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Biomedical subjects

T J Williams

Publications and source records attributed to T J Williams.

At least 163 records · Page 9Linked to original sources
PubMed1995

Neutrophil chemoattractants generated in two phases during reperfusion of ischemic myocardium in the rabbit. Evidence for a role for C5a and interleukin-8.

The neutrophil chemoattractants generated in a model of myocardial infarction in the anesthetized rabbit were investigated. Coronary artery occlusion was followed by reperfusion for periods from 5 min to 4.5 h. Extracts of myocardial tissue in normal and post-ischemic zones were tested for C5a and interleukin-8 (IL-8) using specific radioimmunoassays. In the post-ischemic zone, immunoreactive C5a was detected within 5 min and rose progressively to reach a plateau at 3-4.5 h. In contrast, immunoreactive IL-8 concentrations rose after a delay and were highest at the last time point tested, 4.5 h. Myeloperoxidase activity levels, an index of neutrophil accumulation, rose progressively as the concentrations of chemoattractants increased. Using cation exchange and reversed phase HPLC, immunoreactive C5a and IL-8 co-eluted with authentic standards. Fractions taken at the C5a and IL-8 peaks from reversed phase HPLC exhibited neutrophil aggregating activity which was neutralized by the respective antibody used in the radioimmunoassays. Depletion of circulating neutrophils virtually abolished immunoreactive IL-8 in the post-ischemic myocardial tissue. These observations suggest a sequential release of chemoattractants: the first, C5a is generated in interstitial fluid, followed by IL-8 generated by infiltrating neutrophils. Thus, over the time period studied, IL-8 generation would be expected to be indirectly dependent on C5a production.

Animals↗
PubMed1995

Effect of a microaerosol barrier filter on the measurement of lung function.

STUDY OBJECTIVE: A disposable barrier filter (Pall Biomedical, United Kingdom) was developed to prevent the contamination of lung function equipment in clinical use. The aims of this study were to examine its resistance characteristics and to determine the effect of the filter on clinical measurements of lung function. MEASUREMENTS: Twenty-one randomly selected patients and four normal subjects had lung function measured with and without the filter between the mouth and measuring equipment. Measurements of ventilatory function were made with a pneumotachograph (Lilly; Hoechberg, Germany), total lung capacity and airway resistance by constant volume plethysmography, and diffusing capacity for carbon monoxide by the single breath method. Resistance was determined in five unused filters over the flow range 1 to 12 L/s and at a single flow rate (12 L/s) just after a normal subject expired 20 forced vital capacity (FVC) breaths through each of them. RESULTS: The resistance (mean +/- SD) of unused filters was 0.19 +/- 0.02 cm H2O/L/s at 1 L/s and increased linearly to 0.56 +/- 0.02 cm H2O/L/s at 12 L/s. There was no significant increase in resistance after use. The addition of the filter to the breathing circuit caused statistically significant decreases in forced expiratory volume in 1 s (FEV1) (0.044 +/- 0.08 L, p = 0.014) and peak expiratory flow rate (PEFR) (0.47 +/- 0.073 L/s, p = 0.004). The filter did not affect other indices of lung function. CONCLUSION: The filter caused a statistically significant reduction in FEV1 and PEFR; however, this difference was believed not to affect the clinical utility of routine lung function testing.

Adult↗
PubMed1995

Lung eosinophilia is dependent on IL-5 and the adhesion molecules CD18 and VLA-4, in a guinea-pig model.

Blood and tissue-eosinophilia is a characteristic feature of a number of disease states. In experimental animals, the intravenous injection of parasitic larvae induces a profound eosinophilia that can be mimicked by the intravenous injection of Sephadex particles. In the present study, this procedure was used to investigate the mechanisms involved in the development of lung eosinophilia in a guinea-pig model. Intravenous administration of Sephadex particles to guinea-pigs resulted in a significant increase in the influx of eosinophils in the airways and in lung tissue eosinophil peroxidase (EPO) activity (at t = 24 hr). An anti-interleukin-5 (IL-5) monoclonal antibody (mAb) totally inhibited the eosinophilia in the airways and significantly reduced the lung tissue EPO activity. The concomitant accumulation of neutrophils and mononuclear cells, however, was not affected by this treatment. Monoclonal antibodies to VLA-4 and CD18 caused 58% and 62% suppression of eosinophilia in the bronchoalveolar lavage (BAL), respectively, whilst having no effect on lung tissue EPO activity. Co-administration of the two mAb resulted in total inhibition of eosinophil accumulation into BAL and significant suppression of lung tissue EPO activity (55% inhibition). This procedure also resulted in 72% inhibition of mononuclear cell influx and 68% inhibition of neutrophil influx in the BAL, the latter effect being entirely due to the actions of the anti-CD18 mAb. The results of this study indicate for the first time a requirement for IL-5 in the development of lung eosinophilia in this model. Further, it is clear that both the molecules VLA-4 and CD18 contribute to the development of this response and that maximal inhibition of lung eosinophilia is achieved only when the two adhesion pathways are simultaneously blocked.

Animals↗
PubMed1995

Prolonged microvascular vasodilation induced by leukotriene B4 in human skin is cyclooxygenase independent.

When the potent chemoattractant leukotriene B4 (LTB4) is applied topically to human skin it causes delayed onset, long-lasting leukocyte accumulation and erythema. We investigated the role of prostaglandins in the increase in local blood flow by applying LTB4 topically to the forearm skin of 22 healthy male volunteers and measuring the effect of the anti-inflammatory compounds tenidap, naproxen and indomethacin. Local microvascular blood flow responses were measured by laser Döppler flow probe and planimetry. LTB4 induced dose-dependent increases in blood flow which were maximal at 48 hr and lasted 4 days. Laser Döppler flow (% flux) at 48 hr was 2.7 +/- 0.1, 20.6 +/- 3.1, 28.7 +/- 2.4 and 30.2 +/- 2.3% in control and 3, 10, 30 ng/site LTB4, respectively (mean +/- S.E.M.). In eight subjects the intradermal injection of indomethacin, at a dose (3 x 10(-9) mol/site) that inhibited significantly the increased flow induced by intradermally injected arachidonic acid (1 x 10(-9) mol/site, n = 6), had no effect on the increased skin blood flow response induced by LTB4 (10 ng/site) at 48 hr. Blood flow in vehicle-injected LTB4 sites was 810 +/- 150% above basal and 819 +/- 149% in sites injected with indomethacin. In 20 subjects, the effect of the anti-inflammatory drugs naproxen and tenidap given orally on the skin blood flow responses to LTB4 were compared in a double-blind crossover design. The 1085 +/- 98% increase in local blood flow induced by 30 ng of LTB4 at 48 hr was unaltered at the end of the treatment periods with either naproxen or tenidap, where blood flow in the LTB4-treated sites was increased 1018 +/- 131% and 1034 +/- 130%, respectively. Because the vasodilator response to exogenous LTB4 was not altered by nonsteroidal anti-inflammatory drugs either injected locally or taken orally, we suggest that endogenous prostaglandins are not involved in this response.

Administration, Oral↗
PubMed1995

LPS-induced 111In-eosinophil accumulation in guinea-pig skin: evidence for a role for TNF-alpha.

Lipopolysaccharide (LPS) is a major component of the cell wall of Gram-negative bacteria with powerful pro-inflammatory activities. Although the mechanisms involved in LPS-induced neutrophil accumulation have been studied extensively, few reports have focused on the effects of LPS on eosinophil infiltration. In this study we have used an in vivo model of local 111In-eosinophil accumulation in the guinea-pig to investigate the mechanisms of LPS-induced eosinophilia. Using a 4-hr in vivo test period, the intradermal injection of LPS (50-1000 ng/site) led to a marked and dose-dependent accumulation of 111In-eosinophils into guinea-pig skin sites. Time-course experiments revealed that this cell infiltration was delayed in onset, becoming significant 1 hr after the intradermal administration of LPS. The slow development of the response and its sensitivity to the locally administered protein synthesis inhibitor, actinomycin D, suggested that the LPS-induced 111In-eosinophil accumulation in vivo is mediated by the generation of de novo proteins. The intravenous pretreatment of guinea-pigs with a soluble tumour necrosis factor-alpha (TNF-alpha) receptor fusion protein (TNFR-IgG, 1 mg/kg), potently inhibited the 111In-eosinophil accumulation induced by LPS. Our results demonstrate that LPS can induce 111In-eosinophil accumulation in vivo in guinea-pig skin, and that this process is mediated by TNF-alpha.

Animals↗
PubMed1994

Eotaxin: cloning of an eosinophil chemoattractant cytokine and increased mRNA expression in allergen-challenged guinea-pig lungs.

Eotaxin was recently identified as the major eosinophil chemoattractant in bronchoalveolar lavage fluid obtained 3h after allergen challenge of sensitised guinea-pigs. We now report the cDNA cloning of this C-C chemokine. The 777 base-pair clone, pEo3122, consists of a 40 base 5' untranslated region, an open reading frame of 288 bases predicting a 73 amino acid mature protein plus a 23 amino acid signal peptide, and a 3' untranslated region of 449 bases containing a poly A tail. Northern blot analysis showed eotaxin mRNA in the lungs of naive and sensitised guinea-pigs, which was considerably increased after allergen challenge. Eotaxin may be an important mediator of eosinophil accumulation and activation in allergic reactions. As eotaxin stimulates human eosinophils, this chemokine and related molecules may be involved in human diseases such as asthma where eosinophil accumulation is a prominent feature.

Allergens↗
PubMed1994

Pro-inflammatory and anti-inflammatory effects of the stable prostaglandin D2 analogue, ZK 118.182.

This study examined the pro- and anti-inflammatory effects of the stable prostaglandin (PG) D2 analogue, ZK 118.182 and the mechanism by which prostaglandins may exert their anti-inflammatory activity. Co-injected locally, ZK 118.182, like PGE2 and PGD2, dose-dependently increased plasma leakage induced by intradermal injection of bradykinin in rabbit skin. Infused i.v., ZK 118.182 (0.45 microgram/kg/min), a dose which did not affect systemic blood pressure, inhibited oedema formation in rabbit skin induced by the neutrophil-dependent agonists, formyl-methionyl-leucyl-phenylalanine (FMLP) and leukotriene B4 (LTB4). However, it did not modify plasma leakage induced by the neutrophil-independent mediators, bradykinin and platelet-activating factor (PAF). In contrast, neutrophil accumulation in response to LTB4 and FMLP was not affected in animals infused with ZK 118.182. In vitro, ZK 118.182, like PGE2 and PGD2 inhibited FMLP-induced superoxide anion (O2-) production by rabbit neutrophils. The compound, however, had minimal effects on O2- production induced by phorbol myristate acetate (PMA). ZK 118.182 inhibited to a small extent FMLP but not PMA-induced neutrophil adherence. These results show that depending on the route of administration, the PGD2 analogue, ZK 118.182, exhibits either pro- or anti-inflammatory effects. The anti-inflammatory effect may be related to the ability of the compound to inhibit increased microvascular permeability induced by neutrophil activation without interfering with neutrophil accumulation. This latter effect may be due to the analogue's capacity to suppress neutrophil secretion to a greater extent than neutrophil adherence.

Animals↗
PubMed1994

Zymosan-induced IL-8 release from human neutrophils involves activation via the CD11b/CD18 receptor and endogenous platelet-activating factor as an autocrine modulator.

We have investigated mechanisms that regulate the generation of IL-8 by human neutrophils on contact with zymosan particles in vitro. Zymosan stimulated IL-8 production, which increased with increasing particle numbers and was abolished by the protein synthesis inhibitor cycloheximide. IL-8 was detectable in culture supernatant at 8 h reaching a maximum at 24 h. In all further experiments IL-8 was measured at 24 h. mAbs to neutrophil CD18 (60.3 and 6.5E) caused a marked suppression of IL-8 generation, but only if added up to 2 h after zymosan stimulation. An anti-CD11b mAb (KIM 225) substantially inhibited zymosan-induced IL-8 release. We investigated whether other mediators generated during phagocytosis modulate IL-8 production. Two selective platelet-activating factor (PAF) receptor antagonists, WEB 2086 and UK 74505, produced a profound suppression of IL-8 generation, when added within 30 min to 1 h of zymosan stimulation. An IL-1R antagonist, a leukotriene B4 antagonist, and an anti-TNF-alpha Ab had no effect on IL-8 generation. FMLP, PAF, and a stable PAF agonist did not stimulate significant IL-8 production, however, a calcium ionophore (A23187) did induce IL-8 release and this was suppressed by UK 74505. We conclude that zymosan-induced IL-8 generation involves stimulation of the neutrophil via a CD11b/CD18 receptor resulting in beta 2-integrin mediated activation of signal transduction mechanisms that leads to cytokine synthesis. Furthermore, endogenously generated PAF, or a PAF, or a PAF-like molecule, appears to have an autocrine function in regulating this pathway of IL-8 production at an early stage after the interaction between the neutrophil and the particles.

Antibodies, Monoclonal↗
PubMed1994

Eotaxin: a potent eosinophil chemoattractant cytokine detected in a guinea pig model of allergic airways inflammation.

Eosinophil accumulation is a prominent feature of allergic inflammatory reactions, such as those occurring in the lung of the allergic asthmatic, but the endogenous chemoattractants involved have not been identified. We have investigated this in an established model of allergic inflammation, using in vivo systems both to generate and assay relevant activity. Bronchoalveolar lavage (BAL) fluid was taken from sensitized guinea pigs at intervals after aerosol challenge with ovalbumin. BAL fluid was injected intradermally in unsensitized assay guinea pigs and the accumulation of intravenously injected 111In-eosinophils was measured. Activity was detected at 30 min after allergen challenge, peaking from 3 to 6 h and declining to low levels by 24 h. 3-h BAL fluid was purified using high performance liquid chromatography techniques in conjunction with the skin assay. Microsequencing revealed a novel protein from the C-C branch of the platelet factor 4 superfamily of chemotactic cytokines. The protein, "eotaxin," exhibits homology of 53% with human MCP-1, 44% with guinea pig MCP-1, 31% with human MIP-1 alpha, and 26% with human RANTES. Laser desorption time of flight mass analysis gave four different signals (8.15, 8.38, 8.81, and 9.03 kD), probably reflecting differential O-glycosylation. Eotaxin was highly potent, inducing substantial 111In-eosinophil accumulation at a 1-2 pmol dose in the skin, but did not induce significant 111In-neutrophil accumulation. Eotaxin was a potent stimulator of both guinea pig and human eosinophils in vitro. Human recombinant RANTES, MIP-1 alpha, and MCP-1 were all inactive in inducing 111In-eosinophil accumulation in guinea pig skin; however, evidence was obtained that eotaxin shares a binding site with RANTES on guinea pig eosinophils. This is the first description of a potent eosinophil chemoattractant cytokine generated in vivo and suggests the possibility that similar molecules may be important in the human asthmatic lung.

Amino Acid Sequence↗
PubMed1994

Modelling the effect of charge on selective deposition of particles in a diseased lung using aerosol boli.

The technique of using a charged bolus of aerosol to deliver a drug or other agent is advantageous since sites of interest within the lung can be selectively targeted. Ideally, the volume of the bolus should match that of the targeted region allowing the aerosol bolus particles to be confined to the selected area during the pause period after inhalation. Our existing computer model for predicting the deposition of charged aerosol particles has been developed to encompass aerosol boli, some diseased lung morphologies and drug dose administered per breathing cycle. Aerosol deposition in the targeted region is found to be enhanced by increasing particle charge, pause period and particle size. For particles in the size range 1-2.5 microm, aerosol deposition in the region affected by bronchoconstriction does not alter significantly with flow rate variation (range 250-1000 ml s(-1)) for a targeted charged bolus of matched volume. The technique may enable the optimal delivery of therapeutic or other agents to diseased or normal lungs.

Administration, Inhalation↗
PubMed1994

Protein kinase C is a mediator of lipopolysaccharide-induced vascular suppression in the rat aorta.

Treatment of vascular tissue with lipopolysaccharide (LPS) in vitro induces hyporesponsiveness to contractile agonists. We investigated whether protein kinase C (PKC) transduces the LPS signal into contractile dysfunction. Rat aortic tissue was incubated .5-18 h with LPS (10 or 30 ng/mL) or alpha- and beta-phorbol 12,13-dibutyrate (PDB, .1 or 1 microM), either alone or combined with cycloheximide (50 microM) or the kinase inhibitors sphingosine (20 microM), H7 (1-(5-isoquinolinylsulfonyl)-2-methyl piperazine, 25 microM), and HA1004 (N-(2-guanidinoethyl)-5-isoquinolinesulfonamide, 25 microM). LPS and beta-PDB induced a sustained translocation of PKC activity from the cytosol to the membrane, an increased protein synthesis-dependent expression of nitric oxide synthase (NOS) activity, and an impaired contractility that could be partially reversed by treatment with the NOS inhibitor N omega-nitro-L-arginine methyl ester. Incubation with alpha-PDB, an inactive isomer of beta-PDB, did not alter any of the tissue functions. Sphingosine blocked LPS- and beta-PDB-induced NOS activity and LPS-induced impairments in tissue contractility and PKC translocation. Incubation with H7 also protected against LPS-induced vasoplegia, while HA1004, used as a negative control for H7, provided little protection against LPS. These data indicate that PKC plays a role as an intracellular mediator of LPS-induced NOS activity and vascular suppression.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1994

Effects of phosphodiesterase isoenzyme inhibitors on cutaneous inflammation in the guinea-pig.

1. Inflammation is central to the pathophysiology of asthma. The recent findings that different inflammatory cells may express different phosphodiesterase (PDE) isoenzymes have centered attention on inhibitors of these isoenzymes as new drugs for the treatment of asthma. In this study, we investigated the effect of different PDE isoenzyme inhibitors on the accumulation of 111In-labelled eosinophils and local oedema formation at sites of allergic- and mediator-induced inflammation in guinea-pig skin. 2. Systemic treatment with SK&F 94120, a type III PDE inhibitor, or zaprinast, a type V PDE inhibitor, had no effect on the 111In-eosinophil accumulation and oedema formation induced by i.d. injection of zymosan-activated plasma (ZAP), PAF, histamine or in a passive cutaneous anaphylaxis (PCA) reaction. 3. Systemic treatment with rolipram, a type IV PDE inhibitor, effectively inhibited 111In-eosinophil accumulation induced by ZAP, PAF, histamine and in a PCA reaction. However, oedema formation measured in the same sites was not affected. Systemic administration of higher doses of theophylline produced similar results. In contrast, 111In-neutrophil accumulation induced by ZAP or in a PCA reaction was not altered by systemic treatment with rolipram. 4. Locally-injected rolipram had little effect on 111In-eosinophil accumulation and oedema formation induced by histamine, PAF and in a PCA reaction. 5. These data show that systemic, but not local, treatment with rolipram effectively inhibits allergic- and mediator-induced 111In-eosinophil accumulation but not oedema formation or 111In-neutrophil accumulation. This, taken together with the potent inhibitory effects of PDE type IV inhibitors on eosinophil function in vitro, suggest that this class of drugs may be beneficial in disease states such as asthma where eosinophils are thought to play a major pathophysiological role.

Animals↗
PubMed1994

Role of adhesion glycoproteins CD18 and intercellular adhesion molecule-1 in complement-mediated reactions of rabbit skin.

1. The role of the adhesion glycoproteins CD18 and intercellular adhesion molecule-1 (ICAM-1) in inflammatory responses produced during a reversed passive Arthus (RPA) reaction and induced by zymosan and zymosan-activated plasma (ZAP) were studied in rabbit skin. 2. Oedema formation and haemorrhage were quantified by measuring accumulation of 125I-albumin and 111In-labelled red blood cells (111In-RBC) respectively. 3. Monoclonal antibody (mAb) R15.7 (anti-CD18), administered intravenously, abolished accumulation of 125I-albumin and 111In-RBC in dermal RPA reactions and in response to locally injected zymosan and ZAP. 4. When administered intravenously, the mAb RR1/1 (anti-ICAM-1) suppressed 125I-albumin and 111In-RBC accumulation in dermal RPA reactions and at sites treated with zymosan and ZAP. 5. Oedema formation in response to platelet-activating factor (PAF) and bradykinin (BK) either in the presence or absence of prostaglandin E2 (PGE2) were not affected by mAb R15.7 or by mAb RR1/1.1.1. 6. We conclude that oedema formation and haemorrhage associated with RPA reactions and in responses to zymosan and ZAP are completely CD18-dependent, and are mediated, at least in part, via ICAM-1. Responses to the neutrophil-independent oedema forming mediators, PAF and BK are not dependent upon CD18 or ICAM-1.

Animals↗
PubMed1994

Role of CD18 in the accumulation of eosinophils and neutrophils and local oedema formation in inflammatory reactions in guinea-pig skin.

1. Intradermal injection of the complement fragment C5a des Arg induces local oedema formation that, in rabbits and man, is dependent on circulating neutrophils. Monoclonal antibodies to the leukocyte adhesion molecule CD11/CD18 block neutrophil accumulation and prevent neutrophil-dependent oedema formation. The role of CD11/CD18 in mediating eosinophil accumulation in vivo is less established. In this study we have used an anti-human CD18 monoclonal antibody, 6.5E, to investigate the neutrophil-dependency of oedema formation induced by C5a des Arg in guinea-pig skin. We also studied the role of CD18 in mediating eosinophil accumulation in the same model. 2. Stimulated adhesion of 111In-labelled guinea-pig neutrophils and eosinophils to serum-coated plastic was inhibited in a dose-dependent manner by 6.5E suggesting that the monoclonal antibody recognizes and blocks the guinea-pig CD18 adhesion molecule. 3. The accumulation of 111In-labelled neutrophils induced by zymosan-activated plasma (ZAP, as a source of C5a des Arg) in skin sites was reduced by up to 89% in animals treated intravenously with F(ab')2 fragments of 6.5E. ZAP-induced accumulation of 111In-labelled eosinophils was also greatly reduced (by up to 78%) by treatment with 6.5E. 4. Despite the inhibition of ZAP-induced neutrophil accumulation by 6.5E, local oedema formation in the same skin sites was unaffected, except at the top dose of ZAP, by treatment with the anti-CD18 monoclonal antibody, suggesting that the oedema response was largely neutrophil-independent. Indeed, ZAP-induced oedema formation was reduced by up to 81% by the H1 receptor antagonist, mepyramine. 5. Accumulation of 111 In-labelled eosinophils in a passive cutaneous anaphylactic (PCA) reaction was also blocked by treatment with 6.5E, while oedema formation in the same skin sites was unaffected.Intradermal injection of cationic protein-containing extracts of Schistosoma mansoni larvae also induced the accumulation of 111 In-labelled neutrophils and eosinophils which was abrogated by intravenous 6.5E.In contrast, extract-induced local oedema formation was similar in control and 6.5E-treated guinea-pigs.6. In summary, the local accumulation of radiolabelled neutrophils at sites of inflammation in guinea pigskin was dependent on the adhesion molecule CD18 while, in contrast, there was no evidence for neutrophil-dependent oedema formation in this species. Accumulation of radiolabelled eosinophils was also dependent on CD18.

Animals↗