Ali A. Mustafa

Verapamil enhances the inhibitory effect of diclofenac on the chemiluminescence of human polymorphonuclear leukocytes and carrageenan-induced rat's paw oedema

Diclofenac dose-dependently (1.25, 2.5 and 5 mg/kg, i.p.) inhibited the oedema produced by carrageenan in the rats paw. This anti-inflammatory effect was enhanced by the co-administration of various doses (10, 20, and 30 mg/kg i.p.) of verapamil. Diclofenac or the calcium channel blocker, verapamil, when added separately, inhibited the chemiluminescence (CL) response of isolated human polymorphonuclear leukocytes (PMNs) stimulated by either the soluble agent, phorbol myristate acetate, (PMA) or by particulate opsonized zymosan (OPZ) in a dose-dependent manner. When verapamil was combined with diclofenac, in vitro, the inhibitory effect on PMA or OPZ-induced CL response was synergistic. This inhibitory effect on either diclofenac or verapamil on the isolated PMNs was readily reversible when the PMNs were washed with phosphate buffered saline (PBS). Additionally, diclofenac or verapamil did not significantly affect the viability of PMNs. It is concluded that verapamil enhances the anti-inflammatory effect of diclofenac in vivo and potentiates its inhibitory effect on the CL of isolated human PMNs in vitro.

Natural honey prevents ischaemia-reperfusion-induced gastric mucosal lesions and increased vascular permeability in rats

Objective: It has been proposed that natural honey may contain a ‘sucralfate‐like’ substance. Recent studies have shown that sucralfate affords protection against ischaemia‐reperfusion‐induced injuries in the rat stomach. Therefore, the effect of honey was studied on ischaemia‐reperfusion‐induced gastric lesions, intraluminal bleeding, vascular permeability and non‐protein sulphhydryls (NP‐SH) in the rat stomach. Methods: Rats were subjected to 30min of gastric ischaemia in the presence of 100 mM HCI and reperfusion period of 60min. Intraluminal bleeding was assessed macroscopically and the gastric lesions were graded microscopically under an inverted microscope. Vascular permeability was quantified by measuring spectrophotometrically the extravasated Evans blue dye in the stomach. NP‐SH levels were measured spectrophotometrically. A luminol‐dependent chemiluminescence method was used to assess antioxidant effects of honey in vitro. Results: There were significantly more gastric lesions, more severe intraluminal bleeding, more leakage of Evans blue and depletion of NP‐SH during the reperfusion period as compared to controls. Pre‐treatment with honey (0.078‐0.625 g/kg, orally) or dimethyl sulphoxide (0.02‐0.08g/kg, intraperitoneally) 30min before the ischaemia‐reperfusion dose‐dependently reduced the gastric lesions and intraluminal bleeding and decreased the vascular permeability. Furthermore, honey reversed the ischaemia‐reperfusion‐induced depletion of NP‐SH levels and inhibited the luminol‐dependent chemiluminescence induced in a cell‐free xanthine‐xanthine oxidase system. Conclusion: These results suggest that gastric protection by honey may be a result of its antioxidant effect. It is suggested that this property of honey may be due to the presence of a ‘sucralfate‐like’ substance.

A substance in broad beans (Vicia faba) is protective against experimentally induced convulsions in mice

Vicia faba (VF, broad beans) constitutes a major food item for the River Nile populations. Contrary to tropical Africa, the prevalence rate of epilepsy (0.9-1 per 1000) among schoolchildren of Khartoum Province, Sudan, is lower compared with the rates in Europe and North America. To explore whether broad beans contain any anticonvulsant that can explain this observation, Balb/c mice were either treated with VF extract (0.01 mL/g) or kept as a control. Various doses of strychnine and picrotoxin were used to explore the effect of VF extract on strychnine-sensitive glycine receptors and GABA(A) receptors. Diazepam (DIZ) was used as anticonvulsant. Thin-layer chromatography was run for the extract against phenobarbital, DIZ, and/or glycine. VF extract demonstrated a clear protective effect against strychnine-induced convulsions and death in Balb/c mice. Diazepam (20 mg/kg, intraperitoneally), administered 20 minutes prior to strychnine (0.112 mg/kg, intraperitoneally), increased the survival rate to 66.7% and, when given with VF extract (0.01 mL/g), to 100%. Various doses of DIZ protected against picrotoxin-induced convulsions (40 mg/kg, intraperitoneally) and deaths. Pretreatment of mice with VF extract was not protective. On chromatography, VF extract separated in a manner similar to the glycine spot, and revealed one peak coinciding with, but not identical to that of glycine. The extract of broad beans (VF) protects against convulsions probably through the inhibitory glycine receptors, and may contain a substance that is intimately related to glycine. Further research is needed to substantiate this by directly assessing the binding of the VF extract to the glycine receptors or a change in receptor physiology.

Evaluating the prophylactic potential of zafirlukast against the toxic effects of acetic acid on the rat colon.

The present work was conducted to assess the possible protective effects of zafirlukast against the toxic damage induced by acetic acid in rat colon. Zafirlukast is a potent and selective cysteinyl leukotriene receptor antagonist which is used mainly in the prophylaxis of bronchial asthma. Two doses of zafirlukast were used (40 and 80 mg/kg) dissolved in gum acacia and given either orally or rectally (0.5 ml/kg). Several parameters including, macroscopic score, histopathological and biochemical such as malondialdehyde (MDA), myeloperoxidase (MPO), catalase and reduced glutathione (GSH) levels were measured using standard assay procedures. The study showed that pretreatment with zafirlukast in a dose of 80 mg/kg orally produced a significant decrease in tissue malondialdehyde, myeloperoxidase, and an increase in both reduced glutathione and catalase levels, while there was no significant changes with the rectal route. The 40 mg/kg dose had no significant protective effects when given either orally or rectally. The available data indicate that the inhibition of leukotriene synthesis or action may have a role in inflammatory bowel disease (IBD) as they are considered as important mediators in this condition.

Mechanisms of l-NG-nitro arginine methyl ester-induced antinociception in mice: A role for serotonergic and adrenergic neurons

1. The mechanisms involved in the antinociceptive action of L-NG-nitro arginine methyl ester (L-NAME) were investigated in mice. 2. Intraperitoneal administration of L-NAME produced a dose-dependent antinociception in the tail-flick, hot-plate and phenyl-p-quinone-induced writhing tests. 3. Pretreatment with the catecholamine depletors 6-hydroxydopamine (5 micrograms i.c.v.) or reserpine (5 mg/kg i.p.) or the serotonin synthesis inhibitor, p-chlorophenylalanine methyl ester (200 mg/kg i.p. on 2 consecutive days) resulted in a significant decrease in the antinociceptive effect of L-NAME. 4. Similarly, pretreatment with the selective alpha 1-adrenoceptor antagonist prazonin (2.5 mg/kg, i.p.), or the non-selective alpha-adrenoceptor blocker, phentolamine (5 mg/kg, i.p.) antagonized the antinociceptive effect of L-NAME. 5. However, the administration of the selective alpha 2-adrenoceptor antagonist, idazoxan (2.5 mg/kg i.p.) was without effect. 6. Likewise, pretreatment with the serotonin 5-HT2 receptor blocker, ketanserin (1 mg/kg, i.p.), the D2 dopamine receptor antagonist (+/-) sulpiride (30 mg/kg, i.p.) or the opioid antagonist naloxone (5 mg/kg, i.p.) did not inhibit the antinociceptive effect of L-NAME. 7. These results suggest that L-NAME produces antinociception in the mouse probably by an action on adrenergic and serotonergic synapses.

Ocular neostigmine drops for diagnosing myasthenia gravis

Disclosed is a method for aiding in the diagnosis of myasthenia gravis. Neostigmine, for example one drop of standard intravenous neostigmine solution (2.5 mg/ml) is instilled into each symptomatic or ptotic eye of patients with suspected or probable myasthenia gravis. The patient is later evaluated for possible changes in ptosis. An observable increase of the palpebral fissure height of at least 2 mm, e.g., after 30-60 minutes after neostigmine instillation is considered to be diagnostic.

Bromocriptine-induced hypothermia in Balb/C mice: Its possible mechanism of action

1. Administration of bromocriptine (0.1-2.5 mg/kg, i.p.) to mice produced hypothermia. 2. Pretreatment with the alpha 1-adrenoceptor blocker, prazosin (2.0 mg/kg, i.p.) or the alpha 2-adrenoceptor antagonist yohimbine (2.5 mg/kg, i.p.) had no effect on this response. 3. The inhibitor of catecholamine synthesis, alpha-methyl-p-tyrosine, and the muscarinic antagonist, atropine (10 mg/kg, i.p.) failed to alter the hypothermia. 4. Pretreatment with the dopamine (DA) receptor antagonists haloperidol (0.02 mg/kg, i.p.) or cis-flupenthixol (0.01 mg/kg, i.p.) completely blocked this response while trans-flupenthixol (0.05 mg/kg, i.p.) was inactive. 5. Depletion of 5-HT in the brain by p-chlorophenylalanine reduced the hypothermic response. 6. Similarly, pretreatment with the serotonergic (5-HT) receptor blocker ketanserin (1 mg/kg, i.p.) attenuated the hypothermia and at a dose of 2 mg/kg (i.p.) it completely blocked the hypothermic response. 7. Methysergide (5 mg/kg, i.p.) was also effective in antagonizing the hypothermia. 8. It was concluded that both DA and 5-HT mechanisms are involved in bromocriptine-induced hypothermia in mice.

Effects of zafirlukast on the function of humanpolymorphonuclear neutrophil leukocytes in asthmatic patients: A prospective, controlled, in vitro study

BACKGROUND Reactive oxygen species (ROSS) play an important role in the pathogenesis of asthma, and oxidative stress contributes to the initiation and worsening of inflammatory respiratory disorders (eg, asthma). Thus, antioxidant drugs may have a role in reducing or preventing damage in asthma. OBJECTIVE The aim of the study was to investigate the antioxidant effect of zafirlukast, a leukotriene receptor antagonist, in asthma. METHODS This prospective, controlled, in vitro study was conducted at KingKhalid University Hospital, Riyadh, Saudi Arabia. The generation of ROSS by polymorphonuclear neutrophil leukocytes (PMNs) in patients with mild to moderate asthma (forced expiratory volume in 1 second [FEVI], >70% of the predicted value) and healthy volunteers was assessed using chemiluminescence (CL) with phorbol 12-myristate 13-acetate (PMA) and opsonized zymosan (OPZ) in the presence of different concentrations of zafirlukast (1.25-60 μg/mL). The xanthine/xanthine oxidase (X-XOD) reaction was used to test the scavenging effect of the drug. RESULTS Six asthmatic patients (4 women, 2 men; mean age, 30.8 years; meanFEVI, 82.5% of the predicted value) and 8 healthy volunteers (4 women, 4 men; mean age, 28.8 years) were enrolled. A dose-dependent inhibition of the CL response was observed in both groups. However, patients with asthma required higher concentrations of zafirlukast to achieve an inhibitory effect similar to that in healthy controls. This difference was significant at concentrations of 20 to 60 μg/mL (all, P ≤ 0.05). When PMNs were challenged with OPZ, inhibition was also dose dependent in controls at all concentrations (all, P ≤ 0.05), but the inhibitory effect was not significant in the asthmatic patients at any concentration. The difference in the inhibitory effect between the 2 groups was significant at 30, 40, and 60 μg/mL (P < 0.02, <0.01, and <0.01, respectively). The mean (SEM) viability of the PMNs in the healthy controls was significantly affected only at the highest concentration compared with the control saline dose (86.5% [5.8%] vs 97.0% [8.%]; P < 0.05). No scavenging effect of zafirlukast was found using the X XOD system. Incubating PMA-stimulated cells with zafirlukast (5 and 10 μg/mL) for 10 minutes to 1 hour significantly increased the inhibitory effect of the drug by 15% to 46% (all, P < 0.001). When zafirlukast was tested for reversibility of its inhibitory effect on ROS production, its action was found to be irreversible at a concentration of 30 μg/mL (P < 0.001) and partially reversible at 60 μg/mL compared with the baseline saline control. CONCLUSIONS Zafirlukast inhibited ROS generation by PMNs in a dose-dependentmanner in asthmatic patients and healthy subjects. However, asthmatic patients required much higher concentrations compared with controls. The incubation of the stimulated cells with zafirlukast increased the inhibitory effect. This finding suggests that the therapeutic effect of zafirlukast in asthma may be in part related to its antioxidant action.

Differential effects of fluoxetine on isoprenaline-stimulated water intake in ethanol-treated rats: a role for β-adrenoceptors

We examined the effects of subchronic (4 days) administration of the 5-hydroxytryptamine (5-HT) re-uptake inhibitors, fluoxetine, fluvoxamine and zimelidine and the noradrenaline-uptake inhibitor, desipramine, on isoprenaline-induced water drinking in rats treated with ethanol. These rats demonstrated significant increases in water drinking as compared to control rats that had received only i.p. injections of distilled water (P < 0.01). Administration of fluoxetine (5-20 mg/kg daily i.p., for 4 days) dose-dependently decreased water intake as compared to that of rats treated with ethanol only. In contrast, fluvoxamine, zimelidine (10 mg/kg i.p.) and desipramine (5 mg/kg i.p.) produced no significant effects on water intake. Pretreatment of animals with spiperone, methysergide, ritanserin, zacopride and BRL 43694A, together with fluoxetine, failed to reverse the inhibitory effect of the latter on isoprenaline-stimulated water intake. The results of the present study indicate that the action of fluoxetine on isoprenaline-stimulated water drinking in ethanol-treated rats may be mediated by an action on beta-adrenoceptors.