Inclusive jet production in pp(macro) collisions

We report a new measurement of the pseudorapidity (eta) and transverse-energy ( E(T)) dependence of the inclusive jet production cross section in pp(macro) collisions at square root of s = 1.8 TeV using 95 pb(-1) of data collected with the D0 detector at the Fermilab Tevatron. The differential cross section d(2)sigma/(dE(T)d eta) is presented up to eta = 3, significantly extending previous measurements. The results are in good overall agreement with next-to-leading order predictions from QCD and indicate a preference for certain parton distribution functions.

Search for large extra dimensions in dielectron and diphoton production

We report a search for effects of large extra spatial dimensions in pp collisions at a center-of-mass energy of 1.8 TeV with the D0 detector, using events containing a pair of electrons or photons. The data are in good agreement with the expected background and do not exhibit evidence for large extra dimensions. We set the most restrictive lower limits to date, at the 95% C.L. on the effective Planck scale between 1.0 and 1.4 TeV for several formalisms and numbers of extra dimensions.

The 3' untranslated region of tumor necrosis factor alpha mRNA is a target of the mRNA-stabilizing factor HuR

Posttranscriptional regulation is important for tumor necrosis factor alpha (TNF-alpha) expression in monocytes and macrophages, and an AU-rich element (ARE) in the 3' untranslated region (UTR) of TNF-alpha mRNA is implicated in control of its translation and mRNA stability. Regulation of mRNA turnover is thought to be mediated by trans-acting proteins, which bind the ARE and stabilize or destabilize the transcript. However, with the exception of the destabilizing factor tristetraprolin, the identity and function of the proteins binding the TNF-alpha mRNA ARE have not been established. To identify other proteins involved in the posttranscriptional control of TNF-alpha, the subcellular location of TNF-alpha mRNA was determined in the macrophage-like cell line RAW 264.7. TNF-alpha mRNA was located in the pellet following centrifugation of cytoplasm at 100,000 x g (P100 fraction). This fraction also contained proteins which formed two distinct ARE-specific complexes with the TNF-alpha mRNA 3' UTR in electrophoretic mobility shift assays (EMSAs). A protein present in these two complexes was purified and identified by peptide mass mapping and tandem mass spectrometry as HuR. In EMSAs both complexes were supershifted by an anti-HuR antibody, while Western blotting also demonstrated the presence of HuR in the P100 extract. A HeLa cell tetracycline-regulated reporter system was used to determine the effect of HuR on mRNA stability. In this system, overexpression of HuR resulted in stabilization of an otherwise unstable reporter-mRNA containing the TNF-alpha ARE. These results demonstrate that the TNF-alpha ARE is a target of the mRNA-stabilizing factor HuR.

Dexamethasone destabilizes cyclooxygenase 2 mRNA by inhibiting mitogen-activated protein kinase p38

The stability of cyclooxygenase 2 (Cox-2) mRNA is regulated positively by proinflammatory stimuli acting through mitogen-activated protein kinase (MAPK) p38 and negatively by anti-inflammatory glucocorticoids such as dexamethasone. A tetracycline-regulated reporter system was used to investigate mechanisms of regulation of Cox-2 mRNA stability. Dexamethasone was found to destabilize beta-globin-Cox-2 reporter mRNAs by inhibiting p38. This inhibition occurred at the level of p38 itself: stabilization of reporter mRNA by a kinase upstream of p38 was blocked by dexamethasone, while stabilization by a kinase downstream of p38 was insensitive to dexamethasone. Inhibition of p38 activity by dexamethasone was observed in a variety of cell types treated with different activating stimuli. Furthermore, inhibition of p38 was antagonized by the anti-glucocorticoid RU486 and was delayed and actinomycin D sensitive, suggesting that ongoing glucocorticoid receptor-dependent transcription is required.

Regulation of tumour necrosis factor alpha mRNA stability by the mitogen-activated protein kinase p38 signalling cascade

The translation of tumour necrosis factor alpha (TNFalpha) mRNA is regulated by the stress-activated protein kinase p38, which also controls the stability of several pro-inflammatory mRNAs. The regulation of TNFalpha gene expression in a mouse macrophage cell line RAW264.7 was re-examined using an inhibitor of stress-activated protein kinases. Stimulation of these cells with bacterial lipopolysaccharide resulted in stabilisation of TNFalpha mRNA, which was reversed by specific inhibition of p38. An adenosine/uridine-rich element from the TNFalpha 3' untranslated region conferred p38-sensitive decay in a tetracycline-regulated mRNA stability assay. Therefore the p38 pathway also controls TNFalpha mRNA turnover.

Transmittance properties of flurandrenolide tape for psoriasis: helpful adjunct to phototherapy

BACKGROUND

Flurandrenolide tape is a valuable agent in the treatment of lichen simplex chronicus and in psoriasis. The corticosteroid is helpful for reducing the symptoms and induration of the lichen simplex chronicus lesion, and occlusion of the lesion with the tape reduces the patient's opportunity to rub and scratch the affected area.

OBJECTIVES

The purpose of this study was to determine to what extent flurandrenolide tape may block ultraviolet (UV) light and interfere with phototherapy of psoriasis.

METHODS

Flurandrenolide tape was applied to quartz spectroscopy cuvettes, and the absorption spectrum was determined using a Beckman DU-600 spectrophotometer. The effect of the tape on UV light transmission was also determined using our UVA-UVB office phototherapy unit.

RESULTS

Flurandrenolide tape has considerable UV absorption in the UVC range with less absorption in the UVB and UVA range. The transmittance is greater (less absorption) with longer wavelengths. There was greater UV absorption in the UVB range than in the UVA range.

CONCLUSION

Although flurandrenolide tape may be left in place during PUVA therapy, adjustment of UV dose or removal of the tape is probably needed during UVB phototherapy.

Probing Balitsky-Fadin-Kuraev-Lipatov dynamics in the dijet cross section at large rapidity intervals in pp collisions at sqrt[s]=1800 and 630 GeV

Inclusive dijet production at large pseudorapidity intervals (Deltaeta) between the two jets has been suggested as a regime for observing Balitsky-Fadin-Kuraev-Lipatov (BFKL) dynamics. We have measured the dijet cross section for large Deltaeta in pp collisions at sqrt[s]=1800 and 630 GeV using the D0 detector. The partonic cross section increases strongly with the size of Deltaeta. The observed growth is even stronger than expected on the basis of BFKL resummation in the leading logarithmic approximation. The growth of the partonic cross section can be accommodated with an effective BFKL intercept of alphaBFKL(20 GeV)=1.65+/-0.07.

Measurement of the W-->taunu production cross section in pp collisions at square root s=1.8 TeV

We report on a measurement of sigma(pp-->W+X)B(W-->taunu) in pp collisions at sqrt[s]=1.8 TeV at the Fermilab Tevatron. The measurement is based on an integrated luminosity (lum) of 18 pb-1 of data collected with the D0 detector during 1994-1995. We find that sigma(pp-->W+X)B(W-->taunu)=2.22+/-0.09 (stat)+/-0. 10 (syst)+/-0.10 (lum) nb. Lepton universality predicts that the ratio of the tau and electron electroweak charged current couplings to the W boson, gWtau/gWe, be unity. We find gWtau/gWe=0.980+/-0.031, in agreement with lepton universality.

Regulation of cyclooxygenase 2 mRNA stability by the mitogen-activated protein kinase p38 signaling cascade

A tetracycline-regulated reporter system was used to investigate the regulation of cyclooxygenase 2 (Cox-2) mRNA stability by the mitogen-activated protein kinase (MAPK) p38 signaling cascade. The stable beta-globin mRNA was rendered unstable by insertion of the 2, 500-nucleotide Cox-2 3' untranslated region (3' UTR). The chimeric transcript was stabilized by a constitutively active form of MAPK kinase 6, an activator of p38. This stabilization was blocked by SB203580, an inhibitor of p38, and by two different dominant negative forms of MAPK-activated protein kinase 2 (MAPKAPK-2), a kinase lying downstream of p38. Constitutively active MAPKAPK-2 was also able to stabilize chimeric beta-globin-Cox-2 transcripts. The MAPKAPK-2 substrate hsp27 may be involved in stabilization, as beta-globin-Cox-2 transcripts were partially stabilized by phosphomimetic mutant forms of hsp27. A short (123-nucleotide) fragment of the Cox-2 3' UTR was necessary and sufficient for the regulation of mRNA stability by the p38 cascade and interacted with a HeLa protein immunologically related to AU-rich element/poly(U) binding factor 1.

The emerging role of physician assistants in the delivery of dermatologic health care

The NAMCS provides a wealth of information on use of PAs in all practices, including dermatology. Two important points regarding the NAMCS and SDPA data are addressed here: the number of visits to PAs for dermatologic symptoms and the expected growth of PA use in dermatologists' offices. Dermatologic symptoms were evaluated frequently by PAs, accounting for 14% of PA visits. These statistics do not address the number of referrals those PAs made to dermatologists. Perhaps PAs as a group should be targeted for increased dermatologic education, particularly stressing the need for appropriate referral to a dermatologist. PAs could increase the number of dermatology referrals from primary care offices with improved understanding of the importance of the dermatologist in the management of patients' overall skin health. At projected growth rates, the number of PAs employed by dermatologists should exceed 500 by the end of 2000. Most of this growth has been in private practices and rarely in HMOs or in large multispecialty clinics. There are a number of reasons for this growth, as follows: A PA may help reduce the patient load on the dermatologist, especially with sameday appointments and drop-ins. Some dermatologists are moving away from clinical dermatology into cosmetics, which not only leaves a vacuum in clinical dermatology, but also creates job opportunities for PAs in cosmetic dermatology. Regarding managed care growth, PAs can have a positive impact on the problem of having to see more patients for less money. PAs are cost-effective. In the 1998 SDPA survey, the ratio of billings generated (production) to gross income for the average dermatology PA ranged from 3:1 to 6:1. Even with inexperienced PAs new to dermatology, this ratio was usually at least 2:1 at the end of the first year. PAs can cover satellite offices, allowing for practice expansion. Effective with the new Medicare laws of January 1, 1998, PAs can now see new Medicare patients or Medicare patients with new conditions without the physician being on site, opening up the possibility for satellite offices in remote areas. Just as dermatologists may move toward specialization in surgery, cosmetics, or medical dermatology, PAs may do the same, filling a niche in a particular practice. As in other specialties, patient acceptance of seeing dermatology PAs has not been a significant problem. Continued access to the dermatologist remains unfettered, but, over time, many patients become willing to see either. Are PAs likely to become future competitors of dermatologists? Genuinely concerned dermatologists worry that a dermatology-trained PA will become part of a gatekeeper system that impedes patient access to dermatologists. This is not happening and is not at all likely to become a trend, for a number of reasons. First, primary care cannot compete with dermatology practices in remuneration for PAs. Just as financial benefits in high-production specialty practices entice physicians, the same benefits entice PAs as well. Second, according to member surveys of the SDPA, virtually 100% of fellow members work with dermatologists. Although PAs can work in any type of practice and evaluate dermatologic symptoms just as a general practitioner would, PAs who specialize in dermatology primarily practice with dermatologists, a collegial association most PAs seek out. PAs have steadfastly maintained their dependent, noncompetitive relationship with physicians and would not have it any other way. Although PAs see a good number of patients (2.8 million) with dermatologic symptoms, the NAMCS data indicate that most (72%) of these patients are also seen by a physician. Third, physicians are ultimately responsible for the actions of their PA employee. A general practitioner not trained to perform excisions or manage certain dermatologic conditions should not allow a PA to perform such duties. Similar to much of medicine, the PA profession continues to evolve, with many members moving awa

Treatment of psoriasis: an algorithm-based approach for primary care physicians

Psoriasis is characterized by red, thickened plaques with a silvery scale. The lesions vary in size and degree of inflammation. Psoriasis is categorized as localized or generalized, based on the severity of the disease and its overall impact on the patient's quality of life and well-being. Patient education about the disease and the treatment options is important. Medical treatment for localized psoriasis begins with a combination of topical corticosteroids and coal tar or calcipotriene. For lesions that are difficult to control with initial therapy, anthralin or tazarotene may be tried. The primary goal of therapy is to maintain control of the lesions. Cure is seldom achieved. If control becomes difficult or if psoriasis is generalized, the patient may benefit from phototherapy, systemic therapy and referral to a physician who specializes in the treatment of psoriasis.

p38 mitogen-activated protein kinase regulates cyclooxygenase-2 mRNA stability and transcription in lipopolysaccharide-treated human monocytes

p38 mitogen-activated protein kinase (MAPK) is activated by inflammatory stimuli such as bacterial lipopolysaccharide (LPS), interleukin-1, and tumor necrosis factor. We have previously shown that the pyridinyl imidazole SB 203580, which inhibits it, blocks the interleukin-1 induction of cyclooxygenase-2 (COX-2) and matrix metalloproteinase 1 and 3 mRNAs in fibroblasts. Here we explore the role of p38 MAPK in the response of human monocytes to LPS. 0.1 microM SB 203580 significantly inhibited the LPS induction of COX-2 and tumor necrosis factor protein and mRNAs. The activity of MAPK-activated protein kinase-2 (a substrate of p38 MAPK) in the cells was commensurately reduced. Some isoforms of c-jun N-terminal kinase (which is also activated by LPS) are sensitive to SB 203580; the inhibitor had little effect on monocyte c-jun N-terminal kinases up to 2 microM. We investigated the mechanism of inhibition of COX-2 induction. Transcription (measured by a nuclear run-on assay) was 60% inhibited by SB 203580 (2 microM). Importantly, we found that p38 MAPK was essential for stabilizing COX-2 mRNA: when cells stimulated for 4 h with LPS were treated with actinomycin D, COX-2 mRNA decayed slowly. Treatment of stimulated cells with 2 microM SB 203580 caused a rapid disappearance of COX-2 mRNA, even with actinomycin D present. We conclude p38 MAPK plays a role in the transcription and stabilization of COX-2 mRNA.

Disappointing initial results with transurethral alprostadil for erectile dysfunction in a urology practice setting

PURPOSE

We evaluate the response to intraurethral alprostadil administration using the Medicated Urethral System for Erection (MUSE) in unselect men with a history of erectile dysfunction. We determine the effects on blood pressure during in office monitoring and assess safety of this form of treatment. We compare the efficacy of MUSE in an office setting with the placebo controlled pivotal study.

MATERIALS AND METHODS

A total of 115 men with erectile dysfunction underwent in office testing with MUSE following the algorithm recommended by the manufacturer and outlined in the original pivotal study. Patients were asked to rate the rigidity of erection from 1 to 5 with scores 4 and 5 for erections sufficient for intercourse, and level of discomfort from 1 (very uncomfortable) to 5 (very comfortable) at 15-minute intervals. Patients who did not achieve a sufficient erection were scheduled to return for in office testing using the next higher dose up to 1,000 microg. Patient supine and sitting blood pressures were recorded by a nurse before and every 15 minutes after administration. Telephone contact with patients 2 to 3 months after the last in office testing was made to determine whether they were using the system.

RESULTS

Mean plus or minus standard deviation rigidity scores independent of dosage increased from 2.34+/-0.99 at 15 minutes to 2.49+/-0.96 at 30 minutes and decreased thereafter. Although the 1,000 microg. dosage resulted in highest mean score at all times, the differences between dosages were not significant. Rigidity score 4 or 5 was achieved in 13.2% (500 microg.) and 30% (1,000 microg.) of patients at 30 minutes. Mean level of discomfort was 3.6+/-1.2 at 15 minutes and improved thereafter. Comfort levels were not significantly different among dosages. Overall, at 15 minutes 16.8% of patients were uncomfortable (score 1 or 2) and 41.3% were somewhat uncomfortable (1, 2 or 3). For all dosages supine and sitting systolic and diastolic blood pressures decreased significantly from before treatment to 15 minutes and stayed lower during monitoring. Defined by strict criteria 41.2% of patients experienced orthostatic hypotension during in office testing. A total of 21 patients had adverse events, including pain, discomfort and burning in the penis (the most common), dizziness and chest pain. One patient had a syncopal episode and fell in the office. At last followup only 18.6% of the tested patients continued to use MUSE at home, while the remainder discontinued treatment due to pain, insufficient erections for intercourse and cost.

CONCLUSIONS

We were unable to achieve similar results to the pivotal study following manufacturer instructions and the algorithm provided by that study. Independent of age and etiology no more than 30% of patients at any given time using any dose achieved erections sufficient for intercourse during in office testing. Because of this limited efficacy, discomfort, pain and burning associated with treatment, and cost, more than 80% of patients did not continue to use MUSE at home.

A p38 MAP kinase inhibitor regulates stability of interleukin-1-induced cyclooxygenase-2 mRNA

The mechanism by which p38 mitogen-activated protein kinase (MAPK) regulates the induction of cyclooxygenase (COX)-2 by interleukin-1 (IL-1) has been investigated in HeLa cells. SB 203580, an inhibitor of p38 MAPK, in the range 0.1-1 microM inhibited IL-1-stimulated PGE2 (but not arachidonic acid) release and this was associated with inhibition of induction of COX-2 protein and mRNA. IL-1 stimulated COX-2 transcription in HeLa cells about 2-fold as judged by both reporter gene and nuclear run-on assays. The inhibitor had no significant effect on this. However, in cells previously stimulated with IL-1 it caused rapid destabilisation of COX-2 mRNA independently of on-going transcription. The results suggest a novel function for p38 MAPK in the regulation of mRNA stability.

Inspiratory flow rate and dynamic lung function in cystic fibrosis and chronic obstructive lung diseases

STUDY OBJECTIVES

The peak inspiratory flow rates (PIFRs) generated by cystic fibrosis (CF) and COPD patients through a range of clinically relevant resistances have not yet been reported (to our knowledge). The objectives of this study were to (1) explore a relevant range of resistive loads and address whether patients with stable CF and COPD can generate the PIFR sufficient to disperse dry-powder inhalants (DPI) and (2) determine whether the optimal inspiratory flow rate effective for delivery of aerosolized pharmacologic therapeutic agents can be attained with a comfort rating acceptable to subjects.

DESIGN

Prospective, controlled, subject-blinded study.

SETTING

Pulmonary function laboratory at the VA Palo Alto Health Care System.

PATIENTS OR PARTICIPANTS

Thirty-six subjects, including 12 healthy volunteers, 12 subjects with CF, and 12 subjects with COPD were studied.

MEASUREMENTS

Studies of dynamic lung function and PIFR without and with varying resistances were obtained at a single laboratory visit.

RESULTS

Dynamic lung function and PIFR varied inversely with the resistive load for all patient groups and did not correlate with the disease severity, as indicated by FEV1 of percent predicted. The average subjective comfort rating for any given resistive load was similar for subjects with CF and COPD.

CONCLUSIONS

These results support the conclusion that subjects with stable CF and COPD of varying severity can comfortably generate the necessary flow rates to operate new and currently available DPIs over a wide range of inspiratory resistances.

Psoriasis

Psoriasis is a common skin condition that can be controlled in nearly every patient. The diagnosis of psoriasis is generally made on the basis of identification of skin lesions of characteristic morphology in characteristic locations. A variety of treatments and resources are available to patients with psoriasis and to the physicians who treat them. Development of an appropriate treatment regimen is facilitated by categorization of psoriasis into localized versus generalized forms.

Papular dermatitis (subacute prurigo, "itchy red bump" disease): pilot study of phototherapy

BACKGROUND

Some patients with a subacute or chronic pruritic erythematous papular eruption are refractory to treatment. We previously described a number of these patients with papular dermatitis or subacute prurigo.

OBJECTIVE

The purpose of this study was to examine the effectiveness of different types of phototherapy for treatment of papular dermatitis.

METHODS

We reviewed the medical records of 11 patients who were diagnosed with papular dermatitis and who underwent phototherapy within the last 5 years.

RESULTS

Eleven patients had a total of 17 phototherapy courses: psoralen-UVA (PUVA; 9), UVA/UVB light (3), and UVB alone (5). Within the PUVA treatment group, three of nine patients experienced total clearing, and six of nine patients experienced partial improvement. Although patients in all groups relapsed with time, overall the PUVA-treated patients had the best response rate and the best chance of the condition remaining clear after treatment was stopped.

CONCLUSION

PUVA may be an effective treatment for papular dermatitis. The frequency of relapse indicates that maintenance treatments may be necessary for long-term control of the disease.

The incidence of allergic contact dermatitis in patients with psoriasis vulgaris

BACKGROUND

Contact dermatitis is said to be rare in psoriasis patients, possibly because of accelerated epidermal turnover, the isomorphic (Koebner) response, and lymphocyte functional alterations.

OBJECTIVE

To identify contact allergy in patients with psoriasis.

METHODS

A written questionnaire was completed by 100 patients with psoriasis about contact history, flare factors for psoriasis, topical skin care, medications, and occupational/hobby exposures. Of these patients, 20 agreed to be patch tested with a standard screening series (Hermal) and a 20-item psoriasis patch-test series that included ingredients that might be found in topical psoriasis products.

RESULTS

Of the 100 patients, eight suspected a topical medication caused a reaction that worsened their psoriasis, 29 gave a history of atopy, 11 reported reactions to metal jewelry, and 29 reported an allergy to poison ivy. Patch-test results identified four of the 20 patients with six positive patch tests to the materials tested: three of the six positive tests were interpreted as relevant to the patient's psoriasis (coal tar, ethylenediamine and dithranol), two patients tested positive to nickel and one to thimerosal. Five patients had irritant reactions to dithranol.

CONCLUSIONS

In this small study, 20% of self-selected psoriasis patients had positive allergic reactions on patch testing. A screening contact and atopic history in psoriasis patients may help to identify a subset of patients who could benefit from a search for more relevant contact allergens with patch test evaluation. This could improve treatment strategies and possibly reduce disability.

The effect of inhaling a dry powder of sodium chloride on the airways of asthmatic subjects

Wet aerosols of 4.5% sodium chloride (NaCl) are often used to assess the bronchial responsiveness associated with asthma. We questioned whether dry NaCl could be used as an alternative. Dry powder NaCl was inhaled from capsules containing either 5, 10, 20 or 40 mg to a cumulative dose of 635 mg. The powder was delivered via an Inhalator or Halermatic. The airway sensitivity to the dry and wet NaCl was compared in 24 patients with asthma aged 19-39 yrs. All subjects responded to both preparations and the geometric mean (95% confidence intervals) for the provocative dose of NaCl causing forced expiratory volume in one second (FEV1) to fall 20% from baseline (PD[20,NaCl]) for dry NaCl was 103 mg (68-157) versus 172 mg (102-292), p<0.03 for the wet NaCl. The response to dry NaCl was reproducible and on repeat challenge the PD20 was 108 mg (75-153). The mean maximum fall in FEV1 was approximately 25% on each of the two test days. Spontaneous recovery occurred within 60 min after challenge with dry NaCl and within 5 min after bronchodilator. There were no serious side-effects requiring medical attention, however some patients coughed on inhalation of the 40 mg dose and three gagged. Arterial oxygen saturation remained within normal limits. We conclude that a suitably prepared dry powder of sodium chloride could potentially replace wet sodium chloride to assess bronchial responsiveness in patients with asthma, but further studies are required to establish the long-term stability of the dry powder preparation.

The economic impact of psoriasis increases with psoriasis severity

BACKGROUND

Psoriasis treatments are known to be costly, but little is known about the financial impact of psoriasis and the way in which it relates to the severity of the disease.

OBJECTIVE

This study was performed to obtain an estimate of the treatment costs faced by patients with psoriasis.

METHODS

A total of 578 anonymous mail surveys were distributed to patients with psoriasis; 318 surveys were returned (55%). Psoriasis severity was assessed with the previously validated Self-Administered Psoriasis Area Severity Index (SAPASI).

RESULTS

The total and out-of-pocket expenses to care for psoriasis were correlated with psoriasis severity (r = 0.26, p = 0.0001). There were no sex (p = 0.9) or racial (p = 0.4) differences in total expenditures. Severity was correlated with how bothersome to the patient was the cost of treatment (r = 0.30, p = 0.0001), the time required for treatment (r = 0.38, p = 0.0001), and the time lost from work (r = 0.23, p = 0.0001). Lower quality of life at work and in money matters also correlated with severity of psoriasis. Higher family income was associated with less time spent caring for psoriasis and less interference with work around the home.

CONCLUSION

As expected, the expenses caring for psoriasis are greater for patients with more severe disease. These costs and other financial implications are associated with lower quality of life for patients with more severe psoriasis.

A new method for bronchial-provocation testing in asthmatic subjects using a dry powder of mannitol

We developed a bronchial provocation test (BPT) with a dry powder preparation of mannitol. The mannitol was inhaled from gelatin capsules containing 5, 10, 20, or 40 mg to a cumulative dose of 635 mg, and was delivered via an inhalator, Halermatic, or Dinkihaler device. We studied the airway sensitivity to inhaled mannitol, the repeatability of the response, and the recovery after challenge in 43 asthmatic subjects 18 to 39 yr of age who had a 20% decrease in FEV1 in response to inhaling a 4.5% NaCl. We compared this with the airway response to methacholine in 25 subjects. The geometric mean (GM) for the dose of dry mannitol required to reduce the FEV1 by 15% of the baseline value (PD15) was 64 mg, with a 95% confidence interval (CI) of 45 to 91. Subjects responsive to mannitol had a PD20 to metacholine of < 7.8 mumol, with a GM of 0.7 mumol (CI: 0.4 to 1.2). For the first of two challenges to mannitol the PD15 was 59 mg (CI: 36 to 97) and for the second the PD15 was 58 mg (CI: 35 to 94) p = 0.91 (n = 23). Spontaneous recovery to within 5% of baseline occurred within 60 min and within 10 min after 0.5 mg terbutaline sulfate was inhaled. Arterial oxygen saturation (SaO2) remained at 93% or above during mannitol challenge. Subjects tolerated the inhalation of the mannitol well. A dry powder preparation of mannitol may be suitable to develop for bronchial provocation testing.