Effect of treatment with zileuton, a 5-lipoxygenase inhibitor, in patients with asthma. A randomized controlled trial. Zileuton Clinical Trial Group

OBJECTIVE

To study the effect of 3 months of treatment with zileuton, an inhibitor of the enzymatic pathway (5-lipoxygenase) leading to leukotriene formation, on disease control in patients with mild to moderate asthma.

DESIGN

Randomized, double-blind, parallel-group study in 401 patients. A 10-day placebo lead-in was followed by a double-blind treatment period of 13 weeks.

SETTING

Asthma study clinics in university hospitals and private practices.

PATIENTS OR OTHER PARTICIPANTS

Patients with mild to moderate asthma (forced expiratory volume in the first second [FEV1], 40% to 80% of predicted) whose only treatment was inhaled beta-agonists.

INTERVENTIONS

Treatment with 600 mg or 400 mg of zileuton or placebo (each taken four times daily.)

MAIN OUTCOME MEASURES

Frequency of asthma exacerbation requiring treatment with corticosteroids, use of inhaled beta-agonists, pulmonary function tests, asthma symptom assessment, and quality-of-life evaluation. Safety was evaluated by monitoring adverse events.

RESULTS

Only eight (6.1%) of 132 patients receiving 600 mg of zileuton four times a day required corticosteroid treatment for asthma vs 21 (15.6%) of 135 patients receiving placebo (P=.02), giving a relative risk of 2.6. At the time of expected peak drug concentration, the average FEV1 improved 15.7% in the 600-mg zileuton group vs 7.7% in the placebo group (P=.006). Quality-of-life assessments significantly improved in the 600-mg zileuton group and not in the placebo group (P=.007 for the overall score). Elevations in liver function tests (more than three times normal), all of which reversed with drug withdrawal, occurred in five patients (P=.03 vs placebo), three patients (P=.12 vs placebo), and no patients treated with 600 mg of zileuton, 400 mg of zileuton, or placebo, respectively.

CONCLUSIONS

Three months of 5-lipoxygenase inhibition produced a significant improvement in asthma control. These data indicate that 5-lipoxygenase products of arachidonic acid metabolism are mediators of inflammation with an important role in the biology of asthma.

Inhibition of exercise-induced bronchospasm by zileuton: a 5-lipoxygenase inhibitor

Recent evidence suggests that leukotrienes may have a causative role in exercise-induced asthma. Twenty-four subjects with exercise-induced asthma received either 600 mg zileuton, a 5-lipoxygenase inhibitor, or a placebo four times daily for 2 d prior to exercise challenge (a total of nine doses). The last dose was administered in the laboratory 2 h before the exercise challenge. There was no bronchodilation after nine doses of the 5-lipoxygenase inhibitor (p=0.95). The administration of zileuton inhibited bronchospasm after exercise challenge by 40.75% as compared with placebo. Five minutes after the completion of exercise, the zileuton group's FEV1 was 85.76% of the preexercise value, compared with 73.92% of the preexercise value in the placebo group (p<0.01). The maximum percent change in baseline FEV1 after zileuton was a 15.58% decrement from the preexercise level, as compared with a 28.1% decrease after placebo (p<0.001). Five minutes after exercise, the FVC after zileuton was 92.76% of the preexercise value, as compared with 86.26% after placebo (p<0.05). This is the first study in which a 5-lipoxygenase inhibitor has been shown to attenuate exercise-induced asthma. These results suggest that leukotrienes are important biochemical mediators in the development of exercise-induced bronchospasm, and that leukotriene inhibit may have a role in the treatment of this disorder.

Efficacy and safety of oral granisetron versus oral prochlorperazine in preventing nausea and emesis in patients receiving moderately emetogenic chemotherapy

PURPOSE

To compare the efficacy and safety of oral granisetron hydrochloride tablets with that of oral prochlorperazine sustained-release capsules in preventing nausea and emesis induced by moderately emetogenic chemotherapeutic agents.

PATIENTS AND METHODS

In this multicenter, double-blind, randomized, parallel group study, oral granisetron and oral prochlorperazine were compared in 230 chemotherapy-naive, adult cancer patients who received moderately emetogenic chemotherapy. Patients were stratified by gender and randomized to receive either 1.0 mg oral granisetron HCI twice a day for 7 days, or 10 mg oral prochlorperazine sustained-release capsules twice a day for 7 days. The first dose was given 1 hour before initiation of chemotherapy and the second dose 12 hours after the first dose. Patients were evaluated for emetic episodes, extent of nausea, and adverse events for 7 days after the start of chemotherapy. Primary efficacy parameters were complete response (no emetic episodes, no greater than mild nausea, no antiemetic rescue) and total control (no emetic episodes, no nausea, no antiemetic rescue) in the 24 hours after the start of chemotherapy.

RESULTS

Granisetron was significantly more effective than prochlorperazine in achieving a complete response (74% vs. 41%, respectively) and total control of nausea and vomiting (58% vs. 33%, respectively) at the 24-hour assessment. Complete response at 24 hours was significantly higher in the granisetron-treated patients than in prochlorperazine-treated patients. In women, granisetron showed a complete response rate of 69% versus 38% with prochlorperazine; in men, granisetron showed a complete response rate of 92% versus 61% with prochlorperazine. Both regimens were well tolerated, with headache (36% for granisetron, 29% for prochlorperazine) and constipation (31% for granisetron, 6% for prochlorperazine) the most common adverse events.

CONCLUSIONS

: Oral granisetron 1 mg twice a day was significantly more effective than oral prochlorperazine sustained release capsules 10 mg twice a day in complete response and total control of nausea and vomiting at 24 hours after chemotherapy. Both agents were well tolerated.

Mild systolic dysfunction in heart failure (left ventricular ejection fraction >35%): baseline characteristics, prognosis and response to therapy in the Vasodilator in Heart Failure Trials (V-HeFT)

OBJECTIVES

This analysis sought to evaluate the clinical characteristics and outcome in heart failure with mild systolic dysfunction.

BACKGROUND

Although heart failure with mild systolic dysfunction occurs commonly, this is an understudied area because clinical trials have usually excluded patients with ejection fraction >35%.

METHODS

The 422 patients with left ventricular ejection fraction </=35% were compared with 172 with a left ventricular ejection fraction >35% in the Vasodilator in Heart Failure Trial (V-HeFT I), whereas in V-HeFT-II 554 patients with a left ventricular ejection fraction </=35% were compared with 218 patients with a left ventricular ejection fraction >35% for mortality and clinical care. For a left ventricular ejection fraction >35%, treatment with hydralazine/isosorbide dinitrate was compared with prazosin and placebo therapy in V-HeFT I, and hydralazine/isosorbide dinitrate was compared with enalapril in V-HeFT II for mortality, clinical course and change in physiologic variables: ejection fraction, plasma norepinephrine levels, ventricular tachycardia and echocardiographic variables.

RESULTS

In both studies, patients with a left ventricular ejection fraction >35% differed principally in hypertensive history, higher functional capacity and radiographic and echocardiographic cardiac dimension from patients with a left ventricular ejection fraction </=35%, and plasma norepinephrine levels differed in V-HeFT II (p < 0.01). Patients with a left ventricular ejection fraction >35% had a lower cumulative mortality than those with a left ventricular ejection fraction </=35% (p < 0.0001) and less frequent hospital admissions for heart failure (p < 0.014, V-HeFT I; p < 0.005, V-HeFT II). Although cumulative mortality and morbidity did not differ between treatment groups in V-HeFT I, enalapril decreased overall mortality versus hydralazine/isosorbide dinitrate (p < 0.035) in V-HeFT II. For physiologic variables in V-HeFT II, enalapril decreased ventricular tachycardia at follow-up (p < 0.05).

CONCLUSIONS

In V-HeFT, heart failure with mild systolic dysfunction was associated with different characteristics and a more favorable prognosis than heart failure with more severe systolic dysfunction. Enalapril decreased overall mortality and sudden death compared with hydralazine/isosorbide dinitrate. Prospective trials are needed to address therapy for heart failure with mild systolic dysfunction.

A controlled trial of the effect of the 5-lipoxygenase inhibitor, zileuton, on lung inflammation produced by segmental antigen challenge in human beings

BACKGROUND

Segmental antigen challenge (SAC) and bronchoalveolar lavage (BAL) have been proven useful for investigating IgE-mediated lung inflammation in volunteers with allergies.

OBJECTIVE

This model was used to evaluate the pulmonary antiinflammatory effects of an experimental 5-lipoxygenase inhibitor (zileuton) in subjects allergic to ragweed. We hypothesized that decreased generation of leukotrienes by inhibition of the 5-lipoxygenase pathway of arachidonic acid metabolism would diminish the subsequent inflammatory response resulting from antigen challenge.

METHODS

Ten subjects with allergies received zileuton or placebo, 600 mg administered orally four times a day for 8 days, and then underwent bronchoscopy, BAL of a control segment, and SAC in the contralateral lung followed by BAL of the challenged segment 24 hours later in a double-blind, placebo-controlled, crossover protocol. Urinary excretion of leukotriene E4 induced by antigen challenge plus total and differential cell counts and the amount of total protein, albumin, urea, and eosinophil cationic protein in BAL fluid were determined.

RESULTS

A significant inhibition of leukotriene production (approximately 86%) was observed in subjects receiving zileuton. In addition, there was a statistically significant increase in eosinophils after antigen challenge (0.6 +/- 0.2 x 10(4) eosinophils/ml increasing to 49.0 +/- 25.0 x 10(4) in subjects receiving placebo, whereas the influx of eosinophils in subjects receiving zileuton was not statistically different from baseline (1.1 +/- 0.7 x 10(4) eosinophils/ml increasing to 16.5 +/- 4.1 x 10(4); analysis of variance for repeated measures with post hoc comparisons).

CONCLUSIONS

Treatment with zileuton altered the inflammatory response after antigen challenge. Products of the 5-lipoxygenase pathway appear to be important in recruiting eosinophils to the lung after SAC.

Acute trimethyltin exposure produces nonspecific effects on learning in rats working under a multiple repeated acquisition and performance schedule

Previous research has explored the adverse effects of trimethyltin (TMT) on learning and memory in laboratory animals. Virtually all studies of TMT effects on learning have not, however, included appropriate controls to establish a selective effect on learning. This experiment investigated the effects of TMT on the repeated acquisition (learning) and performance of response sequences. Adult male Long-Evans rats, maintained at 300 g b.wt., were trained with food reinforcement under a multiple repeated acquisition (RA) and performance (P) schedule. The RA component required rats to learn a different three-member response sequence during each session (Center Right Left, RLC, RCL, LCR, or LRC); the correct response sequence remained constant in the P component (CLR). RA and P components alternated twice during a session. Rats were given 0, 4, or 8 mg/kg TMT IV after 30 sessions of stable baseline performance, and an additional 40 sessions were conducted following TMT. Prior to TMT, all groups maintained comparable accuracy levels in both RA and P components. Following TMT, significant decreases in both accuracy and response rate were obtained in the 8 mg/kg group. Thereafter, response rate and accuracy both recovered to near baseline levels, although large individual differences were observed. No selective effects of TMT were obtained on RA when compared to P. These data suggest that TMT-induced impairments on learning may be due to a generalized performance decrement rather than a specific effect on learning.

Effect of chronic 5-lipoxygenase inhibition on airway hyperresponsiveness in asthmatic subjects

The leukotrienes are known bronchoactive agonists with potential proinflammatory effects that may be involved in mediating airway hyperresponsiveness. We investigated the effects of zileuton, an inhibitor of 5-lipoxygenase (5-LO), on airway responsiveness to cold, dry air in patients with moderate asthma. A group of 10 asthmatic patients underwent cold, dry air hyperventilation challenge; challenges were performed before drug treatment and 1 to 10 d after the completion of treatment with study drugs. The cold air minute ventilation required to cause a 15% decrease in FEV1 (PD15 VE) increased by 58% compared with the response before treatment, 1 to 10 d after the completion of 13 wk of treatment with zileuton. The geometric mean (geometric mean/SEM and geometric mean x SEM) PD15 VE increased from 24.5 (20.4, 29.5) L/min to 38.8 (34.7, 43.7) L/min (p = 0.01). Zileuton treatment inhibited 5-LO as measured ex vivo by ionophore-stimulated LTB4 levels in whole blood. In four of seven subjects, LTB4 levels before zileuton ingestion fell from 110.88 +/- 25.42 to 5.40 +/- 1.95 ng/ml 2 h post-zileuton dosing (p = 0.02, pre- versus 2 h postzileuton ingestion). Consistent with the short half-life of zileuton, 6 h postzileuton dosing the ionophore-stimulated, LTB4 levels in whole blood had increased to 89.68 +/- 35.54 ng/ml (p = 0.41, pre- versus 6 h postzileuton ingestion). Based on the first-order kinetics of zileuton, its effect on 5-LO activity should have been dissipated less than 16 h postingestion. Thus, chronic zileuton treatment decreased airway hyperresponsiveness as determined by reactivity to cold, dry air.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of 5-lipoxygenase inhibition on bronchoconstriction and airway inflammation in nocturnal asthma

To investigate the contribution of leukotrienes (LTs) to inflammation and bronchoconstriction in nocturnal asthma, we performed a randomized trial in 12 asthmatic patients and 6 normal control subjects. This study involved pulmonary function testing, methacholine challenge, bronchoscopy for cell counts, LT and thromboxane (TX) levels in bronchoalveolar lavage (BAL) fluid, and collection of urine for LTs at 4:00 P.M. and 4:00 A.M. At 4:00 P.M. BAL fluid LTB4 and sulfidopeptide LT levels in asthmatic and control subjects were not statistically different. At 4:00 A.M. alone, LTB4 and cysteinyl LT levels increased to become significantly greater in asthmatic than in control subjects, LTB4 levels correlating significantly (r = -0.66, p < 0.0001) with nocturnal fall in FEV1. Nocturnal asthmatic urinary LTE4 levels were also significantly higher than those of control subjects. The 4:00 A.M. testing was repeated during treatment with a 5-lipoxygenase inhibitor, zileuton. In asthmatic subjects, zileuton decreased BAL fluid LTB4 (p = 0.01) and urinary LTE4 (p = 0.01) while showing a trend for improving nocturnal FEV1 (p = 0.086). These decreases in LTB4 levels and improvement in FVE1 were associated with significant reductions in 4 A.M. BAL fluid and blood eosinophil percentages on zileuton compared with placebo administration. These findings demonstrate the importance of LTs in both the inflammation and the physiology of nocturnal asthma.

Structural requirements of synthetic and natural product lipo-chitin oligosaccharides for induction of nodule primordia on Glycine soja

Rhizobia synthesize a class of lipo-chitin oligosaccharides that induce root hair deformation and induce the initiation of nodule structures on legume roots. These lipo-chitin oligosaccharides are tetra- and penta-lipo-oligosaccharides of N-acetylglucosamine with an acyl substitution on the nonreducing end and are commonly known as Nod factors. In this study, we demonstrate that synthetic analogs of natural product Nod factors have the same biological activities. To determine structure-activity relationships, a collection of synthetic and natural product lipo-chitin oligosaccharides was assayed on Glycine soja. All biologically active lipo-chitin oligosaccharides induced both root hair deformation and nodule initiations on G. soja. The most active lipo-chitin oligosaccharides deformed root hairs at 10(-15) M and induced nodules at 1 ng of lipo-chitin oligosaccharide per spot inoculation. Plant responses demonstrate an interdependence of backbone length and the presence of substitutions on the reducing end. Lipo-chitin oligosaccharides containing four N-acetylglucosamine residues were active only without a reducing end modification, whereas lipo-chitin oligosaccharides containing five N-acetylglucosamine residues were active only with reducing end modification. The plant thus recognizes lipo-chitin oligosaccharides without reducing end substitutions despite the importance of these modifications for host range.

Insights into IgE-mediated lung inflammation derived from a study employing a 5-lipoxygenase inhibitor

We have recently reported that the 5-lipoxygenase (5-LO) inhibitor, zileuton, alters lung inflammation produced by segmental antigen challenge in ragweed-allergic human subjects. Specifically, zileuton inhibited the urinary excretion of leukotriene E4 produced by antigen challenge, and the significant increase in bronchoalveolar lavage (BAL) eosinophils observed in subjects on placebo was not seen in subjects on zileuton. In this manuscript, we report additional data obtained during that study which provide information about mechanisms important during IgE-mediated inflammatory reactions in the lung. Three different areas are addressed: 1) the time to recovery of the lung from an IgE-mediated inflammatory response; 2) mechanisms related to the generation of cyclooxygenase products in the lung after antigen challenge and the effect of 5-LO inhibition on the production of cyclooxygenase metabolites; and 3) mechanisms responsible for the production of peptide leukotrienes in the lung and lung injury (as shown by albumin influx into the alveolar air space) 24 h after antigen challenge. We observed the following: 1) a significant BAL eosinophilia and basophilia remained 31 days (range 21-48) after segmental antigen challenge and bronchoalveolar lavage; 2) a decreased quantity of BAL cyclooxygenase products, as well as lipoxygenase products, in the presence of 5-LO inhibition; and 3) correlative analyses which suggest that while eosinophils appear most important for the production of peptide leukotrienes and lung injury 24 h after antigen challenge in subjects taking placebo, other effector mechanisms, perhaps those involving basophils and the initial mast cell triggering event, appear to gain in importance when the IgE-mediated inflammatory reaction is blunted by 5-LO inhibition.

Repeated acquisition of response sequences: the analysis of behavior in transition

Repeated acquisition (RA) procedures are behavioral preparations in which subjects are required to learn new response sequences within each experimental session. Such procedures avoid problems inherent in nonRA learning procedures. For example, as the subject masters nonRA tasks, one begins to measure performance of a learned response rather than learning itself. Advantages to using RA procedures include (a) the strength of the within-subjects design, including the ability to establish dose effect curves within individual subjects; (b) the ability to assess learning phenomena over extended periods of time; (c) the ability to use chronic dosing regimens; and (d) the ability to assess treatments with permanent or long-lasting effects. In addition, analysis of the response patterns committed during acquisition allows for a description of how behavioral strategies may change in response to experimental manipulation. Difficulties include the relatively long training period often preceding attainment of a stable baseline of acquisition. This review examines the history of RA paradigms, with an emphasis on procedural comparisons.

Direct evidence for a role of the mast cell in the nasal response to aspirin in aspirin-sensitive asthma

BACKGROUND

A subset of patients with asthma experience adverse nasoocular reactions after ingestion of aspirin or agents that inhibit cyclooxygenase. Recent evidence has implicated the leukotrienes in the nasoocular reaction, but the cellular sources and mechanism of activation are unknown. We used nasal lavage with and without a 5-lipoxygenase inhibitor, zileuton, to define the role of leukotrienes and to profile nasal cellular activation during this reaction.

METHODS

A group of eight patients with asthma shown to have adverse reactions to aspirin documented by a 15% or greater decrease in forced expiratory volume in 1 second, accompanied by an elevation in urinary leukotriene E4 after ingestion of aspirin, received aspirin or placebo in a study with a crossover design. Nasal symptoms and nasal tryptase, histamine, leukotriene, and eosinophil cationic protein levels were evaluated. Serum tryptase and urinary histamine levels were also assessed. Subjects were then randomized to receive a week of treatment with zileuton or placebo, according to a double-blind, crossover design followed by aspirin challenge and measurement of the same mediators.

RESULTS

Aspirin ingestion produced a marked increase in nasal symptoms from a baseline symptom score of 2.1 +/- 0.7 to a maximum of 8.4 +/- 1.2 (p < 0.0007). Aspirin ingestion produced a mean maximal increase in nasal tryptase of 3.5 +/- 2.6 ng/ml, whereas placebo ingestion produced a mean maximal increase of 0.1 +/- 0.2 ng/ml (p < 0.05, aspirin vs placebo). Mean maximal nasal histamine increased 1.73 +/- 1.16 ng/ml versus 0.08 +/- 0.08 ng/ml from baseline (p < 0.05, aspirin vs placebo). Aspirin produced a mean maximal increase in nasal leukotriene value of 152 pg/ml versus a 16 pg/ml decrease after placebo ingestion (p < 0.05). Zileuton treatment blocked the increase in nasal symptoms after aspirin ingestion (maximum nasal symptom score of 1.6 +/- 0.6 with zileuton vs 5.5 +/- 0.9 with placebo [p < 0.0053]). It also blocked the rise in nasal tryptase (p = 0.011) and nasal leukotriene (p < 0.05) levels after aspirin ingestion. Zileuton treatment had no significant effect on the recovery of nasal histamine.

CONCLUSION

The increase in nasal symptoms in aspirin-sensitive patients with asthma after aspirin ingestion is associated with increases in nasal tryptase, histamine, and cysteinyl leukotriene levels. This mediator profile is consistent with mast cell activation during the nasal response to aspirin and suggests that 5-lipoxygenase products are essential for the nasal response to aspirin.

Lead exposure potentiates the effects of NMDA on repeated learning

Several studies now suggest that Pb exposure disrupts NMDA receptor complex function, findings which may have implications for understanding the basis of Pb-induced learning impairments. To further evaluate this possibility, the behavioral properties of the glutamate agonist NMDA were compared in rats that had been chronically exposed to 0, 50, or 250 ppm Pb acetate in drinking water from weaning. Acute administration of NMDA (20-50 mg/kg IP) decreased accuracy in both the repeated acquisition (RA) and performance (P) components of this multiple schedule with a selective effect on the learning component in the second half of the session. Analyses of error patterns revealed that the disruption of RA accuracy derived from initial perseverative errors followed by errors of skipping forward and backwards in the 3-member response sequence. Response rates in both RA and P were suppressed by NMDA. Pb-exposure potentiated the accuracy-impairing effects of NMDA by further increasing the frequencies of these error classes, and likewise potentiated the rate-suppressing effects of NMDA. These findings add further support to the possible involvement of Pb with the NMDA receptor complex.

The effect of inhibition of 5-lipoxygenase by zileuton in mild-to-moderate asthma

OBJECTIVE

To evaluate the effectiveness of inhibiting the formation of the 5-lipoxygenase products of arachidonic acid by the 5-lipoxygenase inhibitor zileuton in the treatment of mild-to-moderate asthma.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

University hospitals and private allergy and pulmonary practices.

PATIENTS

A total of 139 persons with asthma who had a forced expiratory volume in 1 second (FEV1) of 40% to 75% of the predicted value and who were not being treated with inhaled or oral steroids.

INTERVENTION

Zileuton, 2.4 g/d or 1.6 g/d, or placebo for 4 weeks.

MEASUREMENTS

Airway function, beta-agonist use, and symptoms; inhibition of 5-lipoxygenase assessed by measurement of urinary leukotriene E4 (LTE4).

RESULTS

Zileuton produced a 0.35-L (95% CI, 0.25 to 0.45 L) increase in the FEV1 within 1 hour of administration (P < 0.001 compared with placebo), equivalent to a 14.6% increase from baseline. After 4 weeks of zileuton therapy, airway function and symptoms improved, with the greatest improvements occurring in the 2.4 g/d group: This group's FEV1 increased by 0.32 L (CI, 0.16 to 0.48 L), a 13.4% increase, compared with a 0.05-L (CI, -0.10 to 0.20 L) increase in patients taking placebo (P = 0.02). Symptoms and frequency of beta-agonist use also decreased with zileuton, 2.4 g/d. The mean urinary LTE4 level decreased by 39.2 pg/mg creatinine (CI, 18.1 to 60.4 pg/mg creatinine) and 26.5 pg/mg creatinine (CI, 6.6 to 46.5 pg/mg creatinine) in the 2.4 g/d and 1.6 g/d groups, respectively, compared with a slight increase in the placebo group (P = 0.007 and P = 0.05). No difference was noted in the number of adverse events among treatment groups.

CONCLUSIONS

Inhibition of 5-lipoxygenase can improve airway function and decrease symptoms and medication use in patients with asthma, suggesting that this inhibition can be useful therapy for asthma. Also, 5-lipoxygenase products may mediate part of the baseline airway obstruction in patients with mild-to-moderate asthma.

The pivotal role of 5-lipoxygenase products in the reaction of aspirin-sensitive asthmatics to aspirin

A subset of persons with asthma develop bronchospasm, naso-ocular, gastrointestinal, and/or dermal reactions after ingesting aspirin (ASA) or agents with the capacity to inhibit cyclooxygenase. The bronchopulmonary reactions have been associated with a rise in urinary LTE4. We examined the effects of an inhibitor of 5-lipoxygenase, zileuton, in a group of eight asthmatic patients with known sensitivity to ASA accompanied by LTE4 hyperexcretion. We first confirmed ASA sensitivity and an increase in urinary LTE4 after ASA ingestion in these patients using a placebo-controlled ASA challenge. Subjects were then randomized to a double-blind, crossover trial to examine the effects of zileuton versus placebo on the response to ASA. Zileuton treatment decreased baseline urinary LTE4 excretion from a mean of 469 +/- 141 pg/mg creatinine to 137 +/- 69 pg/mg creatinine (p < 0.02) and blunted the maximum increase in urinary LTE4 after ingestion of ASA (3,539 +/- 826 pg/mg creatinine versus 1,120 +/- 316 pg/mg creatinine [p < 0.01]). The pre-ASA challenge FEV1 was unchanged by zileuton (3.41 +/- 0.15 L versus 3.35 +/- 0.17 L, zileuton versus placebo). Zileuton prevented the fall in FEV1 in response to ingestion of ASA; post-ASA ingestion the mean of the minimal FEV1 fell to 2.72 +/- 0.18 L on the placebo day while there was no significant fall on the zileuton day (3.26 +/- 0.17 L; p < 0.014). Zileuton also prevented the development of the nasal, gastrointestinal (p < 0.006 and p < 0.025, respectively), and dermal symptoms which developed after ASA ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Vascular abnormalities in non-insulin-dependent diabetes mellitus identified by arterial waveform analysis

PURPOSE

The arterial pressure waveform is derived from the complex interaction of the left ventricular stroke volume and the physical properties of the arterial circulation. Widespread abnormalities in the physical characteristics of the arterial vessels associated with diabetes mellitus can produce consistent changes in the shape of the pressure pulse waveform, providing information about arterial structure and tone that can be quantitated by pulse contour analysis.

PATIENTS AND METHODS

We analyzed intraarterial brachial artery waveforms in 28 patients with non-insulin-dependent diabetes mellitus and 22 control subjects matched for age and sex. A computer-based assessment of the diastolic pressure decay and a modified Windkessel model of the circulation were employed to quantify changes in arterial waveform morphology in terms of the large-artery compliance (C1), the oscillatory diastolic waveform (C2), inertance, and systemic resistance.

RESULTS

No differences were found in heart rate, mean arterial pressure, cardiac output, or stroke volume between groups. The mean oscillary arterial compliance estimate was significantly reduced in diabetic subjects versus controls: 0.02 (95% confidence interval [CI], 0.01 to 0.03) mL/mm Hg versus 0.08 (95% CI, 0.04 to 0.12) mL/mm Hg (p < 0.001). Oscillatory compliance values were uniformly reduced in the diabetic subjects regardless of the presence or absence of physical complications of the disease. No differences in large-artery compliance, inertance, or systemic resistance were found between groups. No positive correlations were found between indices of glycemic control, the known duration of diabetes, and any of the hemodynamic variables.

CONCLUSIONS

Quantitative changes in the arterial pressure pulse waveform, reflected by a reduced oscillatory compliance estimate, were found in patients with non-insulin-dependent diabetes mellitus. This estimate appears to act as an early marker for the vascular abnormalities associated with diabetes before complications of the disease become clinically apparent. By contrast, no changes in large-artery compliance were found in this patient population free from clinically obvious macrovascular disease.

Impedance cardiography: the failure of sternal electrodes to predict changes in stroke volume

A study was conducted on 26 healthy male adults comparing the stroke volume (SV) and cardiac output (CO) measured with green dye and impedance cardiography in supine, sitting and during 50 W bicycle exercise. The impedance voltage pick-up electrodes were modified from the standard band location and placed at the suprasternal notch and 10 cm below. The percentage change of SV going from supine to sitting was -27.2 +/- 7.4% and -16.9 +/- 22% for the dye and impedance values respectively. The percentage change of SV going from sitting to exercise was 20.9 +/- 11.9% and 36.7 +/- 32.9% for the dye and impedance values respectively. The percentage change in SV determined by impedance shows poor correlation (supine to sitting R = 0.16 and sitting to exercise R = 0.42) with dye values. The individual impedance values for a given change in position or exercise showed considerably more variation compared with the dye. Impedance determination of SV using electrodes on the sternum does not appear to be a valid method for SV and CO measurements.

Histoplasmosis of the larynx

INTRODUCTION

Laryngeal histoplasmosis was first described in 1952. Since then, fewer than 100 cases had been reported. This dimorphic fungus is endemic in the Mississippi and Ohio River Valleys. The yeast phase is responsible for human infection.

METHODS

We report a 44-year-old woman who developed laryngitis. The markedly abnormal larynx, which could have been mistaken for papillomatosis, was biopsied, at which time the diagnosis of histoplasmosis was confirmed. Treatment with oral ketoconazole was instituted.

RESULTS

Objective voice assessment showed abnormalities of maximum phonation time, speaking fundamental frequency, perturbation, percent voicing, mean flow rate, and spectral pattern. Subsequent to antifungal therapy, objective measures were improved.

CONCLUSION

This represents the first case of laryngeal histoplasmosis in which response to therapy is documented by objective vocal assessment.

Complications of trochanteric osteotomy. Long-term implications

Cemented total hip arthroplasties (THAs) were performed through a Charnley transtrochanteric approach in 1162 patients from 1970 through 1986. Trochanteric separations numbered 58 (5%). Rate of nonunion was related to gender, preoperative diagnosis, and prior THA or endoprosthesis. Nonunion patients had lower mean Charnley pain and function mean scores than union patients at the 45- and 49-month examinations, respectively. A Trendelenberg gait was noted in 17% of nonunions compared with 6% of united patients. Revision rates were nearly three times higher in nonunion patients. These results indicate there is a quantifiable risk for a surgeon who chooses to use a trochanteric osteotomy.

Subsensitivity of lead-exposed rats to the accuracy-impairing and rate-altering effects of MK-801 on a multiple schedule of repeated learning and performance

Exposure to lead (Pb) has been reported to inhibit MK-801 binding and to alter other NMDA receptor complex-associated functions. These reported changes are provocative since both NMDA receptor antagonism and Pb exposure are know to impair learning processes. Whether the Pb-induced changes in NMDA function relate to the learning impairments associated with Pb exposure, however, has not been explored. The contention of this study was that if changes in NMDA function produced by Pb serve as the basis of Pb-associated learning impairments, then such changes should be of sufficient biological magnitude and clinical relevance to induce alterations in sensitivity at the level of the whole animal, i.e., changes in behavioral sensitivity to glutamatergic compounds. Thus, in this study, dose-effect curves of control and Pb-treated rats working on a multiple schedule of repeated learning (repeated acquisition, RA) and performance (P) were compared following acute administration of MK-801, the non-competitive NMDA antagonist. Based on the nature of the reported effects of Pb on NMDA systems, it was expected that the curves of Pb-exposed rats would be right-shifted relative to controls, if differential behavioral sensitivity was evident. Rats were chronically exposed to 0, 50 or 250 ppm Pb acetate in drinking water from weaning and trained on the multiple RA and P schedule beginning at 55 days old. The RA component required the rat to learn a new 3-member sequence of responses during each experimental session (center right left, RLC, CLR, RCL, or LRC), while the correct sequence of responses for the P component was constant across sessions (LCR), requiring performance of an already learned response. Acute administration of MK-801 (0.05-0.3 mg/k, i.p.) resulted in decrements in accuracy in both the RA and P components of the schedule, indicative of non-specific effects on behavior rather than selective effects on learning. The declines in accuracy during the RA component of the schedule were primarily the result of increased perseverative responding, i.e., repetitive responding on a single lever. Both the decline in RA accuracy and the increases in perseverative responding produced by MK-801 were attenuated by Pb exposure. Moreover, dose-effect curves relating MK-801 dose to changes in rates of responding were significantly shifted to the right in Pb-exposed rats relative to controls. Taken together, these data demonstrate a subsensitivity of Pb-exposed rats to both the accuracy-impairing and response rate-altering properties of MK-801.(ABSTRACT TRUNCATED AT 400 WORDS)

Lead retards development of Drosophila melanogaster

1. Lead (Pb) is a ubiquitous environmental toxicant which has been reported to have growth-retarding effects. That premise was examined in the current study of the effects of developmental exposure to Pb on the maturation of the fruitfly Drosophila melanogaster. 2. Flies were raised from egg to adulthood in media to which 0, 100, 250, or 500 ppm Pb acetate added. 3. There was a dose-dependent delay of maturation but no apparent effect on survival to adulthood. There were no significant differences in this effect between male and female flies. 4. Weights of fly offspring and their fecundity were not related to increasing exposure levels, suggesting that the delays were not due to gross nutritional deficits. 5. Analyses of Pb content indicated exposure-dependent body burdens of Pb in flies. Timed analyses of the Pb content of media itself indicated a heterogeneous distribution of Pb in the media, suggesting some precipitation of Pb at the highest exposure, occurring primarily during the first hour. 6. The mechanistic bases of the Pb-induced retardation of D. melanogaster development remain unknown, but it is concluded that because of the extensive body of knowledge on D. melanogaster genetics, molecular biology, and developmental biology, this procedure could serve as a model system for further study of the developmental consequences of exposure to Pb or other toxicants. 7. Environmental Pb exposure resulting in retarded development could have deleterious repercussions for insect populations exposed chronically to high levels of Pb.

New strategies in nonantibiotic treatment of gram-negative sepsis

Gram-negative bacterial infections are difficult to control and often lead to septic shock or septic syndrome. Many physiologic changes in sepsis are due to bacterial triggering of host responses. Improved understanding of these mechanisms has led to new treatment modalities that aim to block the runaway inflammatory process of sepsis. New therapeutic agents are currently being evaluated in animal and human studies. By combining these advances with adequate antibiotic therapy, it may be possible to improve overall survival in patients with gram-negative sepsis.

Differential effects of MK-801, NMDA and scopolamine on rats learning a four-member repeated acquisition paradigm

The glutamatergic (NMDA) and cholinergic neurotransmitter systems have been extensively implicated as neurochemical mediators of learning processes. These two systems may differentially affect learning; for example, although both the cholinergic antagonist scopolamine and the NMDA antagonist MK-801 reduced overall accuracy of rats in a 3-member repeated acquisition paradigm, the nature of the underlying error patterns produced by the two drugs differed significantly: rats administered scopolamine produced a pattern of skipping errors, while administration of MK-801 predominantly increased perseverative errors (Cohn et al., 1992). The present experiment extended that study to examine whether a more complex task, i.e. a 4-member repeated acquisition paradigm, would alter the nature of the error patterns resulting from administration of each drug, and whether NMDA itself would increase accuracy on the repeated acquisition paradigm. MK-801 (0.05-0.3mg/kg i.p.) significantly decreased overall accuracy in a dose-dependent manner, and the rats produced a pattern of errors similar, although not identical to, that noted in the 3-member paradigm, including perseverative errors early in the sequence, but additional skipping errors at later points in the sequence. MK-801 dramatically decreased correct initiation of a sequence following an error at any point in the sequence. NMDA (10.0-30.0mg/kg) itself did not facilitate sequence acquisition, i.e. it did not affect overall accuracy. However, it was the only drug to increase the frequency of correctly reinitiating a sequence following an incorrect first or an incorrect second sequence member. Like MK-801, scopolamine (0.5-3.0mg/kg i.p.) also produced a decline in overall accuracy which was again achieved primarily through increased skipping errors. Scopolamine did not, however, interfere with correctly reinitiating a sequence either after successful completion of a sequence, or after an error. These findings suggest that cholinergic and glutamatergic compounds exert their effects on learning through different behavioral mechanisms.