Inhaled nitric oxide versus conventional therapy: effect on oxygenation in ARDS

A randomized, controlled clinical trial was performed with patients with acute respiratory distress syndrome (ARDS) to compare the effect of conventional therapy or inhaled nitric oxide (iNO) on oxygenation. Patients were randomized to either conventional therapy or conventional therapy plus iNO for 72 h. We tested the following hypotheses: (1) that iNO would improve oxygenation during the 72 h after randomization, as compared with conventional therapy; and (2) that iNO would increase the likelihood that patients would improve to the extent that the FI(O2) could be decreased by > or = 0.15 within 72 h after randomization. There were two major findings. First, That iNO as compared with conventional therapy increased Pa(O2)/FI(O2) at 1 h, 12 h, and possibly 24 h. Beyond 24 h, the two groups had an equivalent improvement in Pa(O2)/FI(O2). Second, that patients treated with iNO therapy were no more likely to improve so that they could be managed with a persistent decrease in FI(O2) > or = 0.15 during the 72 h following randomization (11 of 20 patients with iNO versus 9 of 20 patients with conventional therapy, p = 0.55). In patients with severe ARDS, our results indicate that iNO does not lead to a sustained improvement in oxygenation as compared with conventional therapy.

Angiotensin II generation at the cell surface of activated neutrophils: novel cathepsin G-mediated catalytic activity that is resistant to inhibition

Human neutrophils express inducible, catalytically active cathepsin G on their cell surface. Herein, we report that membrane-bound cathepsin G on intact neutrophils has potent angiotensin II-generating activity. Membrane-bound cathepsin G on activated neutrophils 1) converts both human angiotensin I and angiotensinogen to angiotensin II; 2) expresses angiotensin II-generating activity equivalent to 8.6 +/- 2.3 (+/-SD) x 10(-18) mol of free cathepsin G (5.2 +/- 1.4 x 10(6) molecules)/cell; and 3) has similar high affinity for angiotensin I compared with free cathepsin G (Km = 5.9 x 10(-4) and 4.6 x 10(-4) M; k(cat) = 4.0 and 2.0/s, respectively). In marked contrast to soluble cathepsin G, membrane-bound enzyme was substantially resistant to inhibition by plasma proteinase inhibitors and converted angiotensin I to angiotensin II even in undiluted plasma. There was a striking inverse relationship between inhibitor size and its effectiveness against membrane-bound cathepsin G activity. Alpha1-antichymotrypsin was a markedly ineffective inhibitor of membrane-bound enzyme (IC50 = 2.18 microM and 1.38 nM when tested against 1 nM membrane-bound and free cathepsin G, respectively). These data indicate that membrane-bound cathepsin G expressed on neutrophils is an inducible and mobile angiotensin II-generating system that may exert potent local vasoactive and chemoattractant properties at sites of inflammation.

Cytokines regulate membrane-bound leukocyte elastase on neutrophils: a novel mechanism for effector activity

Membrane-bound leukocyte elastase activity on neutrophils may have potent proinflammatory effects. Herein, we report the effects of tumor necrosis factor-alpha (TNF-alpha), platelet-activating factor (PAF), N-formyl-leucyl-methionyl-phenylalanine (fMLP), and interleukin-8 (IL-8) on membrane-bound elastase expression. TNF-alpha or PAF alone induced only approximately two- to threefold increases in membrane-bound elastase but exhibited marked dose- and time-dependent priming effects for subsequent stimulation with fMLP or IL-8 (up to 20-fold increases in membrane-bound human leukocyte elastase compared with unstimulated cells). Optimally PAF-primed and fMLP-stimulated cells expressed 1.105 +/- 0.25 (SD) x 10(-17) mol [6.65 +/- 1.51 (SD) x 10(6) molecules] membrane-bound elastase activity/cell or approximately 12% of the content of unstimulated cells. Elastase binds to the cell surface by a charge-dependent mechanism since 1) incubation of cells with cationic molecules abrogated agonist-induced upregulation of membrane-bound elastase and 2) elastase was progressively eluted from the cell surface by solutions with increasing ionic strength. Thus interactions between proinflammatory mediators strikingly upregulate membrane-bound elastase on neutrophils, which may promote inflammatory responses and/or contribute to tissue injury.

Phosphorylcholine coating of ePTFE grafts reduces neointimal hyperplasia in canine model

This study attempts to prevent neointimal hyperplasia by coating the graft luminal surface with a derivative of phosphorylcholine (PC), thereby providing a biocompatible surface with the assumption of limiting pannus tissue ingrowth from the graft anastomoses. Bilateral carotid artery bypass grafts were placed in six dogs using expanded polytetrafluoroethylene (ePTFE). In each animal, one carotid arterial-arterial conduit was constructed using a graft having a PC coating over the entire luminal surface of the graft. On the contralateral side, uncoated graft served as a control. The processed specimens were analyzed for graft neointimal area and neointimal thickness. Cell proliferation was assessed by staining for bromodeoxyuridine (BrdU) incorporation. All grafts were patent except one control graft that was occluded at 4 weeks. There was a significant reduction in the anastomotic graft neointimal area between the treated and control groups (0.27 +/- 0.17 mm2 versus 0.53 +/- 0.13 mm2, respectively; p = 0.008). Furthermore, the BrdU labeling index in the graft neointimal tissues was significantly smaller (p < 0.001) in the treated group (2.64 +/- 0.77%) as compared with the control group (5.07 +/- 0.83%). These data demonstrate that PC coating of ePTFE significantly reduces graft neointimal hyperplasia and cell proliferation in a canine carotid artery bypass model. The application of PC within the ePTFE graft effectively blocks tissue ingrowth from the adjacent native vessel, thereby preserving the anastomosis luminal diameter.

Quantum proteolysis resulting from release of single granules by human neutrophils: a novel, nonoxidative mechanism of extracellular proteolytic activity

Proteinase inhibitors confine the activity of proteolytic enzymes of inflammatory cells, but fail to protect substrates in the immediate pericellular zone. We report quantitative imaging that demonstrates discrete, evanescent, quantized proteolytic events attributable to the release of single azurophil granules from neutrophils. The images provide information about the dynamics of this nonequilibrium system, which is characterized by overwhelmingly high local concentrations of enzymes that rapidly dissipate. With physiologic concentrations of extracellular human leukocyte elastase inhibitors (32.8 microM), the radii of the unit proteolytic events are 1.32 microm (approximately 8 times the radius of the azurophil granule) and are inversely and nonlinearly related to the concentration of proteinase inhibitor that is present in the bathing medium. We have obtained identical results with alpha1-antitrypsin, alpha2m, recombinant secretory leukocyte proteinase inhibitor, and ICI 200,355, and we have found that phagocyte-derived oxidants are not required for the genesis of this catalytic activity. Our results reveal that the enzyme:inhibitor ratio is the primary delimiter of quantized proteolysis in the local microenvironment.

Quantum proteolysis resulting from release of single granules by human neutrophils: a novel, nonoxidative mechanism of extracellular proteolytic activity

Proteinase inhibitors confine the activity of proteolytic enzymes of inflammatory cells, but fail to protect substrates in the immediate pericellular zone. We report quantitative imaging that demonstrates discrete, evanescent, quantized proteolytic events attributable to the release of single azurophil granules from neutrophils. The images provide information about the dynamics of this nonequilibrium system, which is characterized by overwhelmingly high local concentrations of enzymes that rapidly dissipate. With physiologic concentrations of extracellular human leukocyte elastase inhibitors (32.8 microM), the radii of the unit proteolytic events are 1.32 microm (approximately 8 times the radius of the azurophil granule) and are inversely and nonlinearly related to the concentration of proteinase inhibitor that is present in the bathing medium. We have obtained identical results with alpha1-antitrypsin, alpha2m, recombinant secretory leukocyte proteinase inhibitor, and ICI 200,355, and we have found that phagocyte-derived oxidants are not required for the genesis of this catalytic activity. Our results reveal that the enzyme:inhibitor ratio is the primary delimiter of quantized proteolysis in the local microenvironment.

Inducible binding of bioactive cathepsin G to the cell surface of neutrophils. A novel mechanism for mediating extracellular catalytic activity of cathepsin G

Catalytically active cathepsin G that is bound to the cell surface of human neutrophils may play a variety of roles in normal neutrophil biology and in pathobiology associated with inflammation. In this study, we describe expression of neutrophil cell surface-bound cathepsin G in response to TNF-alpha and platelet-activating factor (PAF) under conditions in which minimal free release of cathepsin G is detected. TNF-alpha and PAF alone induced modest (two- to threefold) increases in cell surface-bound cathepsin G, but exhibited a marked dose- and time-dependent priming effect for subsequent chemoattractant-induced responses (up to 15- to 25-fold increases in cell surface expression). When optimally primed (TNF-alpha, 100 U/ml, or PAF, 10(-9) M), neutrophils expressed five- to sixfold more cell surface-bound cathepsin G, in comparison with cells exposed to FMLP alone. Priming responses were more rapid with PAF (15 s to 5 min) than with TNF-alpha (1 to 60 min). Optimally primed and FMLP-stimulated neutrophils express approximately 160 ng of catalytically active cathepsin G per 10(6) cells, which represents approximately 11% of the cellular content of unstimulated cells. Cathepsin G binds to the cell surface by a charge-dependent mechanism since: 1) incubation of cells with highly positively charged molecules abrogated agonist-induced up-regulation of the cell surface expression of cathepsin G and 2) cathepsin G was eluted from the cell surface by high concentrations of NaCl. These data indicate that interactions between biologically relevant pro-inflammatory cytokines and chemoattractants serve to markedly up-regulate cell surface-bound cathepsin G. The focused catalytic activity of cell surface-bound cathepsin G may alter endothelial and epithelial barriers, promote thrombogenesis, injure extracellular matrix, and/or facilitate directed migration of neutrophils during inflammation.

Inducible binding of bioactive cathepsin G to the cell surface of neutrophils. A novel mechanism for mediating extracellular catalytic activity of cathepsin G

Catalytically active cathepsin G that is bound to the cell surface of human neutrophils may play a variety of roles in normal neutrophil biology and in pathobiology associated with inflammation. In this study, we describe expression of neutrophil cell surface-bound cathepsin G in response to TNF-alpha and platelet-activating factor (PAF) under conditions in which minimal free release of cathepsin G is detected. TNF-alpha and PAF alone induced modest (two- to threefold) increases in cell surface-bound cathepsin G, but exhibited a marked dose- and time-dependent priming effect for subsequent chemoattractant-induced responses (up to 15- to 25-fold increases in cell surface expression). When optimally primed (TNF-alpha, 100 U/ml, or PAF, 10(-9) M), neutrophils expressed five- to sixfold more cell surface-bound cathepsin G, in comparison with cells exposed to FMLP alone. Priming responses were more rapid with PAF (15 s to 5 min) than with TNF-alpha (1 to 60 min). Optimally primed and FMLP-stimulated neutrophils express approximately 160 ng of catalytically active cathepsin G per 10(6) cells, which represents approximately 11% of the cellular content of unstimulated cells. Cathepsin G binds to the cell surface by a charge-dependent mechanism since: 1) incubation of cells with highly positively charged molecules abrogated agonist-induced up-regulation of the cell surface expression of cathepsin G and 2) cathepsin G was eluted from the cell surface by high concentrations of NaCl. These data indicate that interactions between biologically relevant pro-inflammatory cytokines and chemoattractants serve to markedly up-regulate cell surface-bound cathepsin G. The focused catalytic activity of cell surface-bound cathepsin G may alter endothelial and epithelial barriers, promote thrombogenesis, injure extracellular matrix, and/or facilitate directed migration of neutrophils during inflammation.

Nonisotropic enzyme--inhibitor interactions: a novel nonoxidative mechanism for quantum proteolysis by human neutrophils

Traditional theories of enzyme kinetics do not model the influences of rapidly changing and nonisotropic enzyme concentrations in real-world systems. We have modeled local enzyme concentrations in space and time following quantal release of human leukocyte elastase (HLE) from cytoplasmic granules of polymorphonuclear neutrophils (PMN). Calculations from first principles indicate that approximately 67,000 molecules of HLE are stored in each azurophil granule at a mean concentration of 5.33 mM, which exceeds pericellular inhibitor concentrations in vivo by nearly 3 orders of magnitude. Diffusion analysis predicts obligate catalytic activity (excess of local enzyme over inhibitor concentration) that extends to 1.33 microns from the site of granule extrusion (7.8-fold larger than the mean radius of the granule), with a duration of 12.4 ms, when the pericellular concentration of alpha 1-antitrypsin equals that of normal plasma. In contrast, when PMN are bathed in alpha 1-antitrypsin concentrations found in plasma from individuals with alpha 1-antitrypsin deficiency, the radius and duration of obligate catalytic activity are increased 2.5-fold and 6.2-fold, respectively. These simulations agree remarkably well with our recent direct observations and provide a novel, nonoxidative mechanism by which quantum bursts of extracellular proteolytic activity occur despite proteinase inhibitors in the bathing medium. Titration of local enzyme-inhibitor concentration is the dominant determinant of the size and duration of such events. This construct provides new insights into the pathogenesis of tissue injury in alpha 1-antitrypsin deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Neutrophil proteinases and matrix degradation. The cell biology of pericellular proteolysis

Neutrophil proteinases have the capacity to degrade almost every component of the extracellular matrix. In marked contrast to the wealth of available data about the structure and activity of these proteinases when they are free in solution, there has been relatively little information about the mechanisms by which neutrophils use and control their proteolytic enzymes in an extracellular milieu that is replete with proteinase inhibitors. However, recent data have provided insights into several mechanisms that permit these enzymes to evade inhibition: (1) compartmentalization; (2) localized inactivation of proteinase inhibitors; (3) tight binding of enzymes to substrates; and (4) binding of proteinases to the neutrophil's cell surface.

Cell surface-bound elastase and cathepsin G on human neutrophils: a novel, non-oxidative mechanism by which neutrophils focus and preserve catalytic activity of serine proteinases

Serine proteinases of human polymorphonuclear neutrophils play an important role in neutrophil-mediated proteolytic events; however, the non-oxidative mechanisms by which the cells can degrade extracellular matrix in the presence of proteinase inhibitors have not been elucidated. Herein, we provide the first report that human neutrophils express persistently active cell surface-bound human leukocyte elastase and cathepsin G on their cell surface. Unstimulated neutrophils have minimal cell surface expression of these enzymes; however, phorbol ester induces a 30-fold increase. While exposure of neutrophils to chemoattractants (fMLP and C5a) stimulates modest (two- to threefold) increases in cell surface expression of serine proteinases, priming with concentrations of lipopolysaccharide as low as 100 fg/ml leads to striking (up to 10-fold) increase in chemoattractant-induced cell surface expression, even in the presence of serum proteins. LPS-primed and fMLP-stimulated neutrophils have approximately 100 ng of cell surface human leukocyte elastase activity per 10(6) cells. Cell surface-bound human leukocyte elastase is catalytically active, yet is remarkably resistant to inhibition by naturally occurring proteinase inhibitors. These data indicate that binding of serine proteinases to the cell surface focuses and preserves their catalytic activity, even in the presence of proteinase inhibitors. Upregulated expression of persistently active cell surface-bound serine proteinases on activated neutrophils provides a novel mechanism to facilitate their egress from the vasculature, penetration of tissue barriers, and recruitment into sites of inflammation. Dysregulation of the cell surface expression of these enzymes has the potential to cause tissue destruction during inflammation.

Application of enzyme immunoassays for testing haemocompatibility of biomedical polymers

In this study enzyme immunoassays are presented for the assessment of platelet adhesion/activation and fibrinogen adsorption/conformation. The estimation of platelet adhesion and activation was performed with two enzyme immunoassays (EIAs) using monoclonal antibodies directed against CD42b (GP lb) and CD 62 (GMP 140 or P-Selectin). The applicability of EIA was first demonstrated in microtitre plates coated with fibrinogen. The thrombogenic substrate showed that platelet adhesion and activation reached a plateau level within 30 min. The use of EIA for testing biomaterials was demonstrated with polymeric reference materials where a differentiation of materials with respect to adhesion and activation was achieved. To validate the EIA scanning electron microscopy was applied and confirmed the different extent of adhesion and activation of platelets on reference materials. In addition, polyurethaneureas, based on 4,4'-diphenylmethane diisocyanate and polytetramethylene glycols, with different hard segment content and composition were investigated. It was found that both adhesion and activation were not simply dependent on the hard segment content but also on the hard segment composition. To get more insight into the mechanism of this process, two EIAs for the binding of fibrinogen using polyclonal and monoclonal antibodies were developed. There it was shown that the adhesion and activation of platelets on polyurethaneureas was not simply dependent on the total amount of adsorbed fibrinogen but rather on its conformation, indicated by the binding of the monoclonal antibody directed vs the gamma-chain of fibrinogen.

Protein adsorption, lymphocyte adhesion and platelet adhesion/activation on polyurethane ureas is related to hard segment content and composition

Segmented polyurethane ureas with different hard segment content and composition were synthesized using 4,4'-diphenylmethane diisocyanate and polytetramethylene glycols. Using polyols with different molecular weights, it was possible to synthesize polyurethane ureas with either: (i) a constant ratio of urethane to urea bonds; (ii) a constant urethane content; or (iii) a constant urea content. Bulk properties were assessed by dynamic mechanical analysis. Surface properties were estimated by contact angle measurements and streaming potential measurements. Haemocompatibility was evaluated in vitro by measuring the adsorption of human serum albumin (HSA) and fibrinogen (Fg), the adhesion of human peripheral blood lymphocytes (PBL), and the presence of activated platelets on the biomaterial surfaces. Enzyme immuno assays (EIA) have been specially developed for this purpose for the detection of antibody-recognizable plasma proteins and platelet surface membrane proteins. No simple correlation between chemical structure of the polymers and surface properties was found. Parameters of haemocompatibility correlated more closely with hard segment content and chemical composition than with the surface characteristics of the polymers. Adsorption of plasma proteins, adhesion of lymphocytes and the adhesion/activation of platelets were found to increase with increasing hard segment content of the polyurethane ureas. However, the monoclonal-antibody recognisable fibrinogen and the platelet activation were nearly constant with increasing hard segment content, if the urea content was kept constant.

Ability to distinguish whisky (uisge beatha) from brandy (cognac)

OBJECTIVE

To assess ability to distinguish between first rate malt whisky and brandy and between different brands of each.

DESIGN

Crossover with two sessions of 12 blindfold tastings of two whiskies and two brandies before and after supper, repeated not more than seven days later.

SETTING

Dundas, Ontario.

PARTICIPANTS

4 volunteers aged 50-68 years, all moderate drinkers of alcohol and members of a wine club.

MAIN OUTCOME MEASURES

Proportion of samples correctly identified (whisky v brandy) and, of those, the proportion of brands correctly identified.

RESULTS

Only one participant produced irrefutable statistical evidence (P < 0.0001) of being able to distinguish between whisky and brandy, correctly identifying 50/51 (98%) samples. Two participants achieved some success in identification (72%, P = 0.0031 and 65% P = 0.031). The fourth participant's responses reflected pure guesswork. Brandy was no easier to identify than whisky (P = 0.84). The participant who was best able to distinguish between whisky and brandy was also best able to identify correctly the brand of whisky (100%, P < 0.0001).

CONCLUSION

Despite the fact that not all participants completed the full number of tastings the results show that some participants could distinguish neither between malt whisky and brandy nor between different brands of whisky and brandy. However, the success of one participant shows that "it can be done" and that his whisky specific ability is acquired not innate.

Monocytes recruited to sites of inflammation express a distinctive proinflammatory (P) phenotype

Only a minor proportion of monocytes responds to chemoattractants. To test the possibility that chemoattractant-responsive monocytes have distinctive functional characteristics, we enriched or depleted monocyte preparations for cells having a proinflammatory (P) phenotype and tested their responses to biologically relevant chemoattractants. We prepared monocyte subpopulations by one of three independent techniques to minimize the chances of artifacts: 1) depletion of P monocytes by adherence to fibronectin; 2) enrichment for P monocytes by negative selection for HLA-DR antigen; and 3) flow cytometric sorting. We measured responsiveness of monocyte subpopulations to N-formyl-Met-Leu-Phe, C5a, zymosan-activated serum, and monocyte chemoattractant protein-1 by three parameters: 1) polarization, 2) actin polymerization, and 3) directed migration. With each chemoattractant and each parameter, there was a striking direct relationship between the responsiveness of the monocyte preparations and their content of P monocytes. Our data indicate that the capacity of monocytes to be recruited rapidly from the vasculature into sites of inflammation is a property of a subpopulation of monocytes with a distinctive, neutrophil-like proinflammatory phenotype.

A discrete subpopulation of human monocytes expresses a neutrophil-like proinflammatory (P) phenotype

We have demonstrated that a discrete and naturally occurring subpopulation of human monocytes expresses a neutrophil-like proinflammatory (P) phenotype. P monocytes constitute 20-30% of the circulating monocyte pool and are characterized by 1) avid adherence to extracellular matrix through high-level cell-surface expression of alpha 5-, beta 1-, and beta 2-integrins; 2) high capacity to produce reactive oxygen species; 3) high content of serine proteinases and alpha 1-proteinase inhibitor; and 4) proteolytic activity against a soluble peptide human leukocyte elastase substrate, [3H]elastin, and solid-phase fibronectin, even in the presence of proteinase inhibitors. However, P monocytes express little or no cell-surface HLA-DR antigen, suggesting that they are unable to participate in specific immune responses. In contrast, the remainder of circulating monocytes have a low proinflammatory potential but contain the population of monocytes with high-level expression of HLA-DR antigen. P monocytes can readily be separated from the remainder of monocytes on the basis of 1) their capacity to adhere to fibronectin; and 2) their absent expression of HLA-DR antigen when flow cytometry or immunomagnetic beads are used. Our data indicate that, when recruited to sites of inflammation, P monocytes can either promote resolution of inflammation or contribute to tissue injury.

Biocompatible surfaces using methacryloylphosphorylcholine laurylmethacrylate copolymer

Many materials used in the medical device industry were not originally developed for these applications. In general, these materials elicit adverse biologic responses when in contact with body fluids such as blood, and the mechanisms of the response of blood to an artificial surface are well characterized. Protein adsorption, platelet adhesion, and activation of the coagulation pathway can subsequently lead to thrombus formation with grave clinical consequences in the absence of anticoagulant. However, the use of anticoagulants can result in complications. In recent years various approaches for overcoming these problems by improvement of the biocompatibility of materials have been advocated. One approach is that of biomembrane mimicry, whereby the surface of a material is coated with a derivative of phosphorylcholine (PC). PC is the major lipid head group component found in the outer surface of biologic cell membranes. In this paper, the application of PC coatings to a range of materials is discussed together with characterization of the surfaces using in vitro biocompatibility tests. Studies of fibrinogen and platelet binding have shown significant reductions in adsorption of these components to various PC coated materials relative to uncoated controls. Materials tested, amongst others, include PVC, polyethylene, polycarbonate, and nylon. The stability of the PC coatings has been studied using radiolabeled derivatives. Results using several materials show that physiadsorbed PC coatings are extremely stable, thus making the coatings suitable for use in a wide variety of medical applications. Extensive biologic evaluations to assess the toxicologic profile of PC derivatives and coated devices have also been carried out and in all tests the materials have been shown to be nontoxic, thus making them suitable for human use. Ex vivo animal and human studies performed support the in vitro data.

The proteinase-antiproteinase balance in alpha-1-proteinase inhibitor-deficient lung transplant recipients

We examined the proteinase-antiproteinase balance in the bronchoalveolar lavage (BAL) fluid from alpha-1-proteinase inhibitor (alpha 1PI)-deficient lung transplant recipients to determine whether they would derive benefit from intravenous augmentation therapy with alpha 1PI. BAL fluid from 11 alpha 1PI-deficient lung transplant recipients and eight control subjects was assayed for free neutrophil elastase activity, immunoreactive alpha 1PI, and elastase inhibitory capacity. Samples were obtained during intervals of health and respiratory illness. BAL fluid from healthy alpha 1PI-deficient lung transplant recipients had minimal or unmeasurable free elastase activity, which was not different from that of control subjects. alpha 1PI concentrations in BAL fluid from alpha 1PI-deficient lung transplant recipients were reduced when compared with those of control subjects. Despite this observation, all but one alpha 1PI-deficient patient had the ability to inhibit exogenous elastase. During respiratory illness, however, three of seven alpha 1PI-deficient lung transplant recipients had measurable free elastase activity, which was inhibited ex vivo by addition of alpha 1PI. We conclude that alpha 1PI-deficient lung transplant recipients demonstrate free elastase activity in BAL fluid during severe lower respiratory tract inflammation, which is not present during health. Intravenous supplementation of alpha 1PI-deficient lung transplant recipients with exogenous alpha 1PI during respiratory tract inflammation may be indicated to inhibit elastase-mediated injury to the transplanted lung.

Factors contributing to dyspnoea during bronchoconstriction and exercise in asthmatic subjects

The purpose of the present study was to identify: 1) whether dyspnoea during bronchoconstriction and exercise is related, in asthmatic subjects; and 2) to what extent baseline pulmonary function and respiratory muscle strength contribute to dyspnoea under both conditions. One hundred and seventy five consecutive subjects, referred with suspected asthma, rated the intensity of dyspnoea (Borg scale 0-10): 1) during the administration of doubling concentrations of methacholine to 32 mg.ml-1 methacholine, or until the baseline forced expiratory volume in one second (FEV1) was reduced by 20%; and 2) during incremental cycle ergometry (100 kpm.min-1 each minute) to maximal capacity. 138/175 subjects achieved a 20% reduction in their baseline FEV1; 18 of the 138 were excluded, 2 children and 16 with complicating pulmonary disorders (diffusing capacity of the lung for carbon monoxide (DLCO) and/or total lung capacity (TLC) < 70% predicted). The remaining 120 out of 175 constituted the study population. Dyspnoea following a 20% reduction in the baseline FEV1 (Dys20%) was linearly interpolated, using the rating of dyspnoea and the FEV1 at the two final concentrations of methacholine. In the 120 asthmatic subjects, the mean intensity of dyspnoea was "moderate" (2.9, SD 1.91; Borg 0-10) and the intensity across subjects was not significantly related to baseline FEV1, vital capacity (VC), FEV1/VC, DLCO, TLC and maximal static inspiratory pressure (MIP), alone or in combination.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors contributing to dyspnoea during bronchoconstriction and exercise in asthmatic subjects

The purpose of the present study was to identify: 1) whether dyspnoea during bronchoconstriction and exercise is related, in asthmatic subjects; and 2) to what extent baseline pulmonary function and respiratory muscle strength contribute to dyspnoea under both conditions. One hundred and seventy five consecutive subjects, referred with suspected asthma, rated the intensity of dyspnoea (Borg scale 0-10): 1) during the administration of doubling concentrations of methacholine to 32 mg.ml-1 methacholine, or until the baseline forced expiratory volume in one second (FEV1) was reduced by 20%; and 2) during incremental cycle ergometry (100 kpm.min-1 each minute) to maximal capacity. 138/175 subjects achieved a 20% reduction in their baseline FEV1; 18 of the 138 were excluded, 2 children and 16 with complicating pulmonary disorders (diffusing capacity of the lung for carbon monoxide (DLCO) and/or total lung capacity (TLC) < 70% predicted). The remaining 120 out of 175 constituted the study population. Dyspnoea following a 20% reduction in the baseline FEV1 (Dys20%) was linearly interpolated, using the rating of dyspnoea and the FEV1 at the two final concentrations of methacholine. In the 120 asthmatic subjects, the mean intensity of dyspnoea was "moderate" (2.9, SD 1.91; Borg 0-10) and the intensity across subjects was not significantly related to baseline FEV1, vital capacity (VC), FEV1/VC, DLCO, TLC and maximal static inspiratory pressure (MIP), alone or in combination.(ABSTRACT TRUNCATED AT 250 WORDS)

Metalloproteinases and tissue inhibitor of metalloproteinases in mesothelial cells. Cellular differentiation influences expression

Mesothelial cells play a critical role in the remodeling process that follows serosal injury. Although mesothelial cells are known to synthesize a variety of extracellular matrix components including types I, III, and IV collagens, their potential to participate in matrix degradation has not been explored. We now report that human pleural and peritoneal mesothelial cells express interstitial collagenase, 72- and 92-kD gelatinases (type IV collagenases), and the counterregulatory tissue inhibitor of metalloproteinases (TIMP). Our initial characterization of the mesothelial cell metalloenzymes and TIMP has revealed: (a) they are likely identical to corresponding molecules secreted by other human cells; (b) they are secreted rather than stored in an intracellular pool; (c) a primary site of regulation occurs at a pretranslational level; (d) phorbol myristate acetate, via activation of protein kinase C, upregulates expression of collagenase, 92-kD gelatinase, and TIMP, but has no effect on expression of 72-kD gelatinase; and (e) lipopolysaccharide fails to upregulate the biosynthesis of either metalloproteinases or TIMP. Of particular interest is the observation that the state of cellular differentiation has a striking influence on the expression of metalloenzymes and TIMP, such that epitheloid cells display a more matrix-degradative phenotype (increased 92-kD gelatinase and decreased TIMP) than their fibroblastoid counterparts. We speculate that mesothelial cells directly participate in the extracellular matrix turnover that follows serosal injury via elaboration of metalloproteinases and TIMP. Additionally, the reactive cuboidal mesothelium which is characteristic of the early response to serosal injury may manifest a matrix-degenerative phenotype favoring normal repair rather than fibrosis.

Exercise capacity and ventilatory, circulatory, and symptom limitation in patients with chronic airflow limitation

Dyspnea, leg effort (Borg 0 to 10 scale), ventilation, and heart rate (VEmax/VEcap; HRmax/HRcap expressed as a percentage of capacity) were measured at maximal exercise (cycle ergometer) in 97 patients with chronic airflow limitation (CAL) (FEV, 46.6 +/- 14.23% of predicted) and compared with 320 matched control subjects. Patients with CAL achieved a maximum power output of 86 +/- 39.5 W (60 +/- 23.2% of predicted) compared with 140 +/- 37.5 W (98 +/- 14.5% of predicted) in controls (p less than 0.0001), VEmax/VEcap was 72 +/- 19.3% compared with 53 +/- 18.6% (p less than 0.0001), and HRmax/HRcap was 76 +/- 13.5% compared with 82 +/- 13% (p less than 0.001). These findings were expected. The median intensity of dyspnea was 6 (severe to very severe) and leg effort was 7 (very severe) in both groups, and these findings were unexpected. The patients with CAL were handicapped by an increase in both dyspnea and peripheral muscular effort relative to the actual power output. The rating of dyspnea exceeded leg effort in 25 (26%) of CAL versus 69 (22%) control subjects: the rating of leg effort exceeded dyspnea in 42 (43%) CAL and 117 (36%) control subjects; both were rated equally in 30 (31%) CAL and 134 (42%) control subjects, respectively (NS). VEmax/VEcap and HRmax/HRcap were not significantly different in those limited by dyspnea, leg fatigue, or a combination of both. All values are expressed +/- SD.

Mechanical properties of suture materials in vitro and after in vivo implantation in horses

Tensile testing of reproducible loops of size 5 braided polyester, size 2 polyglycolic acid, size 2 monofilament nylon, and size 2 polydioxanone sutures was performed in vitro and after subcutaneous implantation in horses for 7, 14, and 28 days. Maximum breaking strength, energy absorption, and percentage elongation to breakage point were measured. Size 5 braided polyester had the highest maximum breaking strength and energy absorption over 28 days. Polydioxanone had better mechanical performance over 28 days than did polyglycolic acid. On day 28, none of these parameters was measurable in polyglycolic acid. Monofilament nylon had the lowest breaking strength of the three materials tested on day 28.

Dyspnea and leg effort during incremental cycle ergometry

The aim of this study was to establish the perceived magnitude of dyspnea (discomfort associated with breathing) and leg effort experienced by normal subjects during a standardized incremental exercise test to maximal capacity; 460 normal subjects (297 male and 163 female 20 to 70 yr of age) were studied. The perceptual magnitude of both symptoms was rated using simple descriptive phrases (slight, moderate, maximal) tagged to numbers from zero to 10 on the Borg scale, which is an interval scale with ratio properties. Leg effort and dyspnea increased with power output, were higher in women than in men (p less than 0.0001), increased with advancing age (p less than 0.0001), and declined as height increased (p less than 0.0001). Leg effort = 4.82 + 0.007 kpm/min + 1.05 sex + 0.04 age - 0.055 Ht (r = 0.78; SD, 1.80). Dyspnea = 4.96 + 0.006 kpm/min + 0.96 sex + 0.04 age - 0.05 Ht (r = 0.74; SD, 1.80) (m = 1; f = 2). With power output expressed as a percentage of maximal power output (%MPO) both symptoms increased in an alinear manner. Effort = 0.0014 * %MPO1.86 (r = 0.86; SD, 1.50). Dyspnea = 0.0016 * %MPO1.79 (r = 0.81; SD, 1.57). Sex, age, or stature did not contribute to the rating of effort or dyspnea when power output was normalized in this way.

Monocyte adherence to fibronectin: role of CD11/CD18 integrins and relationship to other monocyte functions

Adherence of monocytes to extracellular matrix components is critical for their accumulation at sites of infection. To gain insight into the factors that regulate monocyte recruitment, we have studied monocyte adherence with regard to the regulatory effects of bacterial lipopolysaccharide (LPS) and the mechanisms involved; moreover, we have contrasted the phenotypes of adherent and nonadherent cells. Our results show that only a minor subpopulation of monocytes (20-25%) adhere spontaneously to fibronectin and that LPS stimulated a threefold increase in the proportion of adherent cells. Basal adherence and LPS-stimulated adherence of monocytes to fibronectin were substantially mediated by CD11/CD18 integrins. Further studies revealed that spontaneously adherent monocytes were 14-fold more actively phagocytic, released 1.6-fold more superoxide anion, and contained 20-fold more peroxidase activity than nonadherent cells, whereas LPS-adherent cells had an intermediate phenotype. These results indicate that LPS may enhance the accumulation of monocytes with an antimicrobial phenotype and thereby promote resolution of tissue infection.