A selective α2 B adrenoceptor agonist (A-1262543) and duloxetine modulate nociceptive neurones in the medial prefrontal cortex, but not in the spinal cord of neuropathic rats.

BACKGROUND: The noradrenergic system contributes to pain modulation, but the roles of its specific adrenoceptors are still being defined. We have identified a novel, potent (rat EC50 = 4.3 nM) and selective α2B receptor agonist, A-1262543, to further explore this adrenoceptor subtype's contribution to pathological nociception. METHODS: Systemic administration of A-1262543 (1-10 mg/kg, intraperitoneal) dose-dependently attenuated mechanical allodynia in animals with a spinal nerve ligation injury. To further explore its mechanism of action, the activity of nociceptive neurones in the spinal cord and medial prefrontal cortex (mPFC) were examined after injection of 3 mg/kg of A-1262543 (intravenous, i.v.). These effects were compared with duloxetine (3 mg/kg, i.v.), a dual noradrenaline (NA) and serotonin (5-HT) reuptake inhibitor. RESULTS: Systemic administration of A-1262543 or duloxetine did not alter the spontaneous or evoked firing of spinal wide dynamic range and nociceptive-specific neurones in the neuropathic rats, indicating that neither compound engaged spinal, peripheral or descending pathways. In contrast to the lack of effect on spinal neurones, both A-1262543 and duloxetine reduced the evoked and spontaneous firing of 'pain-responsive' (PR) neurones in the mPFC. Duloxetine, but not A-1262543, also inhibited the firing of pain non-responsive (nPR) neurones in the mPFC probably reflecting duloxetine's contribution to modulating non-pain endpoints. CONCLUSIONS: These data highlight that activation of the α2B adrenoceptor as well as inhibiting NA and 5-HT reuptake can result in modulating the ascending nociceptive system, and in particular, dampening the firing of PR neurones in the mPFC.

Age-Related Resistance to Phytophthora Fruit Rot in 'Dickenson Field' Processing Pumpkin and 'Golden Delicious' Winter Squash Fruit.

Phytophthora fruit rot, caused by Phytophthora capsici, is a major constraint to cucurbit production for the processing industry in Michigan. Age-related resistance to Phytophthora fruit rot has been identified in pepper and some cucurbit fruit. In this study, 'Dickenson Field' processing pumpkin (Cucurbita moschata) and 'Golden Delicious' winter squash (C. maxima) were evaluated for age-related resistance to Phytophthora fruit rot. Hand-pollinated fruit were harvested 3, 7, 10, 14, 21, 28, 42, or 56 days post pollination (dpp), and inoculated with P. capsici isolate 12889. Susceptibility to Phytophthora fruit rot decreased with fruit age in Dickenson Field processing pumpkin, whereas Golden Delicious winter squash remained susceptible to fruit rot even as fruit reached full physiological maturity. Less than 15% of Dickenson Field fruit 21 dpp or older became diseased. Conversely, about 80% of Golden Delicious fruit 21 dpp or older became diseased. Lesion diameter and pathogen growth density ratings differed significantly (P < 0.0001) among fruit ages for both cultivars, and were negatively correlated (ρ = -0.37 to -0.87) with fruit age. Lesion diameter and pathogen growth were generally greater on younger fruit than older fruit. Lesion diameter was greatest on 7- and 10-dpp-old fruit of Dickenson Field and Golden Delicious, respectively. Pathogen growth density ratings were greatest on 3-dpp-old fruit of both cultivars. Several morphological and physiological changes were observed as fruit matured. Soluble solids content and exocarp firmness of both cultivars increased with fruit age. Lesion diameter and pathogen growth density ratings were negatively correlated (ρ = -0.29 to -0.73) with soluble solids content and exocarp firmness.

Using Soil-Applied Fungicides to Manage Phytophthora Crown and Root Rot on Summer Squash.

Phytophthora crown and root rot (Phytophthora capsici) of summer squash is especially difficult to manage because all commercial cultivars are highly susceptible to P. capsici. Producers have traditionally relied on foliar fungicide applications to control Phytophthora crown and root rot despite their limited efficacy. Soil fungicide applications, including via subsurface drip chemigation, have recently gained interest as a method of improving control of P. capsici infections. In this study, soil drenches and foliar applications of 11 fungicides were compared for control of Phytophthora crown and root rot of summer squash in replicated field and greenhouse trials. Fungicides were applied at 7-day intervals. Incidence (%) of plant death was assessed from 7 to 42 days post inoculation (dpi) in field trials. Crown rot severity was rated on a scale of 1 (no wilting) to 5 (plant death) from 5 to 21 dpi in greenhouse trials. Results of field and greenhouse trials were similar. Plant death of 'Cougar' following inoculation with P. capsici isolate 12889 occurred at all growth stages from first true-leaf to full maturity in field trials. Plant death 42 dpi differed significantly (P ≤ 0.0001) among fungicides and application methods. The fungicide-application method interaction also was significant. Some fungicides were ineffective regardless of application method. In general, soil drenches were more effective than foliar applications at limiting plant death but no treatment completely controlled disease symptoms. Mean plant death 42 dpi was 41% for soil drenches and 92% for foliar sprays. Drenches of fluopicolide, mandipropamid, or dimethomorph limited plant death to ≤10% and prevented yield loss associated with root and crown rot. Foliar applications generally did not reduce plant death compared with the untreated, inoculated control, and were unable to prevent yield loss in field trials. In greenhouse trials, crown rot severity differed significantly (P ≤ 0.0001) among fungicides, application methods, and cultivars when plants were inoculated with P. capsici isolate 12889 or SP98. Crown rot was less severe and disease progress was slower following soil drenches than foliar applications. Some fungicide treatments were more effective on 'Leopard,' which was less susceptible to P. capsici than 'Cougar.' Soil application methods, including soil drench and drip chemigation, should be evaluated when fungicides are registered for soilborne disease control, because these methods provide better control of Phytophthora crown and root rot than foliar application.

Influence of Host Resistance on Stewart's Wilt Forecasts and Probability of Exceeding Thresholds for Use of Seed-Treatment Insecticides on Sweet Corn.

Many sweet corn (Zea mays) hybrids commercially available today have higher levels of resistance to Stewart's disease (caused by Pantoea stewartii subsp. stewartii) than the cultivars from which Stevens developed the first forecast of this disease in the 1930s. Incorporating levels of host resistance into forecasts of the seedling wilt phase of Stewart's disease (i.e., Stewart's wilt) could improve control decisions for sweet corn which are made prior to planting. Incidence of systemic infection of seedlings was assessed on 27 sweet corn hybrids with a range of reactions to P. stewartii. In total, 741 observations were collected from 1998 to 2009 in 79 field trials at 15 locations throughout Illinois and one each in Kentucky and Delaware. Relative frequency distributions of the incidence of systemic Stewart's wilt were developed for combinations of hybrids with different levels of resistance and ranges of winter temperature from Stewart's wilt forecasts. The probability of exceeding thresholds of 1 or 5% incidence that warrant the use of seed-treatment insecticides on sweet corn grown for fresh market or processing, respectively, was determined from these frequency distributions. Levels of host resistance affected the incidence of systemic seedling wilt within ranges of winter temperatures used by Stewart's wilt forecasts. For moderate and resistant hybrids, frequency distributions of Stewart's wilt incidence and mean incidence ranging from 0.7 to 1.8% did not differ among three winter temperature ranges above -2.8°C. Conversely, distributions of Stewart's wilt incidence on susceptible hybrids differed among each of the four ranges of winter temperature from the Stevens-Boewe forecast (i.e., >0.6, -1.1 to 0.6, -2.8 to -1.1, and <-2.8°C), with mean incidence ranging from 0.5 to 8.5%. Occurrence of Stewart's wilt also differed among trials varying in number of winter months above -4.4°C, the criterion used by the Iowa State forecast of this disease. Levels of host resistance to P. stewartii also affected the occurrence of Stewart's wilt as predicted by the Iowa State method. The probability of exceeding economic thresholds of 1 or 5% incidence of systemic Stewart's wilt depended on levels of host resistance and winter temperature. Stewart's wilt is unlikely to exceed economic thresholds when the mean winter temperature is below -4.4°C. When mean winter temperature was above -2.8°C, the probability of exceeding 1% incidence of systemic Stewart's wilt was 0.59 for susceptible sweet corn hybrids and 0.28 for moderate and resistant hybrids. When mean winter temperature was below -2.8°C, the probability of exceeding 1% incidence of systemic Stewart's wilt was 0.22 for susceptible hybrids and 0.04 for moderate or resistant sweet corn hybrids. The probability of exceeding 5% incidence was less than 0.1, except when the mean winter temperature was above -2.8°C and susceptible hybrids were grown.

Increased Severity of Foliar Diseases of Sweet Corn Infected with Maize Dwarf Mosaic and Sugarcane Mosaic Viruses.

Maize dwarf mosaic (MDM), caused by Maize dwarf mosaic virus (MDMV) and Sugarcane mosaic virus (SCMV), is an economically important viral disease of sweet corn (Zea mays). MDM is known to increase the severity of fungal root rots and southern corn leaf blight (SCLB). The effect of infection with MDMV-A and SCMV on eight foliar diseases was evaluated on 32 sweet corn hybrids (27 MDM-susceptible hybrids and five MDM-resistant hybrids) in 2007, 2008, and 2009. Virus infection substantially increased the severity of five diseases, including: SCLB, northern corn leaf spot (NCLS), gray leaf spot (GLS), Diplodia leaf streak (DLS), and eyespot. Among MDM-susceptible hybrids, mean severity of SCLB, NCLS, GLS, DLS, and eyespot on virus-infected plants was typically double that of plants that were asymptomatic of viral infection. Three diseases were not substantially increased by MDM, including: common rust, northern corn leaf blight (NCLB), and Stewart's wilt. Virus infection appeared to affect the severity of diseases caused by necrotrophic foliar fungi that colonize mesophyll tissue. MDM did not appear to substantially affect the severity of diseases caused by pathogens that form haustoria or invade the vascular system. The extent to which SCLB severity is increased by MDM in terms of changes in level of host resistance also was determined. For MDM-susceptible hybrids, reactions to SCLB ranged from resistant to moderately susceptible in MDM-free treatments, but each of these hybrids was classified as moderately susceptible to susceptible when infected with MDMV-A and/or SCMV. The results of this experiment demonstrate the importance of breeding for MDM resistance, not only to control this important viral disease of sweet corn, but also to lower the potential for detrimental effects from several other foliar diseases that often are of minor importance on sweet corn in the absence of MDM.

Peripheral and central sites of action for the non-selective cannabinoid agonist WIN 55,212-2 in a rat model of post-operative pain.

BACKGROUND AND PURPOSE: Activation of cannabinoid (CB) receptors decreases nociceptive transmission in inflammatory or neuropathic pain states. However, the effects of CB receptor agonists in post-operative pain remain to be investigated. Here, we characterized the anti-allodynic effects of WIN 55,212-2 (WIN) in a rat model of post-operative pain. EXPERIMENTAL APPROACH: WIN 55,212-2 was characterized in radioligand binding and in vitro functional assays at rat and human CB(1) and CB(2) receptors. Analgesic activity and site(s) of action of WIN were assessed in the skin incision-induced post-operative pain model in rats; receptor specificity was investigated using selective CB(1) and CB(2) receptor antagonists. KEY RESULTS: WIN 55,212-2 exhibited non-selective affinity and agonist efficacy at human and rat CB(1) versus CB(2) receptors. Systemic administration of WIN decreased injury-induced mechanical allodynia and these effects were reversed by pretreatment with a CB(1) receptor antagonist, but not with a CB(2) receptor antagonist, given by systemic, intrathecal and supraspinal routes. In addition, peripheral administration of both CB(1) and CB(2) antagonists blocked systemic WIN-induced analgesic activity. CONCLUSIONS AND IMPLICATIONS: Both CB(1) and CB(2) receptors were involved in the peripheral anti-allodynic effect of systemic WIN in a pre-clinical model of post-operative pain. In contrast, the centrally mediated anti-allodynic activity of systemic WIN is mostly due to the activation of CB(1) but not CB(2) receptors at both the spinal cord and brain levels. However, the increased potency of WIN following i.c.v. administration suggests that its main site of action is at CB(1) receptors in the brain.

A CB(2) receptor agonist, A-836339, modulates wide dynamic range neuronal activity in neuropathic rats: contributions of spinal and peripheral CB(2) receptors.

We investigated the systemic and site-specific actions of a selective CB(2) receptor agonist, A-836339 on mechanically evoked (10 g von Frey hair) and spontaneous firing of spinal wide dynamic range (WDR) neurons in neuropathic (L5 and L6 ligations) and sham rats. Systemic administration of A-836339 (0.3-3 micromol/kg, i.v.) reduced both evoked and spontaneous WDR neuronal activity in neuropathic, but not sham rats. The effects in neuropathic rats were blocked by pre-administration of a CB(2), but not a CB(1), receptor antagonist. Similar to systemic delivery, intra-spinal injection of A-836339 (0.3 and 1 nmol) also attenuated both von Frey-evoked and spontaneous firing of WDR neurons in neuropathic rats. Intra-spinal injections of A-836339 were ineffective in sham rats. Application of A-836339 (3-30 nmol) onto the ipsilateral L5 dorsal root ganglion (DRG) of neuropathic rats reduced the von Frey-evoked activity of WDR neurons, but spontaneous firing was unaltered. All effects of A-836339 on WDR neuronal activity following either intra-spinal or intra-DRG administration were blocked by pre-administration of a CB(2) receptor antagonist. Pre-administration of a CB(1) receptor antagonist did not alter the site-specific effects of A-836339. Injection of A-836339 (300 nmol) into the neuronal receptive field on the ipsilateral hind paw did not affect evoked or spontaneous firing of WDR neurons. Thus, the current data demonstrate that modulation of spinal neuronal activity by a CB(2) receptor agonist is enhanced following peripheral nerve injury, and further delineate the contribution of spinal and peripheral CB(2) receptors to this modulation.

First Report of Phomopsis Stem Canker of Sunflower in Illinois Caused by Phomopsis helianthi.

Stem cankers were observed on confection sunflower (Helianthus annuus) plants growing in a field in Champaign County, Illinois in August 2008. Lesions were brown to reddish brown, elongated (approximately 10 to 15 cm long), and centered over the area where leaf petioles connected to the stems. Stem tissues underneath the lesions were degraded. Lesions from diseased stems were cut into 5- to 7-mm pieces and immersed in a 0.5% NaOCl solution for 1 min, rinsed with sterilized distilled water, and placed into petri dishes containing acidified potato dextrose agar (APDA; 4 ml of 25% lactic acid per liter). Fungal colonies that grew from the stem lesion pieces on APDA were white, floccose, and dense with dark colored substrate mycelia. On the basis of the symptoms on sunflower plants and the growth characteristics on APDA, the fungus was tentatively identified as Phomopsis helianthi (1). To confirm the identity of the fungus, PCR amplification of the small subunit rDNA and internal transcribed spacer (ITS) region with primers EF3RCNL and ITS4 was done (2). The PCR product was sequenced with these primers at the Keck Biotechnology Center at the University of Illinois, Urbana. The resulting nucleotide sequence was compared with small subunit rDNA and ITS sequences deposited in the nucleotide database ( http://www.ncbi.nlm.nih.gov ) and showed highest homology to sequences of Diaporthe helianthi, teleomorph of P. helianthi. To confirm pathogenicity of the fungus, sunflower plants (cv. Cargill 270) were grown in the greenhouse and inoculated with the isolated fungus. The stems of sunflower plants between the V2 and V4 growth stages (3) were excised just below the uppermost node. Mycelia plugs of the fungus were placed into the large end of disposable micropipette tips (200 µl). The micropipette tip containing the fungus was subsequently placed over a cut sunflower stem. The fungal isolate was used to inoculate five stems. To serve as controls, five cut sunflower stems were inoculated with micropipette tips containing plugs of noninfested PDA and five cut stems were not inoculated. Mean lesion length on the stem was measured from the inoculated tip toward the soil line 7 days after inoculation. The experiment was replicated over time. Mean lesion length over both replications averaged 24 mm on the fungus-inoculated plants, 2 mm on the noninfested PDA-inoculated control plants, and no lesions were present on the noninoculated control plants. The fungus was reisolated on PDA from the inoculated plants in the greenhouse. To our knowledge, this is the first report of P. helianthi causing a stem canker of sunflower in Illinois. Although commercial sunflower production in Illinois is currently limited, it is being evaluated as a potential crop to follow winter wheat in portions of the state. If sunflower production were to increase in the state, growers may have to monitor for and manage Phomopsis stem canker. References: (1) T. Gulya et al. Sunflower diseases. Page 263 in: Sunflower Technology and Production. American Society of Agronomy, Madison, WI, 1997. (2) N. S. Lord et al. FEMS Microbiol. Ecol. 42:327, 2002. (3) A. A. Schneiter and J. F. Miller, Crop Sci. 21:901, 1981.

alpha7 nicotinic acetylcholine receptor agonist properties of tilorone and related tricyclic analogues.

BACKGROUND AND PURPOSE: The alpha7 nicotinic acetylcholine receptor (nAChR) has attracted considerable interest as a target for cognitive enhancement in schizophrenia and Alzheimer's Disease. However, most recently described alpha7 agonists are derived from the quinuclidine structural class. Alternatively, the present study identifies tilorone as a novel alpha7-selective agonist and characterizes analogues developed from this lead. EXPERIMENTAL APPROACH: Activity and selectivity were determined from rat brain alpha7 and alpha4beta2 nAChR binding, recombinant nAChR activation, and native alpha7 nAChR mediated stimulation of ERK1/2 phosphorylation in PC12 cells. KEY RESULTS: Tilorone bound alpha7 nAChR (IC(50) 110 nM) with high selectivity relative to alpha4beta2 (IC(50) 70 000 nM), activated human alpha7 nAChR with an EC(50) value of 2.5 microM and maximal response of 67% relative to acetylcholine, and showed little agonist effect at human alpha3beta4 or alpha4beta2 nAChRs. However, the rat alpha7 nAChR maximal response was only 34%. Lead optimization led to 2-(5-methyl-hexahydro-pyrrolo[3,4-c]pyrrol-2-yl)-xanthen-9-one (A-844606) with improved binding (alpha7 IC(50) 11 nM, alpha4beta2 IC(50)>30 000 nM) and activity at both human and rat alpha7 nAChR (EC(50)s 1.4 and 2.2 microM and apparent efficacies 61 and 63%, respectively). These compounds also activated native alpha7 nAChR, stimulating ERK1/2 phosphorylation in PC12 cells. CONCLUSIONS AND IMPLICATIONS: Tilorone, known as an interferon inducer, is a selective alpha7 nAChR agonist, suggesting utility of the fluorenone pharmacophore for the development of alpha7 nAChR selective agonists. Whether alpha7 stimulation mediates interferon induction, or whether interferon induction may influence the potential anti-inflammatory properties of alpha7 nAChR agonists remains to be elucidated.

Differential effects of cannabinoid receptor agonists on regional brain activity using pharmacological MRI.

BACKGROUND AND PURPOSE: Activation of cannabinoid CB1 and/or CB2 receptors mediates analgesic effects across a broad spectrum of preclinical pain models. Selective activation of CB2 receptors may produce analgesia without the undesirable psychotropic side effects associated with modulation of CB1 receptors. To address selectivity in vivo, we describe non-invasive, non-ionizing, functional data that distinguish CB1 from CB2 receptor neural activity using pharmacological MRI (phMRI) in awake rats. EXPERIMENTAL APPROACH: Using a high field (7 T) MRI scanner, we examined and quantified the effects of non-selective CB1/CB2 (A-834735) and selective CB2 (AM1241) agonists on neural activity in awake rats. Pharmacological specificity was determined using selective CB1 (rimonabant) or CB2 (AM630) antagonists. Behavioural studies, plasma and brain exposures were used as benchmarks for activity in vivo. KEY RESULTS: The non-selective CB1/CB2 agonist produced a dose-related, region-specific activation of brain structures that agrees well with published autoradiographic CB1 receptor density binding maps. Pretreatment with a CB1 antagonist but not with a CB2 antagonist, abolished these activation patterns, suggesting an effect mediated by CB1 receptors alone. In contrast, no significant changes in brain activity were found with relevant doses of the CB2 selective agonist. CONCLUSION AND IMPLICATIONS: These results provide the first clear evidence for quantifying in vivo functional selectivity between CB1 and CB2 receptors using phMRI. Further, as the presence of CB2 receptors in the brain remains controversial, our data suggest that if CB2 receptors are expressed, they are not functional under normal physiological conditions.

In vitro and in vivo characterization of A-796260: a selective cannabinoid CB2 receptor agonist exhibiting analgesic activity in rodent pain models.

BACKGROUND AND PURPOSE: Selective cannabinoid CB2 receptor agonists have demonstrated analgesic activity across multiple preclinical pain models. AM1241 is an indole derivative that exhibits high affinity and selectivity for the CB2 binding site and broad spectrum analgesic activity in rodent models, but is not an antagonist of CB2 in vitro functional assays. Additionally, its analgesic effects are mu-opioid receptor-dependent. Herein, we describe the in vitro and in vivo pharmacological properties of A-796260, a novel CB2 agonist. EXPERIMENTAL APPROACH: A-796260 was characterized in radioligand binding and in vitro functional assays at rat and human CB1 and CB2 receptors. The behavioural profile of A-796260 was assessed in models of inflammatory, post-operative, neuropathic, and osteoarthritic (OA) pain, as well as its effects on motor activity. The receptor specificity was confirmed using selective CB1, CB2 and mu-opioid receptor antagonists. KEY RESULTS: A-796260 exhibited high affinity and agonist efficacy at human and rat CB2 receptors, and was selective for the CB2 vs CB1 subtype. Efficacy in models of inflammatory, post-operative, neuropathic and OA pain was demonstrated, and these activities were selectively blocked by CB2, but not CB1 or mu-opioid receptor-selective antagonists. Efficacy was achieved at doses that had no significant effects on motor activity. CONCLUSIONS AND IMPLICATIONS: These results further confirm the therapeutic potential of CB2 receptor-selective agonists for the treatment of pain. In addition, they demonstrate that A-796260 may be a useful new pharmacological compound for further studying CB2 receptor pharmacology and for evaluating its role in the modulation of pain.

In vitro pharmacological characterization of AM1241: a protean agonist at the cannabinoid CB2 receptor?

BACKGROUND AND PURPOSE: The CB2 receptor has been proposed as a novel target for the treatment of pain, and CB2 receptor agonists defined in in vitro assays have demonstrated analgesic activity in animal models. Based on its in vivo analgesic efficacy, AM1241 has been classified as a CB2-selective agonist. However, in vitro characterization of AM1241 in functional assays has not been reported. EXPERIMENTAL APPROACH: In this study, AM1241 was characterized across multiple in vitro assays employing heterologous recombinant receptor expression systems to assess its binding potencies at the human CB2 and CB1 receptors and its functional efficacies at the human CB2 receptor. KEY RESULTS: AM1241 exhibited distinct functional properties depending on the assay conditions employed, a unique profile in contrast to those of the agonist CP 55,940 and the inverse agonist SR144528. AM1241 displayed neutral antagonist activities in FLIPR and cyclase assays. However, when cyclase assays were performed using lower forskolin concentrations for stimulation, AM1241 exhibited partial agonist efficacy. In addition, it behaved as a partial agonist in ERK (or MAP) kinase assays. CONCLUSIONS AND IMPLICATIONS: The unusual phenomenon of inconsistent functional efficacies suggests that AM1241 is a protean agonist at the CB2 receptor. We postulate that functional efficacies displayed by protean agonists in various assay systems may depend on the levels of receptor constitutive activities exhibited in the assay systems, and therefore, efficacies observed in in vitro assays may not predict in vivo activities.

Acetabular dysplasia after treatment for developmental dysplasia of the hip. Implications for secondary procedures.

Untreated acetabular dysplasia following treatment for developmental dysplasia of the hip (DDH) leads to early degenerative joint disease. Clinicians must accurately and reliably recognise dysplasia in order to intervene appropriately with secondary acetabular or femoral procedures. This study sought early predictors of residual dysplasia in order to establish empirically-based indications for treatment. DDH treated by closed or open reduction alone was reviewed. Residual hip dysplasia was defined according to the Severin classification at skeletal maturity. Future hip replacement in a subset of these patients was compared with the Severin classification. Serial measurements of acetabular development and subluxation of the femoral head were collected, as were the age at reduction, type of reduction, and Tonnis grade prior to reduction. These variables were used to predict the Severin classification. The mean age at reduction in 72 hips was 16 months (1 to 46). On the final radiograph, 47 hips (65%) were classified as Severin I/II, and 25 as Severin III/IV (35%). At 40 years after reduction, five of 43 hips (21%) had had a total hip replacement (THR). The Severin grade was predictive for THR. Early measurements of the acetabular index (AI) were predictive for Severin grade. For example, an AI of 35 degrees or more at two years after reduction was associated with an 80% probability of becoming a Severin grade III/IV hip. This study links early acetabular remodelling, residual dysplasia at skeletal maturity and the long-term risk of THR. It presents evidence describing the diagnostic value of early predictors of residual dysplasia, and therefore, of the long-term risk of degenerative change.

Structure-activity studies for a novel series of bicyclic substituted hexahydrobenz[e]isoindole alpha1A adrenoceptor antagonists as potential agents for the symptomatic treatment of benign prostatic hyperplasia.

In search of a uroselective alpha1A subtype selective antagonist, a novel series of 6-OMe hexahydrobenz[e]isoindoles attached to a bicyclic heterocyclic moiety via a two-carbon linker was synthesized. It was found that in contrast to the previously described series of tricyclic heterocycles,(1) this bicyclic series has very specific requirements for the heterocyclic attachments. The most important structural features contributing to the alpha1A/alpha1B selectivity of these compounds were identified. In vitro functional assays for the alpha1 adrenoceptor subtypes were used to further characterize the most selective compounds, and in vivo models of vascular vs prostatic tone were used to assess uroselectivity. Compound 48 showed the highest degree of selectivity in the radioligand binding assays (56-fold), in the in vitro functional tests (80-fold), and for in vivo prostate selectivity (960-fold).

Two novel and potent 3-[(o-methoxyphenyl)piperazinylethyl]-5-phenylthien.

The synthesis and in vitro characterization of A-119637 and A-123189, two novel, selective and potent alpha1D antagonists, are described.

Pharmacological properties of A-204176, a novel and selective alpha1A adrenergic agonist, in in vitro and in vivo models of urethral function.

A-204176 (N-[5-(1H-imidazol-4-y1)-5,6,7,8-tetrahydro-1-naphthalenyl]methanesulfonamide) is a potent and selective alpha1A adrenoceptor agonist that binds with 17-fold and 9-fold greater affinity to the alpha1A (Ki=176 nM) than the alpha1b and alpha1d subtypes, respectively. In functional studies A-204176 is potent (pD2=6.4) and efficacious (83% of maximum control phenylephrine response) at rabbit urethra alpha1A receptors, with weaker potency and greatly reduced efficacy at rat spleen alpha1B (pD2=5.3, 11%) and rat aorta alpha1D (pD2=4.4, 10%) subtypes. In anesthetized female dogs, A-204176 is more potent than the non-selective alpha1 adrenoceptor agonist phenylpropanolamine (PPA) to increase measures of urethral tone and is more efficacious to increase pressure in the proximal region of the urethra. Significant increases on parameters of the urethral pressure profilometry were induced at 100 and 300 nmol/kg, i.v., by A-204176 and PPA, respectively. A-204176 was more potent than PPA to increase the abdominal pressure required to produce leakage. In the simultaneous measurement of intraurethral pressure and mean arterial blood pressure, A-204176 displays enhanced urethral selectivity relative to PPA. However, despite its selectivity for alpha1A versus alpha1B and alpha1D adrenoceptors in vitro, A-204176 did not display the degree of urethral selectivity in vivo that would have been expected. The observed effect of A-204176 on blood pressure may be due to the presence of extra-synaptic alpha1A adrenoceptors in the vasculature or to activation of spinal and supraspinal alpha1A adrenoceptors. These data indicate that A-204176 may represent a useful pharmacological tool to investigate the functional role of the alpha1A adrenoceptor in the urethra and to elucidate the lack of uroselectivity observed in vivo.

The therapeutic potential of nicotinic acetylcholine receptor agonists for pain control.

Due to the limitations of currently available analgesics, a number of novel alternatives are currently under investigation, including neuronal nicotinic acetylcholine receptor (nAChR) agonists. During the 1990s, the discovery of the antinociceptive properties of the potent nAChR agonist epibatidine in rodents sparked interest in the analgesic potential of this class of compounds. Although epibatidine also has several mechanism-related toxicities, the identification of considerable nAChR diversity suggested that the toxicities and therapeutic actions of the compound might be mediated by distinct receptor subtypes. Consistent with this view, a number of novel nAChR agonists with antinociceptive activity and improved safety profiles in preclinical models have now been identified, including A-85380, ABT-594, DBO-83, SIB-1663 and RJR-2403. Of these, ABT-594 is the most advanced and is currently in Phase II clinical evaluation. Nicotinically-mediated antinociception has been demonstrated in a variety of rodent pain models and is likely mediated by the activation of descending inhibitory pathways originating in the brainstem with the predominant high-affinity nicotine site in brain, the alpha4beta2 subtype, playing a critical role. Thus, preclinical findings suggest that nAChR agonists have the potential to be highly efficacious treatments in a variety of pain states. However, clinical proof-of-principle studies will be required to determine if nAChR agonists are active in pathological pain.

Spinal mechanisms underlying A-85380-induced effects on acute thermal pain.

Systemic administration of nicotinic receptor (nAChR) agonists is antinociceptive in models of acute pain whereas their intrathecal (i. t.) administration has been reported to be antinociceptive, nociceptive or without effect. It has been hypothesized that the action induced is dependent upon the subtype and location of the nAChR activated. In addition, there is considerable evidence that nAChR ligand-induced antinociception is mediated by other neurotransmitter systems via descending pathways from the brainstem to the spinal cord. The present study investigated the effects of i. t. and systemic administration of A-85380, a novel nAChR agonist, in the paw withdrawal model of acute thermal pain in the rat. Given i.t. , A-85380 (1 and 10 nmol/rat) decreased the latency to paw withdrawal by 2-4 s. This pronociception was accompanied by a spontaneous flinching behavior. Both of these effects were differentially blocked by i.t. pretreatment with the nAChR antagonists mecamylamine (10 nmol)>MLA (100 nmol)>DHbetaE (50% with 1000 nmol) but not by alpha-bungarotoxin (0% at 0.63 nmol). Given systemically, A-85380 (0.56 micromol/kg, i.p.) induced antinociception as indicated by an increased latency to paw withdrawal, an effect differentially altered by i.t. pretreatment with monoaminergic antagonists (100 nmol/rat). While mecamylamine and prazosin had no effect, scopolamine, methysergide and MDL 72222 partially antagonized and idazoxan completely antagonized A-85380-induced antinociception. Finally, as measured by in vivo microdialysis, levels of 5-HT, but not NE, in the i.t. space of the lumber region of the spinal cord were significantly increased following the systemic administration of A-85380. Together these data suggest that the nociceptive properties of spinally administered nAChR agents are not mediated by either an alpha(4)beta(2) or an alpha(7) subtype nAChR, whereas the antinociceptive properties of systemically-administered nAChR agents are mediated by descending noradrenergic, serotonergic and muscarinic inhibitory pathways.

Reduced nicotinic receptor-mediated antinociception following in vivo antisense knock-down in rat.

Pharmacological activation of neuronal nicotinic acetylcholine receptors can produce non-opioid antinociception in rodents. However, multiple nAChR subtypes exist, the most abundant of which contain alpha4 and beta2 subunits. The purpose of the present study was to investigate the role of alpha4-containing nAChRs in mediating nicotinic antinociception using an in vivo antisense strategy. Both i.c.v. infusion and repeated bolus injections into the cerebral aqueduct of an antisense oligonucleotide against the alpha4 subunit significantly attenuated the antinociceptive effects of the nAChR agonist A-85380 in the paw withdrawal test of acute thermal pain. Rats treated with a scrambled oligonucleotide displayed a full antinociceptive response to A-85380, while discontinuing antisense treatment restored the antinociceptive effects of the nicotinic agonist. Double immunohistochemical labeling revealed near-complete overlap of expression of the serotonin marker tryptophan hydroxylase and the alpha4 nAChR subunit in the dorsal raphe nucleus. The expression of alpha4-containing nAChRs by serotonergic neurons in the dorsal raphe offered a means to address nonspecific alpha4 knock-down, i.e., oligonucleotide-induced neurotoxicity. Immunohistochemical detection of alpha4 expression was reduced by nearly 50% in the dorsal raphe of antisense-treated rats as compared to either saline or missense-treated controls. In contrast, the expression of tryptophan hydroxylase, as well as, the alpha7 nAChR subunit in antisense-infused rats was similar to that observed in saline- and missense-treated controls. The results of these studies suggest that alpha4-containing nAChRs, possibly expressed by serotonergic neurons, are involved in nicotinic-mediated analgesia. However, these data do not eliminate the possibility that other nicotinic subunit combinations may also play a role in antinociception produced by nAChR activation.

Structural aspects of high affinity ligands for the alpha 4 beta 2 neuronal nicotinic receptor.

Neuronal nicotinic acetylcholine receptors (nAChRs) are a heterogeneous family of related ion channels that are widely distributed throughout the central and peripheral nervous systems. They all share a common architecture of five subunit proteins that combine at the cell surface to create a ligand-gated cation permeable pore. Significant effort is currently being expended by medicinal chemistry teams to synthesize ligands that exhibit selectivity for central over peripheral nAChR subtypes. Within the CNS, multiple nAChR subtypes are recognized, and the discovery of ligands exhibiting selectivity among these subtypes offers an opportunity for the development of novel therapeutic agents. The alpha 4 beta 2 subtype is one of the most abundant nAChR subtypes within the CNS, and has been the primary focus of high affinity ligand design. Nicotine (1), and more recently, epibatidine (2) have served as structural templates for the design of the majority of active compounds. Although the diversity of nAChR ligands is growing, the structural requirements necessary for high affinity binding with the alpha 4 beta 2 receptor remain poorly understood. The putative pharmacophoric elements common to all potent alpha 4 beta 2 ligands include (1) a basic or quaternized nitrogen atom, and (2) a less basic nitrogen or a carbonyl oxygen that presumably interact with electron rich and electron deficient sites on the receptor, respectively. The family of currently known high affinity analogs consists of a diverse array of azacycles containing a basic amine. Several additional basic amine fragments have been identified, including the pyrrolizidine nucleus (exemplified by 8) and the 2-azabicyclo[2.2.1]heptane skeleton (exemplified by 9). In addition, we have found that the furo[2,3-b]pyridine heterocycle (compound 10) serves as useful bioisosteric replacement for the pyridyl substituent of nicotine. A preliminary pharmacophore model is proposed in which a reasonable superposition of the putative pharmacophoric elements of the diverse array of high affinity ligands for the alpha 4 beta 2 nAChR reported herein may be accommodated.