Effect of cyclooxygenase blockade on gas exchange and hemodynamics in Pseudomonas pneumonia

Acute bilateral Pseudomonas aeruginosa pneumonia was induced in 10 anesthetized dogs, after which five dogs received intravenous indomethacin (2 mg/kg) (indomethacin group), whereas five others were infused with saline (2 ml/kg) (control group). Plasma levels of 6-ketoprostaglandin F1 alpha(6-keto-PGF1 alpha) and thromboxane B2 (TxB2), stable metabolites of prostacyclin (PGI2) and thromboxane A2 (TxA2), respectively, were measured by radioimmunoassay. Although TxB2 levels were not different before and after inoculation in either group, 6-keto-PGF1 alpha levels increased from their base-line value in each animal as pneumonia developed (indomethacin group: less than 100 to 330 +/- 90 pg/ml; control group: less than 100 to 630 +/- 300 pg/ml). Both prostaglandins fell to less than 100 pg/ml in each dog after indomethacin infusion, whereas they remained elevated in the control group after infusion of normal saline. Perfusion of consolidated lung regions (Qp/QT), measured with radioactive microspheres and expressed as a percent of total pulmonary blood flow, was dramatically reduced after indomethacin (35 +/- 3 to 16 +/- 1%) with consequent improvement in pulmonary shunt (Qs/QT: 30 +/- 8 to 18 +/- 6%) and arterial O2 tension (PaO2: 123 +/- 25 to 274 +/- 77 Torr). These parameters remained unchanged or deteriorated further in the control group after infusion of saline. Three additional dogs with Pseudomonas pneumonia were studied in which the indomethacin-induced reduction in Qp/QT was substantially but not completely reversed by intravenous infusion of PGI2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of ozone on lung mechanics and cyclooxygenase metabolites in dogs.

To determine if acute exposure to ozone can cause changes in the production of cyclooxygenase metabolites of arachidonic acid (AA) in the lung which are associated with changes in lung mechanics, we exposed mongrel dogs to 0.5 ppm ozone for two hours. We measured pulmonary resistance (RL) and dynamic compliance (Cdyn) and obtained methacholine dose response curves and bronchoalveolar lavagate (BAL) before and after the exposures. We calculated the provocative dose of methacholine necessary to increase RL 50% (PD50) and analyzed the BAL for four cyclooxygenase metabolites of AA: a stable hydrolysis product of prostacyclin, 6-keto-prostaglandin F1 alpha (6-keto-PgF1 alpha); prostaglandin E2 (PgE2); a stable hydrolysis product of thromboxane A2, thromboxane B2 (TxB2); and prostaglandin F2 alpha (PgF2 alpha). Following ozone exposure, RL increased from 4.75 +/- 1.06 to 6.08 +/- 1.3 cm H2O/L/sec (SEM) (p less than 0.05), Cdyn decreased from 0.0348 +/- 0.0109 TO .0217 +/- .0101 L/cm H2O (p less than 0.05), and PD50 decreased from 4.32 +/- 2.41 to 0.81 +/- 0.49 mg/cc (p less than 0.05). The baseline metabolite levels were as follows: 6-keto PgF1 alpha: 96.1 +/- 28.8 pg/ml; PgE2: 395.8 +/- 67.1 pg/ml; TxB2: 48.5 +/- 11.1 pg/ml; PgF2 alpha: 101.5 +/- 22.6 pg/ml. Ozone had no effect on any of these prostanoids. These studies quantify the magnitude of cyclooxygenase products of AA metabolism in BAL from dog lungs and demonstrate that changes in their levels are not prerequisites for ozone-induced changes in lung mechanics or airway reactivity.     

Relationship of leukotriene C4 and D4 to hypoxic pulmonary vasoconstriction in dogs

Leukotrienes C4 and D4 have been implicated as possible mediators of hypoxic pulmonary vasoconstriction. To test this hypothesis, the relationship between pulmonary leukotriene (LT) synthesis in response to hypoxia and alterations in pulmonary hemodynamics was evaluated in pentobarbital sodium-anesthetized, neuromuscular-blocked, male, mongrel dogs. A reduction in the fraction of inspired O2 (FIO2) in vehicle-treated animals (n = 12) from 0.21 to 0.10 was associated with increases in LTC4 and LTD4 in bronchoalveolar lavage fluid (BALF). After 30 min of continuous hypoxia, LTC4 and LTD4 increased from control values of 59.4 +/- 10.4 and 91.7 +/- 18.1 ng/lavage to 142.7 +/- 31.8 (P less than 0.05) and 156.3 +/- 25.3 (P less than 0.01) ng/lavage, respectively. Concomitantly, mean pulmonary arterial pressure (Ppa) and pulmonary vascular resistance (PVR) were increased over control by 67 +/- 7 (P less than 0.001) and 62 +/- 7% (P less than 0.001), respectively. In contrast, in animals treated with diethylcarbamazine (n = 5), a leukotriene A4 synthase inhibitor, identical reductions in FIO2 were not associated with increases in LTC4 and LTD4 in BALF, although at the same time period, Ppa and PVR were increased over control by 60 +/- 13 (P less than 0.05) and 112 +/- 31% (P less than 0.05), respectively. These results, therefore, do not support the contention that leukotrienes mediate hypoxic pulmonary vasoconstriction in dogs.     

Effects of ozone on cyclooxygenase metabolites in the baboon tracheobronchial tree

Short-term exposure to 0.5 parts per million (ppm) ozone has been shown to cause an increase in respiratory resistance in primates that can be diminished by 50% with pretreatment with cromolyn sodium. Because of the known membrane-stabilizing effects of cromolyn and the resultant inhibition of mediator production, we hypothesized a role for the products of arachidonic acid (AA) metabolism in these events. We exposed five adult male baboons to 0.5 ppm ozone on two occasions, once with cromolyn pretreatment and once without. Pulmonary resistance (RL) was monitored and bronchoalveolar lavage (BAL) was performed before and after each exposure. The BAL was analyzed for a stable hydrolysis product of prostacyclin, 6-keto-prostaglandin (PG) F1 alpha, PGE2, a stable hydrolysis product of thromboxane (Tx) A2, TxB2, and PGF2 alpha. RL increased after ozone exposure (1.62 +/- 0.23 to 3.77 +/- 0.51 cmH2O.l-1.s, difference 2.15; P less than 0.02), and this effect was partially blocked by cromolyn (1.93 +/- 0.09 to 3.18 +/- 0.40 cmH2O.l-1.s, difference 1.25; P less than 0.02). The base-line levels of the metabolites of AA in the BAL were as follows (in pg/ml): 6-keto-PGF1 alpha 72.78 +/- 12.6, PGE2 145.92 +/- 30.52, TxB2 52.52 +/- 9.56, and PGF2 alpha 22.28 +/- 5.42. Ozone exposure had no effect on the level of any of these prostanoids (P = NS). These studies quantify the magnitude of cyclooxygenase products of AA metabolism in BAL from baboon lungs and demonstrate that changes in the levels of these mediators in BAL are not prerequisites for ozone-induced increases in respiratory resistance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Thromboxane contributes to the immediate antigenic response of canine peripheral airways

The actions of specific humoral mediators in the immediate response of the canine peripheral airways to antigen challenge are not well understood. Using a method which allows localized exposure of the peripheral lung to antigen, we investigated the role of locally released thromboxane A2 (TxA2) in the immediate response of collateral airways to aerosolized antigen. In dogs with native sensitivity to Ascaris suum antigen, resistance to flow through the collateral system (Rcs) was measured using a wedged bronchoscope technique. Local administration of antigen aerosol (25 microliters, 1:10,000 dilution) produced a gradual increase in Rcs which reached a maximum of 365% of base line in 4-8 min. Analysis of bronchoalveolar lavage fluid obtained from the exposed segment at the peak of the response demonstrated significantly more TxB2 compared with control lavage samples (41.8 +/- 7.8 pg/ml vs. 27.9 +/- 8.3; P less than 0.025). After inhibition of thromboxane synthase with UK-37,248 (3 mg/kg iv) or OKY-046 (5 mg/kg iv), the increase in Rcs was significantly reduced at 40 s (P less than 0.001) and 2 min (P less than 0.01) after antigen delivery, and the maximal increase was attenuated by 41% (P less than 0.005). In contrast, the magnitude and time course of the airway response to aerosols of a stable thromboxane analog (U-46619) were not affected by blockade. Despite a similar attenuation (42%) of the maximal increase in Rcs by sodium meclofenamate (3 mg/kg iv), this cyclooxygenase inhibitor had no effect on the time course of the antigenic response.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increased leukotriene B4 in bronchoalveolar lavage fluid and plasma of endotoxemic pigs

We hypothesized that leukotriene B4 (LTB4) might be produced during endotoxin-induced acute respiratory failure (ARF) observed in young pigs. We used radioimmunoassay (RIA) and reverse phase-high performance liquid chromatography (RP-HPLC) to determine the presence of LTB4 in plasma and bronchoalveolar lavage fluid (BALF) of saline- and endotoxin-treated pigs. Endotoxin was infused at 5 micrograms/kg for 1 hour (hr) followed by 2 micrograms/kg/hr for an average of 3 hrs. Arterial plasma (collected at 0.5 hr intervals for 4 hrs) immunoreactive (i)-LTB4 was significantly increased from 2.5 to 4 hrs of endotoxemia with the peak value occurring at 3.5 hrs (i.e. 282% of baseline value). Analysis of plasma extracts using RP-HPLC revealed an ultraviolet (UV) absorbance peak (270 nm) that was coincident with authentic LTB4 standard. The levels of i-LTB4 were significantly increased in BALF recovered from endotoxemic pigs (337 +/- 71 vs 53 +/- 13 pg/ml for saline controls). Endotoxin also increased the postmortem wet/dry ratio of bloodless lung and BALF albumin concentration, indicating pulmonary edema and increased permeability of the alveolar-capillary membrane, respectively. We conclude that LTB4 is increased in plasma and BALF recovered from endotoxemic pigs and that this lipoxygenase metabolite could possibly be an important factor contributing to the pathophysiology of endotoxin-induced ARF.     

Uteroplacental production of eicosanoids in ovine pregnancy

Dramatic cardiovascular alterations occur during normal ovine pregnancy which may be associated with increased prostaglandin production, especially of uteroplacental origin. To study this, we examined (Exp 1) the relationships between cardiovascular alterations, e.g., the rise in uterine blood flow and fall in systemic vascular resistance, and arterial concentrations of prostaglandin metabolites (PGEM, PGFM and 6-keto-PGF1 alpha) in nonpregnant (n = 4) and pregnant (n = 8) ewes. To determine the potential utero-placental contribution of these eicosanoids in pregnancy, we also studied (Exp 2) the relationship between uterine blood flow and the uterine venous-arterial concentration differences of PGE2, PGF2 alpha, PGFM, 6-keto-PGF1 alpha, and TxB2 in twelve additional late pregnant ewes. Pregnancy was associated with a 37-fold increase in uterine blood flow and a proportionate (27-fold) fall in uterine vascular resistance (p less than 0.01). Arterial concentrations of PGEM were similar in nonpregnant and pregnant ewes (316 +/- 19 and 245 +/- 38 pg/ml), while levels of PGFM and PGI2 metabolite 6-keto-PGF1 alpha were elevated 23-fold (31 +/- 14 to 708 +/- 244 pg/ml) and 14-fold (12 +/- 4 to 163 +/- 78 pg/ml), respectively (p less than 0.01). Higher uterine venous versus uterine arterial concentrations were observed for PGE2 (397 +/- 36 and 293 +/- 22 pg/ml) and 6-keto-PGF1 alpha (269 +/- 32 and 204 +/- 32 pg/ml), p less than 0.05, but not PGF2 alpha or TxB2. Although PGFM concentrations appeared to be greater in uterine venous (1197 +/- 225 pg/ml) as compared to uterine arterial (738 +/- 150 pg/ml) plasma, this did not reach significance (0.05 less than p less than 0.1). In normal ovine pregnancy arterial levels of PGI2 are increased, which may in part reflect increased uteroplacental production. Moreover the gravid ovine uterus also appears to produce PGE2 and metabolize PGF2 alpha.     

Hydroxyeicosatetraenoic acids are increased in bronchoalveolar lavage fluid of endotoxemic pigs

We hypothesized that lipoxygenase metabolites of arachidonic acid might be produced during endotoxin-induced acute respiratory failure (ARF) observed in young pigs. We used radioimmunoassay (RIA) to determine the presence of 5-hydroxyeicosatetraenoic acid (5-HETE), 12-HETE, and 15-HETE in bronchoalveolar lavage fluid (BALF) of saline (n = 12)- and endotoxin (n = 18)-treated pigs. Endotoxin, infused at 5 micrograms/kg for 1 hr followed by 2 micrograms/kg/hr for an average of 3 hrs, caused pulmonary hypertension, a biphasic increase in pulmonary vascular resistance, hypoxemia, bronchoconstriction, leukopenia, and thrombocytopenia. Relative to saline controls, the levels of immunoreactive (i)-5-HETE (816 +/- 209 pg/ml), i-12-HETE (1589 +/- 517 pg/ml), and i-15-HETE (448 +/- 78 pg/ml) were significantly (P less than 0.05) increased in BALF recovered from endotoxemic pigs at postmortem. Relative to control BALF i-HETE concentrations, the endotoxin values were 3.5x, 5.1x, and 2.8x higher for i-5-HETE, i-12-HETE, and i-15-HETE, respectively. We conclude that during porcine endotoxemia, the 5-, 12-, and 15-lipoxygenase pathways are activated and that HETES might be involved in the pathophysiology of endotoxin-induced ARF.     

Differential effects of various vasoactive drugs on basal and stimulated levels of TXB2 and 6-keto-PGF1 alpha in rat brain

Thromboxane B2 and 6-keto-PGF1 alpha (6KPGF1 alpha), the major stable metabolites of thromboxane and prostacyclin, are present in the CNS, where they appear to be mainly produced within and/or acting upon the vascular district. Their concentrations are of few pg/mg protein in rat brain cortex of animals sacrificed by microwave (MW) radiation, procedure which inactivates tissue enzymes and allows the determination of endogenous "basal" levels of eicosanoids. Levels of 6KPGF1 alpha and especially those of TxB2 increase several fold over the basal values in brain cortex of animals sacrificed by decapitation followed by a few minute interval before analysis (post-decapitation ischemia, PDI). Pretreatment of animals with the vasoactive drug papaverine, resulted in elevation of brain basal levels of 6KPGF1 alpha and with the carbochromene derivative AD6 in reduction of basal levels of TxB2, whereas the calcium antagonist nifedipine and dipyridamole did not modify basal levels of the two eicosanoids. Treatments with papaverine and AD6 reduced the accumulation of TxB2 and enhanced that of 6KPGF1 alpha occurring after PDI, to different extents, both resulting, however, in reduction of the TxB2/6KPGF1 alpha ratio. Nifedipine instead, decreased the release of both eicosanoids and resulted in elevation of the TxB2/6KPGF1 alpha ratio, whereas dipyridamole had no effect. In conclusion, the evaluation of the overall effects of drug treatments on the TxB2/6KPGF1 alpha ratio in cerebral tissue, provided useful informations on the pharmacological modulation of vascular eicosanoids in this district.     

Inhalation of an endothelin receptor A antagonist attenuates pulmonary inflammation in experimental acute lung injury

We recently demonstrated that inhalation of the endothelin receptor A (ETA) antagonist LU 135252 improved arterial oxygenation and reduced pulmonary artery pressure in experimental acute lung injury (ALI). In this study we analyzed potential immune modulatory effects of inhaled LU 135252 in experimental ALI. ALI was induced by repeated lung lavage in intubated (100% O2) and anesthetized piglets. Animals were randomly assigned to inhale either nebulized LU 135252 (0.3 mg.kg-1, ALI + LU group, n = 8) or saline buffer (ALI control group, n = 16), both for 30 min. Surviving animals were sacrificed 6 h after induction of ALI, and lung tissue specimens were obtained from all animals for histology and immunhistochemistry. Induction of ALI significantly decreased arterial oxygenation in all animals. Inhalation of LU 135252 significantly reduced mortality and induced significant and sustained increase in Pao2 (316 +/- 47 mm Hg vs. control 53 +/- 3 mm Hg, p < 0.001). We measured a significant reduction in the number of pulmonary leukocyte L1 antigen-positive cells in ALI + LU animals (8% +/- 1% positive cells vs. control 12% +/- 2% positive cells, p < 0.05). The number of CD3-positive cells was not altered by treatment with LU 135252. Pulmonary tissue concentration of IL-6 was significantly suppressed by LU 135252 inhalation (4 +/- 1 pg.100 mg-1 wet weight vs. control 7 +/- 1 pg.100 mg-1 wet weight, p < 0.05). Concentrations of TNF-alpha, IL-1beta, and ET-1 in pulmonary tissue were not influenced by inhalation of LU 135252. In conclusion, we demonstrated that inhalation of LU 135252 not only improves mortality and gas exchange, but also blunts the local immune response in experimental ALI.     

Chlorpropamide-ethanol induced met-enkephalin secretion in dogs: release mechanisms and biochemical characterisation

Circulating met-enkephalin-like immunoreactivity (MLI) rises in man after chlorpropamide and ethanol although the origin and molecular forms of circulating MLI are not well defined. We have studied the response to oral ethanol in conscious and anaesthetised dogs pretreated with chlorpropamide. In conscious dogs MLI rose from a basal level of 29 +/- 7 pg/ml to a peak of 55 +/- 14 pg/ml 10 min after ethanol (P less than 0.001). In anaesthetised animals, following ethanol, plasma MLI rose in caval (35 +/- 6 pg/ml to a peak of 70 +/- 10 pg/ml), in portal (28 +/- 6 pg/ml to 51 +/- 6 pg/ml) and in adrenal blood (897 +/- 316 pg/ml to 1483 +/- 298 pg/ml; P less than 0.001). Biogel P-4 chromatography of caval and portal basal plasma showed 87% of MLI measured coeluted with the synthetic pentapeptide, while chromatography of peak plasma showed that only 65% coeluted with the pentapeptide and the remaining 35% was of larger molecular size. Sephadex G75 chromatography of adrenal vein plasma revealed three peaks of MLI of differing molecular sizes (8 k = 69.7%; 3-5 k = 12.1% and the pentapeptide = 18.2%). Treatment of the column fractions with trypsin and carboxypeptidase B resulted in the generation of new MLI with peaks of approximate molecular sizes 31 k (10.4%), and 18 k (37.1%) in addition to 8 k (40.0%), 3-5 k (5.0%) and the pentapeptide (7.5%). Acetaldehyde involvement in MLI release was investigated. Following acetaldehyde infusion, plasma MLI rose both in caval (35 +/- 9 pg/ml to 86 +/- 8 pg/ml) and adrenal vein (417 +/- 121 pg/ml to 1768 +/- 433 pg/ml) bloods. Thus we have established an animal model which enables further study of the mechanisms of MLI release and characterisation of the molecular forms. The adrenal medulla, unlike the gut, may be an important source of circulating met-enkephalin and acetaldehyde formation an essential intrinsic component of chlorpropamide-ethanol induced met-enkephalin release.     

Trypanosomiasis-induced infertility in dromedary (Camelus dromedarius) bulls: changes in plasma steroids concentration and semen characteristics

The effect of Trypanosomiasis on concentrations of plasma steroids and semen characteristics was studied in 24 dromedary bulls. Based upon the parasitological and serological diagnosis, 18 bulls were found infected with Trypanosoma evansi (Group 2) and six were found to be free from infection and served as controls (Group 1). The infected animals exhibited signs of anaemia indicated by the decrease of packed cell volume (PCV) and haemoglobin concentration (Hb), pale mucus membranes, weight loss, lethargy, weakness and dullness. However, five animals (27.8%) of the infected group revealed elevated rectal temperatures and three animals (16.7%) revealed testicular degeneration upon palpation of their scrotal contents. Concentrations of plasma oestradiol-17beta (86.5 +/- 8.6 pg/ml versus 232.5 +/- 74.4 pg/ml) and testosterone (4.8 +/- 0.7 ng/ml versus 2.7 +/- 1.5 ng/ml) were significantly different (P < 0.05) between the control and infected bulls. Evaluation of the semen collected by electroejaculation and evaluated by a computerized cell motion analyzer revealed normal semen characteristics in the control animals compared to deteriorated ones in the infected bulls. There were highly significant (P < 0.01) decreases in sperm count (12.2 +/- 1.3/ml versus 6.5 +/- 4.9 x 10(6)/ml), motility percentage (68.2 +/- 6.7% versus 27.4 +/-15.6%), percentage of live spermatozoa (73.2 +/- 8.3% versus 35.8 +/- 8.2%) and increases in percentage of morphological abnormalities (3.3 +/- 0.6% versus 15.9 +/- 1.0%) in the infected group. An examination of the plasma hormonal profiles and semen characteristics in the infected bulls indicated that altered Sertoli cell function due to formation of immune complexes in four bulls (Group 2A), pituitary dysfunction in six bulls (Group 2B), testicular degeneration in three bulls (Group 2C) and finally trypanotolerancy in five bulls (Group 2D) are possible factors responsible for poor semen characteristics and infertility induced by T. evansi infection in dromedary bulls.     

Enhanced microvascular permeability of PMA-induced acute lung injury is not mediated by cyclooxygenase products.

Products of cyclooxygenase activity have been proposed to mediate the pulmonary hypertension and increased microvascular permeability associated with phorbol myristate acetate- (PMA) induced acute lung injury. Previously, we reported that thromboxane (Tx) does not mediate PMA-induced pulmonary hypertension in intact anesthetized dogs. In the present study, PMA was administered to isolated canine lungs perfused with autologous blood at constant flow to investigate a possible role for Tx in the PMA-induced increase in microvascular permeability. Changes in permeability were assessed by determining changes in the capillary filtration coefficient (Kfc). In lobes pretreated with papaverine to prevent PMA-induced increases in pulmonary vascular resistance, Kfc increased from a baseline value of 0.2 +/- 0.03 to 1.5 +/- 0.29 ml.min-1.cmH2O-1.100 g wet lobe wt-1 (P < 0.01) 30 min after PMA (5.8 x 10(-8) M, n = 10). Concomitantly, TxB2, the stable metabolite of TxA2, increased from 138 +/- 44 to 1,498 +/- 505 pg/ml (P < 0.05) in the blood. Both the selective Tx synthase inhibitor, OKY-046 (7 x 10(-4) M, n = 6), and the cyclooxygenase inhibitor, indomethacin (10(-4) M, n = 7), prevented the PMA-induced increase in TxB2, but neither compound attenuated the PMA-induced increase in Kfc. ONO-3708 (10(-6) M), a selective prostaglandin (PG) H2/TxA2 receptor antagonist, prevented the vasoconstriction resulting from administration of U-46619, a stable PGH2/TxA2 receptor agonist, but it did not prevent the PMA-induced increases in Kfc (n = 6).(ABSTRACT TRUNCATED AT 250 WORDS)     

Systemic and pulmonary oxidative stress in idiopathic pulmonary fibrosis.

An oxidant/antioxidant imbalance has been proposed in patients with idiopathic pulmonary fibrosis (IPF). We tested this hypothesis by measuring various parameters of the oxidant/antioxidant balance in the plasma of 12 patients with IPF (7 nonsmokers and 5 smokers); in the bronchoalveolar lavage fluid (BALF) of 24 patients with IPF (17 nonsmokers and 7 smokers) and 31 healthy subjects (23 nonsmokers and 8 smokers). The trolox equivalent antioxidant capacity (TEAC) in plasma and BALF was lower in nonsmoking patients with IPF (plasma 0.55+/-0.1 mM, p<.001; BALF 4.8+/-1.2 microM, mean +/-SEM, p<.01), compared with healthy nonsmokers (plasma 1.33+/-0.03 mM; BALF 10+/-2 microM). Similar trends in plasma and BALF TEAC were observed in smoking patients with IPF in comparison with healthy smokers. The decrease in BALF TEAC was concomitant with a decrease in BALF protein thiol levels, but the decrease TEAC levels in plasma in IPF patients was not accompanied by a decrease in protein thiol levels. Reduced glutathione (GSH) was lower in BALF in nonsmoking patients with IPF (1.0+/-0.1 microM) compared with healthy nonsmokers (2.3+/-0.2 microM, p<.001). In contrast, GSH levels were higher in smoking patients with IPF (5.2+/-1.1 microM, p<.001) than in nonsmoking patients. GSSG levels were not different in any of the groups. The levels of products of lipid peroxidation measured as thiobarbituric acid reactive substances (TBARS) in plasma and BALF were significantly increased in both smoking (plasma 2.2+/-0.5 microM, p<.01; BALF 0.18+/-0.04 microM, p<.001), and nonsmoking (plasma 2.1+/-0.3 microM, p<.01; BALF 0.22+/-0.05 microM, p<.001) IPF patients, compared with healthy nonsmokers (plasma 1.4+/-0.3 microM; BALF 0.05+/-0.004 microM). These data show evidence of oxidant/antioxidant imbalance in the lungs of patients with IPF, which is also reflected as systemic oxidant stress.     

Endotoxin tolerance is associated with altered GTP-binding protein function.

Previous studies have suggested that guanine nucleotide regulatory (G) proteins modulate endotoxin-stimulated peritoneal macrophage arachidonic acid (AA) metabolism. Endotoxin-stimulated metabolism of AA by peritoneal macrophages is decreased in endotoxin tolerance (Rogers et al. Prostaglandins 31: 639-650, 1986). These observations led to a study of G protein function and AA metabolism by peritoneal macrophages in endotoxin tolerance. Endotoxin tolerance was induced by the administration of sublethal doses of endotoxin. AA metabolism was assessed by measurement of thromboxane B2 (TxB2), a cyclooxygenase metabolite. NaF (5 mM), an activator of G proteins, significantly stimulated TxB2 synthesis in control macrophages from 7.7 +/- 0.2 to 19.1 +/- 0.6 (SE) ng/ml (P less than 0.05) at 2 h and was partially inhibited by pertussis toxin, suggesting a G protein-dependent mechanism. Salmonella enteritidis endotoxin (50 micrograms/ml) stimulated a similar increase in TxB2 levels (23 +/- 0.4 ng/ml, P less than 0.05). In contrast to control macrophages, macrophages from endotoxin-tolerant rats stimulated with either NaF or S. enteritidis endotoxin had TxB2 levels that were only 30 and 2% of the respective stimulated control cells. Basal guanosine-triphosphatase (GTPase) activity (33 +/- 6 pmol.mg-1.min-1) in endotoxin-tolerant macrophage membranes was significantly lower (P less than 0.05) than control basal activity (158 +/- 5 pmol.mg-1.min-1). This suppression of macrophage GTPase activity was apparent 48 h after the first in vivo sublethal endotoxin injection (100 micrograms/kg ip). The reduced GTPase activity paralleled in vitro cellular hyporesponsiveness to endotoxin-stimulated TxB2 production.(ABSTRACT TRUNCATED AT 250 WORDS)     

Adrenomedullin ameliorates lipopolysaccharide-induced acute lung injury in rats

Adrenomedullin (AM), an endogenous peptide, has been shown to have a variety of protective effects on the cardiovascular system. However, the effect of AM on acute lung injury remains unknown. Accordingly, we investigated whether AM infusion ameliorates lipopolysaccharide (LPS)-induced acute lung injury in rats. Rats were randomized to receive continuous intravenous infusion of AM (0.1 microg x kg(-1) x min(-1)) or vehicle through a microosmotic pump. The animals were intratracheally injected with either LPS (1 mg/kg) or saline. At 6 and 18 h after intratracheal instillation, we performed histological examination and bronchoalveolar lavage and assessed the lung wet/dry weight ratio as an index of acute lung injury. Then we measured the numbers of total cells and neutrophils and the levels of tumor necrosis factor (TNF)-alpha and cytokine-induced neutrophil chemoattractant (CINC) in bronchoalveolar lavage fluid (BALF). In addition, we evaluated BALF total protein and albumin levels as indexes of lung permeability. LPS instillation caused severe acute lung injury, as indicated by the histological findings and the lung wet/dry weight ratio. However, AM infusion attenuated these LPS-induced abnormalities. AM decreased the numbers of total cells and neutrophils and the levels of TNF-alpha and CINC in BALF. AM also reduced BALF total protein and albumin levels. In addition, AM significantly suppressed apoptosis of alveolar wall cells as indicated by cleaved caspase-3 staining. In conclusion, continuous infusion of AM ameliorated LPS-induced acute lung injury in rats. This beneficial effect of AM on acute lung injury may be mediated by inhibition of inflammation, hyperpermeability, and alveolar wall cell apoptosis.     

Experimental hypergastrinaemia in the dog.

In order to investigate chronic hypergastrinaemia in dogs, studies with various excluded antrum preparations were performed. Gastric secretion was collected from denervated fundic pouches and gastrin levels were measured pre- and postoperatively by radioimmunoassay. In some samples the gastrins were separated according to their molecular size. Distinct hypergastrinaemia and acid hypersecretion developed in dogs where the antrum was excluded by a mucosal septum. Gastrin levels rose to 349 +/- 64 pg/ml (normal 76 +/- 19 pg/ml). Analysis of the gastrin pattern showed a predominance of smaller gastrin components. Although there was marked hypersecretion in most of the dogs with hypergastrinaemia, no close correlation was evident between these parameters. Some of the dogs with hypergastrinaemia developed anastomotic ulcers.     

Angiogenesis in hypersensitivity pneumonitis

Angiogenesis is an essential process required for growth and tissue repair after injury, but it may also contribute to the pathology of a number of human disorders including neoplasias, atherosclerosis and inflammatory diseases. Vascular endothelial growth factor (VEGF) is a potent angiogenic peptide upregulated by many cytokines and endothelium shear stresses. Lung is a highly vascular tissue with finely organized and regulated microvascular beds, and its inflammation may lead to dysregulated angiogenesis. Hypersensitivity pneumonitis (HP) is a lung disorder characterized by chronic lymphocytic inflammation and endothelial damage. However, neovascularization has not been previously explored. In this study, we examined the expression and localization of VEGF in 38 patients with HP and 14 healthy control subjects (CS). VEGF levels in bronchoalveolar lavage fluid (BALF) were measured by ELISA, and cellular lung localization was determined by immunohistochemistry. In addition, VEGF expression was analyzed in lung tissue by RT-PCR. Our results showed sera levels significantly increased in HP patients compared with CS (209.3 +/- 189.3 vs. 55.3 +/- 31.4 pg/ml; p = 0.004). By contrast, BALF levels of VEGF were significantly decreased in HP patients compared with CS (35.3 +/- 51.5 pg/ml vs. 185.1 +/- 191.4 pg/ml; p < 0.001). VEGF was primary expressed by epithelial cells, smooth muscle cells, and interstitial macrophages in HP tissue. Flt-1 and Flk-1 receptors were highly expressed by endothelial cells from medium and small vessels in HP tissue. By RT-PCR the VEGF RNA was increased compared with those in normal lung. Our results suggest that abnormal expression of VEGF may contribute to impair the lung repair in HP.     

Role for tumor necrosis factor as mediator of lung injury following lower torso ischemia

Ischemia and reperfusion of the ischemic lower torso lead to a neutrophil- (PMN) dependent lung injury characterized by PMN sequestration and permeability edema. This mimics the injury seen after infusion of tumor necrosis factor alpha (TNF), a potent activator of PMN and endothelium. This study tests whether TNF is a mediator of the lung injury after lower torso ischemia. Anesthetized rats underwent 4 h of bilateral hindlimb tourniquet ischemia, followed by reperfusion for 10 min, 30 min, 1, 2, 3, and 4 h (n = 6 for each time point). Quantitative lung histology indicated progressive sequestration of PMN in the lungs, 25 +/- 3 (SE) PMN/10 high-power fields (HPF) 10 min after reperfusion vs. 20 +/- 2 PMN/10 HPF in sham animals (NS), increasing to 53 +/- 5 PMN/10 HPF after 4 h vs. 23 +/- 3 PMN/10 HPF in sham animals (P less than 0.01). There was lung permeability, shown by increasing protein accumulation in bronchoalveolar lavage (BAL) fluid, which 4 h after reperfusion was 599 +/- 91 vs. 214 +/- 35 micrograms/ml in sham animals (P less than 0.01). Similarly, there was edema, shown by the lung wet-to-dry weight ratio, which increased by 4 h to 4.70 +/- 0.12 vs. 4.02 +/- 0.17 in sham animals (P less than 0.01). There was generation of leukotriene B4 in BAL fluid (720 +/- 140 vs. 240 +/- 40 pg/ml, P less than 0.01), and in three of six rats tested at this time TNF was detected in plasma, with a mean value of 167 pg/ml. TNF was not detectable in any sham animal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impact of infection on glucose-dependent liver glucose uptake during TPN: interaction with insulin

Chronic total parenteral nutrition (TPN) markedly augments net hepatic glucose uptake (NHGU). This adaptive increase is impaired by an infection despite accompanying hyperinsulinemia. In the nonadapted state, NHGU is dependent on the prevailing glucose levels. Our aims were to determine whether the adaptation to TPN alters the glucose dependence of NHGU, whether infection impairs this dependence, and whether insulin modulates the glucose dependence of NHGU during infection. Chronically catheterized dogs received TPN for 5 days. On day 3 of TPN, dogs received either a bacterial fibrin clot to induce a nonlethal infection (INF, n = 9) or a sterile fibrin clot (Sham, n = 6). Forty-two hours after clot implantation, somatostatin was infused. In Sham, insulin and glucagon were infused to match the level seen in Sham (9 +/- 1 microU/ml and 23 +/- 4 pg/ml, respectively). In infected animals, either insulin and glucagon were infused to match the levels seen in infection (25 +/- 2 microU/ml and 101 +/- 15 pg/ml; INF-HI; n = 5) or insulin was replaced to match the lower levels seen in Sham (13 +/- 2 microU/ml), whereas glucagon was kept elevated (97 +/- 9 pg/ml; INF-LO; n = 4). Then a four-step (90 min each) hyperglycemic (120, 150, 200, or 250 mg/dl) clamp was performed. NHGU increased at each glucose step in Sham (from 3.6 +/- 0.6 to 5.4 +/- 0.7 to 8.9 +/- 0.9 to 12.1 +/- 1.1 mg.kg(-1).min(-1)); the slope of the relationship between glucose levels and NHGU (i.e., glucose dependence) was higher than that seen in nonadapted animals. Infection impaired glucose-dependent NHGU in both INF-HI (1.3 +/- 0.4 to 2.9 +/- 0.5 to 5.5 +/- 1.0 to 7.7 +/- 1.6 mg.kg(-1).min(-1)) and INF-LO (0.5 +/- 0.7 to 2.2 +/- 0.6 to 4.2 +/- 1.0 to 5.8 +/- 0.8 mg.kg(-1).min(-1)). In summary, TPN augments glucose-dependent NHGU, the presence of infection decreases glucose-dependent NHGU, and the accompanying hyperinsulinemia associated with infection does not sustain the glucose dependence of NHGU.