Decreased mobility, lack of social support, haemosiderosis and use of antidepressant medications may predict recurrent venous leg ulcers within 12 months of healing: A prospective longitudinal study.

AIM: To identify clinical, medical and psychosocial predictors of venous leg ulcer recurrence within 12 months of healing. METHODS: A multi-site study was conducted in Australia in community and hospital outpatient settings. Adults with venous leg ulcers were recruited within 4 weeks of healing and data were collected on preventative treatments and health, medical, clinical and psychosocial factors. Follow-up data on recurrences were collected every 3 months until ulcer recurrence, or until 12 months after healing pending which occurred first. Factors associated with time to recurrence were analysed using a Cox proportional hazards regression model. DESIGN: Secondary data analysis of a multi-site, prospective longitudinal study to validate a risk assessment tool for recurrence. RESULTS: A sample of 143 participants was recruited (51% male, Mage = 73 years, SD 13.6). Almost half (49.6%) had an ulcer recurrence within 12 months, with a mean time to ulcer recurrence of 37 weeks (SE 1.63, 95% CI 33.7-40.1). Factors measured at the time of healing that were significant independent predictors of recurrence were: prescribed antidepressant medications (p = .035), presence of haemosiderosis (p = .006), decreased mobility (longer sitting times) (p = .007) and lower social support scale scores (p = .002). Participants who wore compression systems providing 20 mmHg or higher for at least 5 days/week were less likely to recur, although not reaching statistical significance (p = .06). CONCLUSION: Results provide evidence that antidepressant medications, haemosiderosis, decreased mobility and lack of social support are risk factors associated with ulcer recurrence; therefore, these variables are modifiable and could guide early intervention.

Ulcer area reduction at 2 weeks predicts failure to heal by 24 weeks in the venous leg ulcers of patients living alone.

OBJECTIVE: Chronic wounds are costly and affect approximately 1-2% of the population. Venous disease is responsible for about 60% of all chronic leg ulcers and these ulcers can be debilitating, with evidence of a decreased quality of life. Unfortunately, up to 30% of venous leg ulcers (VLUs) fail to heal, despite best practice treatment. This study aimed to identify risk factors associated with delayed healing in participants with VLUs and in particular, whether psychosocial factors play a part in this process. METHOD: A secondary analysis was conducted of a large data set of clinical, wound healing, health, social, economic and psychological data collected in previous prospective studies of participants with VLUs. Generalised linear mixed modelling was used to identify independent predictors of failure to heal after 24 weeks. RESULTS: We recruited 247 participants with 318 VLUs from hospital and community settings. Findings revealed that four early predictors were independently significantly associated with failure to heal by 24 weeks. These were: participants who lived alone (OR 2.3, 95%CI [1.13-4.61], p=0.03); had less than 25% reduction in ulcer area within two weeks of treatment (OR 10.07, 95%CI [4.60-22.19], p<0.001); had higher ulcer severity scores (OR 5.1, 95%CI [2.33-11.88], p=0.001); and participants who were not treated with high level compression therapy (i.e.>30 mmHg) at the time of assessment (OR 4.18, 95% CI [1.95-8.97], p=0.002). CONCLUSION: Identified risk factors offer an opportunity for clinicians to determine realistic outcomes for their patients and to guide decisions on early referral and implementation of tailored adjunctive interventions. Additionally, findings from this study suggest health professionals need to assess and address not only clinical risk factors but also social risk factors, when planning interventions to promote healing.

What matters to women: a systematic scoping review to identify the processes and outcomes of antenatal care provision that are important to healthy pregnant women.

BACKGROUND: Global uptake of antenatal care (ANC) varies widely and is influenced by the value women place on the service they receive. Identifying outcomes that matter to pregnant women could inform service design and improve uptake and effectiveness. OBJECTIVES: To undertake a systematic scoping review of what women want, need and value in pregnancy. SEARCH STRATEGY: Eight databases were searched (1994-2015) with no language restriction. Relevant journal contents were tracked via Zetoc. DATA COLLECTION AND ANALYSIS: An initial analytic framework was constructed with findings from 21 papers, using data-mining techniques, and then developed using meta-ethnographic approaches. The final framework was tested with 17 more papers. MAIN RESULTS: All continents except Australia were represented. A total of 1264 women were included. The final meta-theme was: Women want and need a positive pregnancy experience, including four subthemes: maintaining physical and sociocultural normality; maintaining a healthy pregnancy for mother and baby (including preventing and treating risks, illness and death); effective transition to positive labour and birth; and achieving positive motherhood (including maternal self-esteem, competence, autonomy). Findings informed a framework for future ANC provision, comprising three equally important domains: clinical practices (interventions and tests); relevant and timely information; and pyschosocial and emotional support; each provided by practitioners with good clinical and interpersonal skills within a high quality health system. CONCLUSIONS: A positive pregnancy experience matters across all cultural and sociodemographic contexts. ANC guidelines and services should be designed to deliver it, and those providing ANC services should be aware of it at each encounter with pregnant women. TWEETABLE ABSTRACT: Women around the world want ANC staff and services to help them achieve a positive pregnancy experience.

Self-hypnosis for intrapartum pain management in pregnant nulliparous women: a randomised controlled trial of clinical effectiveness.

OBJECTIVE: (Primary) To establish the effect of antenatal group self-hypnosis for nulliparous women on intra-partum epidural use. DESIGN: Multi-method randomised control trial (RCT). SETTING: Three NHS Trusts. POPULATION: Nulliparous women not planning elective caesarean, without medication for hypertension and without psychological illness. METHODS: Randomisation at 28-32 weeks' gestation to usual care, or to usual care plus brief self-hypnosis training (two × 90-minute groups at around 32 and 35 weeks' gestation; daily audio self-hypnosis CD). Follow up at 2 and 6 weeks postnatal. MAIN OUTCOME MEASURES: Primary: epidural analgesia. Secondary: associated clinical and psychological outcomes; cost analysis. RESULTS: Six hundred and eighty women were randomised. There was no statistically significant difference in epidural use: 27.9% (intervention), 30.3% (control), odds ratio (OR) 0.89 [95% confidence interval (CI): 0.64-1.24], or in 27 of 29 pre-specified secondary clinical and psychological outcomes. Women in the intervention group had lower actual than anticipated levels of fear and anxiety between baseline and 2 weeks post natal (anxiety: mean difference -0.72, 95% CI -1.16 to -0.28, P = 0.001); fear (mean difference -0.62, 95% CI -1.08 to -0.16, P = 0.009) [Correction added on 7 July 2015, after first online publication: 'Mean difference' replaced 'Odds ratio (OR)' in the preceding sentence.]. Postnatal response rates were 67% overall at 2 weeks. The additional cost in the intervention arm per woman was £4.83 (CI -£257.93 to £267.59). CONCLUSIONS: Allocation to two-third-trimester group self-hypnosis training sessions did not significantly reduce intra-partum epidural analgesia use or a range of other clinical and psychological variables. The impact of women's anxiety and fear about childbirth needs further investigation.

Risk factors for delayed healing in venous leg ulcers: a review of the literature.

BACKGROUND: Chronic leg ulcers, remaining unhealed after 4-6 weeks, affect 1-3% of the population, with treatment costly and health service resource intensive. Venous disease contributes to approximately 70% of all chronic leg ulcers and these ulcers are often associated with pain, reduced mobility and a decreased quality of life. Despite evidence-based care, 30% of these ulcers are unlikely to heal within a 24-week period and therefore the recognition and identification of risk factors for delayed healing of venous leg ulcers would be beneficial. AIM: To review the available evidence on risk factors for delayed healing of venous leg ulcers. METHODS: A review of the literature in regard to risk factors for delayed healing in venous leg ulcers was conducted from January 2000 to December 2013. Evidence was sourced through searches of relevant databases and websites for resources addressing risk factors for delayed healing in venous leg ulcers specifically. RESULTS: Twenty-seven studies, of mostly low-level evidence (Level III and IV), identified risk factors associated with delayed healing. Risk factors that were consistently identified included: larger ulcer area, longer ulcer duration, a previous history of ulceration, venous abnormalities and lack of high compression. Additional potential predictors with inconsistent or varying evidence to support their influence on delayed healing of venous leg ulcers included: decreased mobility and/or ankle range of movement, poor nutrition and increased age. DISCUSSION: Findings from this review indicate that a number of physiological risk factors are associated with delayed healing in venous leg ulcers and that social and/or psychological risk factors should also be considered and examined further. CONCLUSION: The findings from this review can assist health professionals to identify prognostic indicators or risk factors significantly associated with delayed healing in venous leg ulcers. This will facilitate realistic outcome planning and inform implementation of appropriate early strategies to promote healing.

The perspectives of adults with venous leg ulcers on exercise: an exploratory study.

OBJECTIVE: Exercise has the potential to offer a range of health benefits in addition to improving healing outcomes for people with venous leg ulcers (VLUs). However, despite evidence-based recommendations, most of these individuals do not engage in regular exercise. The aim of this study was to gain an understanding of the perspectives of adults with VLUs, in relation to exercise. METHOD: This was a qualitative design using semi-structured interviews and discussions. Ten participants with venous leg ulceration volunteered to participate. Recruitment was through a specialist wound clinic. Verbatim data were collected by an experienced moderator using a semi-structured guide. Data saturation was reached after three group discussions and two interviews. A random selection of transcripts was sent back to the participants for verification. Thematic content analysis was used to determine major themes and categories. Two transcripts were independently analysed, categories and themes independently developed, cross checked and found comparable. Remaining transcripts were analysed using the developed categories and codes. RESULTS: Regardless of their current exercise routine, participants reported exercising before venous leg ulceration and expressed an interest in either becoming active or maintaining an active lifestyle. Overall, four themes emerged from the findings: i) participant understanding of the relationship between chronic venous insufficiency and exercise patterns; ii) fear of harm impacts upon positive beliefs and attitudes to exercise; iii) perceived factors limit exercise; and iv) structured management facilitates exercise. CONCLUSION: The value of exercise in improving outcomes in VLUs lies in its capacity to promote venous return and reduce the risk of secondary conditions in this population. Despite motivation and interest in being exercise active, people with VLUs report many obstacles. Further exploration of mechanisms that assist this patient population and promote understanding about management of barriers, coupled with promotion of enabling factors, is vital for improving their exercise participation.

'Weighing up and balancing out': a meta-synthesis of barriers to antenatal care for marginalised women in high-income countries.

BACKGROUND: In high-resource settings around 20% of maternal deaths are attributed to women who fail to receive adequate antenatal care. Epidemiological evidence suggests many of these women belong to marginalised groups often living in areas of relative deprivation. Reasons for inadequate antenatal attendance have yet to be fully evaluated. OBJECTIVES: To identify the factors affecting access to antenatal care for marginalised pregnant women living in developed countries. SEARCH STRATEGY: We included qualitative studies from developed countries published in English language journals (1980-2007). SELECTION CRITERIA: Qualitative studies exploring the views of marginalised women living in developed countries who either failed to attend for any antenatal care or did so late or irregularly. DATA COLLECTION AND ANALYSIS: Eight studies fulfilled the selection criteria and were synthesised in accord with the techniques derived from meta-ethnography. MAIN RESULTS: Initial access is influenced by late pregnancy recognition and subsequent denial or acceptance. Continuing access appears to depend on a strategy of weighing up and balancing out of the perceived gains and losses. Personal resources in terms of time, money and social support are considered alongside service provision issues including the perceived quality of care, the trustworthiness and cultural sensitivity of staff and feelings of mutual respect. CONCLUSIONS: A nonthreatening, nonjudgemental antenatal service run by culturally sensitive staff may increase access to antenatal care for marginalised women. Multiagency initiatives aimed at raising awareness of, and providing access to, antenatal care may also increase uptake.

A cost-effectiveness analysis of two community models of care for patients with venous leg ulcers.

AIM: To conduct a cost-effectiveness analysis based on data from a randomised controlled trial comparing traditional community home nursing with a community Leg Club model for chronic venous leg ulcer management in the south-east metropolitan area of Queensland, Australia. METHOD: Participants were randomised to the Leg Club (n=28) or home visits (n=28). Data were obtained on resources/related costs incurred by the service provider, clients and carers, and the community. RESULTS: From the collective perspective (service provider, clients and carers, and the community), at six months the incremental cost per healed ulcer was dollars AU515 (Euros 318) and the incremental cost per reduced pain score was dollars AU322 (Euros 199). For the service provider, Leg Club intervention resulted in cost savings and better health effects when compared with home nursing. CONCLUSION: On both clinical and economic grounds, the Leg Club model appears to be more cost-effective than traditional home nursing for the treatment of chronic venous leg ulcers. However, clients and the local community contribute substantial financial and in-kind support to the operation of both services.

[3H]dofetilide binding to HERG transfected membranes: a potential high throughput preclinical screen.

The pharmacological characteristics of [3H]dofetilide binding were examined in membranes prepared from human embryonic kidney (HEK293) cells stably expressing human ether-á-go-go related gene (HERG) K+ channels. The classIII antiarrhythmic compounds dofetilide, clofilium, 4'-[[1-[2-(6-methyl-2-pyridyl)ethyl]-4-piperidyl]carbonyl]methanesulfonanilide (E-4031), N-methyl-N-[2-[methyl-(1-methyl-1H-benzimidazol-2-yl)amino]ethyl]-4-[(methylsulfonyl)amino]benzene-sulfonamide (WAY-123,398) and d-sotalol all inhibited [3H]dofetilide binding. In addition, the structurally unrelated compounds pimozide, terfenadine and haloperidol, all of which prolong the QT interval in man, also inhibited binding. These data indicate that a [3H]dofetilide binding assay using HERG membranes may help identify compounds that prolong the QT interval.

Characterisation of [(125)I]-apamin binding sites in rat brain membranes with HE293 cells transfected with SK channel subtypes.

The pharmacology of [(125)I]-apamin binding sites was examined in rat cortical and hippocampal tissue and compared with membranes prepared from human embryonic kidney (HEK293) cells transfected with SK channel subtypes hSK1, rSK2 and rSK3. The K(D) of [(125)I]-apamin in rat cortex and hippocampus was similar to the apamin-sensitive subtypes, rSK2 and rSK3 (K(D) (pM): 6.4, 7.08, 6.56 and 8.94, respectively). In addition, [(125)I]-apamin had a K(D)=270.4pM for the putatively 'apamin-insensitive' hSK1. Apamin had about a three-fold higher affinity than [(125)I]-apamin in brain tissue and in the cells expressing the different SK channel subtypes. Pancuronium, bicuculline and d-tubocurarine displayed micromolar affinity for all five-membrane preparations, whereas dequalinium and gallamine appear to show some subtype selectivity. Tetraethylammonium (TEA) and 4-aminopyridine (4-AP) had millimolar affinity and linopirdine had no effect. In conclusion, the pharmacology of [(125)I]-apamin binding in the cortex and hippocampus was similar to that in the apamin-sensitive clones, rSK2 and rSK3. In addition, we demonstrated low affinity [(125)I]-apamin binding for hSK1 and identified compounds that show subtype selectivity. These data cast further doubt on the identification of SK1 as encoding for the K(+) channel responsible for the apamin-insensitive sAHP.

[3H]dofetilide binding in SHSY5Y and HEK293 cells expressing a HERG-like K+ channel?

The pharmacological characteristics of [3H]dofetilide binding in SHSY5Y, HEK293 and CHO-K1 cells were examined, and in parallel whole cell recordings used to characterise HERG-like K+ currents. Dofetilide affinity was similar in the human cell lines, SHSY5Y (Kd=99.6 nM) and HEK293 (Kd=102.9 nM), but 10 times lower in CHO-K1 cells (Kd=1200 nM). In contrast, clofilium and E4031 had a similar affinity in all three cell lines, whereas WAY 123,398 had no effect. Electrophysiological studies showed that SHSY5Y cells contained a HERG-like K+ current blocked by application of dofetilide to either side of the membrane. Block was faster when dofetilide was applied intracellularly. In contrast, HEK293 and CHO-K1 cells contained no such current, despite the presence of a partial cDNA for HERG in the former. That [3H]dofetilide is specific for I(Kr)/HERG may be questionable, as HEK293 and CHO-K1 cells contain no such functional K+ current.

Factors influencing student nurses in their choice of a rural clinical placement site.

INTRODUCTION: Rural health and government bodies have identified the need for greater numbers of health professionals in rural and remote health care settings. Providing students with the opportunity to experience a rural clinical placement has been suggested as one strategy for future health professionals to gain familiarity with the rural workplace and an awareness of the employment opportunities available in these areas. Although substantial numbers of student nurses have participated in a rural undergraduate clinical placement program at Queensland University of Technology, Australia, since 1996, available places remain unfilled. This study aimed to investigate the factors influencing student nurses in their choice of a rural or metropolitan clinical placement. METHODS: This study utilised a descriptive survey design. In the 24-item questionnaire, questions related to demographics, previous experience of a rural lifestyle, previous work experience and issues of importance regarding the clinical placement experience. All final-year Bachelor of Nursing students in the year 2000 (n = 212) were included in the sample, with a 65% response rate for the pre-test (n = 137). Frequency distributions, chi2 analysis (for nominal data) and ANOVA (for interval data) were used to describe differences between the characteristics of students choosing a rural or remote placement and students choosing a metropolitan placement. RESULTS: Findings demonstrated that possession of a rural background, previous work experience in a rural community and family, financial and/or employment commitments all influenced students' choice of undertaking a rural clinical placement. CONCLUSION: Students who have previously lived and/or worked in a rural area are more likely to choose a rural setting for clinical placements or postgraduate employment. However, the value of rural clinical placements as a method of increasing awareness of employment opportunities in the rural setting is considerable. Family, financial and employment commitments should be considered in the development of recruitment and retention strategies for health professionals to rural areas.

Pyrazolopyridine derivatives act as competitive antagonists of brain adenosine A1 receptors: [35S]GTPgammaS binding studies.

The effects of adenosine receptor ligands and three novel pyrazolopyridine derivatives on guanosine-5'-O-(3-[35S]thio)triphosphate ([35S]GTPgammaS) binding to rat cerebral cortical membranes were examined. [35S]GTPgammaS binding was stimulated in a concentration dependent manner by several adenosine receptor agonists. The adenosine A2a receptor selective agonist, 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamidoadenosine (CGS 21680), was ineffective confirming specificity for adenosine A1 receptor activation. 2-Chloro-N6-cyclopentyladenosine (CCPA; 10(-7) M)-stimulated [35S]GTPgammaS binding was inhibited by xanthine and pyrazolopyridine based adenosine receptor antagonists. The concentration-response curve for CCPA-stimulated [35S]GTPgammaS binding was shifted to the right with increasing concentrations of antagonist without significant changes in maximal response. Schild analyses determined pK(B) values of 8.97, 8.88, 8.21, 8.16, 7.79 and 7.65 for 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), (R)-1-[(E)-3-(2-phenylpyrazolo[1,5a]pyridin-3-yl) acryloyl]-2-piperidine ethanol (FK453), 6-oxo-3-(2-phenylpyrazolo[1,5a]pyridin-3-yl)-1(6H)-pyridazinebutyric+ ++ acid (FK838), 9-chloro-2-(2-furyl)[1,2,4]triazolo-[1,5c]quinazolin-5-amine (CGS 15943), 8-cyclopentyl-1,3-methylxanthine (CPT) and (R)-1-[(E)-3-(2-phenylpyrazolo[1,5a]pyridin-3-yl) acryloyl]-piperidin-2-yl acetic acid (FK352), respectively. Schild slopes were close to unity, confirming that these novel pyrazolopyridine derivatives act as competitive antagonists at rat brain adenosine A1 receptors.

Pharmacological characterization of a simple behavioral response mediated selectively by central adenosine A1 receptors, using in vivo and in vitro techniques.

The behavioral profile of a range of adenosine receptor ligands was examined in rats using a locomotor activity model. Adenosine receptor agonists, including the selective A1 receptor agonist, N6-cyclopentyladenosine (CPA) and the A2A agonist, 2-[(2-aminoethylamino)carbonylethyl-phenylethylamino]- 5'-ethylcarboxa midoadenosine (APEC), reduced spontaneous motor activity in a dose-dependent manner. CPA-induced locomotor depression was attenuated by adenosine A1 receptor selective antagonists, such as 8-cyclopentyl-1,3-dipropylxanthine (DPCPX), (R)-1-[(E)-3-(2-phenylpyrazolo[1, 5-a]pyridin-3-yl)-acryloyl]-2-piperidine ethanol (FK453), and (R)-1-[(E)-3-(2-phenylpyrazolo[1, 5-a]pyridin-3-yl)-acryloyl]-piperidin-2-yl acetic acid (FK352), but not by the A2A receptor antagonist, (E)-1,3-dipropyl-8-(3, 4-dimethoxystyryl)-7-methylxanthine (KF17837). By contrast, APEC-induced hypolocomotion was attenuated by KF17837 but not by DPCPX, confirming that adenosine A1 and A2A receptor activation mediates locomotor output independently. It was found that two peripheral adenosine receptor antagonists, 8-(p-sulphophenyl)-1, 3-dipropylxanthine (DPSPX) and 8-(p-sulphophenyl)-1, 3-dimethylxanthine (8-PST), did not alter CPA-induced hypolocomotion. This confirmed that pharmacological reversal of the adenosine A1 receptor-mediated response involved a central site of drug action. The relationship between occupancy of central adenosine A1 receptors and behavioral effect was therefore assessed. Regression analysis on log transformed data confirmed associations between antagonist affinity for brain [3H]DPCPX binding sites and, in order of increasing significance, the equivalent behavioral dose (EBD) for reversal of CPA-induced hypolocomotion (r2 = 0.32), the serum concentration of drug (r2 = 0.65), and most significantly with the brain concentration of drug detected 20 min after administration of the (EBD) (r2 = 0.95). These data suggest that competition between agonists and antagonists, for occupancy of central adenosine A1 receptors, is intrinsic to the pharmacological reversal of CPA-induced hypolocomotion. The validity of the model as a simple predictive screen for the blood/brain barrier permeability of adenosine A1 receptor antagonists was thereby confirmed.

Species differences in brain adenosine A1 receptor pharmacology revealed by use of xanthine and pyrazolopyridine based antagonists.

1. The pharmacological profile of adenosine A1 receptors in human, guinea-pig, rat and mouse brain membranes was characterized in a radioligand binding assay by use of the receptor selective antagonist, [3H]-8-cyclopentyl-1,3-dipropylxanthine ([3H]-DPCPX). 2. The affinity of [3H]-DPCPX binding sites in rat cortical and hippocampal membranes was similar. Binding site affinity was higher in rat cortical membranes than in membranes prepared from guinea-pig cortex and hippocampus, mouse cortex and human cortex. pKD values (M) were 9.55, 9.44, 8.85, 8.94, 8.67, 9.39 and 8.67, respectively. The binding site density (Bmax) was lower in rat cortical membranes than in guinea-pig or human cortical membranes. 3. The rank order of potency of seven adenosine receptor agonists was identical in each species. With the exception of 5'-N-ethylcarboxamidoadenosine (NECA), agonist affinity was 3.5-26.2 fold higher in rat cortical membranes than in human and guinea-pig brain membranes; affinity in rat and mouse brain membranes was similar. While NECA exhibited 9.3 fold higher affinity in rat compared to human cortical membranes, affinity in other species was comparable. The stable GTP analogue, Gpp(NH)p (100 microM) reduced 2-chloro-N6-cyclopentyladenosine (CCPA) affinity 7-13.9 fold, whereas the affinity of DPCPX was unaffected. 4. The affinity of six xanthine-based adenosine receptor antagonists was 2.2-15.9 fold higher in rat cortical membranes compared with human or guinea-pig membranes. The rank order of potency was species-independent. In contrast, three pyrazolopyridine derivatives, (R)-1-[(E)-3-(2-phenylpyrazolo[1,5-a]pyridin-3-yl) acryloyl]-2-piperidine ethanol (FK453), (R)-1-[(E)-3-(2-phenylpyrazolo[1,5-a]pyridin-3-yl) acryloyl]-piperidin-2-yl acetic acid (FK352) and 6-oxo-3-(2-phenylpyrazolo[1,5-a]pyridin-3-yl)-1(6H)-pyridazinebutyric acid (FK838) exhibited similar affinity in human, guinea-pig, rat and mouse brain membranes. pKi values (M) for [3H]-DPCPX binding sites in human cortical membranes were 9.31, 7.52 and 7.92, respectively. 5. Drug affinity for adenosine A2A receptors was determined in a [3H]-2-[4-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamido ade nosine ([3H]-CGS 21680) binding assay in rat striatal membranes. The pyrazolopyridine derivatives, FK453, FK838 and FK352 exhibited pKi values (M) of 5.90, 5.92 and 4.31, respectively, compared with pKi values of 9.31, 8.18 and 7.57 determined in the [3H]-DPCPX binding assay in rat cortical membranes. These novel pyrazolopyridine derivatives therefore represent high affinity, adenosine A1 receptor selective drugs that, in contrast to xanthine based antagonists, exhibit similar affinity for [3H]-DPCPX binding sites in human, rat, mouse and guinea-pig brain membranes.

Detection of adenosine receptor antagonists in rat brain using a modified radioreceptor assay.

The present study describes a modified radioreceptor binding assay using brain homogenate or serum from drug treated animals as the 'competing drug' in a conventional in vitro radioligand binding assay. Method validation involved measurement of the brain and serum concentration of three adenosine receptor antagonists following systemic administration, using a [3H]8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX) binding assay. The intrinsic [3H]DPCPX binding capacity of test samples was abolished by protein denaturation (80 degrees C, 15 min) and, endogenous ligand was depleted enzymatically, prior to determination of drug concentration. Brain and serum concentrations of the adenosine A1 receptor antagonist, DPCPX increased in a dose related manner when measured 20 min after intraperitoneal injection. Estimated brain concentrations were 13.8, 87.7 and 288 nM following injection of 0.01, 0.1 and 1.0 mg/kg DPCPX, and serum concentrations were 26.5, 195 and 1370 nM respectively. A time dependent decrease in both brain and serum concentration was noted 20-180 min following injection of 1.0 mg/kg DPCPX. The peripheral adenosine receptor antagonists, 1,3-dipropyl-8-p-sulphophenylxanthine (DPSPX; 5.6 mg/kg) and 8-(p-sulphophenyl)theophylline (8-PST; 20 mg/kg), were not detected in brain tissue 20 min after intraperitoneal injection, despite serum concentrations of 56 and 52 microM respectively. This assay provides a useful and versatile method for determining the central penetration of neuroactive drugs.