Impact of High-Fidelity Microvascular Surgery Simulation on Resident Training

BACKGROUND

 Microsurgery requires a high level of skill achieved only through repeated practice. With duty-hour restrictions and supervision requirements, trainees require more opportunities for practice outside the operating room. Studies show simulation training improves knowledge and skills. While numerous microvascular simulation models exist, virtually all lack the combination of human tissue and pulsatile flow.

METHODS

 The authors utilized a novel simulation platform incorporating cryopreserved human vein and a pulsatile flow circuit for microsurgery training at two academic centers. Subjects performed a standardized simulated microvascular anastomosis and repeated this task at subsequent training sessions. Each session was evaluated using pre- and postsimulation surveys, standardized assessment forms, and the time required to complete each anastomosis. Outcomes of interest include change in self-reported confidence scores, skill assessment scores, and time to complete the task.

RESULTS

 In total, 36 simulation sessions were recorded including 21 first attempts and 15 second attempts. Pre- and postsimulation survey data across multiple attempts demonstrated a statistically significant increase in self-reported confidence scores. Time to complete the simulation and skill assessment scores improved with multiple attempts; however, these findings were not statistically significant. Subjects unanimously reported on postsimulation surveys that the simulation was beneficial in improving their skills and confidence.

CONCLUSION

 The combination of human tissue and pulsatile flow results in a simulation experience that approaches the level of realism achieved with live animal models. This allows plastic surgery residents to improve microsurgical skills and increase confidence without the need for expensive animal laboratories or any undue risk to patients.

0667 Positive Airway Pressure Non-Adherence Interacts With Post-Traumatic Stress Disorder to Increase Risk of Back Pain

Introduction

Altered sleep, as is associated with obstructive sleep apnea (OSA), may increase the risk of back pain (BP). However, little to no evidence regarding the effect of OSA on musculoskeletal pain is currently available, let alone the effect of positive airway pressure (PAP) treatment non-adherence. The purpose of this analysis is to investigate the effect of PAP non-adherence on future BP diagnosis.

Methods

A sample of 1,662 veterans who had a sleep study between January 2003 and October 2006 and receiving PAP treatment for OSA were used for analysis. Measures at baseline included demographic and OSA symptom severity data. Up to 3 weeks of PAP adherence data were collected and patient chart data was collected through May 2010 to determine outcomes. Time was calculated from PAP treatment start to BP diagnosis or censoring, which occurred at date of death or last recorded encounter. Survival analysis was conducted to obtain the hazard ratios (HR) for the effect of PAP non-adherence on BP diagnosis and to investigate whether post-traumatic stress disorder (PTSD) is an effect modifier of this relationship.

Results

PAP treatment non-adherence significantly increased the risk of BP diagnosis (HR 1.88 [95% CI: 1.08, 3.27]) among veterans with PTSD, while non-adherence among veterans without PTSD was not a statistically significant risk factor. Relative excess risk due to interaction (RERI) was 0.97 (95% CI: -0.07, 2.02; p-value=0.068). These estimates are independent of age, sex, race, body mass index, apnea severity (based on Apnea-Hypopnea Index), PTSD diagnosis, income level, and marital status.

Conclusion

PAP treatment non-adherence among veterans with PTSD appears to result in a significant increase in risk of future BP diagnosis. The interaction between PAP non-adherence and PTSD appears to be borderline synergistic. Therefore, improving PAP adherence among veterans with PTSD may decrease risk of future BP diagnosis.

Support

This material is the result of work supported with resources and the use of facilities at the James A. Haley Veterans’ Hospital.

0816 Sleep Correlates Of Nightmares Among Veterans

Introduction

There is an increased prevalence of Nightmare disorder (ND) among patients with obstructive sleep apnea (OSA). A further investigation of objectively measured sleep parameters among patients with and without ND could inform on potential comorbidities. We hypothesize ND correlates with Epworth sleepiness scale (ESS), apnea hypopnea index (AHI), Trough 02% (Sp02 nadir), and periodic limb movement (PLM) index.

Methods

Data presented herein are interim results from an IRB approved study to determine correlates and sequelae of nightmares. A cohort of all patients with ND visiting James A Haley Veterans Hospital between 2007 and 2011 was defined along with a random cohort of control patients. Demographic and outpatient visit data between January 2006 and April 2016 was pulled from VISTA for both the ND and control cohorts, and patients who had undergone a sleep study were identified. To date, sleep summary data has been individually extracted for 111 ND patients and 835 control patients. Logistic regression (SAS 9.4) was used to compare ESS, AHI, Sp02 nadir, and PLM Index.

Results

Mean age for ND was significantly lower at 49.7 ± 14, compared to 58.4 ± 12 for controls. Other demographic measures were similar including gender, race, and marital status. PLM index was significantly lower in ND compared to controls, however this relationship disappeared after adjusting for age. There were neither significant differences between other polysomnographic (PSG) variables, specifically AHI and Sp02 nadir, nor did OSA severity significantly different between ND and controls.

Conclusion

Among veterans undergoing a PSG, there were no significant differences between measured sleep parameters. Our results contradict our hypothesis that ND correlates with ESS, AHI, Sp02 nadir, and PLM index.

Support

This material is the result of work supported with resources and the use of facilities at the James A. Haley Veterans’ Hospital.

Effects of early introduction of non-invasive positive pressure ventilation based on forced vital capacity rate of change: Variation across amyotrophic lateral sclerosis clinical phenotypes

PURPOSE

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease associated with high morbidity and mortality. We evaluated the ability of pulmonary function tests to predict disease progression by ALS clinical phenotypes, and the timing of the introduction of non-invasive positive pressure ventilation (NIPPV).

MATERIALS AND METHODS

A cohort study was performed in all adult patients who fulfilled El Escorial criteria at a tertiary-care academic medical centre for veterans in the USA from 1 January 2010 to 31 December 2014. Eligible patients underwent sitting and supine forced vital capacity (FVC) and the FVC rate of change (RoC) per month was calculated. ALS Functional Rating Scale-Revised (ALSFRS-R) scores were collected.

RESULTS

A total of 137 patients were included in our analysis. The average survival from ALS onset was 31.40 (±40.04) months. The general cohort median (IQR) RoC was -0.87 (-2.55 to 0.34)/-0.65 (-2.55 to 0.70) % per month (P = 0.81) of the sitting/supine FVC, respectively. However, mean monthly RoC varied among the ALS phenotypes, with higher variation among global ALS, where greater decline in RoC was noted. The average time from ALS onset to tracheostomy was 27.88 (±22.21) months. The average sitting/supine FVC RoC for subjects requiring tracheostomy was -2.86 (±3.77)/-3.63 (±3.75) at the time of tracheostomy, compared to -1.190 (±2.38)/-1.07 (±3.78) for those who did not require the procedure. Although NIPPV use did not result in statistically significant improvements in either the sitting or supine FVC %, it did slow the RoC decline of patients with global ALS phenotypes.

CONCLUSIONS

Initiation of NIPPV based on decline in RoC rather than the absolute value of either sitting or supine FVC may result in early stabilisation of ALS patients' pulmonary deterioration for the global clinical phenotype, and thus may have the potential for prolonging survival until tracheostomy or death.

Sleep, Cognitive impairment, and Alzheimer's disease: A Systematic Review and Meta-Analysis

Study Objectives

Mounting evidence implicates disturbed sleep or lack of sleep as one of the risk factors for Alzheimer's disease (AD), but the extent of the risk is uncertain. We conducted a broad systematic review and meta-analysis to quantify the effect of sleep problems/disorders on cognitive impairment and AD.

Methods

Original published literature assessing any association of sleep problems or disorders with cognitive impairment or AD was identified by searching PubMed, Embase, Web of Science, and the Cochrane library. Effect estimates of individual studies were pooled and relative risks (RR) and 95% confidence intervals (CI) were calculated using random effects models. We also estimated the population attributable risk.

Results

Twenty-seven observational studies (n = 69216 participants) that provided 52 RR estimates were included in the meta-analysis. Individuals with sleep problems had a 1.55 (95% CI: 1.25-1.93), 1.65 (95% CI: 1.45-1.86), and 3.78 (95% CI: 2.27-6.30) times higher risk of AD, cognitive impairment, and preclinical AD than individuals without sleep problems, respectively. The overall meta-analysis revealed that individuals with sleep problems had a 1.68 (95% CI: 1.51-1.87) times higher risk for the combined outcome of cognitive impairment and/or AD. Approximately 15% of AD in the population may be attributed to sleep problems.

Conclusion

This meta-analysis confirmed the association between sleep and cognitive impairment or AD and, for the first time, consolidated the evidence to provide an "average" magnitude of effect. As sleep problems are of a growing concern in the population, these findings are of interest for potential prevention of AD.

Objective evidence that bariatric surgery improves obesity-related obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with obesity. Our aim in this study is to report objective improvement of obesity-related OSA and sleep quality after bariatric surgery.

METHODS

Prospective bariatric patients were referred for polysomnography if they scored >or=6 on the Epworth Sleepiness Scale. The severity of OSA was categorized by the respiratory disturbance index (RDI) as follows: absent, 0 to 5; mild, 6 to 20; moderate, 21 to 40; and severe, <40. Patients were referred for repeat polysomnography 6 to 12 months after bariatric surgery or when weight loss exceeded 75 lbs. Means were compared using paired t tests. Chi-square tests and linear regression models were used to assess associations between clinical parameters and RDI; P<.05 was considered statistically significant.

RESULTS

Of 349 patients referred for polysomnography, 289 patients had severe (33%), moderate (18%), and mild (32%) OSA; 17% had no OSA. At a median of 11 months (6 to 42 months) after bariatric surgery, mean body mass index (BMI) was 38 +/- 1 kg/m2 (P<.01 vs 56 +/- 1 kg/m2 preoperatively) and the mean RDI decreased to 15 +/- 2 (P<.01 vs 51 +/- 4 preoperatively) in 101 patients who underwent postoperative polysomnography. In addition, minimum oxygen saturation, sleep efficiency, and rapid eye movement latency improved, and the requirement for continuous positive airway pressure was reduced (P<or=.025). Male gender and increasing BMI correlated with increasing RDI (P<.01) by chi-square analysis. In a multivariate linear regression model adjusted for age and gender, preoperative BMI correlated with preoperative RDI (r=0.27; P<.01).

CONCLUSIONS

OSA is prevalent in at least 45% of bariatric surgery patients. Preoperative BMI correlates with the severity of OSA. Surgically induced weight loss significantly improves obesity-related OSA and parameters of sleep quality.

Ropinirole for restless legs syndrome: a placebo-controlled crossover trial

The authors performed a double-blind, placebo-controlled, crossover study of ropinirole (0.5 to 6.0 mg/day) for restless legs syndrome (RLS). The RLS Rating Scale score improved (p < 0.001) from a mean (SD) of 25 (7) during placebo treatment to 13 (12) during ropinirole treatment. Eight of the 22 patients had complete resolution of symptoms on ropinirole. Adverse events included nausea and dizziness. Ropinirole was effective and well tolerated for treating the symptoms of RLS.

Practice parameters for the use of laser-assisted uvulopalatoplasty: an update for 2000

Laser-assisted uvulopalatoplasty (LAUP) is an outpatient surgical procedure which is in use as a treatment for snoring. LAUP also has been used as a treatment for sleep-related breathing disorders, including obstructive sleep apnea. The Standards of Practice Committee of the American Academy of Sleep Medicine reviewed the available literature, and developed these practice parameters as a guide to the appropriate use of this surgery. Adequate controlled studies on the LAUP procedure for sleep-related breathing disorders were not found in peer-reviewed journals. This is consistent with findings in the original practice parameters on LAUP published in 1994. The following recommendations are based on the review of the literature: LAUP is not recommended for treatment of sleep-related breathing disorders. However, it does appear to be comparable to uvulopalatopharyngoplasty (UPPP) for treatment of snoring. Individuals who are candidates for LAUP as a treatment for snoring should undergo a polysomnographic or cardiorespiratory evaluation for sleep-related breathing disorders prior to LAUP and periodic postoperative evaluations for the development of same. Patients should be informed of the best available information of the risks, benefits, and complications of the procedure.

Practice parameters for the treatment of narcolepsy: an update for 2000

Successful treatment of narcolepsy requires an accurate diagnosis to exclude patients with other sleep disorders, which have different treatments, and to avoid unnecessary complications of drug treatment. Treatment objectives should be tailored to individual circumstances. Modafinil, amphetamine, methamphetamine, dextroamphetamine, methylphenidate, selegiline, pemoline, tricyclic antidepressants, and fluoxetine are effective treatments for narcolepsy, but the quality of published clinical evidence supporting them varies. Scheduled naps can be beneficial to combat sleepiness, but naps seldom suffice as primary therapy. Regular follow up of patients with narcolepsy is necessary to educate patients and their families, monitor for complications of therapy and emergent of other sleep disorders, and help the patient adapt to the disease.

Pramipexole-induced somnolence and episodes of daytime sleep

Pramipexole is a non-ergot dopamine agonist used to treat Parkinson's disease (PD). Because of concern regarding driving safety, we evaluated the incidence and nature of somnolence experienced by patients receiving pramipexole in clinical trials at our center. A retrospective chart review was performed and structured interviews were conducted with patients who had reported moderate or severe somnolence. In addition, two patients underwent polysomnography (PSG) and multiple sleep latency tests (MSLT) while on and 2 weeks after discontinuation of pramipexole. Forty patients with PD participating in pramipexole clinical trials were identified. In the double-blind phases of the studies, 22 patients were randomized to pramipexole and 18 were randomized to placebo. Six patients assigned to pramipexole reported somnolence as an adverse event (1 moderate, 5 mild) compared with two patients assigned to placebo (1 severe, 1 moderate; p = 0.19, one-tailed Fisher's exact test). Thirty-seven patients participated in open-label extension studies. Twenty-one (57%) reported somnolence as an adverse event. Eleven (30%) patients reported moderate somnolence and three (8%) patients reported severe somnolence. For patients with moderate or severe somnolence, the onset of worst-reported somnolence occurred at a mean (+/- standard error) pramipexole dose of 4.0 +/- 0.4 mg (range, 0.75-4.5 mg) per day. Patients had been taking pramipexole for a total of 10.0 +/- 1.5 months (range, .03-22 mos) and at their maximal dose for 6.7 +/- 1.5 months (range, .03-20 mos). During structured interviews with 12 of the 14 patients reporting moderate or severe somnolence, seven reported falling asleep while driving and two reported minor motor vehicle accidents caused by falling asleep. Most patients reported relatively continuous drowsiness that led to falling asleep without acute warning during periods of inactivity. Three patients reported discreet waves of irresistible sleepiness heralded by prodromal symptoms occurring against a background of normal wakefulness. MSLT in two of these patients revealed decreased latency to sleep without early onset of rapid eye movements. Sleep latency normalized after withdrawal of pramipexole. Intensive patient education is necessary to prevent motor vehicle accidents in patients taking pramipexole. We recommend that patients who are experiencing generalized drowsiness and falling asleep during periods of inactivity be instructed not to drive because these patients do fall asleep without acute warning. Somnolence usually resolves with pramipexole dose reduction or discontinuation. Patients should also be alerted to pull over and stop driving immediately if they feel a wave of sleepiness coming on. Patient education and compliance are critical to maximize safety.

Practice parameters for the evaluation of chronic insomnia. An American Academy of Sleep Medicine report. Standards of Practice Committee of the American Academy of Sleep Medicine

Chronic insomnia is the most common sleep complaint which health care practitioners must confront. Most insomnia patients are not, however, seen by sleep physicians but rather by a variety of primary care physicians. There is little agreement concerning methods for effective assessment and subsequent differential diagnosis of this pervasive problem. The most common basis for diagnosis and subsequent treatment has been the practitioner's clinical impression from an unstructured interview. No systematic, evidence-based guidelines for diagnosis exist for chronic insomnia. This practice parameter paper presents recommendations for the evaluation of chronic insomnia based on the evidence in the accompanying review paper. We recommend use of these parameters by the sleep community, but even more importantly, hope the large number of primary care physicians providing this care can benefit from their use. Conclusions reached in these practice parameters include the following recommendations for the evaluation of chronic insomnia. Since the complaint of insomnia is so widespread and since patients may overlook the impact of poor sleep quality on daily functioning, the health care practitioner should screen for a history of sleep difficulty. This evaluation should include a sleep history focused on common sleep disorders to identify primary and secondary insomnias. Polysomnography, and the Multiple Sleep Latency Test (MSLT) should not be routinely used to screen or diagnose patients with insomnia complaints. However, the complaint of insomnia does not preclude the appropriate use of these tests for diagnosis of specific sleep disorders such as obstructive sleep apnea, periodic limb movement disorder, and narcolepsy that may be present in patients with insomnia. There is insufficient evidence to suggest whether portable sleep studies, actigraphy, or other alternative assessment measures including static charge beds are effective in the evaluation of insomnia complaints. Instruments such as sleep logs, self-administered questionnaires, symptom checklist, or psychological screening tests may be of benefit to discriminate insomnia patients from normals, but these instruments have not been shown to differentiate subtypes of insomnia complaints.

Practice parameters for the nonpharmacologic treatment of chronic insomnia. An American Academy of Sleep Medicine report. Standards of Practice Committee of the American Academy of Sleep Medicine

Insomnia is the most common sleep complaint reported to physicians. Treatment has traditionally involved medication. Behavioral approaches have been available for decades, but lack of physician awareness and training, difficulty in obtaining reimbursements, and questions about efficacy have limited their use. These practice parameters review the current evidence with regards to a variety of nonpharmacologic treatments for insomnia. Using a companion paper which provides a background review, the available literature was analyzed. The evidence was graded by previously reported criteria of the American Academy of Sleep Medicine with references to American Psychological Association criteria. Treatments considered include: stimulus control, progressive muscle relaxation, paradoxical intention, biofeedback, sleep restriction, multicomponent cognitive behavioral therapy, sleep hygiene education, imagery training, and cognitive therapy. Improved experimental design has significantly advanced the process of evaluation of nonpharmacologic treatments for insomnia using guidelines outlined by the American Psychological Association (APA). Recommendations for individual therapies using the American Academy of Sleep Medicine recommendation levels for each are: Stimulus Control (Standard); Progressive Muscle Relaxation, Paradoxical Intention, and Biofeedback (Guidelines); Sleep Restriction, and Multicomponent Cognitive Behavioral Therapy (Options); Sleep Hygiene Education, Imagery Training, and Cognitive Therapy had insufficient evidence to be recommended as a single therapy. Optimal duration of therapy, who should perform the treatments, long term outcomes and safety concerns, and the effect of treatment on quality of life are questions in need of future research.

Practice parameters for the treatment of restless legs syndrome and periodic limb movement disorder. An American Academy of Sleep Medicine Report. Standards of Practice Committee of the American Academy of Sleep Medicine

These are the first clinical guidelines published for the treatment of Restless Legs Syndrome (RLS) and Periodic Limb Movement Disorder (PLMD) providing evidence-based practice parameters. They were developed by the Standards of Practice Committee and reviewed and approved by the Board of Directors of the American Academy of Sleep Medicine. The guidelines provide recommendations for the practice of sleep medicine in North America regarding the treatment of RLS and PLMD. Recommendations are based on the accompanying comprehensive review of the medical literature regarding treatment of RLS and PLMD which was developed by a task force commissioned by the American Academy of Sleep Medicine. Recommendations are identified as standards, guidelines, or options, based on the strength of evidence from published studies that meet criteria for inclusion. Dopaminergic agents are the best studied and most successful agents for treatment of RLS and PLMD. Specific recommendations are also given for the use of opioid, benzodiazepine, anticonvulsant, and adrenergic medications, and for iron supplementation. In general, pharmacological treatment should be limited to individuals who meet diagnostic criteria and especially who experience insomnia and/or excessive sleepiness that is thought to occur secondary to RLS or PLMD. Individuals treated with medication should be followed by a physician and monitored for clinical response and adverse effects. It would be desirable for future investigations to employ multicenter clinical trials, with expanded numbers of subjects using double-blind, placebo-controlled designs, and an assessment of long-term response, side effects, and impact of treatment on quality of life. Evaluation of special groups such as children, pregnant women, and the elderly is warranted.

Practice parameters for the use of light therapy in the treatment of sleep disorders. Standards of Practice Committee, American Academy of Sleep Medicine

These clinical guidelines were developed by the Standards of Practice Committee and reviewed and approved by the Board of Directors of the American Academy of Sleep Medicine. The guidelines provide recommendations for the practice of sleep medicine in North America regarding the use of light therapy for treatment of various sleep disorders. This paper is based on a series of articles in the Journal of Biological Rhythms and also includes evidence tables from an updated Medline review covering the period January 1994 to December 1997. Evidence is presented by grade and level. Recommendations are identified as standards, guidelines, or options. Recommendations are provided for delayed sleep phase syndrome (DSPS), advanced sleep phase syndrome (ASPS), non-24-hour sleep-wake syndrome, jet lag, shift work, dementia, and sleep complaints in the healthy elderly. Light therapy appears generally safe if used within recommended intensity and time limits. Light therapy can be useful in treatment of DSPS and ASPS. Benefits of light therapy are less clear and treatment is an option in jet lag, shift work, and non-24-hour sleep-wake syndrome in some blind patients.

Significant tracheal obstruction causing failure to wean in patients requiring prolonged mechanical ventilation: a forgotten complication of long-term mechanical ventilation

INTRODUCTION

Modern low-pressure, high-volume cuffed tracheotomy tubes have been shown to decrease tracheal injury. However, injury still occurs in patients requiring prolonged mechanical ventilation and prevents weaning, delays decannulation, prolongs hospitalization, and may totally obstruct the airway. We describe 37 patients, including the first reported case of failure to wean due to tracheal obstruction.

METHODS

Over a 3-year period, from September 1994 to August 1997, the hospital records of 37 patients requiring prolonged mechanical ventilation (> 4 weeks) and found to have tracheal obstruction were reviewed retrospectively. They were a subgroup of 756 patients admitted to hospitals during the same period. The average endotracheal/tracheostomy cannulation time was 3 weeks/12 weeks (range 2 to 4 weeks/8 to 14 weeks). Average age was 76 years (range, 34 to 81). Underlying diseases included COPD, postcoronary artery bypass graft surgery, postpneumonectomy, severe pneumonia, acute lung injury, and ischemic heart disease.

RESULTS

All 37 patients who initially failed to wean had difficulty in breathing and developed intermittent high peak airway pressures either early or during the weaning process or just on being ventilated. The insertion of a longer tracheal tube bypassed the obstruction, reestablished the airway, decreased peak airway pressures, and allowed the patient to breathe more easily. The obstruction was confirmed on bronchoscopy. Treatment consisted of either placement of a longer tracheal tube (34 of 37 patients) or placement of a tracheal stent. All but two of the patients (5.4%) were able to be weaned within a week. The two patients who still failed to be weaned were subsequently diagnosed as having amyotrophic lateral sclerosis.

CONCLUSION

Tracheal obstruction in patients requiring prolonged mechanical ventilation prevented weaning. Reestablishment of the airway with a longer tracheal tube or tracheal stent allowed most of the patients to be weaned.

Tracheostomy tube occlusion protocol predicts significant tracheal obstruction to air flow in patients requiring prolonged mechanical ventilation

OBJECTIVE

This study was undertaken to test the hypothesis that a tracheal tube occlusion protocol predicts clinically important obstruction to air flow in patients requiring prolonged mechanical ventilation, making routine bronchoscopy unnecessary.

DESIGN

A prospective evaluation of 75 patients who were clinically ready to be decannulated. All patients underwent the tracheal tube occlusion protocol followed by bronchoscopy.

SETTING

Three hospitals affiliated with a college of medicine.

PATIENTS

Over a 24-month period, 52 males and 23 females were enrolled in the study. Mean age was 55 yrs (range 25 to 85). Mean endotracheal/tracheostomy time was 2.4/8.9 wks (range 1 to 4/5 to 14). All patients were mechanically ventilated for at least 4 wks and were successfully weaned from the mechanical ventilator for at least 48 hrs. During spontaneous breathing, these data were observed: minute ventilation of < 10 L/min; resting respiratory rate of < 18 breaths/min; and arterial oxygen saturation of > 90% on 40% oxygen tracheal collar mask. The tracheal tube occlusion protocol consisted of deflating the cuff on the fenestrated tracheal tube and occluding the tube.

INTERVENTIONS

Patients who developed respiratory distress when the tracheal tube was occluded were deemed to have failed the protocol. At bronchoscopy, the patients were asked to cough and hyperventilate in an attempt to forcibly reduce the cross-sectional area of the trachea. A sustained, subjectively assessed decrease of > or = 50% of the effective cross-sectional area of the trachea was considered to be an indication for intervention.

MEASUREMENTS AND MAIN RESULTS

Sixty-three (84%) of 75 patients tolerated the tracheal tube occlusion protocol. Twelve (16%) of 75 patients developed signs of respiratory distress and showed decreased oxygen saturation values necessitating uncapping of the tracheal tube. All patients had some degree of tracheal injury. However, those patients who failed to tolerate the tracheal tube occlusion protocol had clinically important tracheal obstruction to air flow.

CONCLUSION

A tracheal tube occlusion protocol can predict clinically important obstruction to air flow after prolonged mechanical ventilation.

Evidence for three separate electron flow pathways through Complex I: an inhibitor study

The mammalian mitochondrial electron transport chain catalyzes the oxidation of NADH at pH 8.0 and pH 6.5, and the oxidation of NADPH at pH 6.5. The pH-dependencies of the rate of steady-state oxidation of NADPH and NADH by Complex I as well as by its flavoprotein fraction have been extensively studied by the laboratory of Hatefi. One model to explain these pH-dependent oxidations was proposed by Bakker and Albracht (Biochim. Biophys. Acta 850 (1986) 413-422 and 423-428, modified by Van Belzen and Albracht (Biochim. Biophys Acta 974 (1989) 311-320), which predicts that Complex I is a heterodimer with promoter B, containing FMN and Fe-S clusters 1-4 in stiochiometric amounts, catalyzing NADH oxidation at pH 8, and Protomer A, containing FMN and Fe-S clusters 2, 4, catalyzing NAD(P)H oxidation at pH 6.5. A pH-dependent transfer of electrons from protomer A Fe-S clusters 2, 4 to protomer B Fe-S clusters 2, 4 is an obligate step in the oxidation of NAD(P)H at low pH. Strict interpretation of this model allows for only three types of inhibitor: one which inhibits all three oxidase activities (type 1); one which inhibits NADH oxidase, pH 8.0 (type 4) and a third which inhibits NAD(P)H oxidase, pH 6.5 (type 5). Another possibility is that there are three separate pathways of oxidation of NAD(P)H, which would allow for a total of seven different types of inhibitor, e.g., the three types above plus type 2 inhibiting NADH oxidase pH 8.0 and pH 6.5; type 3 inhibiting NADH oxidase pH 8.0, and NADPH oxidase pH 6.5; type 6 inhibiting NADH oxidase pH 6.5; and type 7 inhibiting NADPH oxidase pH 6.5. Using a series of thirteen inhibitors of Complex I activity and the chemical modification reagent ethoxyformic anhydride (EFA), four different inhibitor types were found: seven inhibitors of type 1, four inhibitors of type 2, one inhibitor of type 3 and one inhibitor of type 4. Treatment of submitochondrial particles (SMP) with EFA abolished NADH-dependent reduction of coenzyme Q at both pH 8.0 and 6.5, while inhibiting NADPH-dependent reduction of coenzyme Q at pH 6.5 by only 30%. These results do not support the heterodimer model of Complex I electron transport of Bakker and Albracht, but do support three separate electron flow pathways through complex 1 from reduced pyridine nucleotides to coenzyme Q. A new model of electron flow through Complex I based on these finding is proposed.

Carbocyanine dyes with long alkyl side-chains: broad spectrum inhibitors of mitochondrial electron transport chain activity

Certain indocarbocyanine, thiacarbocyanine, and oxacarbocyanine dyes possessing short alkyl side-chains (one to five carbons) are potent inhibitors of mammalian mitochondrial NADH-ubiquinone reductase (EC 1.6.99.3) activity (Anderson et al., Biochem Pharmacol 41: 677-684, 1991; Anderson et al., Biochem Pharmacol 45: 691-696, 1993; Anderson et al., Biochem Pharmacol 45: 2115-2122, 1993), and act similarly to rotenone. This study examines the inhibitory capacities of twelve other carbocyanine dyes (six indocarbocyanines, four oxacarbocyanines, and two thiacarbocyanines) possessing long alkyl side-chains (seven to eighteen carbons with both saturated and unsaturated side-chains) on mitochondrial NADH, succinate and cytochrome c oxidase activities. Three of the indocarbocyanines inhibited electron transport chain activity, while three were non-inhibitory. Two of the oxacarbocyanines also inhibited electron transport chain activity, while the other two were without effect. Both the thiacarbocyanines were non-inhibitory. In contrast to previous studies, the long alkyl side-chain carbocyanines exhibited a broad spectrum of inhibition of respiratory chain activity, affecting either oxidation of all three substrates or of NADH and cytochrome c, rather than specific inhibition of mitochondrial NADH-ubiquinone reductase activity, indicating that there could be multiple binding sites for these compounds. The five inhibitory long side-chain carbocyanines also inhibited reduction of ferricyanide and coenzyme Q1 by NADH, using submitochondrial particles, but not when tested with purified complex I, indicating that the mitochondrial inner membrane was an integral component in their inhibitory capacity. No general correlation of side-chain length or degree of unsaturation and inhibitory capacity was discernible.

Preservation of pulmonary function by an outer membrane protein F vaccine. A study in rats with chronic pulmonary infection caused by Pseudomonas aeruginosa

This study investigated the ability of a protein F vaccine to reduce macroscopic evidence of lung damage and preserve pulmonary function in immunized animals in a rat model of chronic pulmonary infection caused by Pseudomonas aeruginosa. Other membrane protein F of P aeruginosa was purified by extraction from polyacrylamide gels of cell envelope proteins of the PAO1 immunotype 7 strain. Rats were immunized intramuscularly with either 25 micrograms of the purified protein F or bovine serum albumin on days 0 and 14 and then challenged on day 28 via intratracheal inoculation of agar beads containing cells of an immunotype 3 clinical isolate of P aeruginosa. Also, included was a noninfected control group which received only sterile agar beads. On day 35, the lungs were excised, pulmonary compliance measured, and the lungs examined macroscopically for the presence and severity of lesions. The protein F-immunized rats had a significant (p < 0.01) reduction in the number of severe pulmonary lesions as compared with bovine serum albumin-immunized rats. Lung compliance (CL) was significantly (p < 0.001) reduced in rats which were immunized with bovine serum albumin (n = 17, CL = 0.12 +/- 0.008), whereas CL of protein F-immunized rats (n = 12, CL = 0.17 +/- 0.006) was similar to that of noninfected control rats (n = 5, CL = 0.15 +/- 0.008). This study demonstrated that a protein F vaccine has the ability to decrease macroscopic lung lesions from infection and preserve pulmonary function in actively immunized rats upon subsequent challenge with P aeruginosa in this model of chronic lung infection.

Assessment of hypoxemia in patients with sleep disorders using saturation impairment time

A method of recording cumulative nocturnal oxygen desaturation was utilized to develop a quantitative index of nocturnal hypoxemia (SIT index) to provide reference values and distributional properties for apneic and nonapneic sleep-disordered patients. The SIT indices were compared in patients with varying degrees of obstructive sleep apnea (OSA) as determined by traditional methods of counting apneas and hypopneas. We studied 298 patients who were divided into five groups based on the presence and frequency of apnea or sleep-related respiratory deterioration. SIT indices for patient groups and individual patients were compared with the respiratory disturbance index (apneas + hypopneas x 60/total sleep time = RDI) using scatter plots, Kruskal-Wallis analysis of variance, and Mann-Whitney U tests. The OSA and non-respiratory-impaired patient groups had mean SIT values that were significantly different (p < 0.05). Subjects with severe apnea differed (p < 0.05) from subjects with mild and moderate apnea at SIT index thresholds < baseline, < 90, < 80, and < 70% SaO2, but subjects with mild and moderate apnea did not differ statistically from each other at any threshold. In individual patients with similar RDI values, considerable variation in SIT index can be seen, and the reverse is also true. This suggests that using both RDI and SIT may provide complementary information in assessing the severity of OSA.

Inhibition of mitochondrial and Paracoccus denitrificans NADH-ubiquinone reductase by oxacarbocyanine dyes. A structure-activity study

In this study, we determined that three structurally related oxacarbocyanine dyes, 3,3'-diethyloxacarbocyanine (DiOC2(3)), 3,3'-dipentyloxacarbocyanine (DiOC5(3)), and 3,3'-dihexyloxacarbocyanine (DiOC6(3)), and one oxadicarbocyanine, 3,3'-diethyloxadicarbocyanine (DiOC2(4)), inhibit bovine heart mitochondrial NADH oxidase activity and one of them, DiOC6(3), inhibits Paracoccus denitrificans NADH oxidase activity. The mitochondrial I50 values were 9 microM (DiOC2(3)), approximately 1 microM (DiOC5(3)) and DiOC6(3)), and approximately 3 microM (DiOC2(4)), whereas the I50 value for P. denitrificans was approximately 2 microM (DiOC6(3)). Neither succinate nor cytochrome oxidase (EC 1.9.3.1) activity was inhibited significantly by any of the compounds in either electron transport chain, localizing the inhibitory site of the oxacarbocyanine dyes to the respiratory chain segment between NADH and ubiquinone. With submitochondrial particles (SMP), NADH-dependent reduction of duroquinone and coenzyme Q1 was inhibited markedly by all four compounds with DiOC6(3) being the most potent inhibitor, and the reduction of menadione was inhibited substantially by DiOC6(3). When purified complex I was used, NADH-dependent reduction of ferricyanide was inhibited by DiOC5(3) and coenzyme Q1 reduction was inhibited by all oxacarbocyanines. With P. denitrificans membrane vesicles, DiOC6(3) substantially inhibited NADH-dependent reduction of coenzyme Q1. All the oxacarbocyanines were more effective inhibitors with membrane preparations than with complex I, suggesting that membrane interactions play a role in inhibition. The mechanism of inhibition of the oxacarbocyanines appears to be similar to that of rotenone since (a) essentially only electron acceptors affected by rotenone were affected by the compounds, (b) inhibition of menadione reduction was diminished drastically with rotenone-saturated SMP, and (c) inhibition of coenzyme Q1 was largely eliminated with rotenone-insensitive complex I, and P. denitrificans membrane vesicles.

Cytotoxic effect of thiacarbocyanine dyes on human colon carcinoma cells and inhibition of bovine heart mitochondrial NADH-ubiquinone reductase activity via a rotenone-type mechanism by two of the dyes

Five lipophilic-cationic thiacarbocyanine compounds differing in the side chains (methyl-S13, ethyl-S23, propyl-S33, butyl-S43, and pentyl-S53) and a related thiadicarbocyanine compound with ethyl side chains (S25) exhibited a selective cytotoxic effect on human colon carcinoma cells compared to green monkey kidney epithelial cells. The inhibitory concentration for 50% inhibition of growth (IC50) for the carcinoma cells ranged from 13 nM for S13 and S23 to 160 nM for S25. The carcinoma cells were 4- to 100-fold more sensitive than the normal cells. Two of the five compounds, S13 and S23, selectively inhibited NADH oxidase activity with bovine heart submitochondrial particles (SMP). There was no discernable inhibitory effect by the other three thiacarbocyanine compounds on electron transport chain activity. The primary site of inhibition within the respiratory chain for S13 and S23 appeared to be the NADH to coenzyme Q portion of the mitochondrial electron transport chain. Artificial electron acceptors for this segment of respiratory chain were used to localize the inhibitory site. Using SMP, both S13 and S23 inhibited reduction of menadione, duroquinone, and coenzyme Q. Using purified complex I (NADH-ubiquinone reductase) (EC 1.6.99.3), S13 slightly inhibited reduction of juglone, duroquinone, and coenzyme Q, whereas S23 had no effect on any of the substrates. When rotenone-saturated SMP were used, the inhibitory effects of S13, but not S23, on the reduction of menadione were abolished, as was the inhibitory effect of S13 on coenzyme Q reduction when rotenone-insensitive complex I was used as the source of the enzyme. These results suggest that (1) S13 and S23 inhibition of NADH-ubiquinone reductase activity is enhanced by the membrane environment of the enzyme, and (2) the inhibition appears to be in part akin to the inhibiting mode of rotenone.

Role of extracellular Ca2+ in diaphragmatic contraction: effects of ouabain, monensin, and ryanodine

The effects of zero extracellular Ca2+ on the contractility of rat diaphragmatic strips in vitro were studied in conjunction with various pharmacological agents known to influence the intracellular Ca2+ concentration: the Na+ ionophore, monensin, and the Na(+)-K+ pump inhibitor, ouabain, which enhance [Ca2+]i, caffeine, which induces Ca2+ release from the sarcoplasmic reticulum (SR), and ryanodine, which prevents Ca2+ retention by the SR. The effect of increasing [Ca2+]i on diaphragmatic contraction was assessed by comparing contractions induced by 120 mM K+ in the small muscle strips before and after the addition of ouabain or monensin. Monensin (20 microM) and ouabain (1-100 microM) augmented contractions up to threefold. Treatment of diaphragm strips with 3 nM ryanodine increased baseline tension 360% above the original resting tension but only if the diaphragm was electrically stimulated concurrently; 100 microM ryanodine induced contracture in quiescent tissue. High K+ contractures were of greater magnitude in the presence of ryanodine compared with control, and relaxation time was prolonged by greater than 200%. Ca(2+)-free conditions ameliorated these actions of ryanodine. Ryanodine reduced contractions induced by 10 mM caffeine and nearly abolished them in Ca(2+)-free solution. The data demonstrate that extracellular Ca2+ is important in certain types of contractile responses of the diaphragm and suggest that the processes necessary to utilize extracellular Ca2+ are present in the diaphragm.

Effects of diaphragmatic fatigue on phosphoinositide hydrolysis

We evaluated the effects of diaphragmatic fatigue on muscle phosphatidylinositol phosphate (PIP) metabolism. Results revealed that the total PIP pool was 76% greater in fatigued rat diaphragms compared to controls, which suggests that fatigue was associated with inhibition of sarcolemmal membrane bound PIP hydrolysis.

Chronic cocaine administration decreases norepinephrine-induced phosphoinositide hydrolysis in rat aorta

The effect of chronic cocaine administration on norepinephrine stimulated hydrolysis of inositol 1,4,5-trisphosphate from the membrane phosphatidylinositol phosphate pool in isolated rat aorta was investigated. Rats received saline (controls), or 10 or 20 mg/kg cocaine once a day for 15 days. This treatment resulted in a dose-dependent reduction in norepinephrine (0.36 microM) stimulated phosphoinositide hydrolysis. The effect of acute cocaine was determined by adding 30 microM cocaine to the in vitro incubation solution. When aortas were exposed to cocaine and norepinephrine simultaneously, in vitro, inositol phosphate formation doubled. By itself, cocaine did not affect phosphoinositide hydrolysis. Contraction of aortic helical strips by norepinephrine decreased in tissues from rats chronically treated with 20 mg/kg cocaine. In vitro cocaine shifted the norepinephrine concentration/response curve to the left and increased the maximum response. Neither acute nor chronic cocaine treatment affected prazosin's apparent dissociation constant, suggesting that cocaine did not affect receptor affinity. These data suggest that chronic, but not acute cocaine administration may interfere with pharmacomechanical coupling in rat aorta.

Inhibitory effects of two structurally related carbocyanine laser dyes on the activity of bovine heart mitochondrial and Paracoccus denitrificans NADH-ubiquinone reductase. Evidence for a rotenone-type mechanism

Two cationic, lipophilic laser dyes, 1,1',3,3,3',3'-hexamethylindodicarbocyanine iodide (HIDC) and 1,1',3,3,3',3'-hexamethylindotricarbocyanine iodide (HITC), inhibit bovine heart mitochondrial and Paracoccus denitrificans NADH oxidase activities. The mitochondrial I50 values were 0.5 microM (HIDC) and 1.2 microM (HITC), and the P. denitrificans I50 values 1.2 microM (HIDC) and 1.5 microM (HITC). Neither succinate nor cytochrome oxidase (EC 1.9.3.1) activities were inhibited significantly by either compound, localizing the site of inhibition to the segment of each electron transport chain between NADH and ubiquinone. With submitochrondrial particles (SMP), NADH-dependent reduction of menadione, duroquinone and coenzyme Q1 was inhibited markedly (HIDC was the more potent inhibitor). Using purified complex I, only NADH-dependent reduction of duroquinone and coenzyme Q1 was inhibited markedly (HIDC was the more potent inhibitor) and reduction of menadione was inhibited slightly. With P. denitrificans membrane vesicles, NADH-dependent reduction of menadione, juglone, and coenzyme Q1 was inhibited slightly and duroquinone reduction was inhibited markedly. Membrane-dependent interactions appear to be involved, since the compounds were more inhibitory with membrane preparations than with complex I. The mechanism of inhibition (except for the HIDC effect on coenzyme Q1 reduction with P. denitrificans) appeared to be through the interaction of dye with the rotenone site on NADH-ubiquinone reductase (EC 1.6.99.3), since rotenone-insensitive preparations of complex I and P. denitrificans membrane vesicles were also insensitive to HIDC and HITC inhibition.

Indications for spirometry in outpatients with respiratory disease

It has been suggested that spirometry should be incorporated into the routine examination of every patient, analogous to obtaining vital signs. To determine the impact of spirometry on the management of outpatients with respiratory disease, spirometry was performed on 150 consecutive patients (123 men and 27 women, mean age 57 +/- 12 years) seen in our pulmonary disease outpatient clinics. Patients with obstructive (n = 75), restrictive (n = 31), mixed (n = 26) or other respiratory diseases (n = 18) were initially assessed by history and physical examination and classified as improved, stable, or worse compared to previous visits. A clinical management plan (CMP) was formulated based on this initial evaluation. Spirometric results were then made available to the examiner who could then make changes in the proposed CMP. The addition of spirometric results caused alteration of the CMP in only eight (5 percent) patients; in the remaining 142 patients, results did not affect the CMP. Two clinical findings identified those patients whose CMP was most likely to be altered by spirometry: severity of lung dysfunction (determined from previous spirometry) and deterioration of clinical status (judged by history and physical examination). Of the eight patients whose CMP was changed after review of spirometry, six (75 percent) had previous severe ventilatory dysfunction (FEV1 or FVC less than or equal to 40 percent of predicted or FEV1/FVC ratio less than or equal to 0.40). In 6 of 38 patients (16 percent) with severe ventilatory dysfunction, CMP was altered after spirometry while only 2 of 112 patients (1.8 percent) with mild or moderate dysfunction had changes in their CMP. Patients who were clinically assessed as worse compared to their previous visit were more likely to have their CMP altered after review of spirometry when compared to those considered improved or stable by a ratio of 6:1. These results suggest that spirometry is most likely to supplement the physician's history and physical examination in the management of outpatients with pulmonary disease when the initial evaluation suggests that the patient has clinically deteriorated since the previous clinic visit, or when he or she has previous severe ventilatory dysfunction.

Effect of amiloride on diaphragmatic contractility: evidence of a role for Na(+)-Ca2+ exchange

Extracellular Ca2+ has been shown to be important for the normal function of the diaphragm. In this study we have examined the potential importance of Na(+)-Ca2+ exchange as a mechanism for Ca2+ influx during the contractile process by studying the effect of inhibition or stimulation of Na(+)-Ca2+ exchange. Blockade of Na(+)-Ca2+ exchange with amiloride attenuated the twitch response, altered the force-frequency response curve, and enhanced the development of fatigue. The effect of amiloride could be partially reversed by increasing the extracellular Ca2+ concentration. The ability of amiloride to decrease force was associated with decreased Ca2+ uptake by the diaphragm. Enhancing intracellular Na(+)-extracellular Ca2+ exchange by inhibiting the Na(+)-K+ pump significantly decreased the rate of the development of muscle fatigue (89%). The maximal inhibition of diaphragmatic force produced by the amiloride analogue benzamil, which possesses 10-fold greater selectivity for Na(+)-Ca2+ exchange, was not significantly different from that produced by amiloride (76.2 +/- 1.1%), with a concentration that decreased maximum force by 50% equal to 46 microM compared with 460 microM for amiloride. Both agents slowed the maximal rate of relaxation up to 90%. Benzamil elevated resting tension during continuous stimulation of the diaphragm at 0.15 Hz. The results suggest that Na(+)-Ca2+ exchange may have a role in the normal function of the diaphragm.

Mycoplasmal pneumonia. Are you thinking of atypical presentations?

The presentations of mycoplasmal pneumonia can be varied and sometimes complicated. The atypical nature of this illness, as opposed to the clear pattern of findings in classic bacterial pneumonias, leads the physician to the diagnosis. Appropriate therapy then allows quick improvement as a rule, with few sequelae.

Mucoid impaction of upper lobe bronchi in the absence of proximal bronchiectasis

Mucoid impaction is a complication of asthma and is frequently recurrent in patients with allergic bronchopulmonary aspergillosis (ABPA). This report describes a patient with asthma and recurrent bilateral well-circumscribed densities on chest roentgenogram in the absence of ABPA. Recognition of this clinical presentation may avoid the need for invasive diagnostic procedures or steroid therapy.

Tracheoesophageal fistula formation in intubated patients. Risk factors and treatment with high-frequency jet ventilation

Two ventilator dependent patients developed tracheoesophageal fistulas. Their subsequent treatment using high frequency jet ventilation resulted in transient clinical improvement. Risk factors for the development of tracheoesophageal fistulas in intubated patients are discussed and preventive measures are outlined. High frequency jet ventilation may be useful in managing these patients by preventing death from respiratory failure and allows time for definitive therapy.

Diaphragmatic fatigue is associated with decreased inositol 1,4,5-trisphosphate formation

The ability of the rat diaphragm to produce inositol 1,4,5-trisphosphate (InsP3) in response to a maximal contractile stimulus was determine in vitro in both fatigued and nonfatigued diaphragms. InsP3 was produced during a maximal contraction of the diaphragm. After inducing fatigue, there was a significant reduction in the production of InsP3 compared with that in nonfatigued muscle. The maximal force generated by the diaphragm was also decreased after fatigue. A significant positive linear correlation was found between the force developed by the diaphragm and the amount of InsP3 liberated.

Substrate channeling of NADH and binding of dehydrogenases to complex I

The binding of porcine heart mitochondrial malate dehydrogenase and beta-hydroxyacyl-CoA dehydrogenase to bovine heart NADH:ubiquinone oxidoreductase (complex I), but not that of bovine heart alpha-ketoglutarate dehydrogenase complex, is virtually abolished by 0.1 mM NADH. The malate dehydrogenase and beta-hydroxyacyl-CoA enzymes compete in part for the same binding site(s) on complex I as do the malate dehydrogenase and alpha-ketoglutarate dehydrogenase complex enzymes. Associations between mitochondrial malate dehydrogenase and bovine serum albumin were observed. Subtle convection artifacts in short-time centrifugation tests of enzyme association with the Beckman Airfuge are described. Substrate channeling of NADH from both the mitochondrial and cytoplasmic malate dehydrogenase isozymes to complex I and reduction of ubiquinone-1 were shown to occur in vitro by transient enzyme-enzyme complex formation. Excess apoenzyme causes little inhibition of the substrate channeling reaction with both malate dehydrogenase isozymes in spite of tighter equilibrium binding than the holoenzyme to complex I. This substrate channeling could, in principle, provide a dynamic microcompartmentation of mitochondrial NADH.

Inhibition of bovine heart mitochondrial and Paracoccus denitrificans NADH----ubiquinone reductase by dequalinium chloride and three structurally related quinolinium compounds

1. Dequalinium chloride (DECA) and three related quinolinium compounds inhibit bovine heart mitochondrial and Paracoccus denitrificans electron transport activity, with inhibition localized between NADH and ubiquinone in both electron transport chains. 2. Structure-activity studies reveal that two quinolinium rings and a long bridging group are necessary for significant inhibition of reduction of artificial electron acceptors and coenzyme Q, whereas only one quinolinium ring and a long hydrocarbon side chain are required for significant inhibition of NADH oxidase activity. 3. Inhibition of coenzyme Q reduction by DECA is not reversed by dialysis. 4. Studies comparing DECA inhibition of rotenone-sensitive with rotenone-insensitive preparations indicate that DECA acts by a different inhibitory mechanism than rotenone on mammalian mitochondrial and P. denitrificans NADH----ubiquinone reductase.

Massive retroperitoneal hemorrhage from an asymptomatic adrenal cortical adenoma. Report of a case

A 52-year-old man was admitted to the General Surgical Service, with acute onset of left back and flank pain. Two weeks prior to admission he had been subjected to a 3G to 4G acceleration in an ejection seat training simulator. On the day of admission, he had performed a 100 yard swim in flight gear following a seven foot jump into water. He denied any injury during the above exercises or any other trauma. A falling hematocrit was demonstrated by serial determinations and a computerized tomography scan revealed a left retroperitoneal hematoma with normal bilateral renal function and no obvious renal injury. Continued hemorrhage resulted in laparotomy, which showed an 11 cm left adrenal tumor with massive hemorrhage into the retroperitoneum. Histologically the tumor was a benign non-functioning adrenal cortical adenoma.

Clinical significance of an isolated reduction in residual volume

To determine the significance of an isolated reduction in residual volume (RV), the medical records and chest radiographs of 69 patients who had a RV less than or equal to 65% of predicted and normal VC, DLCO, and expiratory flow rates were reviewed. Sixty-three of 69 patients (92%) had clinical conditions that could account for their decreased RV. Definite disease was considered to be present in the 39 patients with radiographically apparent parenchymal (n = 18) or chest wall (n = 21) abnormalities, whereas 24 others with clinical diagnoses such as congestive heart failure or toxic inhalation were considered to have probable disease. All patients who had a RV below 50% of predicted had either definite or probable disease. Follow-up testing of 19 patients 31 +/- 21 months after their initial reduction in RV was first documented indicated that the RV accurately reflected the patient's current clinical status in that it increased by 17 +/- 16% of predicted in those who were clinically improved and decreased by 27 +/- 7% in those who were clinically worse. In patients who were clinically stable, the isolated reduction in RV was a persistent finding. We conclude that an isolated reduction in RV is a clinically significant finding indicative of pulmonary or chest wall disease. Interval changes in RV reflect alterations in disease activity.

Hemodynamic and non-bronchial effects of ipratropium bromide

Older anticholinergic agents such as stramonium and atropine have significant non-pulmonary effects. The non-pulmonary effects of a new quaternary anticholinergic, ipratropium bromide, have been studied both in the United States and abroad; these effects include inhibition of salivation, interference with micturition, and ocular effects such as pupil size, visual acuity, and intraocular pressure. Hemodynamic effects such as heart rate, blood pressure, and blood gas changes have also been studied. These evaluations have been performed in animals and in healthy and sick human subjects, following administration of ipratropium parenterally and by inhalation in a variety of dosage ranges. Ipratropium, a muscarinic inhibitor, would be expected to have effects similar to those of atropine. The most conspicuous result of these studies has been the low incidence of significant changes, even at high dose levels, when ipratropium bromide is administered by inhalation.

The molecular morphology of bovine heart mitochondrial NADH----ubiquinone reductase. Native disulfide-linked subunits and rotenone-induced conformational changes

Bovine heart mitochondrial NADH----ubiquinone reductase (complex I), contains two disulfide-linked subunits of 75 and 33 kDa as revealed by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis with beta-mercaptoethanol omitted from preparation of the sample for the first dimension. Two unidentified polypeptides (110-115 and 69 kDa) are also found in disulfide linkage with the two complex I subunits. The 110-115-kDa polypeptide appears to be pyridine dinucleotide transhydrogenase by several criteria including selective precipitation with an antibody raised to the purified transhydrogenase. The two disulfide-linked subunits were also found in a product cross-linked for 2 min with dithiobis (succinimidyl propionate) (DSP) along with five other complex I subunits of 53-57, 42, 24-27, 17-18, and 12.5-15.5 kDa (Gondal, J.A., and Anderson, W.M. (1985) J. Biol. Chem. 260, 5931-5935) indicating that these seven subunits lie within 11-12 A of each other at one or more points in space in the enzyme's interior. Cross-linking of complex I with DSP for 2 min in the presence of 1 microM rotenone yielded a cross-linked product consisting of the two natural disulfide-linked subunits and the 110-115- and 69-kDa polypeptides. This suggests that rotenone induces a conformational change in the enzyme that moves the seven DSP cross-linked subunits away from each other and outside the 11-12 A bridging distance of DSP. This alteration in conformation may be communicated to iron-sulfur center N-2 within the hydrophobic outer shell of the enzyme to prevent electron transfer to its natural electron acceptor, ubiquinone. A model of rotenone action based upon these observations is presented.

The molecular morphology of bovine heart mitochondrial NADH-ubiquinone reductase. Cross-linking with dithiobis(succinimidyl propionate)

The molecular morphology of NADH-ubiquinone reductase (complex I) was investigated by cross-linking with the cleavable bifunctional reagent, dithiobis(succinimidyl propionate). Cross-linking inhibits the following activities of the complex--NADH----3-acetylpyridine adenine dinucleotide (oxidized), NADH----2,6-dichloroindophenol, NADH----ferricyanide, and NADH----menadione--to different degrees with the greatest inhibition occurring with either ferricyanide or 3-acetylpyridine adenine dinucleotide as electron acceptor. Addition of 150 microM NADH affords partial protection from inhibition. Cross-linking quenches the FMN fluorescence of complex I (288 nm excitation/515 nm emission), and addition of 150 microM NADH greatly reduces the quenching. Treatment of complex I (1 mg/ml) for 2 min with dithiobis(succinimidyl propionate) (0.2 mg/ml) at 4 degrees C revealed a cross-linked product consisting of the following seven subunits: 75-80, 53-57, 42, 33-35, 24-27, 17-18, and 12.5-15.5 kDa. Five minutes of treatment cross-linked the unidentified polypeptides of 69 and 51 kDa to six of the seven complex I subunits, but the 12.5-15.5-kDa subunit may be missing from this cross-linked product, while 15 min of treatment cross-linked additional unidentified polypeptides of 177, 107, 72, and 63 kDa. Since longer times of cross-linking result in a larger number of unidentifiable polypeptide spots, the shorter cross-linking time results are taken as a more accurate picture of the native enzyme conformation. This would indicate that within complex I the following subunits are within 12 A of each other at one or more points in space: 75-80, 53-57, 42-45, 33-35, 24-27, 17-18, and, perhaps, 12.5-15.5 kDa. These subunits represent portions of all three fractions of the enzyme, i.e. flavoprotein, iron-protein, and insoluble or hydrophobic fractions.