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Biomedical subjects

W B Smith

Publications and source records attributed to W B Smith.

At least 37 records · Page 2Linked to original sources
PubMed1998

A randomized, double-blind, placebo-controlled, parallel-group, multicenter trial of four doses of tasosartan in patients with essential hypertension. Tasosartan Investigator's Group.

Tasosartan, a new, long-acting, nonpeptide angiotensin II receptor antagonist was evaluated in a randomized, double-blind, placebo-controlled, multicenter trial at 21 sites in the United States and Canada. After a 2-week, placebo washout qualification period, 278 patients (187 men/91 women) with a mean age of 53.4+/-9.5 years (range, 30 to 70 years) and a baseline sitting diastolic blood pressure (DBP) of 95 to 114 mm Hg were randomly assigned to receive placebo (n = 56), or 10 mg (n = 57), 30 mg (n = 55), 100 mg (n = 55), or 300 mg (n = 55) tasosartan for 4 weeks. The treatment period was followed by a 2-week washout period. Ambulatory blood pressure (BP) monitoring was performed at the end of the placebo washout period and after at least 4 weeks of double-blind treatment. Clinically significant placebo-adjusted differences in baseline sitting systolic blood pressure (SBP)/DBP were observed in the 10 mg (5/3 mm Hg), 30 mg (5/4 mm Hg), 100 mg (10/7 mm Hg) and 300 mg (10/7 mm Hg) dose groups (P < .05). A dose-response relationship (P < .001) was observed within 1 to 2 weeks of treatment initiation and was maintained throughout the double-blind period. Discontinuation of tasosartan therapy was not associated with rebound hypertension. Moreover, significant (P < .05) placebo-adjusted differences in ambulatory SBP/DBP and a significant dose-response relationship (P < .001) were observed with all tasosartan dosages during the 24-h, daytime, and nighttime periods. Placebo-adjusted trough-to-peak ratios ranged from 87% to 100% for ambulatory SBP and 64% to 81% for DBP. In general, no significant differences were observed between the tasosartan treatment groups and the placebo group in the incidence of adverse events. Headache incidence was significantly lower in the 300 mg dose group than the placebo group. In conclusion, tasosartan at dosages of 10, 30, 100, or 300 mg given once daily produced a significant and dose-related reduction in both clinic and ambulatory BP that was maintained over the 24-h period. Tasosartan was generally well tolerated.

Adult↗
PubMed1996

A role for endothelial NO synthase in LTP revealed by adenovirus-mediated inhibition and rescue.

Pharmacological studies support the idea that nitric oxide (NO) serves as a retrograde messenger during long-term potentiation (LTP) in area CA1 of the hippocampus. Mice with a defective form of the gene for neuronal NO synthase (nNOS), however, exhibit normal LTP. The myristoyl protein endothelial NOS (eNOS) is present in the dendrites of CA1 neurons. Recombinant adenovirus vectors containing either a truncated eNOS (a putative dominant negative) or an eNOS fused to a transmembrane protein were used to demonstrate that membrane-targeted eNOS is required for LTP. The membrane localization of eNOS may optimally position the enzyme both to respond to Ca2+ influx and to release NO into the extracellular space during LTP induction.

Adenoviridae↗
PubMed1996

Transforming growth factor-beta 1 inhibits the production of IL-8 and the transmigration of neutrophils through activated endothelium.

A central mechanism of inflammation is the activation of vascular endothelium by the inflammatory cytokines TNF-alpha and IL-1. These cytokines induce the expression of adhesion molecules, the elaboration of chemokines, and the transendothelial migration of white cells. TGF-beta 1 has anti-inflammatory properties, is expressed in the vessel wall, and has previously been shown to inhibit leukocyte adhesiveness to the endothelium at least in part by inhibiting the expression of E-selectin. We now show that TGF-beta 1 also inhibits the migration of neutrophils through endothelial monolayers activated by TNF-alpha. At a dose of 10 U/ml TNF-alpha, the transmigration of neutrophils was inhibited 42.7 +/- 7.9% (n = 8) by 0.2 ng/ml TGF-beta 1. Furthermore, TGF-beta 1 inhibited, in a time- and dose-dependent fashion, the elaboration of IL-8 by TNF-activated endothelial cells by between 33 and 78% (TNF doses from 100 down to 0.1 U/ml) and the elaboration of mRNA for IL-8 by 69%. TGF-beta 1 treatment did not significantly alter the TNF-induced IL-8 mRNA stability, suggesting that the mechanism of action of TGF-beta 1 is on gene transcription. Neutrophil transmigration through cytokine-activated endothelium involves both IL-8-dependent and IL-8-independent mechanisms. Using an anti-IL-8 Ab, we show that TGF-beta 1 inhibits only the IL-8-dependent pathway, but does not affect the IL-8-independent transendothelial migration mechanism. These and our previous results show that TGF-beta1, achieves its anti-inflammatory properties by inhibiting the expression of at least two genes, E-selectin and IL-8, which are essential in the inflammatory pathway.

Cell Movement↗
PubMed1996

Monoclonal antibody 7G3 recognizes the N-terminal domain of the human interleukin-3 (IL-3) receptor alpha-chain and functions as a specific IL-3 receptor antagonist.

The human interleukin-3 receptor (IL-3R) is expressed on myeloid, lymphoid, and vascular endothelial cells, where it transduces IL-3-dependent signals leading to cell activation. Although IL-3R activation may play a role in hematopoiesis and immunity, its aberrant expression or excessive stimulation may contribute to pathologic conditions such as leukemia, lymphoma, and allergic reactions. We describe here the generation and characterization of a monoclonal antibody (MoAb), 7G3, which specifically binds to the IL-3R alpha-chain and completely abolishes its function. MoAb 7G3 immunoprecipitated and recognized in Western blots the IL-3R alpha-chain expressed by transfected cells and bound to primary cells expressing IL-3R alpha. MoAb 7G3 bound the IL-3R alpha-chain with a kd of 900 pmol/L and inhibited 125I-IL-3 binding to high- and low-affinity receptors in a dose-dependent manner. Conversely, IL-3 but not granulocyte-macrophage colony-stimulating factor (GM-CSF) inhibited 125I-7G3 binding to high- and low-affinity IL-3Rs, indicating that MoAb 7G3 and IL-3 bind to common or adjacent sites. In keeping with the inhibition of IL-3 binding, MoAb 7G3 antagonized IL-3 biologic activities, namely stimulation of TF-1 cell proliferation, basophil histamine release, and IL-6 and IL-8 secretion from human endothelial cells. Two other anti-IL-3R alpha-chain MoAbs failed to inhibit IL-3 binding or function. Epitope mapping experiments using truncated IL-3R alpha-chain mutants and IL-3R alpha/GM-CSFR alpha chimeras revealed that 31 amino acids in the N-terminus of IL-3R alpha were required for MoAb 7G3 binding. MoAb 7G3 may be of clinical significance for antagonizing IL-3 in pathologic conditions such as some myeloid leukemias, follicular B-cell lymphoma, and allergy. Furthermore, these results implicate the N-terminal domain of IL-3R alpha in IL-3 binding. Since this domain is unique to the IL-3/GM-CSF/IL-5 receptor subfamily, it may represent a novel and common binding feature in these receptors.

Animals↗
PubMed1996

Pharmacodynamics of torsemide administered as an intravenous injection and as a continuous infusion to patients with congestive heart failure.

The natriuretic and diuretic effects of a 100-mg dose of torsemide administered as a continuous infusion of torsemide and as a single bolus were compared in a group of patients with stable mild-to-moderate congestive heart failure (CHF). Patients received in random order 100 mg of torsemide as an intravenous bolus and as a 75-mg infusion over 24 hours started simultaneously with a 25-mg loading bolus. Administration of torsemide to patients with CHF as a continuous infusion was an effective dosing regimen, resulting in 24-hour diuresis and natriuresis that was numerically but not statistically greater than that observed with bolus administration. The response with continuous infusion occurred with less torsemide in the urine, resulting in a significantly greater efficiency of torsemide with this regimen. The effectiveness of torsemide as a continuous infusion does not mean that this mode of administration should be used in all patients. The response to 100 mg of torsemide in patients with mild-to-moderate CHF is the same whether administered as an intravenous bolus, a continuous intravenous infusion, or by mouth. This is consistent with the high bioavailability demonstrated in previous studies. The mode of therapy used should be dictated by each individual patient's needs. This study shows that continuous infusion is a viable option for administration of torsemide, and dosing guidelines for use of such a strategy are presented.

Adult↗
PubMed1996

Characterization of a primate model of asthma using anti-allergy/anti-asthma agents.

The following study was performed to further characterize a primate model of asthma using classes of drugs that target allergy (pyrilamine, cetirizine), are bronchodilators for the treatment of asthma (salbutamol, salmeterol) or are anti-inflammatory (dexamethasone). These drugs were examined for their ability to inhibit acute, antigen-induced bronchoconstriction, the development of airway hyperresponsiveness (AHR) and the infiltration of leukocytes into the lungs of atopic cynomolgus monkeys (Macaca facsicularis) using a 10-day, multiple antigen (Ag) challenge protocol. All compounds except dexamethasone and cetirizine significantly (p < 0.05) reduced acute, Ag-induced bronchoconstriction (salbutamol: 74.2%, salmeterol: 52.6%%, pyrilamine: 62.4% inhibition) compared to vehicle control trials. Only dexamethasone and salmeterol prevented the development of AHR to methacholine challenge by 90.4 +/- 6.81% and 85.7 +/- 5.61% respectively. Dexamethasone significantly reduced the Ag-induced increase in BAL eosinophils by 85.9 +/- 8.53%. Cetirizine reduced the eosinophil response in 5 of 6 monkeys and salmeterol demonstrated a trend towards reduced eosinophil increases after multiple Ag challenge, but neither of these were statistically significant. These results further illustrate the utility of this model in predicting compound effects against several relevant functional endpoints that are consistent with the effects of similar classes of compounds in humans.

Albuterol↗
PubMed1996

The effect of 5-lipoxygenase inhibition on Ascaris antigen (Ag)-induced responses in atopic monkeys.

The effects of two 5-lipoxygenase (5LO) inhibitors, ZD2138 or Zileuton, on acute, inflammatory responses to aerosolized Ascaris suum (Ag) were determined in atopic Macaca fascicularis monkeys. Monkeys (n = 6 each group) were dosed with vehicle, 3 or 10 mg/kg ZD2138, or 30 mg/kg Zileuton (p.o.). Both ZD2138 or Zileuton significantly inhibited ex vivo LTB4 production in Ca2+ ionophore-stimulated whole blood from these same monkeys (n = 6 each group) by 45.5% (3 mg/kg ZD2138), 82.5% (10 mg/kg ZD2138) and 84.3% (30 mg/kg Zileuton). ZD2138 (10 mg/kg) reduced bronchoalveolar lavage (BAL) LTE4 levels (65.1% inhibition), BAL neutrophils (88.9% inhibition), and IL-6 (54.0% inhibition) 4h post Ag. Zileuton inhibited these responses and also reduced BAL levels of IL-8 (73.4% inhibition). A second study was performed to evaluate the effects of ZD2138 on chronic Ag-induced responses. Treatment with ZD2138 did not prevent pulmonary inflammation or the development of airway hyperresponsiveness (AHR). Based upon these results, 5LO inhibition significantly reduced ex vivo LTB4 and in vivo LTE4 production as well as several acute inflammatory responses to Ag in the lung. However, ZD2138 did not inhibit more chronic responses following multiple Ag exposure.

Animals↗
PubMed1996

The lennie test for measuring scapular position in healthy young adult females: a reliability and validity study.

Normal scapular rest position is neither adequately described nor agreed upon by authorities. The purpose of this study was to devise and describe a reliable and valid test (the Lennie Test) to measure scapular position, including normal scapular rest position. Fifteen healthy females (age 19-21 years) participated in the study. Horizontal and vertical scapular position in the frontal plane was quantified by three different investigators using a scoliometer and caliper. Same-day radiographs were used to validate scapular position surface measurements. The medial borders of the scapulae were found to be parallel to the thoracic midline. The scapulae were on average 17.19 +/- 1.85 cm apart (at the level of the root of the scapulae) with the dominant arm scapula being on average 0.49 +/- 0.74 cm lower than the nondominant scapula. This difference in height between scapulae was not statistically significant (p > .01). Correlation coefficients between skin surface and radiograph measurements of scapular position ranged from .43 to .82. Intertester intraclass correlation coefficients for surface measurements of scapular position ranged from .64 to .86. The Lennie Test was found to have moderate to high intertester reliability and to provide an accurate measurement of the anatomical location of the scapulae based on X-ray verification. Surface landmark measurements for scapular position were on average within 0.56 cm and within 1.7 degrees of the measurements made from X-rays for linear and angular position, respectively. We propose the use of the Lennie Test in populations, healthy or otherwise, where scapular position needs to be objectively measured.

Adult↗
PubMed1995

Neutrophils activated by granulocyte-macrophage colony-stimulating factor express receptors for interleukin-3 which mediate class II expression.

Freshly isolated peripheral blood neutrophils, unlike monocytes and eosinophils, do not bind interleukin-3 (IL-3) or respond to IL-3). We show that neutrophils cultured for 24 hours in granulocyte-macrophage colony-stimulating factor (GM-CSF) express mRNA for the IL-3 receptor (R) alpha subunit, as shown by RNase protection assays, and IL-3R alpha chain protein, as shown by cytometric analysis using two different specific monoclonal antibodies. This effect was selective for GM-CSF, because granulocyte colony-stimulating factor, tumor necrosis factor-alpha, interferon-gamma, and IL-1 failed to induce the IL-3 receptor. Saturation binding curves with 125I-IL-3 and Scatchard transformation showed the presence of about 100 high-affinity and 4,000 low-affinity receptors. Because neutrophils have been shown to express human leukocyte antigen (HLA)-DR in response to GM-CSF, we examined the possibility that IL-3 could augment HLA-DR expression on GM-CSF-treated cells. We found that neutrophils incubated with 30 ng/mL IL-3 as well as 0.1 ng/mL GM-CSF expressed a mean of 2.1-fold higher levels of HLA-DR than with GM-CSF alone (P < .005), confirming the signaling competence of the newly expressed IL-3R. This increase was seen even at maximal concentrations of GM-CSF and IL-3 can have an additive effect on mature human cells. The augmentation of HLA-DR by IL-3 was specific because it could be inhibited by a blocking anti-IL-3R antibody. Expression of class II molecules by neutrophils under these conditions may have significance for antigen presentation. These results provide further evidence for the role of GM-CSF as an amplification factor in inflammation by inducing neutrophil responsiveness to IL-3 produced by T cells or mast cells.

Cells, Cultured↗
PubMed1995

Interferon-gamma upregulates interleukin-3 (IL-3) receptor expression in human endothelial cells and synergizes with IL-3 in stimulating major histocompatibility complex class II expression and cytokine production.

The human interleukin-3 (IL-3) receptor is constitutively expressed on certain hematopoietic cells where it mediates proliferation and differentiation, or functional activation. We have recently found that human umbilical vein endothelial cells (HUVECs) also express IL-3 receptors and that the expression is enhanced by stimulation with the monokine tumor necrosis factor alpha. In this report we show that the lymphokine interferon gamma (IFN gamma) is a powerful stimulator of the IL-3 receptor of HUVECs and that the combination of IL-3 and IFN gamma has a synergistic effect on major histocompatibility complex (MHC) class II expression and on the production of the early-acting hematopoietic cytokines IL-6 and granulocyte colony-stimulating factor (G-CSF). IFN gamma caused a time- and dose-dependent up-regulation of mRNA for both the alpha and beta chains of the IL-3 receptor, with maximal effects occurring 12 to 24 hours after stimulation with IFN gamma at 100 U/mL. Induction of mRNA correlated with protein expression on the cell surface, as judged by monoclonal antibody staining of both receptor chains and by the ability of HUVEC to specifically bind 125I-labeled IL-3 (125I-IL-3). Scatchard analysis of HUVECs stimulated with IFN gamma at 100 U/mL for 24 hours showed approximately 6,300 IL-3 receptors per cell that were of a high affinity class (dissociation constant [kd] = 500 pmol/L) only. The addition of IL-3 to IFN gamma-treated HUVECs strongly enhanced the expression of MHC class II antigen. Importantly, IFN gamma and IL-3 also exhibited a synergistic effect in the induction of the mRNA for G-CSF and IL-6. This was reflected in increased amounts of G-CSF and IL-6 protein in HUVEC supernatants. In contrast, IFN gamma and IL-3 did not stimulate granulocyte-macrophage colony-stimulating factor (GM-CSF) or IL-8 production in HUVECs. These results show that IFN gamma is a strong stimulator of IL-3 receptor expression in HUVECs and suggest that in vivo T-cell activation, causing the concomitant production of IFN gamma and IL-3, may lead to enhanced endothelial MHC class II expression and to the selective production of early-acting hematopoietic cytokines. Thus, IL-3 could influence immunity and hematopoiesis by acting not only on hematopoietic cells, but also on vascular endothelium.

Drug Synergism↗
PubMed1995

Bioavailability, pharmacokinetics, and pharmacodynamics of torsemide and furosemide in patients with congestive heart failure.

The bioavailability, pharmacokinetics, and pharmacodynamics of torsemide (10 mg orally and intravenously) and furosemide (40 mg orally and 20 mg intravenously) were determined in a randomized crossover clinical trial in 16 patients with compensated congestive heart failure. Torsemide (time to reach maximum concentration [tmax], 1.1 +/- 0.9 hour) was more rapidly absorbed than furosemide (tmax, 2.4 +/- 2.5 hours), the absorption of which was delayed compared with that in healthy volunteers. Bioavailability of torsemide was also greater and less variable than that of furosemide. All four treatments yielded comparable changes from baseline in 24-hour electrolyte excretion. Based on the relationships between sodium excretion rate and fractional sodium and urinary drug excretion rate, response to both diuretic agents at the level of the nephron was decreased compared with previous studies with healthy subjects. Assessment of the clinical relevance, if any, of the difference in the variability of absorption warrants further study.

Administration, Oral↗
PubMed1994

Imipramine in patients with chest pain despite normal coronary angiograms.

BACKGROUND: Ten to 30 percent of patients undergoing cardiac catheterization because of chest pain are found to have normal coronary angiograms. Because these patients may have a visceral pain syndrome unrelated to myocardial ischemia, we investigated whether drugs that are useful in chronic pain syndromes might also be beneficial in such patients. METHODS: Sixty consecutive patients underwent cardiac, esophageal, psychiatric, and pain-sensitivity testing and then participated in a randomized, double-blind, placebo-controlled three-week trial of clonidine at a dose of 0.1 mg twice daily (20 patients), imipramine at a dose of 50 mg nightly with a morning placebo (20 patients), or placebo twice daily (20 patients); this treatment phase was compared with an identical period of twice-daily placebo for all patients (placebo phase). RESULTS: Thirteen (22 percent) of the 60 patients had ischemic-appearing electrocardiographic responses to exercise, 22 of the 54 tested (41 percent) had abnormal esophageal motility, 38 of 60 (63 percent) had one or more psychiatric disorders, and 52 of 60 (87 percent) had their characteristic chest pain provoked by right ventricular electrical stimulation or intracoronary infusion of adenosine. During the treatment phase, the imipramine group had a mean (+/- SD) reduction of 52 +/- 25 percent in episodes of chest pain, the clonidine group had a reduction of 39 +/- 51 percent, and the placebo group a reduction of 1 +/- 86 percent, all as compared with the placebo phase of the trial. Only the improvement with imipramine was statistically significant (P = 0.03). Repeat assessment of sensitivity to cardiac pain while the patients were receiving treatment showed significant improvement only in the imipramine group (P = 0.01). The response to imipramine did not depend on the results of cardiac, esophageal, or psychiatric testing at base line, or on the change in the psychiatric profile during the course of the study, which generally improved in all three study groups. CONCLUSIONS: Imipramine improved the symptoms of patients with chest pain and normal coronary angiograms, possibly through a visceral analgesic effect.

Adult↗
PubMed1994

Dissociation of TNF-alpha cytotoxic and proinflammatory activities by p55 receptor- and p75 receptor-selective TNF-alpha mutants.

Human tumour necrosis factor alpha (TNF-alpha) is a pleiotropic cytokine capable of killing mammalian tumour cells in vitro and in vivo, and of enhancing the proinflammatory activity of leucocytes and endothelium, the latter effects limiting its usage as an antitumour agent in humans. Using TNF-alpha mutants with a selective capacity to bind to the TNF p55 receptor (TNFR55) or to the p75 receptor (TNFR75) we show here that these two major activities of TNF-alpha can be dissociated. The TNFR55-selective mutants (R32W, E146K and R32W-S86T) which bind poorly to TNFR75 displayed similar potency to wild-type TNF in causing cytotoxicity of a human laryngeal carcinoma-derived cell line (HEp-2) and cytostasis in a human leukaemic cell line (U937). However, these TNFR55-selective mutants exhibited lower proinflammatory activity than wild-type TNF. Specifically, TNF-alpha's priming of human neutrophils for superoxide production and antibody-dependent cell-mediated cytotoxicity, platelet-activating factor synthesis and adhesion to endothelium were reduced by up to 170-fold. Activation of human endothelial cell functions represented by human umbilical venular endothelial cell (HUVEC) adhesiveness for neutrophils, E-selectin expression, neutrophil transmigration and IL-8 secretion were also reduced by up to 280-fold. On the other hand, D143F, a TNFR75-selective mutant tested either alone or in combination with TNFR55-selective mutants, did not stimulate these activities despite being able to cause cytokine production in TNFR75-transfected PC60 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1994

Leukotriene D4 receptor antagonism reduces airway hyperresponsiveness in monkeys.

Airway hyperresponsiveness (AHR) and pulmonary inflammation are observations that are consistently associated with asthma and also occur in a well-characterized monkey model of asthma. The following study was performed to determine whether treatment with an LTD4 receptor antagonist, ICI 198,615, could attenuate antigen-induced pulmonary inflammation and AHR in monkeys using the following protocol. On day 0, the PC200 (the concentration of methacholine (MCh) that doubled respiratory system resistance, Rrs) was determined in 6 male, atopic, cynomolgus monkeys, previously characterized in historical control trials (Control #1) as airway hyperresponsive. Bronchoalveolar lavage (BAL) was then performed to determine total and differential leukocyte counts. On days 3, 5 and 7, each monkey received 10 mg/kg ICI 198,615 (im) 30 min prior to Ascaris suum (Ag) aerosol exposures which doubled Rrs. On day 10, the post-Ag PC200 to MCh was determined and BAL was repeated. Five weeks after this trial was complete, a bracketing control trial (Control #2) was performed in which the monkeys were administered vehicle prior to each Ag exposure. In comparison to the response in both control trials, treatment with the LTD4 antagonist significantly (P < 0.05) inhibited the development of AHR and also significantly reduced (P < 0.05) peripheral blood lymphocyte counts after Ag challenge. Treatment with ICI 198,615 reduced the Ag-induced increase in BAL eosinophils, but statistical significance was obtained only when treated animals were compared to Control #1, not Control #2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

The pharmacodynamics of torsemide in patients with congestive heart failure.

The pharmacodynamics of torsemide (a new loop diuretic of the pyridine sulfonylurea class) was studied in 16 subjects who had compensated congestive heart failure and had been receiving stable diuretic therapy. Oral doses of 50, 100, and 200 mg were studied by use of a randomized crossover design. The results of this study show that the pharmacokinetics of torsemide is linear up to at least a dose of 200 mg in patients with congestive heart failure. Approximately 20% of each of the three doses was excreted unchanged, consistent with previous findings in healthy volunteers. A hyperbolic relationship between diuretic effect and drug excretion rate was defined. The maximum urinary sodium excretion rate attained was about 0.6 mEq/min, which is about 20% of that in healthy subjects, indicating diuretic resistance in these patients. Although there was no saturation of the urinary excretory pathway with doses as high as 200 mg, the upper plateau of the dose-response curve was reached with doses of 50 mg, indicating that this dose represents a ceiling dose in patients with New York Heart Association class II and III congestive heart failure.

Administration, Oral↗
PubMed1994

Effects of rolipram on responses to acute and chronic antigen exposure in monkeys.

The following study was performed to test the hypothesis that treatment with rolipram, a specific inhibitor of phosphodiesterase (PDE) IV, should inhibit many pulmonary responses to acute and chronic antigen challenge in atopic monkeys by elevating intracellular cAMP and subsequently inhibiting leukocyte function. Monkeys received subcutaneous injections of either vehicle (2% DMSO) or 10 mg/kg of rolipram 1 h before exposure to Ascaris suum antigen (Ag). Acute responses to Ag, including bronchoconstriction, pulmonary leukocyte infiltration, and cytokine production, were monitored before and 4 h after single Ag aerosol administration. To monitor the effects of rolipram on chronic Ag exposure, a 10-d, multiple-Ag protocol, previously demonstrated to induce airway hyperresponsiveness (AHR) to methacholine (MCh), was performed. Ag exposure increased respiratory system resistance (Rrs) 221.7 +/- 31.88% (n = 5). This increase in Rrs was not significantly altered by rolipram. Rolipram significantly (p < 0.002) increased cAMP levels in bronchoalveolar lavage (BAL) leukocytes 1 h after administration (n = 5). Ag-induced increases in BAL IL-8 and TNF were significantly reduced by rolipram, but IL-1 beta and IL-6 increases were unaffected (n = 9). Ag-induced increases in BAL eosinophils and neutrophils were significantly reduced by rolipram (n = 9). In the multiple-Ag protocol (n = 7), rolipram significantly reduced both the number of BAL eosinophils (p < 0.02) and the development of AHR (p < 0.002). Despite its inability to inhibit acute Ag-induced bronchoconstriction, rolipram was protective against acute and chronic inflammatory responses to Ag and prevented the development of AHR, suggesting that selective PDE-IV inhibition is a relevant target for asthma therapy.

Animals↗
PubMed1994

The role of granulocyte-macrophage and granulocyte colony-stimulating factors in neutrophil transendothelial migration: comparison with interleukin-8.

Granulocyte-macrophage and granulocyte colony-stimulating factors (GM-CSF and G-CSF) have proinflammatory effects on mature neutrophils. Both factors have been reported to cause neutrophil chemotaxis and are produced by cells stimulated by inflammatory mediators, including endothelial cells. We therefore tested the hypothesis that these factors might mediate neutrophil transendothelial migration, either by forming a gradient across the endothelial monolayer or through the production of CSFs by activated endothelium. Studies of neutrophil migration across filters without endothelium showed that migration was promoted in the presence of a gradient of either CSF, but was equally promoted against the gradient; that is, the CSFs are chemokinetic but not chemotactic. The CSFs promoted migration of neutrophils across endothelial monolayers cultured on filters, but the magnitude of this effect was very small compared with that of a prototypic neutrophil chemoattractant, interleukin-8 (IL-8) (migration index [stimulated/unstimulated] 1.8-fold for GM-CSF, 10.8-fold for IL-8). Activation of endothelial monolayers by preincubation with tumor necrosis factor-alpha (TNF-alpha) increased neutrophil transmigration significantly; neutralizing antibodies to IL-8 inhibited this increase by 44%, whereas neutralizing anti-GM-CSF antibodies did not inhibit it. These data suggest little role for the CSFs in neutrophil diapedesis at inflammatory sites in vivo. Exposure of neutrophils to GM-CSF decreased their migration through TNF-activated monolayers, whereas G-CSF did not. This may have implications for the therapeutic administration of these factors.

Antibodies↗