Search PubMedSearch

Biomedical subjects

J W Watson

Publications and source records attributed to J W Watson.

At least 19 recordsLinked to original sources

The effect of the NK1 receptor antagonist CP-99,994 on emesis and c-fos protein induction by loperamide in the ferret.

The site of the anti-emetic action of the neurokinin1 receptor antagonist CP-99,994 was studied in the ferret using the centrally acting opiate receptor agonist loperamide at a dose (0.5 mg/kg s.c.) which induced emesis in all animals tested. CP-99,994 (1 mg/kg, s.c.x2) abolished the emetic response (retching and vomiting) and the behaviours (licking, wet dog shakes, mouth scratching and gagging) induced by loperamide over a 2-h observation period. The enantiomer of this compound CP-100,263 (1 mg/kg, s.c.x2) did not have any significant effect on emesis or related behaviours. Loperamide (0.5 mg/kg s.c.) administration (but not its vehicle) resulted in dense fos-like immunoreactivity (FLI) mainly throughout the rostro-caudal extent of the nucleus tractus solitarius but not the area postrema. Although CP-99,994 (1 mg/kgx2) abolished the loperamide-induced emesis, it did not have any statistically significant effect on FLI in the brainstem. In loperamide and CP-100,263 (1 mg/kg, s.c.x2) treated animals FLI was comparable to that in animals treated with loperamide and CP-99,994. The results from this study taken together with those from previous studies indicate that loperamide exerts its emetic effect via nucleus tractus solitarius dendrites projecting into the area postrema. The lack of significant effect of CP-99,994 on the FLI induced by loperamide in this nucleus suggests that it is acting at a site "deep" in the nucleus tractus solitarius or elsewhere. The marked reduction in behaviours associated with loperamide administration by CP-99,994 provides a preliminary indication that NK1 receptor antagonist (as represented by CP-99,994) may in the clinic have effects on behaviours induced by emetic agents in addition to their previously described effects on retching and vomiting.

Animals

N-carbamoyl analogs of Zafirlukast: potent receptor antagonists of leukotriene D4.

Exploration of the indole nitrogen region of Zafirlukast (1) has uncovered a potent series of cysteinyl leukotriene D4 (LTD4) antagonists. These studies showed that a variety of functionality could be incorporated in this region of the molecule without sacrificing potency. Efforts to exploit this site in order to improve oral efficacy are discussed.

Animals

7-Oxo-4,5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridines as novel inhibitors of human eosinophil phosphodiesterase.

High-throughput file screening against inhibition of human lung PDE4 led to the discovery of 3-ethyl-1-(4-fluorophenyl)-6-phenyl-7-oxo-4, 5,6,7-tetrahydro-1H-pyrazolo[3,4-c]pyridine (11) as a novel PDE4 inhibitor. Subsequent SAR development, using an eosinophil PDE assay, led to analogues up to 50-fold more potent than 11 with IC50 values of 0.03-1.6 microM. One such compound, CP-220,629 (22) (IC50 = 0.44 microM), was efficacious in the guinea pig aerosolized antigen induced airway obstruction assay (ED50 2.0 mg/kg, po) and demonstrated a significant reduction in eosinophil (55%), neutrophil (65%), and IL-1beta (82%) responses to antigen challenge in atopic monkeys (10 mg/kg, po).

Airway Obstruction

The effect of CP-99994 on the responses to provocative motion in the cat.

1. The NK1 receptor antagonist CP-99994 has been shown to prevent vomiting elicited by both peripherally and centrally acting emetogens in ferrets and dogs. These results have now been extended to another stimulus, provocative motion, and another species, the cat. 2. CP-99994 displaced [3H]-substance P from cat cortex with IC50 of 0.52 +/- 0.08 nM. Following s.c. administration, peak plasma drug levels were achieved at 30 min. The plasma drug half life was 1.4 h. 3. Subcutaneous administration of CP-99994 inhibited motion-induced vomiting in the cat with an ED50 of 144 micrograms kg-1 but did not change the epiphenomena associated with provocative motion in the cat over the dose range of 30 to 300 micrograms kg-1. The antiemetic effect of CP-99994 can be attributed to antagonism of the NK1 receptor because its enantiomer, CP-100,263, which is 900 fold weaker as an NK1 antagonist, had no effects on any response to provocative motion. 4. The inhibitory effect of CP-99994 on motion-induced retching and vomiting is consistent with a central site of antiemetic action, potentially at the level of the motor nuclei responsible for these behaviours. 5. An investigation into whether the failure of CP-99994 to alter the epiphenomena will also predict a lack of anti-nausea effects in man will provide critical information on the neural organization of the emetic reflex.

Animals

The phosphodiesterase type 4 (PDE4) inhibitor CP-80,633 elevates plasma cyclic AMP levels and decreases tumor necrosis factor-alpha (TNFalpha) production in mice: effect of adrenalectomy.

Rolipram was previously reported to elevate plasma cyclic adenosine 3',5'-monophosphate (cAMP) and inhibit serum tumor necrosis factor-alpha (TNF-alpha) production in mice. CP-80,633, a new cyclic nucleotide phosphodiesterase (PDE4) inhibitor, has been shown to augment intracellular cAMP levels and to inhibit TNFalpha release from human monocytes in vitro. This study was undertaken to determine the effect of p.o. CP-80,633 on plasma cAMP levels and lipopolysaccharide-induced TNFalpha production in mice with and without adrenal glands. CP-80,633 dose-dependently (3-32 mg/kg p.o.) elevated plasma cAMP levels and decreased systemic TNFalpha production in response to i.p. injection of lipopolysaccharide. Elevated plasma cAMP levels can be detected for up to 4 hr. CP-80,633 (10 mg/kg p.o.) caused a 6-fold increase in the plasma cAMP level, a 2-fold increase in the plasma epinephrine level and a greater than 95% reduction in TNFalpha production. Unlike CP-80,633, neither vinpocetine, dipyridamole, SKB-94,120 nor zaprinast, at 100 mg/kg p.o., modified the cAMP response, which suggests that this response is mediated by inhibition of PDE4. Adrenalectomy reduced the cAMP response and completely blocked the epinephrine response; however, the levels of plasma cAMP in the CP-80,633-treated mice (10 mg/kg p.o.) remained elevated (vehicle: 47.3 +/- 6.8 vs. CP-80,633: 98.4 +/- 10.3 pmol/ml, n = 7, P < .05). This effect is mimicked by treatment of control mice with propranolol, which demonstrates that beta adrenoreceptors contribute to the cAMP response. Removal of adrenal glands significantly increased the LPS-induced elevation of serum TNFalpha. The ability of CP-80,633 to block the TNFalpha response was only slightly affected by adrenalectomy (ED50 = 1.2 mg/kg in controls vs. 3.9 mg/kg in adrenalectomized mice). Taken together, these results show that CP-80,633, when given p.o. to mice, is capable of elevating plasma cAMP and inhibiting TNFalpha production and that adrenal catecholamines contribute significantly to the effect of CP-80,633 on the cAMP response but only slightly to its effect on the systemic TNFalpha response.

3',5'-Cyclic-AMP Phosphodiesterases

Differential in vivo and in vitro bronchorelaxant activities of CP-80,633, a selective phosphodiesterase 4 inhibitor.

CP-80,633, a selective phosphodiesterase (PDE) 4 inhibitor, potently reverses histamine bronchoconstriction in anesthetized guinea pigs (ED50 10 micrograms/kg) but only weakly relaxes histamine-constricted guinea pig trachea (EC50 137 microM). Using CP-80,633 as a prototype PDE4 inhibitor, we evaluated the hypothesis that bronchodilation induced by PDE4 inhibitors is not mediated by direct relaxation of airway smooth muscle. In anesthetized guinea pigs, a bronchodilatory dose of CP-80,633 did not increase plasma catecholamines, nor did propranolol pretreatment significantly alter the ability of CP-80,633 to reverse histamine bronchoconstriction. In an isolated organ system, the activity of bronchorelaxants may be attenuated by the lack of endogenous activators of adenylyl cyclase or by decreased levels of intracellular cyclic nucleotides. Pretreatment with the beta-adrenoceptor agonist, salbutamol, or the PDE3 inhibitor imazodan did not potentiate the bronchorelaxant ability of CP-80,633. Milrinone pretreatment increased the potency of CP-80,633 to relax carbachol-constricted tracheal rings, but only at concentrations where nonspecific effects have been reported. By comparing the bronchorelaxant abilities of PDE inhibitors in tracheal rings with or without epithelium, we determined that the epithelium did not serve as a barrier to drug penetration. In conclusion, CP-80,633 is a potent bronchodilator in vivo, whose activity is neither mediated by direct airway smooth muscle relaxation nor dependent upon endogenous catecholamines.

3',5'-Cyclic-AMP Phosphodiesterases

In vitro and in vivo effects of leukotriene B4 antagonism in a primate model of asthma.

To test the hypothesis that leukotriene (LT) B4 antagonists may be clinically useful in the treatment of asthma, CP-105,696 was evaluated in vitro, using chemotaxis and flow cytometry assays, and in vivo, using a primate asthma model. CP-105,696 inhibited LTB4-mediated monkey neutrophil chemotaxis (isolated cells, LTB4 = 5 nM) and CD11b upregulation (whole blood, LTB4 = 100 nM) with IC50 values of 20 nM and 16.5 microM, respectively. Using a modification of a previously described in vivo protocol (Turner et al. Am. J. Respir. Crit. Care Med. 1994. 149: 1153-1159), we observed that treatment with CP-105,696 inhibited the acute increase in bronchoalveolar lavage (BAL) levels of IL-6 and IL-8 by 56.9 +/- 13.2% and 46.9 +/- 14.5%, respectively, 4 h after challenge with Ascaris suum antigen (Ag). CP-105,696 tended to reduce the increase in BAL protein levels 0.5 h after Ag challenge by 47.5 +/- 18.3%, but this was not statistically significant. In addition, CP-105,696 prevented the significant 11-fold increase in airway responsiveness to methacholine after multiple Ag challenge. These results suggest that LTB4 partially mediates acute and chronic responses to antigen in an experimental primate asthma model and support the clinical evaluation of LTB4 antagonists in human asthma.

Animals

Biarylcarboxylic acids and -amides: inhibition of phosphodiesterase type IV versus [3H]rolipram binding activity and their relationship to emetic behavior in the ferret.

In addition to having desirable inhibitory effects on inflammation, anaphylaxis, and smooth muscle contraction, PDE-IV inhibitors also produce undesirable side effects including nausea and vomiting. In general, compounds that inhibit PDE-IV also potently displace [3H]rolipram from a high-affinity binding site in rat cortex. While this binding site has not been identified, it has been proposed to be an allosteric binding site on the PDE-IV enzyme. Preliminary studies have suggested that the emetic potency of PDE-IV inhibitors is correlated with affinity for the brain rolipram binding site rather than potency at inhibiting PDE-IV enzyme activity. Efforts to eliminate the emetic potential of PDE-IV inhibitors were directed toward developing compounds with decreased [3H]rolipram binding affinity while retaining PDE-IV potency. Thus, a novel series of 4-(3-alkoxy-4-methoxyphenyl)benzoic acids and their corresponding carboxamides were prepared and evaluated for their PDE-IV inhibitory and rolipram binding site properties. Modification of the catechol ether moiety led to phenylbutoxy and phenylpentoxy analogues that provided the desired activity profile. Specifically, 4-[3-(5-phenylpentoxy)-4-methoxyphenyl]-2-methylbenzoic acid, 18, was found to exhibit potent PDE-IV inhibitory activity (IC50 0.41 microM) and possessed 400 times weaker activity than rolipram for the [3H]rolipram binding site. In vivo, compound 18 was efficacious in the guinea pig aerosolized antigen induced airway obstruction assay (ED50 8.8 mg/kg, po) and demonstrated a significant reduction in emetic side effects (ferret, 20% emesis at 30 mg/kg, po).

3',5'-Cyclic-AMP Phosphodiesterases

Characterization of a primate model of asthma using anti-allergy/anti-asthma agents.

The following study was performed to further characterize a primate model of asthma using classes of drugs that target allergy (pyrilamine, cetirizine), are bronchodilators for the treatment of asthma (salbutamol, salmeterol) or are anti-inflammatory (dexamethasone). These drugs were examined for their ability to inhibit acute, antigen-induced bronchoconstriction, the development of airway hyperresponsiveness (AHR) and the infiltration of leukocytes into the lungs of atopic cynomolgus monkeys (Macaca facsicularis) using a 10-day, multiple antigen (Ag) challenge protocol. All compounds except dexamethasone and cetirizine significantly (p < 0.05) reduced acute, Ag-induced bronchoconstriction (salbutamol: 74.2%, salmeterol: 52.6%%, pyrilamine: 62.4% inhibition) compared to vehicle control trials. Only dexamethasone and salmeterol prevented the development of AHR to methacholine challenge by 90.4 +/- 6.81% and 85.7 +/- 5.61% respectively. Dexamethasone significantly reduced the Ag-induced increase in BAL eosinophils by 85.9 +/- 8.53%. Cetirizine reduced the eosinophil response in 5 of 6 monkeys and salmeterol demonstrated a trend towards reduced eosinophil increases after multiple Ag challenge, but neither of these were statistically significant. These results further illustrate the utility of this model in predicting compound effects against several relevant functional endpoints that are consistent with the effects of similar classes of compounds in humans.

Albuterol

The effect of 5-lipoxygenase inhibition on Ascaris antigen (Ag)-induced responses in atopic monkeys.

The effects of two 5-lipoxygenase (5LO) inhibitors, ZD2138 or Zileuton, on acute, inflammatory responses to aerosolized Ascaris suum (Ag) were determined in atopic Macaca fascicularis monkeys. Monkeys (n = 6 each group) were dosed with vehicle, 3 or 10 mg/kg ZD2138, or 30 mg/kg Zileuton (p.o.). Both ZD2138 or Zileuton significantly inhibited ex vivo LTB4 production in Ca2+ ionophore-stimulated whole blood from these same monkeys (n = 6 each group) by 45.5% (3 mg/kg ZD2138), 82.5% (10 mg/kg ZD2138) and 84.3% (30 mg/kg Zileuton). ZD2138 (10 mg/kg) reduced bronchoalveolar lavage (BAL) LTE4 levels (65.1% inhibition), BAL neutrophils (88.9% inhibition), and IL-6 (54.0% inhibition) 4h post Ag. Zileuton inhibited these responses and also reduced BAL levels of IL-8 (73.4% inhibition). A second study was performed to evaluate the effects of ZD2138 on chronic Ag-induced responses. Treatment with ZD2138 did not prevent pulmonary inflammation or the development of airway hyperresponsiveness (AHR). Based upon these results, 5LO inhibition significantly reduced ex vivo LTB4 and in vivo LTE4 production as well as several acute inflammatory responses to Ag in the lung. However, ZD2138 did not inhibit more chronic responses following multiple Ag exposure.

Animals

The in vivo pharmacology of CP-80, 633, a selective inhibitor of phosphodiesterase 4.

The following studies were conducted to characterize the bron-chodilatory and antiinflammatory activity of the novel, selective phosphodiesterase-IV inhibitor, CP-80,633 (2'S)5-[3-(2'-exobicyclo[2.2.1]heptyloxy-4-methoxy-phenyl]te trahydro- 2(1H)-pyrimidone, a compound in clinical development for atopic disease. In IgG1 passively sensitized guinea pigs, aerosolized ovalbumin challenge increases both pulmonary eosinophil peroxidase levels and airway obstruction. CP-80,633, administered before ovalbumin challenge, significantly attenuated both the increase in tissue eosinophil peroxidase levels (ED50 = 1.4 mg/kg, p.o.) and airway obstruction (ED50 = 0.93 +/- 0.14 mg/kg,p.o.) 10 to 30 times more potently than theophyl-line. Intraarterially administered CP-80,633 also reversed an established bronchoconstriction initiated by continuous infusion of histamine to guinea pigs (ED50 of 8.2 micrograms/kg vs. 5.6 mg/kg for theophylline). The antiinflammatory effect of CP-80,633 was also examined in atopic monkeys challenged with Ascaris suum (Ag) aerosol. CP-80,633 (1 mg/kg, qid, s.c., 1 hr before antigen challenge) significantly reduced antigen-induced increases in bronchoalveolar lavage neutrophils (72.8 +/- 15.8% inhibition) and eosinophils (61.1 +/- 5.7% inhibition) 4 hr postchallenge, but did not reduce leukocytes 24 hr postchallenge. CP-80,633 did not inhibit antigen-induced increases in BAL levels of interleukin-1 beta, -6 or -8 as measured by enzyme-linked immunosorbant assay. These results indicate that CP-80,633 possesses bronchodilatory activity in guinea pigs and some antiinflammatory effects in both guinea pigs and monkeys.

3',5'-Cyclic-AMP Phosphodiesterases

In vitro pharmacology of the novel phosphodiesterase type 4 inhibitor, CP-80633.

We present the in vitro pharmacology of a novel adenosine 3'-5' -cyclic monophosphate-specific phosphodiesterase (PDE) type 4 inhibitor, CP-80633 ((2'S)5-[3-(2' -exobicyclo[2.2.1]-heptyloxy)4-methoxyphenyl] tetrahydro-2(1H)-primidone), which has shown efficacy in phase II clinical trials for atopic dermatitis. CP-80633 inhibits PDE4 isozymes (human lung IC50 = 1.27 microM) in the absence of effects on PDE1, PDE2, PDE3 and PDE5 isozymes (IC50 > 100 microM). It exhibits no significant selectivity for any single cloned PDE4A, B, C or D isoform. CP-80633 inhibits adenosine 3'-5'-cyclic monophosphate hydrolysis in partially purified human peripheral blood monocyte cytosol (IC50 = 3.52 microM), eosinophil membrane (IC50 = 1.10 microM) and T cell membrane (IC50 = 2.28 microM) preparations. Inhibition of eosinophil PDE4 adenosine 3'-5'-cyclic mono-phosphate hydrolysis by CP-80,633 occurs in a noncompetitive manner. Unlike theophylline, CP-80,633 is inactive against ratrain adenosine (A1,A2) receptors. Consistent with its action as a PDE4 inhibitor in whole cells, CP-80633 potentiates PGE1 dependent increases in adenosine 3'-5'-cyclic monophosphate levels in human U937 cells, and in human eosinophils, monocytes and T cells (EC200 approximately 1.0 microM). Consequently, CP-80633 inhibits many inflammatory cell functions including 1) human eosinophil superoxide anion production (IC50 < 0.6 microM), 2 C5a-(IC50 = 0.40 microM) and LTB4-(IC50 = 0.20 microM) mediated guinea pig peritoneal eosinophil chemotaxis and 3) lipopolysac-charide-induced tumor necrosis factor-alpha release from human monocytes (IC50 = 0.219 microM). These data clearly demonstrate that CP-80633 is a selective inhibitor of PDE4 isozymes, and support its potential use as a therapeutic agent for a number of inflammatory and immune disorders.

3',5'-Cyclic-AMP Phosphodiesterases

The anti-emetic effects of CP-99,994 in the ferret and the dog: role of the NK1 receptor.

1. The selective NK1 receptor antagonist, CP-99,994, produced dose-related (0.1-1.0 mg kg-1, s.c.) inhibition of vomiting and retching in ferrets challenged with central (loperamide and apomorphine), peripheral (CuSO4) and mixed central and peripheral (ipecac, cisplatin) emetic stimuli. 2. Parallel studies with the enantiomer, CP-100,263 (1 mg kg-1, s.c.), which is > 1,000 fold less potent as a NK1 antagonist, indicated that it was without significant effect against CuSO4, loperamide, cisplatin and apomorphine-induced emesis. Against ipecac, it inhibited both retching and vomiting, expressing approximately 1/10th the potency of CP-99,994. 3. The 5-HT3 receptor antagonist, tropisetron (1 mg kg-1, s.c.) inhibited retching and vomiting to cisplatin and ipecac, but not CuSO4 or loperamide. 4. CP-99,994 (1 mg kg-1, i.v.) blocked retching induced by electrical stimulation of the ventral abdominal vagus without affecting the cardiovascular response, the apnoeic response to central vagal stimulation or the guarding and hypertensive response to stimulation of the greater splanchnic nerves. CP-99,994 (1 mg kg-1, i.v.) did not alter baseline cardiovascular and respiratory parameters and it failed to block the characteristic heart rate, blood pressure and respiratory rate/depth changes in response to i.v. 2-methyl-5-HT challenge (von Bezold-Jarisch reflex). 5. Using in vitro autoradiography, [3H]-substance P was shown to bind to several regions of the ferret brainstem with the density of binding in the nucleus tractus solitarius being much greater than in the area postrema. This binding was displaced by CP-99,994 in a concentration-related manner. 6. In dogs, CP-99,994 (40 micrograms kg-1 bolus and 300 micrograms kg-1 h-1, i.v.) produced statistically significant reductions in vomiting to CuSO4 and apomorphine as well as retching to CuSO4. 7. Together, these studies support the hypothesis that the NK1 receptor antagonist properties of CP-99,994 are responsible for its broad spectrum anti-emetic effects. They also suggest that CP-99,994 acts within the brainstem, most probably within the nucleus tractus solitarius although the involvement of the area postrema could not be excluded.

Animals

Leukotriene D4 receptor antagonism reduces airway hyperresponsiveness in monkeys.

Airway hyperresponsiveness (AHR) and pulmonary inflammation are observations that are consistently associated with asthma and also occur in a well-characterized monkey model of asthma. The following study was performed to determine whether treatment with an LTD4 receptor antagonist, ICI 198,615, could attenuate antigen-induced pulmonary inflammation and AHR in monkeys using the following protocol. On day 0, the PC200 (the concentration of methacholine (MCh) that doubled respiratory system resistance, Rrs) was determined in 6 male, atopic, cynomolgus monkeys, previously characterized in historical control trials (Control #1) as airway hyperresponsive. Bronchoalveolar lavage (BAL) was then performed to determine total and differential leukocyte counts. On days 3, 5 and 7, each monkey received 10 mg/kg ICI 198,615 (im) 30 min prior to Ascaris suum (Ag) aerosol exposures which doubled Rrs. On day 10, the post-Ag PC200 to MCh was determined and BAL was repeated. Five weeks after this trial was complete, a bracketing control trial (Control #2) was performed in which the monkeys were administered vehicle prior to each Ag exposure. In comparison to the response in both control trials, treatment with the LTD4 antagonist significantly (P < 0.05) inhibited the development of AHR and also significantly reduced (P < 0.05) peripheral blood lymphocyte counts after Ag challenge. Treatment with ICI 198,615 reduced the Ag-induced increase in BAL eosinophils, but statistical significance was obtained only when treated animals were compared to Control #1, not Control #2.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

Effects of rolipram on responses to acute and chronic antigen exposure in monkeys.

The following study was performed to test the hypothesis that treatment with rolipram, a specific inhibitor of phosphodiesterase (PDE) IV, should inhibit many pulmonary responses to acute and chronic antigen challenge in atopic monkeys by elevating intracellular cAMP and subsequently inhibiting leukocyte function. Monkeys received subcutaneous injections of either vehicle (2% DMSO) or 10 mg/kg of rolipram 1 h before exposure to Ascaris suum antigen (Ag). Acute responses to Ag, including bronchoconstriction, pulmonary leukocyte infiltration, and cytokine production, were monitored before and 4 h after single Ag aerosol administration. To monitor the effects of rolipram on chronic Ag exposure, a 10-d, multiple-Ag protocol, previously demonstrated to induce airway hyperresponsiveness (AHR) to methacholine (MCh), was performed. Ag exposure increased respiratory system resistance (Rrs) 221.7 +/- 31.88% (n = 5). This increase in Rrs was not significantly altered by rolipram. Rolipram significantly (p < 0.002) increased cAMP levels in bronchoalveolar lavage (BAL) leukocytes 1 h after administration (n = 5). Ag-induced increases in BAL IL-8 and TNF were significantly reduced by rolipram, but IL-1 beta and IL-6 increases were unaffected (n = 9). Ag-induced increases in BAL eosinophils and neutrophils were significantly reduced by rolipram (n = 9). In the multiple-Ag protocol (n = 7), rolipram significantly reduced both the number of BAL eosinophils (p < 0.02) and the development of AHR (p < 0.002). Despite its inability to inhibit acute Ag-induced bronchoconstriction, rolipram was protective against acute and chronic inflammatory responses to Ag and prevented the development of AHR, suggesting that selective PDE-IV inhibition is a relevant target for asthma therapy.

Animals