Leukocyte rolling is exclusively mediated by P-selectinin colonic venules

1. The objective of the present study was to examine the role of the endothelial selectins (i.e. P- and E-selectin) in leukocyte-endothelium interactions in colonic venules by use of intravital microscopy. 2. Balb/c mice were exposed to dextran sodium sulphate (DSS) in the drinking water for 5 days or treated intraperitoneally (i.p.) with tumour necrosis factor-alpha (TNF-alpha) for 3 h. 3. In DSS-treated mice, mRNA of both P- and E-selectin were expressed and leukocyte rolling and adhesion was increased to 27+/-3 cells min(-1) and 36+/-8 cells mm(-1), respectively. An anti-P-selectin antibody abolished DSS-induced leukocyte rolling, whereas an antibody against E-selectin had no effect. Established leukocyte adhesion was insensitive to inhibition of the selectins. 4. DSS markedly increased production of TNF-alpha in the colon. TNF-alpha increased leukocyte rolling to 22+/-3 cells min(-1) and adhesion to 45+/-4 cells mm(-1). Only inhibition of P-selectin significantly reduced (>94%) leukocyte rolling provoked by TNF-alpha. Leukocyte adhesion was not changed by late anti-P-selectin antibody treatment. In contrast, pretreatment with the anti-P-selectin antibody not only abolished leukocyte rolling but also completely inhibited firm adhesion in response to TNF-alpha. 5. This study demonstrates that P-selectin plays an important role in leukocyte rolling in colonic venules, both in experimental colitis and when stimulated with TNF-alpha. Moreover, P-selectin-dependent leukocyte rolling was found to be a precondition for TNF-alpha-induced firm adhesion. Thus, these findings suggest that P-selectin may be a key target to reduce pathological recruitment of inflammatory cells in the colon.     

Protective effect of platelet activating factor antagonists on cultured endothelial cell lysis induced by elastase or activated neutrophils.

1. The mechanism(s) responsible for injury of endothelial cells induced by human leukocyte elastase (HLE) was investigated in an immortalized venous human endothelial cell line (IVEC). 2. First, the proteinase concentrations and incubation delays necessary to trigger a significant IVEC cytotoxicity were determined by chromium assays. Thus, exposure of IVEC for 6 h to 10 micrograms ml-1 HLE resulted in 22 +/- 2.8% lysis and 36.4 +/- 5.4% detachment (mean +/- s.e. mean; n = 4; P < 0.05). 3. WEB 2086, a specific platelet-activating factor (PAF) receptor antagonist, induced a significant concentration-dependent decrease of such a lysis (39.6 +/- 7.7% protection at 100 microM; n = 4). This potential role for PAF was confirmed with two other antagonists of this lipid mediator, i.e., BN 52021 and RP 48740. 4. Finally, we demonstrated that pretreatment of IVEC with WEB 2086 protected significantly against cell lysis induced by stimulated human neutrophils, an experimental model in which HLE participates.     

Characterization of tachykinin receptors mediating plasma extravasation and vasodilatation in normal and acutely inflamed knee joints of the rat.

1. Inflammatory actions of tachykinins in normal rat knee joints were compared with those of animals with acutely inflamed joints induced by intra-articular injection of 2% carrageenan. Plasma protein extravasation in rat knee joints, measured by protein micro-turbidimetry, was induced by intra-articular perfusion of selective tachykinin receptor agonists. Changes in joint blood flow, measured by laser Doppler perfusion imaging, were produced by topical applications of selective tachykinin receptor agonists to the joint capsule. 2. Carrageenan-injected rat knee joints showed significantly higher (P < 0.001) basal plasma extravasation (56 +/- 4 micrograms ml-1, n = 5) than normal rat knee joints (10 +/- 4 micrograms ml-1, n = 6). Intra-articular perfusion of the selective neurokinin1 (NK1) receptor agonist [Sar9, Met(O2)11]-substance P (0.8 nmol min-1) for 60 min elevated the basal plasma extravasation to 90 +/- 17 micrograms ml-1 (n = 6, P < 0.001) in normal joints, and to 150 +/- 14 micrograms ml-1 (n = 5, P < 0.001) in inflamed joints. Perfusion of the selective NK1 receptor antagonist N2-[(4R)-4-hydroxy-1-(1-methyl-1H- indol-3-yl)carbonyl-L-prolyl]-N-methyl-N-phenylmethyl-3-(2-naphthyl)- L-alaninamide (FK888; 0.8 nmol min-1) for 20 min followed by co-perfusion with the NK1 receptor agonist (0.8 nmol min-1) produced complete inhibition of the NK1 receptor agonist-induced plasma extravasation in the two groups of animals (for both groups; n = 3, P < 0.001). 3. Intra-articular perfusion of the selective NK receptor agonist [Nle10]-neurokinin A4-10 (0.8 nmol min-1) and the selective NK3 receptor agonist [MePhe7]-neurokinin B (0.8 nmol min1) produced no increase in plasma extravasation in normal or in inflamed rat knee joints (n = 4 and 11, P > 0.05). 4. Topical bolus applications of the NK1 receptor agonist [Sar9, Met(O2)11]-substance P onto normal joint capsules produced dose-dependent vasodilatation expressed as a voltage increase from control level. The maximum increase in blood flow was 2.05-0.21 V from a basal voltage of 3.42 +/- 0.07 V (n = 13, P < 0.001). To a much lesser extent, administration of the NK2 receptor agonist [Nle10]-neurokinin A4-10 also produced dose-dependent vasodilatation with maximum increase of 0.46 +/- 0.08 V from a basal level of 3.38 +/- 0.1 V (n = 7, P < 0.01). Animals with acutely inflamed joints showed enhanced vasodilator responses to the NK1 and NK2 receptor agonists (for both: P vs non-inflamed joints < 0.001). Thus, the NK1 and NK2 receptor agonists produced maximum increases of 2.56 +/- 0.19 V (basal level = 5.84 +/- 0.07 V; n = 7, P < 0.001) and 1.97 +/- 0.26 V (basal level = 6.31 +/- 0.23 V; n = 11, P < 0.001), respectively. The NK3 receptor agonist [MePhe7]-neurokinin B produced no change in blood flow in normal or in inflamed rat knee joints (n = 7 and 5, P > 0.05). 5. Bolus administration of the NK1 receptor antagonist FK888 (10 pmol) alone followed 5 min later by another dose of 10 pmol FK888 (i.e. total dose of 2 x 10 pmol) applied together with the NK1 receptor selective agonist [Sar9, Met(O2)11]-substance P produced partial, but significant inhibition of the NK1 receptor agonist-induced vasodilatation in both normal (maximum response reduced by 51.9 +/- 5.4%; n = 6, P < 0.001) and inflamed rat knee joints (maximum response reduced by 49.3 +/- 6.1%; n = 5, P < 0.001). The NK2 receptor agonist [Nle10]-neurokinin A4-10-induced vasodilator responses in inflamed joints were not affected by this treatment (n = 6, P > 0.05). However, with two higher doses of FK888 (both 1 nmol), the NK1 and the NK2 receptor agonist-induced vasodilator responses were abolished in the two groups of animals (n = 6-8, P < 0.005). 6. Administration of two doses of the selective NK2 receptor antagonist (S)-N-methyl-N-[4-acetylamino-4-phenylpiperidino)-2-(3,4-dichlorophenyl) -butyl]benzamide (SR48968;...     

The effects of heparin and related molecules upon the adhesion of human polymorphonuclear leucocytes to vascular endothelium in vitro

1. The effects of an unfractionated heparin preparation (Multiparin), a low molecular weight heparin preparation (Fragmin) and a selectively O-desulphated derivative of heparin lacking anticoagulant activity, have been investigated for their effects on the adhesion of human polymorphonuclear leucocytes (PMNs) to cultured human umbilical vein endothelial cells (HUVECs) in vitro. The effect of poly-L-glutamic acid, a large, polyanionic molecule was also studied. 2. Unfractionated heparin (50-1000 U ml-1), the O-desulphated derivative (0.3-6 mg ml-1) and the low molecular weight heparin (50 U-1000 U ml-1) all inhibited significantly the adhesion of 51Cr labelled PMNs to HUVECs stimulated with interleukin-1 beta (IL-1 beta; 10 U ml-1), bacterial lipopolysaccharide (LPS; 2.5 micrograms ml-1) or tumour necrosis factor-alpha (TNF-alpha; 125 U ml-1) for 6 h, whereas poly-L-glutamic acid had no effect. In addition, the three heparin preparations in the same concentration range inhibited significantly the adhesion of f-met-leu-phe-stimulated PMNs to resting HUVECs. 3. The effects of unfractionated heparin upon the expression of adhesion molecules intercellular adhesion molecule-1 (ICAM-1) and E-selection were also investigated, as were the effects of unfractionated heparin upon adhesion of human PMNs to previously stimulated HUVECs. Heparin had little effect upon levels of expression of these adhesion molecules on stimulated HUVECs. However, a profound effect upon PMN adhesion to previously stimulated HUVECs was demonstrated using the same preparation, suggesting that inhibition of adhesion molecule expression is not a major component of the described inhibitory effects of heparin. 4. Pre-incubation of PMNs with heparin followed by washing inhibited their adhesion to HUVECs, under different conditions of cellular activation, implying that heparin can bind to these cells and exert its anti-adhesive effects even when not directly present in the system. 5. These observations would suggest that both heparin and a low molecular weight heparin are capable of inhibiting adhesion of human PMNs to endothelial cells, an effect not dependent solely upon the polyanionic nature of these molecules, nor dependent upon their ability to act as anticoagulants.     

Ginsenosides-induced nitric oxide-mediated relaxation of the rabbit corpus cavernosum.

1. Ginsenosides, the active ingredients extracted from Panax ginseng, have been shown to promote nitric oxide (NO) release in bovine aortic endothelial cells. Since the endothelial cells and the perivascular nerves in penile corpus cavernosum contain NO synthase and an NO-like substance has been shown to be released from these cells which relaxes corpus cavernosum, the possibility that ginsenosides may relax corpus cavernosum by releasing endogenous NO was examined. 2. With an in vitro tissue superfusion technique, ginsenosides (250, 500 and 750 micrograms ml-1) relaxed corpus cavernosum, concentration-dependently. 3. Using an in vitro tissue bath technique, acetylcholine (ACh)-induced relaxations were increased in the presence of ginsenosides (250 micrograms ml-1). 4. Ginsenosides at 100 micrograms ml-1 significantly enhanced the tetrodotoxin (TTX)-sensitive relaxation of corpus cavernosum elicited by transmural nerve stimulation. 5. The ginsenosides-induced, ACh-induced and ginsenosides-enhanced transmural nerve stimulation-elicited relaxations were significantly attenuated by NG-nitro-L-arginine (100 microM) and oxyhaemoglobin (oxyHb; 5-10 microM), and were enhanced by superoxide dismutase (SOD; 50 u ml-1). 6. The relaxations and their attenuation by NG-nitro-L-arginine and TTX were associated with increase and decrease in tissue cyclic GMP levels, respectively. 7. It is concluded that ginsenosides may release NO from endothelial cells, and enhance NO release from endothelial cells elicited by other vasoactive substances and from perivascular nitrergic nerves in the corpus cavernosum. These endothelial and neurogenic effects of ginsenosides in inducing relaxation of the corpus cavernosum may account for the aphrodisiac effect of Panax ginseng.     

Dose of midazolam should be reduced during diltiazem and verapamil treatments.

1. The effects of diltiazem and verapamil on the pharmacokinetics and pharmacodynamics of midazolam were investigated in a double-blind randomized cross-over study of three phases. 2. Nine healthy volunteers were given orally diltiazem (60 mg), verapamil (80 mg) or placebo three times daily for 2 days. On the second day they received a 15 mg oral dose of midazolam, after which plasma samples were collected and performance tests carried out for 17 h. 3. The area under the midazolam concentration-time curve was increased from 12 +/- 1 microgram ml-1 min to 45 +/- 5 micrograms ml-1 min by diltiazem (P < 0.001) and to 35 +/- 5 micrograms ml-1 min by verapamil (P < 0.001). The peak midazolam concentration was doubled (P < 0.01) and the elimination half-life of midazolam prolonged (P < 0.05) by both diltiazem and verapamil treatments. 4. These changes in the pharmacokinetics of midazolam were also associated with profound and prolonged sedative effects. 5. If the administration of midazolam cannot be avoided, the dose of midazolam should be reduced during concomitant treatment with diltiazem and verapamil.     

Inhibition of human monocyte adhesion to endothelial cells by the coumarin derivative, cloricromene.

1. The ability of the coumarin derivative cloricromene (8-monochloro-3-beta-diethylaminoethyl-4-methyl-7-ethoxy- carbonylmethoxycoumarin) to inhibit monocyte adhesion to human cultured umbilical vein endothelial cells (HUVEC) was investigated. 2. Cloricromene (10-200 microM) inhibited, in a concentration-dependent manner, the adhesion of both resting and activated monocytes to HUVEC. Significant inhibition was reached with drug concentrations ranging between 15 to 30 microM. 3. The inhibitory activity was, at least in large part, directed to monocytes since no inhibition was observed after selective preincubation of HUVEC with cloricromene and the drug maintained its effect also on monocyte adhesion to paraformaldehyde-treated HUVEC. 4. Inhibition was maximal after 1 min of exposure of monocytes to cloricromene and persisted even in the absence of the drug. 5. Both basal and chemoattractant-mediated monocyte adhesion was inhibited by cloricromene as it was by TS1/18, a monoclonal antibody (mAb) directed to beta 2 integrins; however, cytofluorimetric analysis showed that cloricromene was unable to modulate the expression of beta 2 integrins on the monocyte surface. 6. When monocyte adhesion was mediated by a large set of adhesive receptors, as obtained after treatment of HUVEC with either interleukin 1 beta (IL-1; 50 ng ml-1) or tumour necrosis factor-alpha (TNF; 100 u ml-1), the inhibitory effect of cloricromene was considerably reduced. 7. The results of this study show that cloricromene may regulate monocyte adhesion to HUVEC, an event relevant in vivo in the pathogenesis of inflammatory and atherosclerotic processes.     

Inhibition of inducible nitric oxide synthase expression by novel nonsteroidal anti-inflammatory derivatives with gastrointestinal-sparing properties.

1. The effects of novel nitric oxide-releasing nonsteroidal anti-inflammatory compounds (NO-NSAIDs) on induction of nitric oxide (NO) synthase by bacterial lipopolysaccharide (LPS) were examined in a murine cultured macrophage cell line, J774. 2. LPS-induced nitrite production was markedly attenuated by the nitroxybutylester derivatives of flurbiprofen (FNBE), aspirin, ketoprofen, naproxen, diclofenac and ketorolac, with each compound reducing accumulated nitrite levels by > 40% at the maximum concentrations (100 micrograms ml-1) used. 3. Further examination revealed that nitrite production was inhibited in a concentration-dependent (1-100 micrograms ml-1) manner by FNBE which at 100 micrograms ml-1 decreased LPS-stimulated levels by 63.3 +/- 8.6% (n = 7). The parent compound flurbiprofen was relatively ineffective over the same concentration-range, inhibiting nitrite accumulation by 24 +/- 0.9% (n = 3) at the maximum concentration used (100 micrograms ml-1). 4. FNBE reduced LPS-induced nitrite production when added to cells up to 4 h after LPS. Thereafter, FNBE caused very little or no reduction in nitrite levels. Furthermore NO-NSAIDs (100 micrograms ml-1) did not inhibit the metabolism of L-[3H]-arginine to citrulline by NO synthase isolated from LPS-activated macrophages. 5. Western blot analysis demonstrated that NO synthase expression was markedly attenuated following co-incubation of J774 cell with LPS (1 microgram ml-1; 24 h) and FNBE (100 micrograms ml-1; 24 h). Thus taken together, these findings indicate that NO-NSAIDs inhibit induction of NO synthase without directly affecting enzyme activity. 6. In conclusion our results indicate that NO-NSAIDs can inhibit the inducible L-arginine-NO pathway, and are capable of suppressing NO synthesis by inhibiting expression of NO synthase. The clinical implications of these findings remain to be established.     

Increased flow-induced ATP release from isolated vascular endothelial cells but not smooth muscle cells.

1. Freshly harvested smooth muscle cells and endothelial cells isolated from the rabbit aorta were perfused (0.5 ml min-1) and stimulated twice by an increase of flow rate (3.0 ml min-1) in order to compare their ability to release adenosine 5'-triphosphate (ATP). 2. In smooth muscle cells, the basal release of ATP (0.0265 +/- 0.0033 pmol ml-1 per 10(6) cells) was not increased during periods of increased flow (P = 0.2). 3. In endothelial cells, the concentration of ATP in the perfusate during periods of low flow (0.0335 +/- 0.0038 pmol ml-1 per 10(6) cells) was significantly increased by 14 times and 5 times during the first and second periods of increased flow, respectively. 4. The release of ATP by endothelial cells did not appear to be caused by the lysis of cells during the period of increased flow because it can be reproduced several times and because there was no difference between lactate dehydrogenase activity in perfused cells and that in non-perfused cells. 5. These results show that, of the two major cell types of the vascular wall, only endothelial cells react to shear stress by releasing ATP.     

Effect of dexamethasone and endogenous corticosterone on airway hyperresponsiveness and eosinophilia in the mouse.

1. Mice were sensitized by 7 intraperitoneal injections of ovalbumin without adjuvant (10 micrograms in 0.5 ml of sterile saline) on alternate days and after 3 weeks exposed to either ovalbumin (2 mg ml-1 in sterile saline) or saline aerosol for 5 min on 8 consecutive days. One day before the first challenge, animals were injected intraperitoneally on a daily basis with vehicle (0.25 ml sterile saline), dexamethasone (0.5 mg kg-1) or metyrapone (30 mg kg-1). 2. In vehicle-treated ovalbumin-sensitized animals ovalbumin challenge induced a significant increase of airway responsiveness to metacholine both in vitro (27%, P < 0.05) and in vivo (40%, P < 0.05) compared to saline-challenged mice. Virtually no eosinophils could be detected after saline challenge, whereas the numbers of eosinophils were significantly increased (P < 0.01) at both 3 and 24 h after the last ovalbumin challenge (5.48 +/- 3.8 x 10(3) and 9.13 +/- 1.7 x 10(3) cells, respectively). Furthermore, a significant increase in ovalbumin-specific immunoglobulin E level (583 +/- 103 units ml-1, P < 0.05) was observed after ovalbumin challenge compared to saline challenge (201 +/- 38 units ml-1). 3. Plasma corticosterone level was significantly reduced (-92%, P < 0.001) after treatment with metyrapone. Treatment with metyrapone significantly increased eosinophil infiltration (17.4 +/- 9.93 x 10(3) and 18.7 +/- 2.57 x 10(3) cells, P < 0.05 at 3 h and 24 h, respectively) and potentiated airway hyperresponsiveness to methacholine compared to vehicle-treated ovalbumin-challenged animals. Dexamethasone inhibited both in vitro and in vivo hyperresponsiveness as well as antigen-induced infiltration of eosinophils (0, P < 0.05 and 0.7 +/- 0.33 x 10(3) cells, P < 0.05 at 3 h and 24 h, respectively). Metyrapone as well as dexamethasone did not affect the increase in ovalbumin-specific immunoglobulin E levels after ovalbumin challenge (565 +/- 70 units/ml-1; P < 0.05; 552 +/- 48 units ml-1, P < 0.05 respectively). 4. From these data it can be concluded that exogenously applied corticosteroids can inhibit eosinophil infiltration as well as airway hyperresponsiveness. Vise versa, endogenously produced corticosteroids play a down-regulating role on the induction of both eosinophil infiltration and airway hyperresponsiveness.     

Plasma metronidazole concentrations after single and repeated vaginal pessary administration.

Metronidazole concentrations in plasma were measured by h.p.l.c. in 12 healthy female volunteers after single and repeated vaginal administration of 500 mg metronidazole pessaries. The area under the plasma concentration-time curve (AUC(0,12 h) was 8.4 +/- 3.9 micrograms ml-1 h (mean +/- s.d.) on day 1 and 20.6 +/- 7.1 micrograms ml-1 h (mean +/- s.d.) on day 5. The peak plasma drug concentration on day 1 was 1.2 +/- 0.6 micrograms ml-1 (mean +/- s.d.) and on day 5 it was 2.0 +/- 0.7 micrograms ml-1 (mean +/- s.d.). The plasma concentration of metronidazole at steady state was above the minimum inhibitory concentration (MIC) for anaerobic Streptococci and Clostridium tetani. These results demonstrate much lower systemic exposure than after oral administration.     

Contrasting effects of fluconazole and ketoconazole on phenytoin and testosterone disposition in man.

Nine healthy male subjects received oral fluconazole 400 mg daily, ketoconazole 200 mg twice daily or no treatment for 6 days according to a randomized, cross-over design. A single 250 mg oral dose of phenytoin suspension was administered on day 5 and serum phenytoin concentrations were measured over the following 48 h. Serum testosterone concentrations were measured for 10 h after each dose of phenytoin. Ketoconazole had no significant effect on phenytoin concentrations while the mean AUC(0,48) for phenytoin was significantly higher with fluconazole (195.2 +/- 47.8 micrograms ml-1 h) than control (146.3 +/- 49.6 micrograms ml-1 h). At 48 h, the serum phenytoin concentration averaged 1.72 micrograms ml-1 under control conditions and 3.99 micrograms ml-1 with fluconazole (132% increase). AUC(0,10) for testosterone was 42% lower than control after ketoconazole administration (P less than 0.05) but increased by 33% from 55.6 +/- 9.4 ng ml-1 h (control) to 73.8 +/- 12.6 ng ml-1 h with fluconazole. AUC(0,10) values for the testosterone precursors androstenedione and 17 alpha-hydroxyprogesterone were significantly higher in the fluconazole treatment phase as were concentrations of luteinizing hormone. The mechanism and clinical significance of the increase in testosterone concentration caused by fluconazole remains to be determined.     

Effect of dehydration and hyperosmolal hydration on lignocaine and metabolites disposition in conscious rabbits.

1. The present study aimed to investigate the effect of dehydration and hyperosmolal hydration on the disposition of lignocaine and two of its metabolites, monoethylglycinexylidide (MEGX) and glycinexylidide (GX). 2. Lignocaine was infused to three groups of conscious rabbits: controls, rabbits previously deprived of water for 48 h and rabbits receiving an infusion of 2.5% NaCl. 3. In dehydrated and hyperosmolal-hydrated rabbits, plasma osmolality was 321 +/- 1 and 313 +/- 1 mOsm kg-1, respectively (P < 0.01 compared to controls, 285 +/- 1 mOsm kg-1). In dehydrated animals, baseline values of plasma arginine vasopressin (AVP) concentrations and plasma renin activity (PRA) were higher than in controls, i.e. 12.4 +/- 1.4 pg ml-1 and 15.4 +/- 1.7 ng AI ml-1 h-1 vs. 3.4 +/- 0.2 pg ml-1 (P < 0.01), and 5.1 +/- 0.6 ng AI ml-1 h-1 (P < 0.01), respectively; atrial natriuretic peptide (ANP) decreased from 55 +/- 11 to 32 +/- 4 pg ml-1 (P < 0.05). Compared to controls, hyperosmolal hydration only increased AVP to 15.5 +/- 0.7 pg ml-1 (P < 0.01). 4. Under both experimental conditions, lignocaine plasma concentrations were almost double (P < 0.01) those in controls, due to a lower systemic clearance, e.g. 54 +/- 3 and 59 +/- 1 vs. 96 +/- 5 ml min-1 kg-1, respectively. Plasma levels of MEGX increased (P < 0.01) only in dehydrated animals, although GX plasma concentrations were augmented (P < 0.01) about three fold in both groups of animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Contribution of intercellular adhesion molecule 1 (ICAM-1) to the pathogenesis of splanchnic artery occlusion shock in the rat.

1. It has been suggested that leukocytes play a key role in the pathogenesis of splanchnic artery occlusion shock. Intercellular adhesion molecule 1 (ICAM-1) is an adhesion molecule of crucial importance in the phenomenon of leukocyte accumulation. 2. We investigated the involvement of ICAM-1 in the pathogenesis of splanchnic artery occlusion shock. Splanchnic artery occlusion (SAO) shock was induced in anaesthetized rats by clamping splanchnic arteries for 45 min. Sham-operated animals were used as controls. Survival time, serum tumour necrosis factor-alpha (TNF-alpha), white blood cell (WBC) count, mean arterial blood pressure, myeloperoxidase activity (MPO; studied as a quantitative means to assess leukocyte accumulation) and the responsiveness to acetylcholine of aortic rings were investigated. SAO shocked rats had a decreased survival time (90 +/- 9.5 min, while sham-shocked rats survived more than 4 h), reduced mean arterial blood pressure, increased serum levels of TNF-alpha (201 +/- 10 mu ml-1) and MPO activity in the ileum (0.15 +/- 0.03 mu x 10(-3) per g tissue) and in the lung (1.9 +/- 0.8 mu x 10(-3) per g tissue), leukopenia and reduced responsiveness to acetylcholine (ACh, 10 nM-10 microM) of aortic rings. 3. Administration of monoclonal antibody raised against rat ICAM-1 significantly increased survival time (225 +/- 9 min), reduced leukopenia and MPO activity both in the ileum (0.031 +/- 0.003 mu x 10(-3) per g tissue) and in the lung 0.23 +/- 0.03 mu x 10(-3) per g tissue), improved the cardiovascular changes and restored the responsiveness to ACh of aortic rings.(ABSTRACT TRUNCATED AT 250 WORDS)     

The influence of cimetidine on the pharmacokinetics of 5-fluorouracil.

The influence of cimetidine pretreatment on the pharmacokinetics of 5-fluorouracil (5FU) has been studied in 15 ambulant patients with carcinoma. Neither pretreatment with a single dose of cimetidine (400 mg) nor with daily treatment at 1000 mg for 1 week altered 5FU pharmacokinetics. Pretreatment with cimetidine for 4 weeks (1000 mg daily) led to increased peak plasma concentrations of 5FU and also area under the plasma concentration-time curve (AUC). The peak plasma concentration after oral 5FU was increased by 74% from 18.7 +/- 4.5 micrograms/ml (mean +/- s.e. mean) to 32.6 +/- 4.4 micrograms/ml (P less than 0.05) and AUC was increased by 72% from 528 +/- 133 micrograms/ml-1 min (mean +/- s.e. mean) to 911 +/- 152 micrograms ml-1 min (P less than 0.05). After intravenous 5FU, AUC was increased by 27% from 977 +/- 96 micrograms ml-1 min (mean +/- s.e. mean) to 1353 +/- 124 micrograms ml-1 min (P less than 0.01). Total body clearance for 5FU following intravenous administration was decreased by 28% from 987 +/- 116 ml/min (mean +/- s.e. mean) to 711 +/- 87 ml/min (P less than 0.01). The elimination half-life of 5FU was not altered by cimetidine. The basis of the interaction between 5FU and cimetidine is uncertain but probably a combination of inhibited drug metabolism and reduced liver blood flow. The therapeutic implications are considerable and additional care should be taken in patients receiving the two drugs concomitantly.     

Dose-dependent pharmacokinetics of zoxazolamine in the rat

Zoxazolamine (ZX) is a model substrate frequently used in studies on (methylcholanthrene-inducible) hepatic cytochrome P-450 activity. The iv pharmacokinetics of ZX were studied in rats at four dose levels: 5 mg X kg-1 (n = 6), 25 mg X kg-1 (n = 6), 50 mg X kg-1 (n = 5), and 60 mg X kg-1 (n = 4). Concentrations of ZX in blood, as well as the urinary excretion of unchanged ZX and chlorzoxazone, were determined. The apparent systemic clearance (CLs,app) decreased with increasing dose from 52.6 +/- 3.9 at 5 mg X kg-1 to 9.3 +/- 0.4 ml X min-1 X kg-1 at 60 mg X kg-1. The apparent elimination half-life, t1/2,app, increased from 16.1 +/- 0.3 min to 141 +/- 28.5 min. There was only slight concentration dependency of plasma protein binding: 86.0 +/- 0.9% at 4.2 +/- 0.2 micrograms X ml-1 (n = 6) vs. 80.4 +/- 0.4% at 27.1 +/- 1.1 micrograms X ml-1 (n = 6). Since from clearance and protein binding data nonrestrictive clearance of ZX could be inferred, this small change in binding was regarded as irrelevant for the interpretation of pharmacokinetic data of ZX. The blood-plasma concentration ratio was larger than unity: 2.11 +/- 0.09 at 5.4 +/- 0.9 micrograms X ml-1, and 1.85 +/- 0.08 at 47.9 +/- 4.9 micrograms X ml-1 (n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)     

Serum drug concentrations after oral administration of paracetamol to patients with surgical resection of the gastrointestinal tract.

Serum concentrations of paracetamol were measured at 30, 60, 120 and 180 min after oral administration of a solution of 1500 mg paracetamol in normal subjects (n = 32) (Group A) and in patients with total gastrectomy (Roux-en-Y reconstruction) (n = 5) (Group B), distal partial gastrectomy (Billroth I reconstruction) (n = 7) (Group C), pylorus preserving pancreatoduodenectomy (Billroth I type reconstruction) (n = 12) (Group D), and short bowel syndrome (n = 5) (Group E). In Group B, the dose was delivery directly into the jejunum 20 cm distal to the duodenojejunal flexure. The highest serum drug concentrations were observed in the 30 min sample in Groups B and C and in the 120 min sample in Groups A, D, and E. Mean (+/- s.d.) concentrations at these times were 18.90 +/- 1.55 micrograms ml-1 (Group B), 12.89 +/- 2.12 micrograms ml-1 (Group C), 11.12 +/- 3.16 micrograms ml-1 (Group A), 9.78 +/- 2.85 micrograms ml-1 (Group D), and 4.89 +/- 1.96 micrograms ml-1 (Group E), respectively. We conclude that in patients with normal intact gastrointestinal tract, most of a dose of oral paracetamol is absorbed from the jejunum distal to the duodenojejunal flexure.     

Induction of L-arginine transport and nitric oxide synthase in vascular smooth muscle cells: synergistic actions of pro-inflammatory cytokines and bacterial lipopolysaccharide.

1. The interactions between pro-inflammatory cytokines and bacterial lipopolysaccharide (LPS) on L-arginine transporter and inducible nitric oxide synthase (iNOS) activities were examined in rat cultured aortic smooth muscle cells. 2. LPS induced a concentration (0.01-100 micrograms ml-1) and time (8-24 h)-dependent stimulation of nitrite production which was accompanied by a parallel increase in L-arginine transport. 3. Unlike LPS, activation of smooth muscle cells with either interferon-gamma (IFN-gamma, 100 u ml-1), tumour necrosis factor-alpha (TNF-alpha, 300 u ml-1) or interleukin-1 alpha (IL-1 alpha, 100 u ml-1) failed to stimulate L-arginine transport or increase nitrite accumulation. 4. When applied in combination with LPS (100 micrograms ml-1) both IFN-gamma and TNF-alpha, but not IL-1 alpha, enhanced the effects observed with LPS alone. Furthermore, activation of cells with LPS and IFN-gamma had no effect on uptake of the neutral amino acid L-citrulline but selectively increased the Vmax for L-arginine transport 2.8 fold and nitrite levels from 24 +/- 7 to 188 +/- 14 pmol micrograms-1 protein 24 h-1. 5. The substrate specificity, Na- and pH-independence of saturable L-arginine transport in both unactivated (K(m) = 44 microM, Vmax = 3 pmol micrograms-1 protein min-1) and activated (K(m) = 75 microM, Vmax = 8.3 pmol micrograms-1 protein min-1) smooth muscle cells were characteristic of the cationic amino acid transport system y+. 6. Cycloheximide (1 microM) abolished induction of L-arginine transport and nitrite accumulation in response to LPS and IFN-gamma. In contrast, the glucocorticoid dexamethasone (10 microM, 24 h) selectively inhibited nitrite production. 7. Our results demonstrate that pro-inflammatory mediators selectively enhance transport of L-arginine under conditions of sustained NO synthesis by vascular smooth muscle cells. In addition, the differential inhibition of iNOS and L-arginine transporter activity by dexamethasone suggests that distinct signalling pathways mediate induction of the cationic transport protein and iNOS. The close coupling between substrate supply and NO production may have important implications in the pathogenesis of several disease states including endotoxin shock.     

Tumour necrosis factor-alpha-induced ICAM-1 expression in human vascular endothelial and lung epithelial cells: modulation by tyrosine kinase inhibitors.

1. Tumour necrosis factor-alpha (TNF alpha) increases the expression of the adhesion molecule intercellular adhesion molecule-1 (ICAM-1) on cultured endothelial and epithelial cells and modulation of this may be important in controlling inflammation. Activation of tyrosine kinase(s) is known to be involved in the signal transduction pathways of many cytokines. In this study we have investigated the effects of the tyrosine kinase inhibitors, ST638, tyrphostin AG 1288 and genistein, on TNF alpha-induced ICAM-1 expression in human alveolar epithelial (A549) and vascular endothelial (EAhy926) cell lines and also normal human lung microvascular endothelial cells (HLMVEC). 2. ICAM-1 expression on cultured cells was determined by a sensitive enzyme-linked immunosorbant assay (ELISA). Endothelial or epithelial monolayers were exposed to increasing doses of TNF-alpha (0.01-10 ng ml-1), in the presence or absence of either ST638 (3-100 microM), AG 1288 (3-100 microM) or genistein (100 microM) and ICAM-1 expression was measured at 4 and 24 h. Control experiments examined the effect of ST638 on phorbol 12-myristate 13-acetate (PMA, 20 ng ml-1, 4 h)-stimulated ICAM-1 and compared it to that of a specific protein kinase C inhibitor, R031-8220 (10 microM). Also, functional consequences of changes in ICAM-1 expression were assessed by measuring adhesion of 111 In-labelled human neutrophils to EAhy926 endothelial and A549 epithelial monolayers treated with TNF alpha, in the presence or absence of ST638. 3. ST638 caused a concentration-dependent reduction in TNF alpha- (0.1-10 ng ml-1)-induced ICAM-1 on EAhy926 endothelial (at 4 h) and A549 epithelial monolayers (at 4 and 24 h). In contrast, ST638 caused a concentration-dependent increase in TNF alpha- (0.1-10 ng ml-1)-induced ICAM-1 on EAhy926 endothelial cells at 24 h. Similar effects were seen with AG 1288 or genistein. ST638 (100 microM) significantly (P < 0.01) inhibited ICAM-1 expression on HLMVEC endothelial cells induced by 0.01 ng ml-1 TNF alpha at 4 or 24 h or 0.1 ng ml-1 at 4 h, but increased ICAM-1 expression induced by 0.1 ng ml-1 TNF alpha at 24 h. ST638 did not significantly change the expression of PMA-stimulated ICAM-1 on either A549 epithelial, EAhy926 or HLMVEC endothelial cells. However, PMA-induced ICAM-1 expression was inhibited by Ro31-8220. Also, treatment of epithelial or endothelial monolayers with TNF alpha and ST638 altered adhesion of human neutrophils to A549 epithelial or EAhy926 endothelial cells in a manner that corresponded to the alteration in ICAM-1 expression. 4. These results show that tyrosine kinase inhibitors alter TNF alpha-induced ICAM-1 expression, but that the cell type, concentration of TNF alpha and time of exposure to this cytokine determine whether expression is decreased or increased by the inhibitor. An increased understanding of the signal transduction pathway(s) involved in TNF alpha-induced ICAM-1 expression on lung epithelial and vascular endothelial cells may be of potential therapeutic value in the treatment of inflammatory disease.