Biomedical subjects

H B Hechtman

Publications and source records attributed to H B Hechtman.

At least 19 recordsLinked to original sources

PubMed1992

Soluble complement receptor type 1 ameliorates the local and remote organ injury after intestinal ischemia-reperfusion in the rat.

We examined the role of C activation in ischemia reperfusion injury by inhibiting C activation in a rat model of mesenteric arterial occlusion. In anesthetized rats, 60 min of mesenteric arterial occlusion was followed by 3 h of reperfusion. PBS alone or containing soluble C receptor 1 (3 or 6 mg) was administered i.v. Controls underwent laparotomy without ischemia. Relative serum C activities were assessed by hemolytic assay, neutrophil (polymorphonuclear leukocyte) sequestration by tissue content of myeloperoxidase (MPO) activity, intestinal mucosal injury by histologic grading, lung vascular permeability by the ratio of bronchoalveolar lavage to blood concentration of radiolabeled BSA, and endothelial cell injury was quantified by measurement of plasma factor VIII-related Ag. After reperfusion, PBS-treated animals had increased intestinal MPO (0.048 +/- 0.007 U/g) compared to sham (0.022 +/- 0.005 U/g (p less than 0.05)) and intestinal mucosal injury score (2.490 +/- 0.221) compared to sham (0.331 +/- 0.045 (p less than 0.05)). Treatment with 6 mg soluble C receptor 1 15 min before reperfusion reduced intestinal MPO (0.017 +/- 0.003 U/g (p less than 0.05)) and mucosal injury (1.733 +/- 0.168 (p less than 0.05)) compared to PBS control. PBS-treated animals also demonstrated increased lung MPO (0.314 +/- 0.025 U/g vs 0.085 +/- 0.018 in sham (p less than 0.05)) and increased lung permeability (bronchoalveolar lavage/blood cpm 11.32 +/- 1.35 x 10(-3) vs sham 2.22 +/- 0.19 x 10(-3) (p less than 0.05)). Treatment with 6 mg soluble C receptor 1 15 min before reperfusion or at reperfusion reduced the lung permeability (bronchoalveolar lavage/blood cpm 3.90 +/- 0.79 x 10(-3) and 5.08 +/- 0.75, respectively (both p less than 0.05)) compared to PBS control, but did not reduce lung MPO (0.342 +/- 0.031 U/g and 0.246 +/- 0.025), respectively. Treatment with sCR1 also reduced the release of factor VIII-related Ag, 5-day mortality, and C hemolytic activity. In this model, C is a major mediator of intestinal injury and extraintestinal injury.

Animals↗

PubMed1992

Adherent neutrophils mediate permeability after atelectasis.

Re-expansion of atelectatic lung is associated with increased permeability. This study tests whether neutrophils mediate this event. Right middle lobar atelectasis was induced in anesthesized rabbits (n = 18) by intraluminal obstruction of the bronchus after a 20-minute ventilation with 100% O2. After 1 hour of bronchial obstruction and 20 minutes after lobar re-expansion, leukopenia was noted, 2870 +/- 210 white blood cells (WBC)/mm3, relative to control animals treated with a noninflated balloon catheter, 6500 +/- 410 WBC/mm3 (p less than 0.05). Three hours after re-expansion, neutrophils were sequestered in the previously atelectatic region 78 +/- 7 polymorphonuclear leukocytes (PMN)/10 high-power field (HPF), as well as in nonatelectatic areas, 40 +/- 3 PMN/10 HPF, higher than control values of 26 +/- 3 PMN/10 HPF (p less than 0.05). In the atelectatic region, neutrophil sequestration was associated with increased protein concentration in lobar bronchoalveolar lavage (BAL) of 1370 +/- 100 micrograms/mL, higher than control values of 270 +/- 20 micrograms/mL (p less than 0.05). Reexpansion also induced increases in lung wet-to-dry weight ratio (W/d) of 6.2 +/- 0.2, higher than control values of 4.3 +/- 0.1 (p less than 0.05). Rendering rabbits neutropenic (n = 18) (0 to 4 PMN/mm3) limited the atelectasis-induced protein accumulations in BAL (520 +/- 60 micrograms/mL) and increase in lung W/d (5.2 +/- 0.1) (both p less than 0.05). Intravenous (I.V.; treatment of another group (n = 18) with an anti-CD 18 monoclonal antibody (R 15.7, 1 mg/kg) before balloon deflation prevented leukopenia (6550 +/- 560 WBC/mm3), minimized neutrophil sequestration (36 +/- 2 PMN/10 HPF), and attenuated protein leak (710 +/- 95 micrograms/mL) and the increased lung W/d (5.6 +/- 0.1) (all p less than 0.05). A final atelectatic group (n = 9) was treated I.V. with the anti-intercellular adhesion molecule-1 monoclonal antibody (RR 1/1, 1 mg/kg), which also prevented leukopenia and showed similar protection of microvascular barrier function. These data indicate that adherent neutrophils in large part mediate lung permeability and edema after atelectasis and re-expansion. Adhesion receptors of both neutrophils and endothelial cells regulate this event.

Animals↗

PubMed1992

Blockade of complement activation prevents local and pulmonary albumin leak after lower torso ischemia-reperfusion.

Lower torso ischemia and reperfusion leads to both local and remote tissue injuries. The purpose of this study was to assess the role of complement in mediating the local and remote microvascular permeability after bilateral hind limb tourniquet ischemia. Four hours of ischemia and 4 hours of reperfusion produced an increased skeletal muscle permeability index (muscle/blood 125I albumin ratio) of 2.90 +/- 0.35 compared with the index in nonischemic muscle of 0.25 +/- 0.02 (p < 0.01). Muscle wet-to-dry-weight ratio increased from 3.93 +/- 0.04 in sham to 5.55 +/- 0.09 in ischemic muscle (p < 0.0001). Lung permeability rose at 4 hours as indicated by the increased bronchoalveolar lavage (BAL)/blood 125I albumin ratio 4.36 +/- 0.41 x 10(-3) versus sham 2.64 +/- 0.28 x 10(-3) (p < 0.05) and neutrophil sequestration 0.28 +/- 0.02 U/g myeloperoxidase (MPO) versus sham 0.14 +/- 0.02 U/g (p < 0.001). Serum lytic activity of the classical but not the alternate complement pathway was reduced. The soluble complement receptor (sCR1) was used to inhibit complement activity and attenuated the increase in the permeability index after reperfusion in ischemic muscle 1.11 +/- 0.08 (p < 0.01) and reduced the lung BAL/blood 125I albumin ratio to sham levels 2.46 +/- 0.39 x 10(-3) (p < 0.05) at 6 mg/animal, without reducing the lung neutrophil sequestration, 0.24 +/- 0.02 U/g. The authors conclude that complement activation occurred during tourniquet ischemia and mediated permeability changes in the ischemic muscle and the lungs during reperfusion.

Albumins↗

PubMed1992

Reactive oxygen species and elastase mediate lung permeability after acid aspiration.

Acid aspiration leads to increased neutrophil (PMN) oxidative metabolism, an event associated with lung leukosequestration and permeability increase. Neutropenia protected the vascular barrier function against acid injury. This study tests whether active oxygen species and elastase (which are presumably released by adherent PMNs) affect the microvascular barrier. Anesthetized rats underwent tracheostomy and insertion of a cannula into a lung segment. This was followed by localized instillation of 0.1 N HCl (n = 18) or saline (n = 18). Sequestration of PMNs in acid-aspirated and nonaspirated segments was 77 and 46 PMNs/high-power field (HPF), respectively, which was higher than control values of 11 and 8 PMNs/10 HPF in saline-aspirated and nonaspirated regions (P less than 0.05). Acid aspiration was associated with increased protein concentration in bronchoalveolar lavage (BAL) fluid to 3,550 and 2,900 micrograms/ml in the aspirated and nonaspirated lungs, respectively, which were higher than control values of 420 and 400 micrograms/ml (P less than 0.05). Acid aspiration also led to increased lung wet-to-dry weight ratios (W/D) of 6.6 and 5.4, which were higher than control values of 3.4 and 3.3 (P less than 0.05). Intravenous treatment of rats (n = 18) 90 min after aspiration with scavengers of reactive oxygen species, superoxide dismutase (1,500 U/kg), and catalase (5,000 U/kg), both conjugated to polyethylene glycol, did not reduce PMN sequestration but attenuated acid aspiration-induced increase in protein accumulation in BAL fluid in the aspirated and nonaspirated segments (990 and 610 micrograms/ml) as well as the increased lung W/D (4.6 and 4.0; all P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Role of neutrophil adherence receptors (CD 18) in lung permeability following lower torso ischemia.

Ischemia and reperfusion of the lower torso lead to leukotriene- and neutrophil (PMN)-dependent lung injury characterized by lung PMN sequestration, increased permeability, and noncardiogenic edema. It is thought that PMNs require adhesion to endothelium to alter barrier function. This study tests the role of CD 18, the PMN adherence receptor, in mediating lung permeability after lower torso ischemia and reperfusion. Anesthetized rabbits (n = 9) underwent 3 hours of bilateral hind limb ischemia. Ten minutes after the release of the tourniquets, plasma leukotriene B4 levels increased to 395 +/- 85 pg/ml, higher than 129 +/- 35 pg/ml in controls (n = 9, p less than 0.01). At this time there was a reduction in circulating white blood cells (x 10(3)), 3.56 +/- 0.49/mm3 relative to 6.07 +/- 0.61/mm3 in controls (p less than 0.01). PMNs were sequestered in the hind limbs, indicated by increased myeloperoxidase activity of 1.06 +/- 0.19 units/g compared with 0.56 +/- 0.09 units/g in controls (p less than 0.05). Four hours after tourniquet release, PMNs were sequestered in the lungs, 52 +/- 4 PMNs per 10 high-power fields, a value higher than 31.5 +/- 3 PMNs per 10 high-power fields in controls; bronchoalveolar lavage fluid protein content increased to 554 +/- 90 micrograms/ml relative to 277 +/- 46 micrograms/ml in controls; and there was lung edema, measured by increased wet weight-to-dry weight ratios of 5.19 +/- 0.10, higher than 4.29 +/- 0.21 in controls (all p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Synergism between leukotriene B4 and thromboxane A2 in mediating acid-aspiration injury.

Acid aspiration leads to thromboxane-dependent lung neutrophil sequestration associated with microvascular permeability increase. Leukotriene B4 (LTB4) is postulated to be a cofactor in the thromboxane-induced inflammatory response. This study tests the interaction between LTB4 and thromboxane, focusing on LTB4 induction of thromboxane-dependent lung neutrophil sequestration after acid aspiration. Anesthetized rats underwent tracheostomy and insertion of a cannula in a left lung segment. This was followed by instillation of either 0.1 ml 0.1N hydrochloric acid (n = 18) or 0.1 ml saline in control rats (n = 18). When assayed at 3 hours, acid aspiration led to increased plasma levels of LTB4 and thromboxane B2 (TxB2), higher than control values (p less than 0.05). The rise in plasma LTB4 was correlated (p less than 0.05; r = 0.83) with sequestration of neutrophils in the nonaspirated lung. The entrapment of thromboxane-dependent lung neutrophil was associated with an increase in protein concentration in bronchoalveolar lavage of the aspirated and nonaspirated sides and an increase in lung wet to dry weight ratio. Pretreatment of other rats (n = 18) with the lipoxygenase inhibitor diethylcarbamazine IV prevented an aspiration-induced rise in plasma LTB4 and TxB2. Further, there was an attenuation of lung leukosequestration and protein leak in bronchoalveolar lavage and lung edema (all p less than 0.05). Pretreatment of other rats (n = 12) with the leukotriene receptor antagonist FPL 55712 IV did not prevent the aspiration-induced rise in LTB4 or TxB2, but otherwise was as effective as diethylcarbamazine in preventing injury. Finally, other hydrochloric acid-aspirated rats (n = 8) were pretreated intravenously with the thromboxane synthetase inhibitor OKY 046 or the thromboxane receptor antagonist SQ 29548. Both agents limited the aspiration-induced rise in plasma LTB4 (p less than 0.05). The data indicate that localized acid aspiration induces synthesis of LTB4 and thromboxane A2. Inhibition of either leukotriene or thromboxane will limit PMN adhesion and increased lung permeability.

Animals↗

PubMed1992

Oxygen free radicals are required for ischemia-induced leukotriene B4 synthesis and diapedesis.

Hind limb ischemia and reperfusion have been shown to result in high plasma levels of leukotriene B4 (LTB4) and polymorphonuclear neutrophil (PMN) sequestration in the pulmonary microvasculature. This study tests whether LTB4 is derived from PMNs and its role in mediating ischemic plasma-induced diapedesis. Plasma derived from rabbit hind limbs after 3 hours of tourniquet ischemia and 10 minutes of reperfusion (n = 6) showed an increased LTB4 level of 560 pg/ml, higher than sham plasma values of 106 pg/ml (p less than 0.05). Introduction of ischemic plasma in abraded skin chambers placed on the dorsum of normal rabbits (n = 6) led after 3 hours to PMN diapedesis of 1175 PMN/mm3, associated with a further increase in LTB4 levels to 820 pg/ml (both p less than 0.05). In contrast, ischemic plasma derived from neutropenic animals (n = 4; nitrogen mustard, 2 mg/kg; PMNs less than 30/mm3) contained lower levels of LTB4, 160 pg/ml (p less than 0.05). When introduced in skin chambers in normal rabbits (n = 4), this plasma induced accumulations of only 163 PMN/mm3, accompanied by a smaller increase in LTB4 levels in the blister fluid after 3 hours, 397 pg/ml (both p less than 0.05). A correlation was found between LTB4 levels in ischemic plasma and PMN accumulations in blister fluid (r = 0.92; p less than 0.05). Intravenous pretreatment of rabbits (n = 4) used in the blister chamber bioassay with the LT receptor antagonist FPL-55712, 40 micrograms/kg/hr, attenuated diapedesis induced by ischemic and ischemic-neutropenic plasma, 103 and 35 PMN/mm3, respectively (both p less than 0.05). Pretreatment with superoxide dismutase, 1500 units/kg, and catalase, 5000 units/kg, both conjugated to polyethylene glycol (n = 4), prevented ischemic plasma-induced LTB4 synthesis, as well as ischemic plasma-induced diapedesis, 12 PMN/mm3 (p less than 0.05). Finally, pretreatment with allopurinol, 25 mg/kg, was similarly effective in preventing LTB4 synthesis and PMN migration. These data suggest that oxygen free radicals are essential for ischemia-induced PMN synthesis of LTB4 that in turn mediates their diapedesis.

Allopurinol↗

PubMed1992

Mast cells and leukotrienes mediate neutrophil sequestration and lung edema after remote ischemia in rodents.

Reperfusion of ischemic hindlimbs leads to leukotriene B4 (LTB4) and polymorphonuclear neutrophil (PMN)-dependent lung injury. Pulmonary mast cells are capable of synthesizing LTB4 and are potential mediators of this inflammatory response. This study tests their role in PMN sequestration and pulmonary edema after hindlimb ischemia. Anesthetized, mast cell-sufficient mice (n = 8) or their congeneic mast cell-deficient strain (n = 8) were subjected to 3 hours of hindlimb ischemia. After another 3 hours of reperfusion, plasma LTB4 levels rose to 651 pg/ml, higher than sham ischemic control (n = 8) values of 202 pg/ml (p less than 0.05). At this time there was sequestration of neutrophils in the pulmonary microcirculation (54 PMN/10 high-power fields [HPF]) and an increase in lung wet/dry weight ratio (W/D) of 4.4. Both these values were higher (p less than 0.05) than those in sham ischemic animals that showed sequestration of 18 PMN/10 HPF and a lung W/D of 3.1. In contrast, mast cell-deficient mice showed an attenuation of ischemia- and reperfusion-induced rise in plasma LTB4 (507 pg/ml), fewer sequestered neutrophils (34 PMNs/10 HPF), and a reduction in lung W/D to 3.9 (all p less than 0.05). To test the role of lung LTB4 in determining PMN sequestration, rats (n = 78) were subjected to 3 hours of hindlimb ischemia. After 3 hours of reperfusion, plasma and bronchoalveolar lavage (BAL) LTB4 concentrations rose to 956 and 211 pg/ml, respectively--higher than sham values of 460 and 121 pg/ml (both p less than 0.05). After 4 hours, plasma LTB4 levels had returned to baseline, whereas BAL LTB4 had increased further to 658 pg/ml, indicating lung origin. Treatment of other rats by localized lung lavage of the lipoxygenase inhibitor diethylcarbamazine (80 mg/kg in 0.1 ml twice) prevented the ischemia- and reperfusion-induced rise in BAL LTB4 (267 pg/ml) and limited local neutrophil sequestration (from 51 PMN/10 HPF after saline aspiration to 36 PMN/10 HPF) and lung W/D (from 4.5 to 4.1) (all p less than 0.05). The data indicate that after hindlimb ischemia pulmonary mast cells and localized LTB4 synthesis mediate, in part, the lung inflammatory response.

Animals↗

PubMed1992

A Mac-1 antibody reduces liver and lung injury but not neutrophil sequestration after intestinal ischemia-reperfusion.

BACKGROUND: Intestinal ischemia and reperfusion (I/R) result in leukosequestration and injury to the liver and lungs. The adherence-dependent oxidative burst of neutrophils requires cell adhesion through the Mac-1 integrin. Neutrophil-mediated tissue injury may depend on this specific cell adhesion event. This study tests the effect of a Mac-1 (CD 11b) monoclonal antibody (MAb) (R17) on liver and lung injury after intestinal I/R. METHODS: After collaterals were ligated in anesthetized rats, the superior mesenteric artery was clamped for 60 minutes followed by 3 hours of reperfusion. Animals were treated with saline solution, R17, or nonspecific immunoglobulin M. Another nonischemic group of rats were sham controls. Lung and intestinal polymorphonuclear leukocyte sequestration was assessed by measurement of myeloperoxidase and lung permeability by bronchoalveolar lavage blood concentration ratio of 125I-labeled bovine serum albumin. RESULTS: At 3 hours of reperfusion lung and intestinal myeloperoxidase and lung permeability were increased. Treatment with R17 MAb did not reduce intestinal or lung myeloperoxidase but prevented increased lung permeability. Similarly, after treatment with saline solution, liver polymorphonuclear leukocyte sequestration increased after 3 hours of reperfusion, and serum alanine aminotransferase level rose eightfold. R17 MAb did not significantly reduce liver neutrophil sequestration; however, it reduced alanine aminotransferase level more than 50% when compared to saline solution controls. At 3 hours of reperfusion there was a leukocytosis (white blood cell count, 14.9 +/- 1.0 x 10(3)/mm3 vs 6.0 +/- 0.8 in sham [p less than 0.05]). The white blood cell count was unaffected by R17 MAb. CONCLUSIONS: These data indicate that a MAb to the neutrophil Mac-1 integrin reduces lung and liver injury after intestinal I/R but does not reduce lung or intestinal leukosequestration.

Animals↗

PubMed1991

Pathophysiology of ischaemia reperfusion injury: central role of the neutrophil.

Ischaemia is a common clinical event leading to local and remote injury. Evidence indicates that tissue damage is largely caused by activated neutrophils which accumulate when the tissue is reperfused. If the area of ischaemic tissue is large, neutrophils also sequester in the lungs, inducing non-cardiogenic pulmonary oedema. Ischaemia reperfusion injury is initiated by production of reactive oxygen species which initially appear responsible for the generation of chemotactic activity for neutrophils. Later, once adherent to endothelium, neutrophils mediate damage by secretion of additional reactive oxygen species as well as proteolytic enzymes, in particular elastase. Therapeutic options for limiting ischaemia reperfusion injury include inhibition of oxygen radical formation, pharmacological prevention of neutrophil activation and chemotaxis, and also the use of monoclonal antibodies which prevent neutrophil-endothelial adhesion, a prerequisite for injury.

Arachidonic Acids↗

PubMed1991

Microvascular endothelial-derived autacoids regulate pericyte contractility.

A silicone rubber assay is used in conjunction with morphometric measurements to characterize in vitro the contractile properties of retinal pericytes in response to endothelial secreted factors. Factor(s) present in conditioned media derived from pulmonary and retinal microvascular endothelial cells and pulmonary artery endothelial cells promote pericyte contractions. Using a radioimmunoassay significant levels of endothelin immunoreactivity are measured in conditioned media obtained from all three cell lines. Thrombin treatment enhanced endothelin-like secretions by pulmonary microvascular endothelial cells, but significantly reduced levels of endothelin-like immunoreactivity secreted by retinal microvascular endothelial cells. Synthetic endothelin and thromboxane A2 (TxA2) stimulate pericyte contractions, whereas prostaglandin I2 (PGI2) promotes pericyte relaxation. Thrombin and angiotension II (ang II) have no effect on pericyte contractility. However, using cocultures of pericytes and endothelial cells we observe endothelial-dependent pericyte contractions in response to thrombin and ang II. Thrombin and ang II stimulate the release of endothelial-derived contracting factors, with characteristics similar to endothelin. These data suggest microvascular endothelial cell-pericyte interactions may regulate, at least in part, microvessel contractility.

Angiotensin II↗

PubMed1991

Thromboxane-induced neutrophil adhesion to pulmonary microvascular and aortic endothelium is regulated by CD18.

Thromboxane (Tx) A2 generation and subsequent selective pulmonary sequestration of neutrophils (PMNs) is characteristic of several forms of the adult respiratory distress syndrome (ARDS). Therefore, we examined PMN-dependent adhesion to cultured pulmonary microvessel and aortic endothelium (EC) in response to U46,619 (Tx mimic). Nonstimulated PMNs were two fold more adherent to pulmonary microvessel EC than to aortic EC (P less than 0.01). PMN pretreatment with Tx mimic (10(-6) M) increased adhesion to both types of EC (P less than 0.01). The Tx mimic-induced adhesion was blocked by receptor antagonists to Tx (SQ29,548) and to leukotrienes (FPL55,712), and by the anti-CD18 mAb TS1/18 (P less than 0.01, all cases). Baseline PMN adhesion also was modulated by Tx, leukotrienes, and CD18, for both EC types. These results indicate pulmonary microvessel EC is intrinsically more adhesive for both nonstimulated and stimulated PMNs than aortic EC and that Tx mediates PMN-dependent adhesion by coupled interaction of Tx and LT receptors via CD18 activation.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed1991

Mercury-arc photolysis: a method for examining second messenger regulation of endothelial cell monolayer integrity.

Cell-cell apposition in bovine pulmonary endothelial cell monolayers was modulated by inducing transient increases in intracellular adenosine 3':5'-cyclic monophosphate (cAMP) and 1,4,5-inositol triphosphate (IP3). This was accomplished by mercury-arc flash photolysis of o-nitrobenzyl derivatives of the second messengers (caged compounds). Second messenger release by the mercury-arc lamp was determined by radioimmunoassay of cAMP to have a t1/2 of approximately 8 min. Each second messenger induced the phosphorylation of a distinct subset of cytoskeletal proteins; however, both IP3 and cAMP increased vimentin phosphorylation. Actin isoform patterns were not altered by the second messengers. Intracellular pulses of IP3 in pulmonary endothelial cells caused disruption of endothelial monolayer integrity as determined by phase-contrast microscopy and by visualization of actin stress fibers with rhodamine-phalloidin. Intracellular pulses of cAMP increased cell-cell contact, cell surface area, and apposition. IP3 appeared to have its greatest effect on the actin peripheral band. In silicone rubber contractility assays this agent caused contraction of pulmonary microvascular endothelial cells as visualized by an increase in wrinkles beneath the cells. On the other hand, cAMP appeared to effect both the peripheral band and centralized actin domains. Caged cAMP caused relaxation of endothelial cells as visualized by a disappearance of wrinkles beneath the cells.

Animals↗

PubMed1991

Thromboxane A2 induces leukotriene B4 synthesis that in turn mediates neutrophil diapedesis via CD 18 activation.

Previous studies have indicated that thromboxane (Tx) and leukotriene (LT) B4 act synergistically to induce neutrophil (PMN) adhesion in the microvasculature. This study explores the ability of Tx to induce LTB4 synthesis, which then leads to activation of PMN and endothelial adhesion receptors. Tx-mimic (U46619, 1 microgram/ml) was administered into abraded skin chambers placed on the backs of rabbits (n = 6). After 3 hr LTB4 was synthesized in the blister fluid at 385 pg/ml, a value higher than levels in saline-treated blisters, 10 pg/ml (P less than 0.05). The LTB4 generation following Tx-mimic was correlated (P less than 0.05, r = 0.70) with neutrophil diapedesis. These averaged 645 PMN/mm3, values higher than saline values of 20 PMN/mm3 (P less than 0.05). Intravenous (iv) treatment of other rabbits (n = 4) with the lipoxygenase inhibitor diethylcarbamazine at 60 mg/kg, followed by 40 mg/kg/hr, prevented Tx-mimic-induced LTB4 synthesis (10 pg/ml) and diapedesis (19 PMN/mm3) (both P less than 0.05). Intravenous treatment of yet other rabbits (n = 4) with the anti-CD 18 monoclonal antibody R 15.7 at 1 mg/kg abolished Tx-induced diapedesis (3 PMN/mm3) (P less than 0.05). In contrast, local administration of 3 ng of the protein synthesis inhibitor actinomycin D, to prevent expression of endothelial adhesion proteins, limited TNF- but not Tx-induced diapedesis. The data indicate that Tx-induced diapedesis is mediated by the generation of LTB4 and the activation of neutrophil CD 18 but not endothelial adhesion proteins.

Animals↗

PubMed1991

Organ and species specific differences in cytoskeletal protein profiles of cultured microvascular endothelial cells.

1. Using two-dimensional gel electrophoresis and immunoblotting techniques we systematically document the structural diversity of cytoskeletal proteins in tight and leaky cultured microvascular endothelial cells (MEC). Bovine pulmonary and eel rete mirabile MEC primarily express cytokeratins 8 and 19. Cytokeratins 8 and 18 were found to be prominent in rat pulmonary MEC. Bovine retinal MEC contained cytokeratins 8, 18 and 19. Bovine adrenal MEC contain vimentin as their sole intermediate filament protein. 2. Four principal actin isoforms were resolved in micro/macrovascular endothelial cells as well as in vascular smooth muscle cells. Retinal pericytes expressed three principal actin isoforms. 3. These results indicate that MEC are diverse, highly differentiated cells displaying a large repertoire of cytoskeletal protein profiles suited for specific tissue functions.

Actins↗

PubMed1991

Interleukin-2 induces early multisystem organ edema mediated by neutrophils.

Interleukin-2 (IL-2), an agent known to activate neutrophils (PMN) with thromboxane (Tx)B2 release, produces pulmonary edema within 6 hours of intravenous infusion. This study tests the role of PMN in mediating the edema. Anesthetized rats received 10(6)U recombinant human IL-2 (n = 15) or vehicle (n = 14) as a constant intravenous infusion during a period of 1 hour. At this time there was leukopenia 3.63 +/- 0.43 (x10(3)/mm3) relative to vehicle-infused control rats 6.12 +/- 0.86 and a decline in PMN, 2.19 +/- 0.14 relative to control value of 3.33 +/- 0.05 (both p less than 0.05). After 6 hours edema, as measured by increase in the wet to dry weight (W/d) ratio, was present in the lungs (4.93 +/- 0.20 relative to control 4.06 +/- 0.10), heart (4.09 +/- 0.11 versus 3.76 +/- 0.08), liver (3.50 +/- 0.10 versus 3.18 +/- 0.10), and kidney (4.25 +/- 0.07 versus 4.00 +/- 0.07) (all p less than 0.05). There was increased lung permeability demonstrated by bronchoalveolar lavage fluid protein concentration of 1970 +/- 210 micrograms/mL relative to control 460 +/- 90 micrograms/mL (p less than 0.05). Interleukin-2 resulted in lung PMN sequestration of 53 +/- 7 PMN/10 high-power fields (HPF) relative to 23 +/- 2 PMN/10 HPF in controls (p less than 0.05) and increased plasma TxB2 levels to 1290 +/- 245 pg/mL relative to control 481 +/- 93 pg/mL (p less than 0.05). Pretreatment of other rats (n = 8) with selective anti-rat neutrophil antiserum 18 hours before the experiment led to a peripheral PMN count 10% of baseline and prevented edema in the lungs (W/d ratio 4.20 +/- 0.16) and heart (3.67 +/- 0.07) (both p less than 0.05) but not liver or kidney. Protein in lung lavage was reduced to 760 +/- 220 micrograms/mL (p less than 0.05). The protection afforded by leukopenia was associated with lack of PMN sequestration and prevention of the increase in plasma Tx levels (484 +/- 120 pg/mL, p less than 0.05). These data indicate that the rapid induction of lung and heart edema with a 1-hour infusion of IL-2 in the rat is mediated, in large part, by activated PMNs.

Animals↗

PubMed1991

Intravascular chemoattractants inhibit diapedesis by selective receptor occupancy.

An extravascular chemoattractant leads to migration of polymorphonuclear neutrophils (PMN) to that site, whereas intravascular administration leads to PMN oxidative activity and sequestration in microvessels but no diapedesis. This study examines the inhibitory role of intravascular chemoattractants. Rabbits (n = 37) were pretreated with zymosan-activated plasma (ZAP), leukotriene (LT) B4, or thromboxane (Tx) mimic. These agents were given intra-arterially, topically into plastic chambers taped atop sites of dermabrasion on the back, or into a lobar bronchus (n = 35). Intra-arterial injection of each chemoattractant resulted, 10 min later, in a 29-42% increase in intracellular PMN H2O2. In saline-infused animals, topical administration of the chemoattractants into dermabrasion chambers resulted in PMN accumulation per cubic millimeter after 3 h of 600 with ZAP, 536 with LTB4, and 643 with Tx mimic; all values higher than 46 with saline and 63 with normal plasma (all P less than 0.05). In other saline-infused animals, lobar lung aspiration of chemoattractants led to diapedesis as measured in bronchoalveolar lavage (BAL) fluid (PMN x 10(4)/ml) after 3 h: 19.0 with ZAP, 11.2 with LTB4 and 14.5 with Tx mimic, all greater than aspiration with saline or normal plasma 4.0 and 4.9, respectively (all P less than 0.05). Intra-arterial chemotactic administration inhibited subsequent PMN diapedesis in response to that same chemoattractant, both in dermabrasion chambers and in BAL fluid. When different intra- and extra-vascular chemoattractants were used diapedesis was promoted. Thus Tx infused intra-arterially and ZAP applied to a blister or lobar bronchus led to rapid cell migration and increased cell numbers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Neutrophil elastase and oxygen radicals: synergism in lung injury after hindlimb ischemia.

Hindlimb ischemia and reperfusion lead to lung injury dependent on activated polymorphonuclear neutrophils (PMN) adherence. This study tests whether elastase and oxygen radicals participate in PMN-induced injury once they have become sequestered in lungs. Anesthetized rats treated with saline (n = 9) or the specific elastase inhibitor methoxysuccinyl-L-Ala-L-Ala-L-Pro-L-Val-chloromethylketone (MAAPV, n = 6) underwent 4 h of bilateral hindlimb tourniquet ischemia followed by 4 h of reperfusion. At this time, in saline-treated rats, PMN were sequestered in lungs as assayed by myeloperoxidase activity [(MPO) 51 +/- 5 U/g tissue], higher than MPO in saline-treated sham rats (n = 9; 18 +/- 3 U/g MPO; P less than 0.01); bronchoalveolar lavage (BAL) fluid leukotriene (LT) B4 levels increased to 594 +/- 46 relative to 200 +/- 38 pg/ml in shams (P less than 0.01); increased permeability was documented by BAL fluid protein content of 599 +/- 91 compared with 214 +/- 35 micrograms/ml in sham animals (P less than 0.01); and edema was shown by increase in lung wet-to-dry weight ratio of 4.77 +/- 0.14 relative to 4.00 +/- 0.09 in sham rats (P less than 0.01). In MAAPV-treated animals, lung neutrophil sequestration (62 +/- 9 U/g MPO) and rise of LTB4 in BAL fluid (780 +/- 244 pg/ml) were not affected, but both BAL fluid protein (335 +/- 32 micrograms/ml) and lung wet-to-dry weight ratio (4.21 +/- 0.17) were reduced (both P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗