion activation then involves, inter alia, the assembly of a complete HR-A coiled coil, with the fusion peptides and transmembrane anchors being brought into close proximity. The structure of NDV-F is fundamentally different than that of influenza virus hemagglutinin, in that the central coiled coil is in the opposite orientation with respect to the viral membrane.

Impact of the physician's participatory style in asthma outcomes and patient satisfaction

OBJECTIVES

To identify factors associated with asthma patients' perceptions of the propensity of pulmonologists to involve them in treatment decision-making, and its association with asthma outcomes.

DESIGN

Cross-sectional observational study performed from June 1995 to December 1997.

SETTING

Pulmonary unit of a university teaching hospital.

PATIENTS

Adult patients with asthma (n = 128).

MEASUREMENTS AND RESULTS

By patient self-report, mean physician's participatory decision-making (PDM) style score was 72 (maximum 100, 95% CI 65, 79). PDM scores were significantly correlated (P < .0001) with the duration of clinic visits (r = .63), patient satisfaction (r = .53), duration of tenure of doctor-patient relationship (r = .37), and formal education (r = .22, P = .023). Significantly higher PDM style scores were reported when visits lasted longer than 20 minutes and when a patient had a >6-month relationship with a particular doctor. PDM scores were also significantly correlated with possession of a written asthma action plan (r = .54, P < .0001), days affected by asthma (r = .36, P = .0001), asthma symptoms (r = .23, P = .017), and preferences for autonomy in asthma management decisions (r = .28, P = .0035). Those with PDM scores <50 reported significantly lower quality of life for all domains of a disease-specific instrument and the Short-Form 36 health survey version 1.0. In multiple regression analysis, PDM style was associated with the length of the office visit and the duration of tenure of the physician-patient relationship (R2 = 0.47, P = .0009). The adjusted odds ratio, per standard deviation decrease in PDM scores, for an asthma hospitalization was 2.0 (95% CI 1.2, 3.2) and for rehospitalization was 2.5 (95% CI 1.2, 4.2).

CONCLUSIONS

Patients' report of their physician's PDM style is significantly associated with health-related quality of life, work disability, and recent need for acute health services. Organizational factors, specifically longer visits and more time seeing a particular physician, are independently associated with more participatory visits. This has significant policy implications for asthma management.

Asthma, inhaled corticosteroid use, and bone mass in prepubertal children

The aim of this cross-sectional study was to describe the role of asthma, asthma severity, and medication usage in bone mineralization of prepubertal children. Asthma severity, medication usage, and physical activity were assessed by questionnaire and objective measures in 330 children. Bone densitometry and body composition were measured by dual-energy x-ray absorptiometry. Asthma ever was reported by 110 subjects (33%). A diagnosis of asthma was not associated with any deficit in bone mass, whereas usage of inhaled corticosteroids (ICS) in the last year (but not past use) was associated with deficits in bone in the total body (only after adjustment for confounders), particularly for doses of > or =400 microg/day. These observations support current recommendations with regard to ICS usage in children, but require confirmation in longitudinal studies.

Effects of alprazolam, caffeine, and zolpidem in humans trained to discriminate triazolam from placebo

This study compared the discriminative stimulus effects of zolpidem, a nonbenzodiazepine hypnotic, to benzodiazepines. Eight participants learned to discriminate triazolam (0.35 mg/70 kg) from placebo. The discriminative stimulus effects, self-reported subjective effects, and performance effects of triazolam (0.05-0.35 mg/70 kg), alprazolam (0.25-1.75 mg/70 kg), zolpidem (2.5-35 mg/70 kg) and caffeine (75-525 mg/70 kg) were assessed under two-response and novel-response drug discrimination procedures. Under the two-response procedure, triazolam, alprazolam and zolpidem fully substituted for triazolam and caffeine did not. Under the novel-response procedure, triazolam and alprazolam substituted for triazolam and zolpidem partially substituted for triazolam. Zolpidem, but not triazolam or alprazolam, also produced some novel responding. Caffeine produced both placebo-appropriate and novel responding. The self-reported effects of triazolam, alprazolam and zolpidem were similar. Overall, zolpidem produced similar, but not identical, effects as the benzodiazepines.

Patient preferences for autonomy in decision making in asthma management

BACKGROUND

Lower patient preferences for autonomy in management decision making during asthma exacerbations have been associated with an increased risk for future hospital admissions. We sought to examine patient preferences for asthma self-management autonomy, and the clinical and psychosocial factors associated with autonomy preferences.

METHODS

A cross sectional observational study was performed with data collected between June 1995 and December 1997 of 212 adult patients with moderate to severe asthma managed, at least in part, at two teaching hospitals. Subjects completed a survey of autonomy preferences, quality of life, clinical morbidity and health service use, asthma knowledge, self-efficacy, coping styles, and psychosocial measures.

RESULTS

Patients preferred clinicians to assume the major role in most decision making about their management. However, patients wished to remain in control in choosing when to seek care and wanted to share decisions regarding initiating changes in medications during a moderate exacerbation. Multiple regression analysis showed that concerns about adverse effects of medications, education level, an active coping style, perceptions of the propensity of physicians to involve them in treatment decision making, and concerns about costs causing delays in seeking medical care were associated with preferences for autonomy in decision making. Autonomy preferences were not related to measures of concurrent clinical asthma control or health related quality of life.

CONCLUSIONS

In a group of patients with moderate to severe asthma, a high proportion of whom were from socioeconomically disadvantaged backgrounds, education level, perceived physician behaviour, cost barriers to care, and psychosocial factors (but not clinical asthma control or management) were related to patient preferences for autonomy in management decision making during asthma exacerbations. This has implications for asthma action plans and design of self-management programmes.