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Biomedical subjects

D Proud

Publications and source records attributed to D Proud.

At least 127 records · Page 7Linked to original sources
PubMed1989

Major basic protein and eosinophil-derived neurotoxin concentrations in nasal-lavage fluid after antigen challenge: effect of systemic corticosteroids and relationship to eosinophil influx.

The late-phase response to nasal challenge with antigen is associated with a mixed inflammatory cell influx in which the eosinophil demonstrates the earliest and greatest proportionate rise. We investigated the evidence for activation of the eosinophil during the late response by measuring the concentration of the eosinophil-derived mediator major basic protein (MBP) and the eosinophil-derived neurotoxin (EDN) in nasal-lavage fluids before and for 11 hours after antigen challenge in 13 subjects with seasonal allergic rhinitis. The subjects received oral prednisone (20 mg three times daily) or placebo in a double-blind, crossover manner for 2 days before each of two antigen challenges. After placebo pretreatment, significant increases over diluent baseline (4.5 +/- 0.4 ng/ml) occurred in the levels of MBP in nasal-lavage fluid during the early (9.8 +/- 2.9 ng/ml; p less than 0.005) and late (15.3 +/- 4.8 ng/ml; p less than 0.01) responses to antigen challenge. Significant increases (p less than 0.05) in the concentration of EDN also occurred during the late response to antigen that correlated with the levels of MBP (r = 0.48; p less than 0.001). The cumulative late-phase increase in MBP correlated closely (rs = 0.96; p less than 0.005) with the total influx of eosinophils. Oral prednisone pretreatment significantly reduced the mean of each subject's peak late-phase concentration of both MBP (30.7 +/- 5.8 ng/ml versus 13.3 +/- 4.3 ng/ml; p = 0.005) and EDN (885 +/- 659 ng/ml versus 71 +/- 41 ng/ml; p less than 0.05). These data provide evidence for eosinophil degranulation during the late response and inhibition of this response by prednisone, supporting its pathogenetic role.

Blood Proteins↗
PubMed1989

Attenuation of allergen sensitivity early in the course of ragweed immunotherapy.

During the course of an open immunotherapy (IT) study of ragweed (RW)-allergic patients, nasal mediator release was studied by provocation testing. All subjects had a history of seasonal RW rhinitis, positive skin puncture test to RW, and RW-specific IgE by RAST. Nasal challenge was performed with serial dilutions of RW extract, before and after 12 weekly injections, providing a cumulative dose of 0.22 microgram of Amb a I. Serum IgE and IgG and basophil histamine release with RW were also measured. By 12 weeks of IT, when only 1% of the usual maintenance level dose had been administered, mean histamine release and TAME-esterase activity in nasal washes decreased significantly (p less than 0.05 and p less than 0.01). Prostaglandin D2 release did not change. Skin sensitivity decreased (p less than 0.05), whereas RW-specific IgE increased (p less than 0.05). No significant change in basophil histamine release was observed for RW or a control antigen. Only six of 40 subjects had an RW-specific IgG rise greater than 0.05 microgram/ml. Changes in nasal sensitivity did not correlate with the increases in IgE or IgG or with the change in skin test sensitivity. These present data indicate that there is a significant decline in nasal sensitivity to inhaled RW very early in the course of IT. There is, however, no indication of a relationship between the decreased nasal sensitivity and the production of RW-specific IgG antibodies.

Adolescent↗
PubMed1989

Inhibition of human bronchial kallikrein in asthma.

Human bronchial kallikrein (HBK) is the major kinin-generating enzyme in the airways of asthmatic subjects. We examined the in vitro inhibition of HBK and its in vivo regulation in asthma. HBK kininogenase activity was measured by cleavage of radiolabeled purified high molecular weight kininogen (HMWK) (125I HMWK). Functional inhibition of the enzyme was present after co-incubation with either normal human plasma (NHP) or preparations of alpha-1-proteinase inhibitor (alpha 1-PI). Stable HBK inhibitor complex was detected at 92 K by immunoblotting employing anti-HUK as a probe. Anti alpha 1-PI probes did not demonstrate the 92 K complex under identical conditions, raising the possibility of an additional co-purifying protein involved in HBK binding. alpha 1-PI antigenic and activity levels were measured in asthmatic bronchoalveolar lavage (BAL) fluid. In only a single sample of the six examined was alpha 1-PI activity detected. In two of the remaining five samples, low levels of alpha 1-PI antigen were present which were functionally inactive. In the BAL fluid containing alpha 1-PI activity, progressive functional inhibition of kininogenase activity correlating with HBK inhibitor complex formation occurred during BAL fluid incubation. In contrast, BAL fluid lacking alpha 1-PI activity failed to show progressive kininogenase inhibition or complex formation under identical conditions. In all experiments, the time course of HBK inhibitor interaction was markedly prolonged, requiring 150-min co-incubation with either NHP or the alpha 1-PI preparation for greater than 80% inhibition of function and near maximal complex formation. The slow rate of inhibition of HBK may allow for its continued activity and kinin generation in the airways of asthmatic subjects.

Adolescent↗
PubMed1989

Cyclooxygenase metabolism of endogenous arachidonic acid by cultured human tracheal epithelial cells.

The epithelial cell may contribute to the regulation of pulmonary function during inflammatory diseases of the airways by producing metabolites of arachidonic acid (AA). We have used human tracheal epithelial cells (HTE), grown in serum-free medium, to examine cyclooxygenase metabolism of endogenous AA by these cells. Gas chromatography-negative ion mass spectrometry demonstrated that, regardless of stimulus (buffer, bradykinin, or the calcium ionophore A23187), epithelial cells produce PGE2 and PGF2 alpha but no detectable levels of PGD2, thromboxane B2, 6-keto-PGF1 alpha, or 9 alpha, 11 beta-PGF2. Preincubation of cultures with medium containing 5% human serum led to striking increases in the production of PGE2 and PGF2 alpha, regardless of stimulus. Concomitant with these increases in prostanoids, serum exposure caused a 3.6-fold increase in total cellular arachidonate. Arachidonate levels increased in all phosphoglyceride classes, with the greatest increases in phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol. In serum-pretreated cells, PGE2 production was 1.46 +/- 0.12, 4.74 +/- 0.6, and 6.35 +/- 0.93 ng/10(6) cells (mean +/- SEM; n = 7) upon exposure to buffer, 10(-6) M bradykinin, and 1 micrograms/ml A23187, respectively, whereas PGF2 alpha levels were 1.53 +/- 0.22, 4.44 +/- 0.36, and 5.77 +/- 0.78 ng/10(6) cells, respectively. The response of HTE to bradykinin was dose-dependent (10(-8) to 10(-6) M) and was maximal within 5 min. We conclude that cyclooxygenase metabolism of endogenous arachidonate in HTE results in the specific production of PGE2 and PGF2 alpha. HTE in culture retain receptors for bradykinin and can be used to study lipid metabolism independent of other cell types.

Adult↗
PubMed1989

The effect of cetirizine on early allergic response.

A double blind, placebo-controlled, cross-over study was performed to determine the effect of cetirizine, an H1 antihistamine, on the immediate nasal allergic response. Ten persons underwent nasal challenge with antigen after premedication with 20 mg of cetirizine or placebo QD for 2 days. The response was monitored by counting the number of sneezes and by measuring the levels of histamine, prostaglandin D2, leukotriene C4, albumin, and TAME-esterase activity in recovered nasal lavages. The results showed a significant reduction in sneezing and in the amounts of recovered albumin, TAME-esterase activity, and leukotriene C4 but no reduction in the amounts of recovered histamine and prostaglandin D2. These results suggest that cetirizine does not inhibit mast cell activation but inhibits the consequences of the released histamine on H1 receptors: sneezing and increased vascular permeability. The results further suggest that mast cell release of histamine is the direct result of antigen stimulation, as opposed to reflex activation, and that other cells in addition to mast cells generate leukotrienes during the early allergic response.

Albumins↗
PubMed1989

In vivo and in vitro effects of antihistamines on mast cell mediator release: a potentially important property in the treatment of allergic disease.

A nasal antigen challenge model of allergic individuals was used to evaluate whether antihistamines could inhibit human mast cell and basophil mediator release in vivo. In placebo-controlled trials, topically applied azatadine base, a tricyclic antihistamine with in vitro antirelease action, effectively reduced symptoms and mediator levels in nasal lavage fluids after antigen challenge, suggesting mast cell inhibition. Both terfenadine and cetirizine, systemically administered antihistamines, were clinically effective in reducing sneezing and changes in vascular permeability. Only terfenadine significantly reduced histamine in antigen-induced nasal secretions. However, cetirizine did reduce the level of leukotriene C4 in these fluids. These results indicate that some antihistamines may be capable of suppressing mediator release from nasal mast cells. The significance of this property in those compounds' overall clinical effect is unclear because of their other concomitant activities.

Administration, Intranasal↗
PubMed1989

The effects of H1 antihistamines on the early allergic response.

To increase understanding of the effect of H1 antihistamines on the immediate response to nasal challenge with antigen, we performed two double blind, placebo-controlled, crossover studies using cetirizine and terfenadine. The subjects underwent nasal challenge with antigen after premedication with either cetirizine (20 mg QD for two days, n = 10), terfenadine (60 mg BID for 1 week, n = 12), or placebo for equivalent periods of time. We monitored the response to challenge by counting the number of sneezes and by measuring the levels of inflammatory substances in recovered nasal lavages. Compared with placebo, both antihistamines significantly reduced sneezing and the levels of recovered albumin and TAME esterase activity, suggesting that both reduced the expected increase in vascular permeability. With cetirizine, there was also a reduction in the levels of LTC4 (not measured in terfenadine studies) but not in those of recovered histamine and prostaglandin D2. These data suggest that cetirizine did not affect mast cell mediator release, that histamine release is due to the direct action of antigen stimulation and that leukotrienes are generated by cells in addition to mast cells. With terfenadine, there were significant reductions in the levels of histamine and kinins (not measured in cetirizine study) seen after nasal challenge with antigen. The reduction in kinins most likely reflects alteration in vascular permeability, whereas the effect on histamine presumably reflects inhibition of mast cell activation. When combined, these experiments demonstrate effects of H1 antihistamines on histamine release beyond those usually described, as well as differences between drugs within a single classification.

Benzhydryl Compounds↗
PubMed1988

A new kinin moiety in human plasma kininogens.

Recently, we isolated a new kinin from human urine and tentatively identified it as [Ala3]-Lys-bradykinin. However, there were inconsistencies between the properties of the naturally occurring new kinin and synthetic [Ala3]-Lys-bradykinin. In the present work, we determined whether the new kinin was released from human plasma kininogen, and further investigated the structure of the new kinin. After incubation of plasma (n = 6) with human urinary kallikrein, kinins were separated by HPLC and measured by RIA. The new kinin and Lys-bradykinin were found representing 23 +/- 3 and 76 +/- 6%, respectively, of total kinins released (2.0 +/- 0.4 micrograms/ml). The new kinin was also released from both purified low- and high-molecular-weight kininogens, representing 40-42% of total kinins released. Amino acid sequencing and composition analysis indicated that the structure of the new kinin was [Hyp3]-Lys-bradykinin (Lys-Arg-Pro-Hyp-Gly-Phe-Ser-Pro-Phe-Arg) and not [Ala3]-Lys-bradykinin. We conclude that an important proportion of human kininogens contain hydroxyproline instead of proline in position three of the bradykinin moiety.

Amino Acid Sequence↗
PubMed1988

Identification of human lung mast cell kininogenase as tryptase and relevance of tryptase kininogenase activity.

We have described previously the IgE-mediated release of kininogenase activity from purified human lung mast cells. Using supernatant fractions from mast cells stimulated with anti-IgE in the presence of deuterium oxide, we have purified this kininogenase to homogeneity by gel filtration and heparin-agarose chromatography and have demonstrated that it is identical to tryptase, the major neutral protease of human lung mast cells. Thus, tryptase and kininogenase activities co-chromatographed through both purification steps with equivalent yields. The final purified kininogenase was free of detectable chymotryptic and carboxypeptidase activities and was identified as tryptase on the basis of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), amino acid composition and inhibition profile. Three such preparations of tryptase were all capable of releasing kinin from each of two different preparations of purified, single-chain, human low molecular weight kininogen. Interestingly, kinin generation was optimal at pH 5.5 and was enhanced by heparin, which has been reported to stabilize tryptase. SDS-PAGE analysis of kininogen hydrolysis by tryptase revealed the formation of a diffusely stained region in the molecular weight range of 60,000-65,000, rather than a discrete heavy chain band. Under optimal conditions, the three tryptase preparations released 10-12 micrograms kinin/hr/mg but released only 2 micrograms kinin/hr/mg at pH 7.2. HPLC analysis revealed that the kinin released was bradykinin. We conclude that the kininogenase activity from human lung mast cells is attributable to tryptase. The unique pH optimum of this reaction of a serine protease, however, raises doubts as to the physiologic significance of this activity.

Amino Acids↗
PubMed1988

Profiling of bisenoic prostaglandins and thromboxane B2 in bronchoalveolar fluid from the lower respiratory tract of human subjects by combined capillary gas chromatography-mass spectrometry.

Methods for the profiling of prostaglandin D2 (PGD2), prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), 15(S),9 alpha,11 beta-trihydroxyprosta-5Z,13E-dien-1-oic acid (9 alpha,11 beta-PGF2), 6-keto-prostaglandin F1 alpha (6kPGF1 alpha), and thromboxane B2 (TxB2) in bronchoalveolar lavage (BAL) fluids from human subjects by combined capillary gas chromatography-mass spectrometry are described. Aliquots (5 ml) of BAL fluid obtained using a standardized lavage protocol were extracted on octadecylsilyl silica cartridges after addition of 0.8 to 2.0 nanograms of tetradeuterated analogs of PGE2, PGF2 alpha, and 6kPGF1 alpha as internal standards. Eluted analytes and internal standards were prepared for vapor phase analysis by sequential reactions resulting in the formation of methyloxime-pentafluorobenzyl ester-trimethylsilyl ether derivatives. The derivatized analytes were detected by simultaneous monitoring of ions at six different masses characteristic for each of the derivatized prostanoids. The samples were of adequate purity for identification and quantitation of each of the prostanoids with detection limits of 0.1 to 0.2 picograms of each analyte per milliliter of BAL fluid. The time required for analysis of each sample was approximately 30 minutes. Standard curves of unlabeled species of the six prostanoids extracted after addition to BAL fluid were linear over a range from subpicogram to nanogram quantities. The differences between the amounts of prostanoid added and the amounts of prostanoid measured were typically less than 19%, and the intra-assay coefficients of variation for repeated measurements of a single sample were less than 20%. PGE2, PGD2, PGF2 alpha, and TxB2 were detectable in BAL fluids from normal subjects with levels of each of these compounds being less than 2.6 picograms/ml. BAL fluids from patients with lung disease presented qualitative and quantitative profiles of prostanoids markedly different than those from normal subjects. These analytical methods provide a basis for in vivo comparisons of prostanoid profiles in the lower respiratory tract of man and should be readily adaptable for use in a variety of clinical studies.

Alveolitis, Extrinsic Allergic↗
PubMed1988

Experimentally induced nasal allergic responses.

To investigate the pathogenesis of allergic rhinitis, we developed a nasal challenge model in which we examined the early, late, and rechallenge responses to antigen provocation. In these three aspects of the allergic reaction the physiologic responses are associated with inflammatory mediator release. Whereas the early response appears to be related mainly to mast cell activation and mediator release, the late reaction involves a different pattern of mediator release and an inflammatory cell influx, consisting of basophils, neutrophils, and eosinophils. Rechallenge with antigen 11 hours later results in an augmented immediate response. Pretreatment with aspirin reduces the levels of cyclooxygenase metabolites in nasal secretions without affecting the immediate physiologic response to antigen or the expected increase in the levels of histamine, N-alpha-tosyl-L-arginine methyl ester-esterase activity, and leukotriene C4. Pretreatment with systemic steroids does not affect the early allergic response, but significantly reduces mediator release during the late and rechallenge responses. The influx of eosinophils is inhibited by pretreatment with systemic steroids, but neutrophil influx is not. In contrast, pretreatment with topical steroids blocks the early response and the late and rechallenge responses. Influx of all cell types, including the neutrophil, was prevented. These studies show unequivocally that an inflammatory process follows the initial response to antigen and that this inflammation is affected by drugs important in the treatment of chronic allergic disease. We speculate that understanding allergic inflammation will lead to new therapeutic development.

Antigens↗
PubMed1988

Studies on the allergic and nonallergic nasal inflammation.

Nasal lavage after antigenic and nonantigenic nasal stimulation has become an important tool for the study of inflammatory phenomena in the upper airway. Biochemical and cytologic information is relatively easily obtainable, and pharmacologic manipulations can be readily monitored. This article is of several studies aiming toward a more profound understanding of the mechanisms of allergic and nonallergic rhinitis by the use of laboratory-challenge procedures and nasal-lavage techniques. An early and a late reaction are detected clinically in the nose after antigen challenge of allergic individuals. In addition, the sensitivity to antigen significantly increases after the initial challenge, and this phenomenon is not obligatorily linked to the presence of a late-phase reaction (LPR). Inflammatory mediators, mostly mast cell- and/or basophil-derived, are detected in the nasal washes and correlate with the symptomatology in both the early and the late reactions. The allergen-induced LPR is marked by an early influx of eosinophils and, later, basophils and neutrophils. Elevation of major basic protein and histamine, but not prostaglandin D2, is detected during the LPR, giving evidence of active eosinophil and basophil participation. Systemic steroids can effectively suppress the clinical, biochemic, and cellular manifestations of antigen-induced LPR. Topical steroids have a similar effect but are also capable of suppressing the early reaction to antigen. A nonallergic form of rhinitis can be induced in the laboratory by nasal inhalation of dry air at freezing temperatures in individuals who report sensitivity to cold and windy environments.(ABSTRACT TRUNCATED AT 250 WORDS)

Environmental Exposure↗
PubMed1988

Kinins are generated during experimental rhinovirus colds.

We investigated the pathophysiology of rhinovirus colds by challenging volunteers with either of two strains of rhinovirus or with placebo. Nasal lavages were done before challenge and every 4 h for five days after challenge. We measured the levels of histamine, kinins, [3H]-N-alpha-p-tosyl-L-arginine methyl ester (TAME)-esterase activity, and albumin and counted the number of neutrophils in the recovered lavage fluid. Subjects who became both infected and symptomatic showed increases in levels of kinins (P less than .03), TAME-esterase activity (P less than .04), and albumin (P less than .05), as well as in the number of neutrophils (P less than .01). The total number of symptoms reported correlated significantly with the net increase in the concentration of kinins (r = .549; P less than .01), albumin (r = .674; P less than .001), TAME-esterase activity (r = .563; P less than .005), and neutrophils (r = .605; P less than .005). Levels of histamine did not change during the course of infection. During symptomatic rhinovirus infections (1) kinins are generated, (2) vascular permeability increases, (3) basophils and mast cells do not participate, and (4) neutrophils enter nasal secretions.

Adult↗
PubMed1988

Is histamine responsible for the symptoms of rhinovirus colds? A look at the inflammatory mediators following infection.

In an attempt to identify inflammatory mediators that may contribute to rhinorrhea, nasal congestion and other cold symptoms, we recruited 40 healthy young adults (median age, 20) for provocative rhinovirus challenge. Mediators measured included histamine, kinins and enzymes with arginine esterase activity. Volunteers were inoculated with rhinovirus or a sham inoculum. Nasal secretions for viral culture were obtained daily, and volunteers were deemed infected if they shed virus or had a 4-fold or greater increase in serum antibody titer. The virus-infected group was subdivided using the Jackson criteria into an ill or non-ill group; each group was compared to the control group. Of the 27 virus-inoculated subjects, 25 had positive cultures for the challenge virus, and 15 became ill. None of the controls had a positive culture. All variables measured--except histamine--grew stronger in direct relationship with the symptoms as the cold increased in severity. In the infected-ill group, the mean kinin level increased more than 10-fold over baseline. The kinin level remained relatively unchanged in the control and non-ill groups. Similar results were found for levels of albumin and enzymes with arginine esterase activity. Histamine levels remained constant in both the infected-ill and non-ill groups, which suggests that mast cells and basophils do not participate in the pathophysiology of rhinovirus infections and that antihistamines should be ineffective in treating rhinovirus colds. Since volunteers who developed cold symptoms exhibited a notable increase in kinin, a potent inflammatory mediator, we recommend further study of a kinin antagonist in reducing nasal symptoms.

Adult↗
PubMed1988

Kinin formation: mechanisms and role in inflammatory disorders.

Although considerable progress has been made in elucidating the molecular events occurring during kinin generation by both the plasma kinin-forming system and the tissue kallikrein system, it is only in recent years that we have come to appreciate their potential role in inflammation in a wide variety of diseases. The importance of the tissue kallikrein system depends upon secretion of the active form of the requisite enzyme in the presence of a source of kininogen. Since tissue kallikreins are widely distributed in tissues, and since lymph and interstitial fluid contains kininogen (271), a local milieu for potential kinin formation is always present. The plasma system will be activated secondary to inflammation initiated by some other process. There may be endothelial or epithelial damage exposing connective tissue. Plasma leakage caused by release of some other permeability factor (including kinin made by tissue kallikrein) would thus lead to activation of the plasma cascade in many forms of inflammation. As with all mediators, however, the contribution of kinins to an inflammatory response can only be definitively evaluated if their actions can be selectively antagonized. Competitive receptor antagonists have recently been synthesized (228) and will, we hope, soon be available for administration to humans. Should these compounds prove effective in vivo, they could be used in conjunction with currently available assays for kallikreins, kininogens, kinins, and their various inactivated or degraded products, to provide new insights into the role of these systems in the pathogeneses of inflammatory diseases.

Angioedema↗
PubMed1988

In vivo release of inflammatory mediators by hyperosmolar solutions.

Hyperosmolar environments induce histamine release from mast cells and basophils in vitro. To assess whether the same stimulus induces mediator release in vivo, 15 healthy human volunteers underwent nasal challenges with instilled solutions of differing osmolalities: lactated Ringer's solution (257 +/- 3 mOsm/kg), isosmolar mannitol (277 +/- 6 mOsm/kg), and hyperosmolar mannitol (869 +/- 8 mOsm/kg). The effect of these challenges on the volume, osmolality, and inflammatory mediator content of subsequent 5-ml isosmolar lavages was determined. The volumes of lavages returned after hyperosmolar challenges were significantly greater than those after isosmolar challenges (5.5 +/- 0.2 ml versus 4.2 +/- 0.1 ml; p less than 0.01) and these lavage solutions had higher osmolalities. Even when corrected for increased volumes, the lavages after hyperosmolar challenges contained significantly higher quantities of inflammatory mediators such as histamine (29.0 versus 10.1 ng; p less than 0.01), TAME-esterase activity (32.7 versus 11.1 cpm x 10(-3); p less than 0.01), and immunoreactive leukotrienes (9.9 versus 3.4 ng; p less than 0.01). The changes in mediators were dose dependent in that incremental increase in challenge osmolality were associated with incremental increases in histamine release. Therefore, when exposed to hyperosmolar stimuli in vivo, the nasal respiratory airway releases inflammatory mediators and fluid rapidly shifts into the airway lumen. It has been suggested that the mediator release observed on breathing cold and dry air is due to increased osmolality of airway secretions; the present data confirm that osmotic variations at the airway surface can provide an adequate stimulus for cell activation.

Adult↗
PubMed1988

Nasal provocation with bradykinin induces symptoms of rhinitis and a sore throat.

Kinins are generated in nasal secretions during allergic reactions and during induced rhinovirus colds. To determine if kinins may contribute to the symptomatology of these inflammatory reactions, 8 subjects were challenged with increasing doses of bradykinin or with placebo. Levels of albumin, histamine, and N-alpha-tosyl-L-arginine methyl ester (TAME)-esterase were measured in nasal lavages, and symptom scores were noted. No symptoms or increases in mediators or protein were observed after placebo challenge. Symptom scores increased in a dose-dependent manner, however, in response to bradykinin challenge. Increased symptoms were associated with significant increases in albumin and TAME-esterase activity, but no increases in histamine were observed. Nasal conductance measurements confirmed that bradykinin induces dose-dependent unilateral obstruction in the challenged nostril. Other common symptoms were rhinorrhea and, of particular relevance to rhinovirus infections, a persistent sore throat. We conclude that bradykinin causes increased vascular permeability and rhinitis, which are independent of mast cell mediator release. Kinins may, therefore, contribute to the symptomatology of inflammatory reactions of the upper airways, including the common cold.

Adult↗