E. Martí-Bonmatí

Olive Oil–Based Lipid Emulsion's Neutral Effects on Neutrophil Functions and Leukocyte–Endothelial Cell Interactions

BACKGROUND Infection remains a drawback of parenteral nutrition (PN), probably related, among other factors, to immunosuppressive effects of its lipid component. Newer preparations may have lesser immunosuppressive impact. This study examines the effects of an olive oil-based lipid emulsion (long-chain triacylglycerols-monounsaturated fatty acids [LCT-MUFA]; ClinOleic) on various functions of human neutrophils in vitro and on rat leukocyte-endothelial cell interactions in vivo compared with LCT (Intralipid) and 50% LCT-50% medium-chain triacylglycerols (MCT; Lipofundin) mixture. METHODS Neutrophils isolated from healthy donors were incubated with concentrations (0.03-3 mmol/L) of lipid emulsions encompassing clinically relevant levels. In vivo leukocyte recruitment was studied with intravital microscopy within rat mesenteric microcirculation. RESULTS LCT-MUFA (3 mmol/L) did not alter the N-formyl-Met-Leu-Phe (FMLP)-induced rise in [Ca2+]i, oxidative burst, chemotaxis, and elastase release, whereas LCT-MCT decreased [Ca2+]i and chemotaxis and increased oxidative burst. FMLP-induced LTB4 production was augmented by lipid emulsions. Serum-opsonized zymosan-induced phagocytosis was unaltered by lipid emulsions. Basal and FMLP-induced CD11b expression was unaffected by lipid emulsions. Lipopolysaccharide (LPS)-induced TNF-alpha, IL-1beta and IL-8 mRNA, and protein expression was unaltered by LCT-MUFA, whereas LCT and LCT-MCT decreased IL-1beta mRNA and protein. LCT-MUFA did not alter apoptosis, but LCT increased apoptosis in absence and presence of GM-CSF. LPS (1 microg/mL)-induced increase in leukocyte rolling flux, adhesion, and emigration was inhibited by LCT and LCT-MCT but unaffected in LCT-MUFA-treated rats. Immunohistochemistry showed LPS-induced increase in P-selectin expression attenuated by LCT and LCT-MCT but not LCT-MUFA. CONCLUSIONS LCT-MUFA showed lower in vitro and in vivo impact on neutrophil function compared with LCT and LCT-MCT.

Effects of zinc acexamate on gastric mucosal resistance factors

The effects of zinc acexamate on gastric defensive systems were evaluated in the rat. Gastric ulcers induced by oral administration of three necrotic agents (0.6 N HCl, 25% NaCl, 100% ethanol) were markedly reduced by different pretreatments with zinc acexamate. This cytoprotective effect was not modified by previous treatment with indomethacin (30 mg/kg orally). Zinc acexamate pretreatment also prevents the disruption of the gastric mucosal barrier induced by aspirin (40 mM) and increases mucus production in the gastric glands and tracheal walls. These observations suggest that the antiulcer effects described for zinc salts could be the result, at least partly, of an action increasing gastric mucosal defensive systems.

EFFECTS OF β‐ADRENOCEPTOR DRUG STIMULATION ON VARIOUS MODELS OF GASTRIC ULCER IN RATS

1 Experiments were designed to evaluate the effect of the pharmacological activation of β‐adrenoceptors on various models of gastric ulcer in the rat. 2 Pretreatment with the β‐adrenoceptor stimulant drugs, isoprenaline or salbutamol, significantly inhibited stress‐induced gastric ulcers. This anti‐ulcer effect was abolished by propranolol but not by atenolol, suggesting that β2‐adrenoceptors mediate this response. 3 In the pylorus‐ligation model, salbutamol inhibited lesion formation and reduced the intragastric content of hydrogen ions, histamine and pepsin although the latter was only affected with the higher dose of salbutamol. 4 Salbutamol also prevented the ulcerogenic action on the gastric mucosa of an exogenously perfused artificial gastric juice, showing that the anti‐ulcer effect is not necessarily dependent on acid inhibition. 5 Salbutamol also reduced the formation of acute ulcers induced by various iatrogenic means (histamine, polymyxin B, reserpine and indomethacin). 6 Long‐term treatment with salbutamol accelerated the healing of experimental chronic gastric ulcer. 7 In anaesthetized rats, salbutamol produced a dose‐related increase in mucosal blood flow which may contribute to its mode of action. 8 It is concluded that β‐adrenoceptor agonists exert preventive and curative effects on gastric damage induced in the rat. This effect seems specific and mediated through β‐adrenoceptor activation.

Effects of calcium channel blockers on gastric emptying and acid secretion of the rat in vivo

1 Experiments were designed to evaluate the effects of three calcium channel blockers (verapamil, diltiazem and cinnarizine) on gastric emptying and secretion in the rat 2 Pretreatment with the calcium blockers delayed gastric emptying of phenol red in a dose‐dependent manner. Verapamil was the most effective of the agents tested. 3 Verapamil and diltiazem inhibited gastric acid secretion in the pylorus‐ligated rat without affecting pepsin output. Cinnarizine was ineffective in this model. 4 When the perfused lumen of the anaesthetized rat was used, verapamil was found to inhibit responses to carbachol or histamine more than those to pentagastrin. Further, we found a greater sensitivity to verapamil for basal compared with vagal‐stimulated (2‐deoxy‐D‐glucose) acid secretion. Neither diltiazem nor cinnarizine modified gastric acid secretion in this experimental model. 5 These findings are discussed in relation to the role of extracellular calcium in gastric motility and secretion, and the existence of a regional and functional selectivity for calcium blockers is proposed.

Effects of cimetidine, atropine and prostaglandin E2 on rat mucosal erosions produced by intragastric distension

The effects of three typical antisecretory agents: cimetidine, atropine and prostaglandin E2 were compared on an acute rat gastric ulcer model which consisted of perfusing the stomach continuously, at a high intraluminal pressure (120 mm H2O), with a simulated gastric juice (0.1 M HCl plus 600 mg pepsin/l). As the acid and pepsin are given exogenously the inhibitory action of the antisecretory drugs is obviated in this model. Cimetidine and atropine failed to reduce gastric erosions, whereas prostaglandin E2 markedly reduced the severity of the mucosal lesions with respect to control values. Long-term treatment with cimetidine also failed to increase the resistance of the gastric mucosa to the digestive action of the artificial gastric juice. These findings indicate that only prostaglandin E2 is cytoprotective and do not support the view that anticholinergics or histamine H2-receptor antagonists have a cytoprotective role on the cells of the gastric mucosa.

Anti-Inflammatory and Anti-Fibrotic Profile of Fish Oil Emulsions Used in Parenteral Nutrition-Associated Liver Disease

Home parenteral nutrition (PN) is associated with many complications including severe hepatobiliary dysfunction. Commercial ω-6 fatty acid-soybean based-lipid emulsions in PN may mediate long term PN associate liver disease (PNALD) whereas ω-3-fish oil parenteral emulsions have shown to reverse PNALD in children. However, its clinical effectiveness in adults has been scarcely reported. In this work, we study the role of soybean and fish oil lipid commercial emulsions on inflammatory and profibrotic liver markers in adults with long term PNALD and in in vitro cellular models. Inflammatory and profibrotic markers were measured in serum of ten adults with long term PNALD and in culture supernatants of monocytes. Liver epithelial to mesenchymal transition (EMT) was induced by transforming growth factor beta 1 (TGFβ1) to evaluate in vitro liver fibrosis. Omegaven®, a 100% fish oil commercial emulsion, was infused during four months in two patients with severe long term PNALD reversing, at the first month, the inflammatory, profibrotic and clinical parameters of PNALD. The effect was maintained during the treatment course but impaired when conventional lipid emulsions were reintroduced. The other patients under chronic soybean oil-based PN showed elevated inflammatory and profibrotic parameters. In vitro human monocytes stimulated with lipopolysaccharide induced a strong inflammatory response that was suppressed by Omegaven®, but increased by soybean emulsions. In other experiments, TGFβ1 induced EMT that was suppressed by Omegaven® and enhanced by soybean oil lipid emulsions. Omegaven® improves clinical, anti-inflammatory and anti-fibrotic parameters in adults with long-term home PNALD.

Changes in α-tocopherol and retinol levels during cardiopulmonary bypass correlate with maximal arterial partial pressure of oxygen

Cardiopulmonary bypass (CPB) is associated with oxidative stress. This study examined antioxidant levels in adults undergoing CPB surgery and their correlation with clinical variables. Arterial blood samples were obtained from 27 patients undergoing CPB. The time-course variation of vitamin C (spectrofluorimetry), α-tocopherol and retinol (HPLC) levels were determined. Plasma vitamin C rose initially but gradually decayed during reperfusion until 60% reduction of baseline values post-surgery. α-Tocopherol and retinol were reduced along CPB with post-operative values ∼25% lower than baseline. No significant changes were found for selenium and glutathione peroxidase. PaO2 values rose steadily throughout CPB. A correlation existed for α-tocopherol and retinol depletion vs maximal PaO2 throughout CPB but no correlation was found for antioxidant consumption vs duration of ischaemia and reperfusion and hypothermia level. In conclusion, consumption of arterial blood antioxidant vitamins occurs with CPB in relation with PaO2 levels but not for other clinical variables measured in this study.

Influence of low temperature on bronchodilatation induced by terbutaline administered by metered dose or dry powder inhalers in asthmatics

Abstract— Low temperatures may affect dose delivery efficacy and clinical effectiveness of medication aerosols. In this study we examine the effect of cold ambient temperature on the bronchodilatation produced by terbutaline delivered from a chlorofluorocarbon pressurized metered dose inhaler (pMDl) compared to a multi‐dose dry powder inhaler (DPI). Fourteen stable asthmatics were studied on two consecutive days. On day 1, after measuring FEV1 at room temperature (22 °C), each patient was randomized to receive 500 μg of terbutaline delivered from pMDI or DPI stored for 24 h at 22 °C with FEV1 recorded 20 min post‐dose; then, patients were placed in a chamber at − 10 °C, and after obtaining FEV1, each patient received 500 μg of terbutaline delivered from pMDI or DPI (same formulation as previously administered) stored for 24 h at − 10 °C, and FEV1 was obtained 20 min post‐dose. On day 2, a similar protocol was followed but each patient received terbutaline as the alternative to the formulation administered on day 1. Pairwise comparisons of the FEV1 (% predicted) values obtained on day 1 and day 2 at 22 °C and − 10 °C (pre‐dose) showed no significant differences. Similar bronchodilatations were observed for terbutaline DPI administration at 22 °C and − 10 °C (24.85 ± 11.72 and 20.08 ± 6.27 % increase of FEV1; P>0.05). By contrast, the bronchodilatation obtained for terbutaline pMDI at 22 °C (21.07 ± 8.55% increase in FEV1) was not reproduced at − 10 °C (0.72 ± 2.84%; P < 0.05 from 22 °C). In five asthmatics a cumulative dose‐response curve for terbutaline pMDI was obtained. This part of the study showed that a higher dose of terbutaline pMDI was necessary at − 10 °C to obtain a bronchodilator response (10.04 ± 6.75% increase of FEV1 after 2 000 μg) that remained lower than the bronchodilatation for 500 μg terbutaline pMDI at − 10 °C. In conclusion, the clinical effectiveness of terbutaline delivered from chlorofluorocarbon pMDIs is compromised by cold storage while DPIs are not affected.

Influence of Storage at Low Temperatures on the Aerosol Output from Metered-Dose and Dry-Powder Inhalation Devices

Objective: To determine whether storage at low temperatures affects the drug delivery efficacy of a chlorofluorocarbon (CFC)-free aerosol and a dry-powder inhaler (DPI). Design: Aerosol output from a CFC-free hydrofluoroalkane (HFA-134a) metered-dose inhaler (albuterol) and a multidose DPI (terbutaline) were examined at different ambient temperatures and canister loads. Results: After the HFA-134a formulation was stored at low temperatures for 24 hours, a small decrease of aerosol output (2.1–2.7% at 0 °C, 5.0–8.0% at −10 °C; p < 0.05 from 22 °C) was observed. In addition, the aerosol output from devices with one-half or one-fifth the initial content was marginally decreased compared with output from inhalers with full content. Image analysis techniques applied to fully formed aerosol plume emitted from the HFA-134a formulation showed that the product could still be aerosolized at 10 °C, but there was a reduction of the distance reached by the aerosol. In contrast, condensed droplets markedly altered the aerosols formed from CFC inhalers at −10 °C. Aerosol output from the DPI apparently was not altered following 24-hour storage at −10 °C. Conclusions: Aerosols emitted by the HFA-134a and DPIs studied were less affected by exposure to cold temperatures compared with those from marketed CFC devices.