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 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.

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.

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.

Computer quantitation of saturation impairment time as an index of oxygenation during sleep.

The measurement of oxygenation during sleep has become a standard procedure in the assessment of hypoxemia in patients with various disorders. However, an accepted method for quantitating this hypoxemia is not available. This study describes the development of computerized data acquisition and analysis programs to quantitate nocturnal hypoxemia in patients with sleep and breathing disorders. The acquisition program samples the voltage output from pulse oximeters used to measure oxyhemoglobin saturation (SpO2) and stores this on an IBM PC or compatible computer. The analysis program integrates the SpO2 over time below the patient's pretest baseline as well as the integral below 90, 80, 70, 60 and 50% saturation. We refer to each integral as Saturation Impairment Time or SIT. In order to compare these integrals between patients or between the same patient but different studies, the integral is divided by the total sleep study time. We refer to each of these integrals, corrected for sleep study time, as the SIT index. Evaluation of the SIT index in 10 consecutive patients referred for various sleep disorders revealed acquisition program detection and deletion of 48 of 57 (86%) oximeter probe artifacts (mean duration of 3 seconds for undetected artifacts). There were no significant artifacts in the analysis program calculation of the SIT index in these same patients. In conclusion, computer programs were developed to measure and quantitate oxygen saturation measured by oximeters. Preliminary results reveal an accuracy of measurement which should prove acceptable in further clinical evaluations.

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.