Comparative study of the pulmonary effects of intravenous leukotrienes and other bronchoconstrictors in anaesthetized guinea pig

Pulmonary responses to intravenous leukotrienes C₄, D₄ and E₄ administered as a bolus injection and by continuous infusion were studied in anesthetized guinea pigs. LTD₄, LTC₄ and LTE₄ (respective ED₅₀ of 0.21 ± .1, 0.64 ± .2 and 2.0 ± .1 μg kg⁻¹) produced dose-dependent increases in insufflation pressure when given as a bolus injection to anesthetized guinea pigs (Konzett-Rössler). Bronchoconstriction was antagonized by FPL-55712 (50–200 μg kg⁻¹), and indomethacin (50–200 μg kg⁻¹) but was not significantly altered by mepyramine (1.0 mg kg⁻¹), methysergide (0.1 mg kg⁻¹), intal (10 mg kg⁻¹) mepacrine (5 mg kg⁻¹) or dexamethasone (10 mg kg⁻¹). The beta adrenoceptor blocker, timolol (5 μg kg⁻¹) produced a significantly greater potentiation of the responses to the leukotrienes than to arachidonic acid, histamine and acetylcholine. Responses to bolus injection of LTE₄ but not LTD₄ or LTC₄ were partially antagonized by atropine (100 μg kg⁻¹) and bilateral vagotomy. In experiments of a different design, continuous infusion of LTD₄ and LTE₄ (2.8–3.2 μg kg⁻¹ min⁻¹) into indomethacin-treated animals produced slowly developing increases in pulmonary resistance and decreases in compliance. The increase in resistance produced by LTE₄ and LTD₄ was partly reversed by intravenous FPL-55712 (1.0 mg kg⁻¹) and atropine (100 μg kg⁻¹) but was almost completely reversed by FPL-55712 (3 – 10 mg kg⁻¹). These findings indicate that leukotrienes can produce bronchoconstriction in guinea pigs through cyclooxygenase-dependent and cyclooxygenase independent mechanisms both of which are blocked by FPL-55712. Cholinergic mechanisms are involved in the mediation of part of the response to bolus injection of LTE₄ as well as a small part of the initial response to continuous infusion of LTD₄ and LTE₄. Intrinsic beta adrenoceptor activation serves to down modulate responses to the leukotrienes to a greater extent than responses to arachidonic acid, histamine and acetylcholine.     

Comparative study of the pulmonary effects of intravenous leukotrienes and other bronchoconstrictors in anaesthetized guinea pigs

Pulmonary responses to intravenous leukotrienes C4, D4 and E4 administered as a bolus injection and by continuous infusion were studied in anesthetized guinea pigs. LTD4, LTC4 and LTE4 (respective ED50 of 0.21 +/- .1, 0.64 +/- .2 and 2.0 +/- .1 microgram kg-1) produced dose-dependent increases in insufflation pressure when given as a bolus injection to anesthetized guinea pigs (Konzett-R?ssler). Bronchoconstriction was antagonized by FPL-55712 (50-200 micrograms kg-1), and indomethacin (50-200 micrograms kg-1) but was not significantly altered by mepyramine (1.0 mg kg-1), methysergide (0.1 mg kg-1), intal (10 mg kg-1) mepacrine (5 mg kg-1) or dexamethasone (10 mg kg-1). The beta adrenoceptor blocker, timolol (5 micrograms kg-1) produced a significantly greater potentiation of the responses to the leukotrienes than to arachidonic acid, histamine and acetylcholine. Responses to bolus injection of LTE4 but not LTD4 or LTC4 were partially antagonized by atropine (100 micrograms kg-1) and bilateral vagotomy. In experiments of a different design, continuous infusion of LTD4 and LTE4 (2.8-3.2 micrograms kg-1 min-1) into indomethacin-treated animals produced slowly developing increases in pulmonary resistance and decreases in compliance. The increase in resistance produced by LTE4 and LTD4 was partly reversed by intravenous FPL-55712 (1.0 mg kg-1) and atropine (100 micrograms kg-1) but was almost completely reversed by FPL-55712 (3 - 10 mg kg-1). These findings indicate that leukotrienes can produce bronchoconstriction in guinea pigs through cyclooxygenase-dependent and cyclooxygenase independent mechanisms both of which are blocked by FPL-55712. Cholinergic mechanisms are involved in the mediation of part of the response to bolus injection of LTE4 as well as a small part of the initial response to continuous infusion of LTD4 and LTE4. Intrinsic beta adrenoceptor activation serves to down modulate responses to the leukotrienes to a greater extent than responses to arachidonic acid, histamine and acetylcholine.     

The in vivo production of peptide leukotrienes after pulmonary anaphylaxis in the rat

Inbred hyper-reactive rats, actively sensitized to OVA, were anesthetized, cannulated, and ventilated with room air. Tracheal instillation of Ag (OVA) resulted in an elevation of airways pressure (14.4 +/- 0.6 cm H2O). Measurement of biliary peptide leukotriene levels before and after Ag challenge using reverse phase HPLC and RIA techniques showed significant elevations in leukotriene (LT) levels, the amounts released being LTC4 (3.65 +/- 0.78), LTD4 (2.8 +/- 1.11), and N-Ac LTE4 (3.87 +/- 1.15) expressed as ng/100 g of body weight, n = 13. Identification of these metabolites were confirmed by HPLC/RIA techniques and LTC4 was further characterized by UV spectroscopy and its enzymatic conversion by gamma-glutamyl transpeptidase to LTD4. [3H]LTC4 (16 ng) administration by tracheal instillation resulted in a 31.4 +/- 4.3% recovery of radioactivity through the bile over 4 h (n = 3) with the major identified metabolite being N-Ac LTE4. [3H]LTC4 (16 ng) plus synthetic LTC4 (5 micrograms) showed a 30.8 +/- 3.1% recovery through the bile after tracheal instillation (3-h collection, n = 4) with significant amounts of LTC4 as well as N-Ac LTE4 present. [3H]LTC4 administration by the portal vein resulted in a 37.4 +/- 8.8% biliary recovery over 60 min (n = 6), the metabolites present in the bile being LTC4, LTD4, LTE4, and N-Ac LTE4. Pretreatment with the 5-lipoxygenase inhibitor L-656,224 (15 mg/kg, 3.5 h pre-p.o.) before Ag challenge resulted in a significant inhibition (greater than 90%, p less than 0.05) of biliary leukotriene levels in this model. Our study demonstrates that peptide leukotrienes are produced in the anesthetized rat after pulmonary anaphylaxis and that biliary leukotriene measurement is suitable for showing the biochemical efficacy of leukotriene inhibitors in vivo. In vivo tracer experiments suggest that the biliary metabolic profile of the peptide leukotrienes is dependent on the site and levels of release as well as the efficiency of the vascular clearance of the various metabolites.     

Modulatory effects of hypercapnia on in vitro and in vivo pulmonary endothelial-neutrophil adhesive responses during inflammation

Reducing tidal volume as a part of a protective ventilation strategy may result in hypercapnia. In this study, we focused on the influence of hypercapnia on endothelial-neutrophil responses in models of inflammatory-stimulated human pulmonary microvascular endothelial cells (HMVEC) and in an animal model of lipopolysaccharide (LPS)-induced acute lung injury. Neutrophil adhesion and adhesion molecules expression and nuclear factor-kappaB (NF-kappaB) were analyzed in TNF-alpha and LPS-treated HMVEC exposed to either eucapnia or hypercapnia. In the in vivo limb, bronchoalveolar lavage fluid cell counts and differentials, adhesion molecule and chemokine expression were assessed in LPS-treated rabbits ventilated with either low tidal volume ventilation and eucapnia or hypercapnia. In both the in vitro and in vivo models, hypercapnia significantly increased neutrophil adhesion and adhesion molecule expression compared to eucapnia. Activity of NF-kappaB was significantly enhanced by hypercapnia in the in vitro experiments. IL-8 expression was greatest both in vitro and in vivo under conditions of hypercapnia and concomitant inflammation. CD11a expression was greatest in isolated human neutrophils exposed to hypercapnia+LPS. Our results demonstrate that endothelial-neutrophil responses per measurement of fundamental molecules of adhesion are significantly increased during hypercapnia and that hypercapnia mimics conditions of eucapnia+inflammation.     

Halothane metabolism. Impairment of hepatic omega-oxidation of leukotrienes in vivo and in vitro.

Omega-oxidation of leukotrienes is the initial step of hepatic degradation and thus inactivation of these proinflammatory mediators. Omega-oxidation is followed by beta-oxidation of leukotrienes from the omega-end. After exposure of rats to a single dose of the anesthetic agent halothane, a transient decrease in leukotriene omega-oxidation was induced both in vivo and in vitro. In untreated rats, 44.1 +/- 6.0% of N-[3H]acetylleukotriene E4 injected intravenously was recovered unchanged in bile collected for 60 min in vivo; 46.5 +/- 3.0% was recovered as omega-/beta-oxidation products, of which 24.7 +/- 4.5% were associated with beta-oxidation products only (mean +/- SEM; n = 5). In rats receiving a single dose of halothane 18 h before the experiment, recovery of unchanged N-[3H]acetylleukotriene E4 was significantly increased to 79.8 +/- 4.8%, while the fraction of omega-/beta-oxidation products decreased to 9.0 +/- 1.7% (n = 5); 90 h after exposure to halothane, N-[3H]acetylleukotriene E4 recovery decreased to 30.0 +/- 3.0% and omega-/beta-oxidation products amounted to 49.1 +/- 3.8%; the fraction of beta-oxidation products was significantly increased to 43.1 +/- 3.4% (n = 5). Ten days after exposure of rats to halothane, the recoveries of N-[3H]acetylleukotriene E4, of omega-/beta-oxidation products, and of beta-oxidation products alone, returned to almost normal values. Microsomal fractions obtained from rat hepatocytes catalyzed the NADPH- and O2-dependent leukotriene omega-oxidation in vitro. The formation of omega-hydroxy-metabolites of leukotriene B4, leukotriene E4, and N-acetylleukotriene E4 was decreased by 50% in microsomal fractions obtained from rats 18 h and 90 h after halothane treatment, and returned back to control levels in microsomal fractions obtained 10 days after halothane treatment. The Km value of leukotriene B4 omega-oxidation revealed no significant change in enzyme affinity towards leukotriene B4; in contrast, as reflected by the reduction of the Vmax value by 65%, a decrease in the amount of the active enzyme in microsomes obtained from rats 18 h after halothane treatment was observed. Halothane-metabolism-dependent trifluoroacetylation of hepatic proteins may mediate this process. Thus, the time course of the density on immunoblots of trifluoroacetylated protein adducts paralleled that of the transient decrease in leukotriene omega-oxidation. In contrast to its omega-oxidation, leukotriene B4 synthesis from 5-hydroperoxyeicosatetraenoate was not inhibited in hepatocyte homogenates obtained from rats pretreated with halothane. The data suggest that metabolism of halothane causes a transient derangement of hepatic leukotriene homeostasis in vivo.     

Sperm factors related to in vitro and in vivo porcine fertility

The prediction of sperm fertilizing ability has great economic importance for breeding herds when artificial insemination is used. Classical methods of semen evaluation generally measure the sperm concentration, progressive motility, percentage of viable cells, and acrosome morphology. These assays are poor in predicting sperm fertility, because only the samples with markedly poor quality can be detected. The development of new sperm tests that measure certain sperm functions is an attempt to solve this problem. On the other hand, the binding and penetration of the zona pellucida is one of the most important barriers the spermatozoa must overcome in the fertilization process. Also, the interaction with the oocyte plasma membrane appears to explain much of the variability in sperm fertilizing potential among fertile boars. Thus, the study of the relationship between sperm factors and in vitro fertility may be a good strategy and assays that include a study of gamete interaction may lead to a better way to predict male fertility than the routine laboratory evaluation of semen. This review will discuss the relationships between sperm factors and fertility in vitro and in vivo (AI trial) with both diluted and frozen-thawed semen. We will also try to analyze the problems and limitations related to the interpretation of boar sperm tests.     

Interactions in vitro and in vivo between anionic and cationic porcine trypsin and porcine plasma proteinase inhibitors

A method for purifying porcine anionic and cationic trypsin is presented. Reaction mixtures with increasing amounts of the two porcine trypsins and porcine serum were studied in vitro to evaluate the relative importance of alpha 1-macroglobulin and alpha 2-macroglobulin as well as alpha 1-proteinase inhibitor in the rapid binding of porcine anionic and cationic trypsin. Porcine cationic trypsin was preferentially bound to alpha 1-macroglobulin, while anionic trypsin exhibited equal binding to both alpha-macroglobulins. Both trypsins were also bound by the alpha 1-proteinase inhibitor but not until alpha 1-macroglobulin approached saturation. Trypsin-alpha-macroglobulin complexes were cleared from plasma with a half-life of 6 min. For trypsin-alpha 1-proteinase inhibitor-complexes the half-life was 120 min. These findings are in accordance with results for other mammalian species, including man.     

猪圆环病毒2型与猪细小病毒共感染对猪肺泡巨噬细胞吞噬功能及其干扰素表达水平的影响

【目的】分析猪圆环病毒2型(PCV2)与猪细小病毒(PPV)共感染对猪肺泡巨噬细胞(PAM)吞噬功能及其干扰素表达水平的影响,为进一步阐明猪断奶后多系统衰减综合征的发病机制提供实验依据。【方法】将48头5周龄健康仔猪随机分为PCV2组、PPV组、PCV2/PPV组和对照组,每组12头。PCV2和PPV组经口鼻途径分别接种PCV2或PPV,PCV2/PPV组同时接种PCV2和PPV,对照组接种细胞营养液。感染后3、7、14和35d(dpi)从每组随机选择3头剖杀,检测PAM的存活率、吞噬活性及其α1型干扰素(IFN-α1)、γ干扰素(IFN-γ)mRNA的表达水平。【结果】PCV2组和PCV2/PPV组PAM的存活率于3、7、14dpi均低于对照组,35dpi均与对照组PAM的存活率接近,PCV2与PCV2/PPV两组之间差异不显著(P>0.05);3个病毒感染组PAM的吞噬功能均显著下降(P<0.01),其中PCV2/PPV组的吞噬功能低于PCV2组(P<0.05);PCV2/PPV组PAM中IFN-α1和IFN-γ mRNA的水平持续低于PCV2、PPV组和对照组的水平(P<0.01)。【结论】PCV2与PPV共感染没有引起PAM的活力进一步下降,但导致其吞噬功能及IFN-α1和IFN-γmRNA的表达水平持续降低。     

Ultrastructure of porcine embryos following development in vitro versus in vivo

The present study examined the ultrastructural appearance of porcine embryos from the four-cell stage to the blastocyst grown either in vivo or in vitro. Embryos were collected at slaughter from superovulated gilts and were fixed for transmission electron microscopy either immediately or after various periods of in vitro culture. In general, the morphology of in vivo and in vitro grown embryos was similar. In vivo grown four-cell stages contained dense fibrillar nucleoli. At the eight-cell stage the nucleoli possessed increasing amounts of chromatin and granules. In both stages the mitochondria were spherical or ovoid in shape and had only few cristae. In morulae and blastocysts the nucleoli were mainly of the fibrillogranular type, and the mitochondria were filamentous and possessed more cristae, of which many were tubular. Two major ultrastructural deviations were observed in about half of the in vitro cultured embryos. First, nucleolus-like structures were found outside the nuclei in the cytoplasm of blastomeres. These structures were spherical and composed of chromatin-like material containing characteristically a single large and several small vacuoles. The structures were frequently associated with profiles of smooth endoplasmic reticulum (SER). A second type of deviation was aggregates of SER appearing as spiral coils or multiangular complexes. Some embryos displayed both types of deviations. The physiological significance of these deviations remains speculative. They may be involved in the considerably reduced capability of porcine embryos to develop to piglets following in vitro culture.     

Comparative proteomics of erythrocyte aging in vivo and in vitro

During aging in vivo and in vitro, erythrocytes display removal signals. Phagocytosis is triggered by binding of autologous IgG to a senescent cell antigen originating on band 3. Erythrocytes generate vesicles as an integral part of the aging process in vivo and in vitro, i.e. during storage. These vesicles display senescent cell antigens as well as phosphatidylserine, that is recognized by scavenger receptors. Recent comparative proteomic analyses of erythrocytes and their vesicles support the hypothesis that aging is accompanied by increased binding of modified hemoglobins to band 3, disruption of the band 3-mediated anchorage of the cytoskeleton to the lipid bilayer, vesicle formation, and antigenic changes in band 3 conformation. Proteomic data also suggest an, until then unknown, involvement of chaperones, stress proteins, and proteasomes. Thus, the presently available comparative proteomic analyses not only confirm previous immunochemical and functional data, but also (1) provide new clues to the mechanisms that maintain erythrocyte homeostasis; (2) open new roads to elucidate the processes that regulate physiological erythrocyte aging and removal, and thereby; (3) provide the foundation for rational interventions to prevent untimely erythrocyte removal, and unwanted interactions between the erythrocyte and the immune system, especially after transfusion.     

Differential effects of leukotrienes B4 and C4 on bovine aortic endothelial cell proliferation in vitro

The effect of leukotrienes derivated from arachidonic acid was studied on vascular endothelium proliferation. The peptido-leukotriene LTC4 (0.1 nM - 0.1 microM) promoted a dose-dependent growth of bovine aortic endothelial cells in culture with a maximal effect at 10 nM. This proliferative activity could be receptor-mediated since LTC4 specifically bound to endothelial cell membranes with a Kd value of 50 nM. The leukotriene B4 did not induce any significant proliferation in the same range of concentrations. This result was consistent with the lack of LTB4 specific binding sites. This data suggests that LTC4 could be one of the factors implicated in angiogenesis during inflammatory processes.     

Differential effects of leukotrienes B4 and C4 on bovine aortic endothelial cell proliferation in vitro

The effect of leukotrienes derivated from arachidonic acid was studied on vascular endothelium proliferation. The peptido-leukotriene (LTC4 (0.1 nM – 0.1 μM) promoted a dose-dependent growth of bovine aortic endothelial cells in culture with a maximal effect at 10 nM. This proliferative activity could be receptor-mediated since LTC4 specifically bound to endothelial cell membranes with a Kd value of 50 nM. The leukotriene B4 did not induce any significant proliferation in the same range of concentrations. This result was consistent with the lack of LTB4 specific binding sites. This data suggests that LTC4 could be one of the factors implicated in angiogenesis during inflammatory processes.