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Biomedical subjects

M K Church

Publications and source records attributed to M K Church.

At least 91 records · Page 5Linked to original sources
PubMed1994

Role of eosinophil activation in the bronchial reactivity of allergic guinea pigs.

Ovalbumin inhalation by sensitized guinea pigs induced a marked increase in the number of eosinophils (0.89 +/- 0.18 to 5.45 +/- 0.77 x 10(5)/ml, n = 10, p < 0.05) and elevations in the amounts of protein and eosinophil-derived major basic protein (MBP) (1,010.7 +/- 184.9 to 4,116.6 +/- 973.0 ng/ml, n = 10, p < 0.05) recovered by bronchoalveolar lavage (BAL). In contrast, no changes in the levels of eosinophil peroxidase (EPO) or in the sensitivity of the airways to bronchoconstriction induced by methacholine were detected. However, when ovalbumin-exposed guinea pigs received an intratracheal instillation of 1 microgram leukotriene (LT)B4 30 min prior to methacholine provocation, elevated levels of EPO and MBP in the BAL fluid and a marked bronchial hyperreactivity to methacholine were noted when compared with saline-challenged LTB4-injected animals (p < 0.05). In contrast, the intratracheal instillation of 1 or 3 micrograms platelet-activating factor (PAF) did not significantly modify the bronchial reactivity to methacholine or the levels of EPO and MBP. PAF and LTB4 induced similar enhancements in the amount of protein in BAL fluids from antigen-exposed guinea pigs, suggesting that increased endothelial/epithelial permeability does not account for hyperreactivity. A significant correlation between the levels of EPO or MBP and the intensity of the bronchial responsiveness to methacholine were shown in ovalbumin-challenged guinea pigs, irrespective of their subsequent treatment, i.e., either with PAF or with LTB4 or with their vehicle (r = 0.579, p = 0.0002 and r = 0.330, p = 0.049, n = 36 for EPO and MBP, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Influence of interleukin-8 challenge in the nasal mucosa in atopic and nonatopic subjects.

Interleukin-8 (IL-8) is a major cytokine in the recruitment of neutrophils (polymorphonuclear leukocytes) to areas of inflammation. It also activates T lymphocytes and cytokine-primed basophils and eosinophils and therefore may be implicated as an effector in allergic inflammation. IL-8 has also been identified as a mediator in such inflammatory pulmonary conditions as cystic fibrosis, allergen challenge, and sarcoidosis. To investigate the bioactivity of IL-8 in humans, we examined the effects of nasal challenge with human recombinant IL-8 in a double-blind placebo-controlled crossover study in which nasal resistance and rhinitic symptoms were monitored for 4 h after challenge. Cellular infiltration was quantified on differentially stained nasal smears obtained at hourly intervals. Cellular responses caused by in vivo priming were assessed by a comparison of atopic and nonatopic patient groups. A significant neutrophilic infiltrate in smear samples was observed in all patients challenged with IL-8 from 12 +/- 4% (mean +/- SEM) at baseline to 60 +/- 6% after 4 h; placebo challenge resulted in an increase in neutrophils to 30 +/- 4% (p < 0.04). Additionally, a significant increase in cumulative eosinophil recruitment occurred over the challenge period. Nasal resistance was significantly increased 10 min after instillation of IL-8 in all subjects compared with placebo, but there was no difference between atopic and nonatopic subjects. Nasal rhinitic symptoms were also increased in all subjects receiving IL-8 compared with placebo. In a further study in 19 subjects, nasal biopsy was performed 3 h after IL-8 or placebo challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Synthetic inhibitors of tissue kallikrein: effects in vivo in a model of allergic inflammation.

We have recently developed synthetic low molecular weight inhibitors of both tissue and plasma kallikreins. Several of these were evaluated in vivo in the ovalbumin-sensitised guinea pig for their ability to prevent the bronchoconstriction elicited by antigen challenge. The selective tissue kallikrein inhibitor CH-694 (but not the selective plasma kallikrein inhibitor CH-684) caused highly significant falls in airways resistance when it was administered at 10 mg/kg intraperitoneally 15 min before and 90 min after challenge. There was also a highly significant fall in the tissue kallikrein activity measured in broncho-alveolar lavage fluid. Inhibitors of tissue kallikrein may prove effective in the treatment of allergic inflammation in man.

Airway Resistance↗
PubMed1993

Nedocromil sodium blocks the early and late phases of allergen challenge in a guinea pig model of asthma.

We developed a model of asthma in conscious guinea pigs in which both early- and late-phase reductions in specific airways conductance are demonstrable after inhalation challenge. Neutrophilia that peaks 17 hours after challenge was discovered by bronchoalveolar lavage in this model, as was eosinophilia that develops more slowly, peaking at 72 hours. Nedocromil sodium blocked both the early- and late-phase reductions in airflow, but salbutamol blocked only the early phase. Both drugs blocked the neutrophilia when given before challenge, but not when given 6 hours afterward. This suggests that the neutrophila is secondary to an intact early phase response. Nedocromil sodium, given 6 hours after challenge, reduced the eosinophilia at 72 hours but not at 17 hours. Salbutamol had no effect on the eosinophilia at either time. These results suggest that nedocromil sodium has antiinflammatory properties in the lung that are not shared by the beta 2-adrenergic stimulant drug, salbutamol.

Aerosols↗
PubMed1993

Adenosine-induced bronchoconstriction and its inhibition by nedocromil sodium.

The inhalation of adenosine or adenosine-5'-monophosphate (AMP) causes a reproducible and transient bronchoconstriction in both atopic and nonatopic asthmatic subjects that is not followed by a late-phase response. The response may be prevented by prophylactic treatment with histamine H1-receptor antagonist, local anesthetics, and atropine, which suggests that both mast cell mediator release and neuronal reflexes are involved. Adenosine- and AMP-induced bronchoconstriction are both blocked by cromolyn sodium and nedocromil sodium, with the PD20FEV1 for the latter approximately four times lower than that of cromolyn sodium in atopic asthmatic patients and approximately 2.3 times lower than that of cromolyn sodium in nonatopic asthmatic patients. We suggest that AMP-induced bronchoconstriction, in combination with other indirect-acting provicants, may be used to determine the effectiveness and mechanism of action of antiasthmatic drugs.

Adenosine↗
PubMed1993

Relative potencies and time course of changes in adenosine 5'-monophosphate airway responsiveness with inhaled furosemide and bumetanide in asthma.

A randomized, double-blind, placebo-controlled study was conducted to compare the effects of two chemically unrelated "loop" diuretics, furosemide (40 mg) and bumetanide (2 mg) on the bronchoconstrictor response to inhaled adenosine 5'-monophosphate (AMP) in 12 subjects with asthma. In eight additional volunteers with asthma, we also carried out a separate randomized, double-blind study to examine in more detail the time course of change in bronchial reactivity to inhaled AMP after administration of nebulized furosemide and bumetanide. Inhaled loop diuretics significantly increased the provocative concentration of AMP causing a 20% fall in forced expiratory volume in 1 second (FEV1) from the value of 21.2 mg/ml (range, 2.5 to 96.9 mg/ml) after placebo administration to 83.4 mg/ml (range, 11.3 to 345.0 mg/ml) (p < 0.01) and 33.8 mg/ml (range, 4.7 to 120.9 mg/ml) (p < 0.05) after administration of furosemide and bumetanide, respectively. After placebo administration, the provocative concentration of AMP causing a 20% fall in FEV1 (PC20 AMP) at 10, 30, and 120 minutes did not differ significantly; their geometric mean (range) values were 57.8 mg/ml (10.9 to 341.0 mg/ml), 55.0 mg/ml (13.2 to 304.1 mg/ml), and 52.8 mg/ml (14.4 to 252.2 mg/ml), respectively. When compared with placebo, inhaled furosemide significantly reduced the airway responsiveness to AMP at all time points; the PC20 AMP values at 10, 30, and 120 minutes were 154.6 mg/ml (29.4 to 658.7 mg/ml) (p < 0.01), 142.6 mg/ml (25.5 to 639.9 mg/ml) (p < 0.01), and 103.9 mg/ml (12.5 to 605.5 mg/ml) (p < 0.05), respectively. The PC20 values for AMP after pretreatment with bumetanide were significantly increased up to 110.2 mg/ml (25.9 to 639.0 mg/ml) (p < 0.01) and to 92.0 mg/ml (21.6 to 531.7 mg/ml) (p < 0.05) at 10 and 30 minutes, respectively. At 120 minutes, inhaled bumetanide failed to affect AMP airway responsiveness; the PC20 AMP was not significantly different from that of placebo, with a value of 71.5 mg/ml (22.6 to 318.0 mg/ml). We conclude that comparable equidiuretic doses of furosemide and bumetanide are effective in attenuating the airway response to AMP, with furosemide being approximately 2.5 times more potent than bumetanide (p < 0.01). The time course of change in bronchial reactivity to AMP is similar for both drugs with a peak effect at 10 minutes. It is possible that the mechanism(s) underlying the protective effects of inhaled loop diuretics in asthma may be distinct from those responsible for their diuretic properties.

Adenosine Monophosphate↗
PubMed1993

Comparison of mechanisms of IL-3 induced histamine release and IL-3 priming effect on human basophils.

We have investigated the mechanisms by which interleukin-3 (IL-3) induces histamine release and primes basophils for increased histamine release in response to anti-IgE- and N-formyl-methionyl-leucyl-phenylalanine (fMLP). The responsiveness of basophils from atopic donors was variable, only 5/11 subjects showing release of > 10%, to IL-3 in the range 0.1-100 ng/ml. IL-3-induced histamine release required both extracellular Ca2+ and cell membrane IgE, removal of membrane IgE by lactate stripping or desensitization of basophils by incubation with anti-IgE in a Ca2+-free medium blocking IL-3-induced histamine release. IL-3 also primed basophils for histamine release by anti-IgE and fMLP in the same concentration range as it evoked histamine release. When IL-3 and either anti-IgE or fMLP were combined, the result was additive or supra-additive depending on the basophil donor. Unlike IL-3-evoked histamine release, IL-3 priming of basophils for fMLP-induced histamine release was shown to be independent of the presence of both cell surface IgE and of extracellular calcium. The protein kinase C (PKC) inhibitor, staurosporine (10 nM), inhibited anti-IgE induced histamine release, but neither IL-3 induced histamine release nor IL-3 priming of IgE- and fMLP-induced histamine release. Pertussis toxin (1.0 microg/ml) inhibited fMLP-induced histamine release but not anti-IgE-induced histamine release, IL-3-evoked histamine release or IL-3 priming. These results indicate that IL-3 modulates mediator release from human basophils by two mechanisms; a direct release of histamine which involves cell surface IgE and the influx of extracellular calcium but which is unlikely to proceed by the same mechanism as cross-linkage of IgE, and a priming effect which is independent of IgE and extracellular Ca2+ and which enhances the secretory effects of a wide range of unrelated secretagogues.

Antibodies, Anti-Idiotypic↗
PubMed1993

Monoclonal antibodies specific for guinea pig eosinophil major basic protein: their use in an ELISA, immunocytochemistry and flow cytometry.

Eosinophil major basic protein (MBP), purified from guinea pig eosinophil granules was used to raise five monoclonal antibodies (MoAbs). Their reactivity with MBP was confirmed by immunoblotting and indirect ELISA. Two of the MoAbs were used to develop a sensitive and specific antigen capture (sandwich) ELISA for guinea pig eosinophil MBP which gives an accurate and reproducible standard curve over the range of 10-10,000 ng/ml. The specificity of the ELISA for MBP was confirmed and its suitability for testing biological samples ascertained by measurement of MBP in bronchoalveolar lavage fluid (BALF) and plasma from guinea pigs sensitized and challenged with ovalbumin. The ELISA was also capable of detecting MBP in culture supernatants from purified eosinophil preparations challenged with calcium ionophore in vitro. One of the monoclonals could be used to strongly and specifically stain guinea pig eosinophils in immunocytochemistry, whilst all five could be used to visualize eosinophils in suspension in BALF or peritoneal lavage fluid by flow cytometry. There was no staining of other guinea pig leucocyte types, nor crossreactivity with human eosinophils by immunocytochemistry or flow cytometry.

Animals↗
PubMed1993

A comparison of the effects of polyarginine and stimulated eosinophils on the responsiveness of the bovine isovolumic bronchial segment preparation.

1. The bovine isovolumic bronchial segment preparation has been used to study the sensitivity and responsiveness of bronchial smooth muscle after various manipulations. 2. Addition of acetylcholine (ACh) to the lumen of the segments elicited an increase in intraluminal pressure as a result of contraction of the airway smooth muscle. However, the increases in intraluminal pressure were greater when the ACh was added to the adventitial surface of the preparation. 3. Addition of polyarginine to the bronchial lumen for 60-120 min resulted in an increased magnitude of response and greater than 100 fold increase in sensitivity to ACh administered into the lumen. Depolarizations induced by KCl were similarly enhanced when the solution was added into the lumen. In contrast, the sensitivity and responsiveness to ACh or K(+)-induced depolarization administered adventitially was unchanged. 4. The mechanical disruption of the epithelium produced a 32 fold increase in sensitivity to ACh introduced via the lumen, whereas the sensitivity to ACh added adventitially remained unaltered. 5. Addition of polyarginine to the adventitial bathing medium resulted in no change in the responsiveness or sensitivity to ACh, irrespective of whether the ACh was given intraluminally or adventitially. 6. Histological examination revealed that polyarginine caused extensive disordering of the normal architecture of the bronchial epithelium. Taken together with the unaltered responsiveness to adventitial ACh (i.e. lack of change in intrinsic muscle sensitivity) these observations suggest that the effect of polyarginine was most likely due to disruption of a diffusion barrier. 7. In contrast to the effects of polyarginine, the only effect of stimulated eosinophils was to produce a small diminution in the responsiveness to ACh that had been added adventitially.

Acetylcholine↗
PubMed1993

Comparative nasal effects of bradykinin and histamine: influence on nasal airways resistance and plasma protein exudation.

BACKGROUND: Bradykinin may contribute to the pathogenesis of allergic rhinitis. Like histamine, nasal challenge with bradykinin induces rhinorrhoea, nasal blockage, and plasma protein leakage. Their comparative nasal potencies have not, however, been fully elucidated. METHODS: Three double blind, randomised, placebo controlled and cross-over studies were undertaken to compare objectively the nasal effects of bradykinin, histamine, and vehicle. RESULTS: Both bradykinin and histamine produced dose dependent increases in nasal airways resistance (NAR). There was no significant difference in the effects of bradykinin and histamine on NAR at any dose level. On a molar basis, however, bradykinin was 6.98 times more potent than histamine in inducing a 50% increase in NAR. Nasal challenge with bradykinin and histamine also induced significant rhinorrhoea compared with vehicle. The amount of rhinorrhoea induced by histamine was significantly greater than that induced by bradykinin at any dose level. Bradykinin and histamine induced dose dependent nasal pain and nasal itch respectively. When administered as single doses both bradykinin (1.9 mumol) and histamine (1.9 mumol) induced significant rhinorrhoea compared with the vehicle. The volume of rhinorrhoea secretions induced by histamine was 29% greater than that induced by bradykinin. In contrast, although NAR was increased significantly more by histamine than by the vehicle, the effect of bradykinin on NAR was significantly greater than histamine and vehicle in both magnitude and duration of effect. The incremental effect of bradykinin on lavage albumin levels was also significantly greater than both histamine and vehicle. CONCLUSIONS: This study shows that the nasal vascular effects of histamine are less prominent than its actions on rhinorrhoea, and that the greater obstructive effect of bradykinin than histamine on NAR may contribute to the relative lack of efficacy of H1 antihistamines on nasal blockage in clinical disease.

Administration, Inhalation↗
PubMed1993

Interactive effect of inhaled bradykinin with histamine and PGD2 in bronchial asthma.

Interaction among mediators such as bradykinin (BK), histamine (H), and prostaglandin (PG) D2 may contribute to reduction in airway caliber in asthma. Ten stable asthmatic subjects took part in a study to investigate possible mediator interaction. The provocative concentration of mediator required to reduce forced expiratory volume in 1 s (FEV1) by 12.5% from the starting baseline value (PC12.5) and that required to reduce the fall in FEV1 from 12.5 to 25% (PC25-12.5) of H, BK, and PGD2 were determined. On three subsequent occasions, subjects inhaled either the vehicle plus BK PC12.5 or the vehicle plus H or PGD2 PC25-12.5, and FEV1 was measured at regular time intervals up to 40 min. Predicted time course curves were calculated from these results. On two additional occasions, interactive time course studies were undertaken when the subject inhaled BK PC12.5 followed by H or PGD2 PC25-12.5. On a further three visits, the time courses of individual mediators were studied. When BK was combined with H and PGD2, the maximum fall in FEV1 and the rate of recovery after inhalation of the second mediator were not significantly different from those values of predicted time course responses for the same combination of mediator. Thus, by employing pharmacologically active concentrations of inhaled BK, H, and PGD2, which act through separate receptor mechanisms, we were unable to demonstrate any pharmacological interaction on airway caliber in asthma.

Adult↗
PubMed1993

Interleukin-8 concentrations are elevated in bronchoalveolar lavage, sputum, and sera of children with cystic fibrosis.

Concurrent pulmonary inflammation and neutrophil infiltration are characteristic of children with cystic fibrosis (CF). The production of the major neutrophil chemotactic cytokine IL-8 by alveolar macrophages or other cells could be of great importance in the pathology of acute lung disease, but its role in the persistent lung inflammation characteristic of CF has not been evaluated. In this study, we have measured, by ELISA, the concentration of IL-8 in sputum, bronchoalveolar lavage, and sera specimens obtained from children with CF. For comparison, IL-8 in bronchoalveolar lavage obtained from asthmatic patients and from non-CF children with or without lung infection and in sera from age-matched controls was measured. High levels of IL-8 were measured in sputum (mean = 2952 pM) and in bronchoalveolar lavage (mean = 6624 pM) from CF patients. In both cases, there was a significant correlation between clinical status (Schwachman score) and IL-8 levels. This was not true for IL-8 levels measured in sera, which nevertheless were significantly higher in CF patients (p = 0.0001) than in normal controls in the over-10-y age group.

Adolescent↗
PubMed1992

Human mast cell tryptase attenuates the vasodilator activity of calcitonin gene-related peptide.

Calcitonin gene-related peptide (CGRP) is localized in and released from sensory nerves. It is a potent and long acting vasodilator which has been suggested to play a role in the control of blood flow. Using HPLC and trichloroacetic acid precipitation techniques, we have examined the ability of human mast cell lysates and a purified preparation of mast cell tryptase to degrade CGRP. We found that CGRP is effectively cleaved by tryptase (Km = 6.8 x 10(-6) mol/L at 37 degrees). Enzymatic activity was inhibited by antipain, leupeptin, N-alpha-p-tosyl-L-lysine chloromethyl ketone, benzamidine or aprotinin, but not by soybean trypsin inhibitor or N-tosyl-L-phenylalanine chloromethyl ketone. The degradation of CGRP by lysates of purified skin mast cells showed a similar pattern of inhibition suggesting that tryptase may be the major enzyme involved. The activity of tryptase was not affected by the presence of heparin. Incubation of CGRP with tryptase resulted in a loss of its vasodilator activity as observed by intravital microscopy of the hamster cheek pouch microvasculature. CGRP preincubated with tryptase failed to relax arterioles when added topically. It is suggested that the catalysis of CGRP by tryptase could represent an important means by which the activity of this neuropeptide is regulated in vivo.

Calcitonin Gene-Related Peptide↗
PubMed1992

The effect of inhaled allergen on circulating basophils in atopic asthma.

There is increasing evidence for the role of basophils in the allergen-induced late asthmatic response (LAR). To study the effect of inhaled allergen on basophil function in subjects with asthma, ex vivo basophil spontaneous histamine release (SHR) in peripheral blood and plasma histamine was measured before and 2, 5, 10, and 15 minutes, and 2, 4, 6, and 8 hours after allergen bronchial challenge (allergen study day) in six subjects with atopic asthma. Allergen inhalation induced an early response and LAR consisting of a mean (+/- SD) 32.5% (+/- 7.9%) and 28.8% (+/- 7.7%) fall in FEV1, respectively. As a control for the effects of bronchoconstriction, on another occasion, methacholine challenge was performed to produce a mean 33.4% (+/- 3.4%) fall in FEV1 during the early response and no LAR, and blood was obtained to measure basophil histamine release (HR) and plasma histamine. There was a small, but significant (p less than 0.05), rise in median SHR from 4.6% to 6.1% of total basophil histamine after allergen but not after methacholine inhalation. HR remained high after allergen inhalation during the 8 hours of study, whereas it demonstrated a steady, significant, decrease between 4 to 8 hours after methacholine inhalation. No significant changes in plasma histamine were recorded on either allergen or methacholine study days. On a third occasion, SHR was measured after challenge with physiologic saline to control for any effects of methacholine on SHR, and a decrease in HR was recorded during the day similar to HR observed after methacholine challenge. These studies suggest an enhancing effect of inhaled allergen on SHR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Circulating histamine and eosinophil cationic protein levels in nocturnal asthma.

1. To investigate the role of mast cells and eosinophils in the pathogenesis of nocturnal asthma, the plasma methylhistamine concentration, serum eosinophil cationic protein level and peak expiratory flow rate were measured 2-hourly for 24 h in 10 patients with nocturnal asthma and in 10 healthy control subjects. Nocturnal asthma was defined as at least one nocturnal awakening per week due to cough, wheeze or breathlessness with an average overnight fall in peak expiratory flow rate of at least 15% during a 2-week run-in period. 2. The lowest peak expiratory flow rate occurred at 02.00-04.00 hours in the group with nocturnal asthma, whose overnight fall in peak expiratory flow rate was 29 +/- 5% in comparison with 5 +/- 1% (means +/- SEM) in the normal subjects. 3. Plasma methylhistamine levels at night (0.200-04.00 hours) were lower than during the day (10.00-20.00 hours) in both asthmatic patients and normal subjects (asthmatic patients: day, median 0.22 ng/ml, 95% confidence intervals 0.18-0.34 ng/ml; night, 0.17 ng/ml, 0.13-0.24 ng/ml; P < 0.01; normal subjects: day, 0.31 ng/ml, 0.24-0.41 ng/ml; night, 0.24 ng/ml, 0.21-0.33 ng/ml; P < 0.01). 4. The serum eosinophil cationic protein level was higher by day (30 ng/ml, 8-47 ng/ml) than by night (21 ng/ml, 5-34 ng/ml; P < 0.04) in the group with nocturnal asthma, but did not change significantly with the time of day in the normal subjects (day: 8 ng/ml, 4-14 ng/ml; night: 8 ng/ml, 5-21 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Asthma. The mast cell.

The mast cell's association with asthma has a long history dating back to the turn of the century, when Dale and Laidlaw described histamine as a spasmogen for guinea-pig airways and a proposed mediator of acute anaphylaxis. Almost half a century elapsed before histamine was localised to the granules of mast cells, although the release of this and other mediators of the acute allergic reaction were known to involve reagin subsequently identified as IgE. The biochemical mechanisms involved in transduction signalling not only results in the calcium and energy-dependent release of preformed mediators by degranulation but also the generation and subsequent release of an array of newly formed products, many of which are derived from phospholipid precursors.

Asthma↗