Risk Factors and Cardiovascular Events in Orthotopic Liver Transplantation

BACKGROUND AND AIMS

Patients undergoing liver transplantation often have significant cardiovascular risk factors and may experience cardiac-related morbidity and mortality. The aim of this study was to assess the frequency of cardiovascular risk factors and outcomes in this population, and to identify factors predictive of post-transplant cardiac morbidity and mortality.

METHODS

We studied 261 patients who underwent liver transplantation at a single Veterans' Affairs Medical center between 1997 and 2015 to evaluate new cardiovascular events post-transplantation.

RESULTS

The cohort consisted of 261 patients (253 men and 8 women) with a mean age of 58.3 (± 6.5 years), mean model for end-stage liver disease score of 18.0 (±7.2), and mean Framingham risk score of 8.1 (± 4.9). After a median follow-up of 82 months a total of 75 (28.7%) patients died, with 13 deaths (17.3%) attributed to a primary cardiovascular event and 9 (12%) deaths due to a coronary-specific event. Coronary events and/ or the need for revascularization post-transplant occurred in 24 (9.2%) patients. The strongest pre-transplant predictors of mortality were age (p=0.01), Framingham risk score (p=0.01), preexisting coronary artery disease (p=0.01), and preexisting dyslipidemia (p=0.01). The strongest post-transplant predictors of mortality were new-onset hypertension (p=0.01) and new-onset diabetes mellitus (p=0.03) post-transplant.

CONCLUSIONS

In this cohort of veterans, coronary artery disease was significantly associated with mortality in the post liver transplantation population; however, the majority of deaths after transplant were attributable to other causes.

Abstract 599: Cardiovascular Risk Factors and Cardiovascular Events in Patients Undergoing Liver Transplantation

Introduction: Patients undergoing liver transplantation often have cardiovascular risk factors and may experience cardiovascular morbidity and mortality. Understanding the role of risk factors and the benefit of treatment is important for the careful selection of liver transplantation candidates to minimize post-transplant cardiac morbidity. We investigated the prevalence of cardiovascular risk factors and their association with cardiovascular events in liver transplantation patients.

Methods: We studied 182 consecutive patients undergoing liver transplantation in our center between 1997 and 2011 to evaluate factors associated with new cardiovascular events after liver transplantation.

Results: The cohort consisted of 179 men and 3 women with a mean age of 58.8 ± 6.2 years, model for end-stage liver disease (MELD) score of 17.4 ±7 at initial evaluation, and Framingham risk score of 9.0 ±5.1. In this cohort 15 ( 8.2%) patients were smokers, 48 (26.4%) had hypertension, 47 (25.8%) had diabetes mellitus, 35 (19.2%) had coronary artery disease, and 27

(14.8%) had dyslipidemia prior to their transplant surgery. After a median follow-up of 5.6 years, a total of 52 (28.6%) patients died and 6 (3.3%) died of cardiac causes. New coronary events and/or revascularization procedures post-transplant occurred in 22 (12%) patients. The pre-transplant variable associated with post-transplant cardiac events and/or revascularization was smoking status at the time of evaluation (P=0.01). Post-transplant factors associated with cardiac events included use of beta-blockers (P=0.01) or statins (P=0.01).

Conclusion: Although cardiovascular risk factors and coronary disease are very common, cardiovascular events are relatively infrequent in patients undergoing liver transplantation. Smoking at time of transplant evaluation and post-transplant medical therapy with beta-blockers and statins are significantly associated with the occurrence of post-transplant cardiac events including revascularization.

Older adults' trait ratings of three age-groups around the Pacific rim

In this paper, we assess the traits that older adults associate with younger, middle-aged, and older adults in five Pacific Rim nations from Western and Eastern cultural traditions (Australia, People's Republic of China (PRC), Hong Kong, Philippines, Thailand). We find cross-cultural trends which replicate patterns found in the US context. In most cultures, attractiveness, strength, activity, liberalism, health, and flexibility are seen to decline with increasing age. Kindness assessments are positively associated with age across cultures. Mixed patterns are found with assessments of wisdom and generosity, with respondents from the PRC and Hong Kong being notably more negative about increasing age than other respondents. Implications for the aging process across cultures are discussed, and suggestions made for future research.

Spontaneous contractions of myometrium from humans, non-human primate and rodents are sensitive to selective oxytocin receptor antagonism in vitro

OBJECTIVES

To determine whether: 1. oxytocin receptor antagonists influence spontaneous contractions of myometrium from humans, non-human primates and rodents (in vitro), and 2. vasopressin V1a receptor antagonism is important for inhibition of spontaneous contractions in human myometrium.

DESIGN

In vitro pharmacology of spontaneous contractions of myometrium from humans and animals.

SETTING

The research laboratories of a university department of obstetrics and gynaecology and a pharmaceutical industry research centre.

INTERVENTIONS

Samples of human myometrium were obtained at caesarean section. Tissue strips were suspended in organ baths for isometric force recording. Cumulative concentration effect curves to a selective oxytocin receptor antagonist (L-371,257) and a mixed oxytocin/vasopressin V1a receptor antagonist (atosiban) were obtained. The effect of L-371,257 was also determined in myometrium from non-pregnant rats and marmosets.

MAIN OUTCOME MEASURES

The inhibition of spontaneous myometrial contractions in vitro.

RESULTS

L-371,257 and atosiban significantly inhibited spontaneous activity of human myometrium in a concentration-related manner (P < 0.05), although the effect was more pronounced with L-371,257. Spontaneous contractions of myometrium from non-pregnant rats and marmosets were also inhibited by L-371,257 (atosiban was not tested).

CONCLUSIONS

Spontaneous contractions of myometrium from humans, marmosets and rats are, at least in part, dependent on oxytocin receptor activity, in vitro. L-371,257 and atosiban may be inverse agonists. Selective non-peptide oxytocin receptor antagonists may be effective tocolytics.

The benefits of using clinical pathways for managing acute paediatric illness in an emergency department

The aim of this study was to provide an evaluation of the overall effectiveness of using a number of clinical pathways in treating common acute paediatric conditions in an emergency department. This was a before and after study conducted on the effectiveness of three clinical pathways (gastroenteritis, asthma, and croup) in the emergency department of the Children's Hospital at Westmead, conducted over two separate yearly periods January to December 1996 and January to December 1999 representing before and after the introduction of clinical pathways in the emergency department. The main outcomes of the effectiveness of the pathways, namely admission to an in-patient bed, length of hospital stay and re-presentation after discharge from the ED were compared. Other outcomes of interest such as parental satisfaction and patient waiting times were also presented. Any deviation from a key clinical pathway process was reported. A total of 2854 children were managed by a clinical pathway compared to 2680 children managed before clinical pathways were introduced. The admission rate was reduced by threefold (9.1% compared to 23.6%) with a twofold reduction in length of hospital stay (32.7 h compared to 17.5 h). In 3.6% of children using a clinical pathway an unscheduled medical visit or re-presentation to the emergency department occurred after discharge, compared to 4.9% before the use of clinical pathways. No adverse events were reported in these children. In 76 cases deviation from a clinical pathway process was reported. High parental satisfaction was reported for clinical pathways throughout the study. Clinical pathways in this emergency department allowed rapid stabilisation of children, reducing admission rate, with a shortened length of hospital stay and few patients re-presenting after discharge and were well accepted by parents.

Paediatric walk-out patients: characteristics and outcomes

OBJECTIVE

To investigate the characteristics and outcomes of patients who walked out from a tertiary children's hospital emergency department (ED) without seeing a medical officer.

METHODS

A prospective study of patients who walked-out from the ED of a children's hospital, without seeing a medical officer. Information collected at triage included demographics, presenting problems, time of arrival, time of departure and reason for leaving. Charts were reviewed and those at high risk of serious illness or adverse outcome were contacted by telephone within 24 h. Further information collected during follow up included outcome, such as adverse events and admission to hospital. Data were analysed by comparing the walk-out and non-walk-out groups with regard to demographic variables, presenting problems and outcomes.

RESULTS

Over a 29 week period, 1037 (5.5%) patients walked out from the ED of the hospital without seeing a medical officer. Comparisons between the walk-out and non-walk-out patients indicated no differences in terms of demographics. However, significant differences were found between the triage categories, presenting problems and arrival time. Of these, 829 (79.9%) were followed up by telephone. This revealed the predominant presenting problem was non-urgent and infectious in nature and no adverse events occurred. The admission rate for walk-out patients (1.5%) was significantly lower in comparison with the non-walk-out group (6.9%; odds ratio 0.2; 95% confidence interval 0.1-0.3). Walk-out patients who were eventually hospitalized had a shorter mean length of stay than non-walk-out patients (20.4 vs 34.8 h, respectively; t = 17.78, P < 0.0001).

CONCLUSIONS

Medical resources are limited and, therefore, some extended waiting in the ED is necessary. Paediatric patients who walk-out of the ED without seeing a medical officer have simple illnesses that resolve without medical intervention or adverse events.

Discovery of 4-[3-(trans-3-dimethylaminocyclobutyl)-1H-indol-5-ylmethyl]-(4S)-oxazolidin-2-one (4991W93), a 5HT(1B/1D) receptor partial agonist and a potent inhibitor of electrically induced plasma extravasation

Utilizing a pharmacophoric model of binding of 3-(2-aminoethyl)indoles to 5HT(1B/1D) receptors, we identified the 3-aminocyclobutyl group as a potential ethylamine isostere. A novel multidimensional chemometric approach was used to predict the intrinsic activity (degree of agonism) at the receptor. A qualitative model for pharmacokinetic properties was then used to guide the synthesis toward molecules likely to have oral bioavailability in humans. A novel synthetic route to 3-(3-dimethylaminocyclobutyl)indoles was developed. Analogues showed generally lower intrinsic activity at 5HT(1B/1D) receptors than their ethylamine counterparts. 4-[3-(trans-3-Dimethylaminocyclobutyl)-1H-indol-5-ylmethyl]-(4S)-oxazolidin-2-one (4991W93, 1) was identified as a partial agonist against 5HT(1B/1D) receptors, with low intrinsic activity. This molecule also has significant activity against 5HT(1F) receptors but is selective over other 5HT receptors. In addition this compound was found to be an exceptionally potent inhibitor of electrically induced plasma extravasation. Compound 1 may have utility in the treatment and prophylaxis of migraine.

The effects of a seamless model of management on the quality of care for emergency department patients

The aim of this study was to examine the effectiveness of the seamless model of management on the quality of care for emergency department (ED) patients. This was a pre- and postintervention study of comparing post intervention data with the baseline on several variables of interest. The intervention was the seamless model of ED management, designed and implemented as a response to the challenge of increasing work load at the ED. Information on patients' waiting times, critical care performance, patients' satisfaction and staff morale was collected at baseline and postintervention for comparison. The results indicated significant improvements on all outcome measures were found postintervention. The average waiting time reduced by 40%, from 92.1 to 55.3 min, as well as the time to craniotomy from 120 to 45 min for more severe patients. Complaints from patients were reduced by 80% and staff morale had improved with a 48% reduction in sick days and a 80% reduction in staff resignations. Ambulatory patients presenting to the department saw a 20% improvement in their waiting time. We report a successful restructuring process that used routinely collected clinical and administrative data to highlight problems. Using these data and through a systematic planning process, appropriate strategies for restructuring were developed by emergency staff in partnership with the hospital executive. Significant improvements in waiting time and patient care were clearly demonstrated.

Use of a dual firefly and Renilla luciferase reporter gene assay to simultaneously determine drug selectivity at human corticotrophin releasing hormone 1 and 2 receptors

The aim of this study was to investigate and validate the use of a dual glow-signal luciferase reporter gene assay to simultaneously evaluate drug activity at two different seven-transmembrane receptor subtypes. Stable cell lines (CHO) transfected with either human corticotrophin releasing hormone 1 (hCRH1) receptors and a firefly luciferase reporter gene or hCRH2 and a Renilla luciferase reporter gene were created to provide different luciferase readouts for CRH1 and CRH2 receptors, respectively. Cells were combined for stimulation and measurement of luciferase luminescence in a 96-well plate format assay. The nonselective CRH agonists rat/human CRH and sauvagine caused concentration-dependent increases in luminescence via activation of CRH1 (firefly luciferase; pEC50 = 8.40 +/- 0.06 and 8.39 +/- 0.08, respectively, n = 8) and CRH2 (Renilla luciferase; pEC50 = 8.89 +/- 0.14 and 8.92 +/- 0.13, respectively, n = 8) receptors. The nonselective CRH antagonist astressin blocked these agonist-induced increases in luciferase at both CRH1 and CRH2 receptors. The selective CRH1 antagonist CP154,526 blocked r/hCRH- and sauvagine-induced increases in luciferase at CRH1 receptors only. These data report the expected pharmacology for CRH1 and CRH2 receptors. This assay enabled two receptor subtypes to be studied simultaneously in the same 96-well plate and generated robust data with low variability. It has the potential advantage of significant time and cost savings, with application to both basic research and compound screening.

Pharmacological characterization of human recombinant melatonin mt(1) and MT(2) receptors

We have pharmacologically characterized recombinant human mt(1) and MT(2) receptors, stably expressed in Chinese hamster ovary cells (CHO-mt(1) and CHO-MT(2)), by measurement of [(3)H]-melatonin binding and forskolin-stimulated cyclic AMP (cAMP) production. [3H]-melatonin bound to mt(1) and MT(2) receptors with pK(D) values of 9.89 and 9.56 and B(max) values of 1.20 and 0.82 pmol mg(-1) protein, respectively. Whilst most melatonin receptor agonists had similar affinities for mt(1) and MT(2) receptors, a number of putative antagonists had substantially higher affinities for MT(2) receptors, including luzindole (11 fold), GR128107 (23 fold) and 4-P-PDOT (61 fold). In both CHO-mt(1) and CHO-MT(2) cells, melatonin inhibited forskolin-stimulated accumulation of cyclic AMP in a concentration-dependent manner (pIC(50) 9.53 and 9.74, respectively) causing 83 and 64% inhibition of cyclic AMP production at 100 nM, respectively. The potencies of a range of melatonin receptor agonists were determined. At MT(2) receptors, melatonin, 2-iodomelatonin and 6-chloromelatonin were essentially equipotent, whilst at the mt(1) receptor these agonists gave the rank order of potency of 2-iodomelatonin>melatonin>6-chloromelatonin. In both CHO-mt(1) and CHO-MT(2) cells, melatonin-induced inhibition of forskolin-stimulated cyclic AMP production was antagonized in a concentration-dependent manner by the melatonin receptor antagonist luzindole, with pA(2) values of 5.75 and 7.64, respectively. Melatonin-mediated responses were abolished by pre-treatment of cells with pertussis toxin, consistent with activation of G(i)/G(o) G-proteins. This is the first report of the use of [(3)H]-melatonin for the characterization of recombinant mt(1) and MT(2) receptors. Our results demonstrate that these receptor subtypes have distinct pharmacological profiles.

Signalling by CXC-chemokine receptors 1 and 2 expressed in CHO cells: a comparison of calcium mobilization, inhibition of adenylyl cyclase and stimulation of GTPgammaS binding induced by IL-8 and GROalpha

The effect of interleukin-8 (IL-8) and growth-related oncogene alpha (GROalpha) on [35S]-guanosine 5'-O-(3-thiotriphosphate) ([35S]GTPgammaS) binding, forskolin-stimulated cyclic AMP accumulation and cytosolic calcium concentration were determined in recombinant CHO cells expressing HA-tagged CXC-chemokine receptors 1 and 2 (CXCR1 and CXCR2). Radioligand binding assays confirmed that the binding profiles of the recombinant receptors were similar to those of the native proteins. IL-8 displaced [125I]-IL-8 binding to CXCR1 and CXCR2 with pKi values of 8.89+/-0.05 and 9.27+/-0.03, respectively. GROalpha, a selective CXCR2 ligand, had a pKi value of 9.66+/-0.39 at CXCR2 but a pKi>8 at CXCR1. Calcium mobilization experiments were also consistent with previous reports on native receptors. Activation of both receptors resulted in stimulation of [35S]GTPgammaS binding and inhibition of adenylyl cyclase. A comparison of the functional data at CXCRI showed that a similar potency order (IL-8> >GROalpha) was obtained in all three assays. However, at CXCR2 whilst the potency orders for calcium mobilization and inhibition of adenylyl cyclase were similar (IL-8 > or = GROalpha), the order was reversed for stimulation of [35S]GTPgammaS binding (GROalpha > IL-8). All of the functional responses at both receptors were inhibited by pertussis toxin (PTX), suggesting coupling to a Gi/Go protein. However, the calcium mobilization induced by IL-8 at CXCR1 was not fully inhibited by PTX, suggesting an interaction with a G-protein of the Gq family. Our results with pertussis toxin also suggested that, in the [35S]GTPgammaS binding assay, CXCR1 displays some constitutive activity. Thus, we have characterized the binding and several functional responses at HA-tagged CXCRs 1 and 2 and have shown that their pharmacology agrees well with that of the native receptors. We also have preliminary evidence that CXCR1 displays constitutive activity in our cell line and that CXCR2 may traffic between different PTX sensitive G-proteins.

Pharmacological characterisation of melatonin mt1 receptor-mediated stimulation of [35S]-GTPgammaS binding

The activation of G-proteins by melatonin mt1 receptors was studied by measuring [35S]-guanosine-5'-(3-thiotriphosphate) ([35S]-GTPgammaS) binding to membranes prepared from Chinese hamster ovary (CHO) cells stably expressing human mt1 receptors. Melatonin stimulated [35S]-GTPgammaS binding in a concentration-dependent manner (pEC50, 8.77+/-0.02). The optimal (212+/-4%) increase over basal levels of binding (basal = 100%) was observed following incubation of membranes (12.5 microg protein/well) for 120 min at 30 degrees with [35S]-GTPgammaS (0.1 nM), in the presence of GDP (10 microM), NaCl (100 mM), and MgCl2 (10 mM). Melatonin analogues stimulated [35S]-GTPgammaS binding with a rank order (2-iodomelatonin > melatonin = S20098 > GR196429 > 6-chloromelatonin = 6-hydroxymelatonin >> N-acetylserotonin > or = GR135531 = mt1 luzindole = 5-HT = 0), which was identical to their affinities for the high affinity state of the receptor (correlation coefficient 0.94). All agonists evoked similar maximum increases in [35S]-GTPgammaS binding. EC50 values were 14- to 63-fold lower than binding affinities. The melatonin receptor antagonist luzindole (0.1-10 microM) evoked a parallel rightward shift in the melatonin concentration-response curve, with a pKB of 7.19+/-0.13, which is similar to its affinity in radioligand binding studies for human mt1 receptors. Stimulation of [35S]-GTPgammaS binding was abolished by pretreatment of cells with pertussis toxin (18 hr, 100 ng/mL) prior to preparation of membranes. Melatonin was without effect in CHO cells which lacked the mt1 receptor. Thus, melatonin and melatonin analogues stimulate [35S]-GTPgammaS binding with a profile which is consistent with binding to mt1 receptors causing activation of Gi/Go G-proteins.

Toxicologic effects of an oligodeoxynucleotide phosphorothioate and its analogs following intravenous administration in rats

The aim of the present study is to evaluate the in vivo toxicologic effects of a phosphorothioate oligodeoxynucleotide (PS oligo) and three of its analogs [PS oligo containing four methylphosphonate linkages at the 3' and 5'-ends (MBO 1), PS oligo containing four 2'-O-methylribonucleosides at both the 3'- and 5'-ends (MBO 2), and PS oligo containing an 8 bp loop region at the 3'-end (self-stabilized oligo)]. Oligodeoxynucleotides were administrated intravenously to male and female rats at doses of 3, 10, and 30 mg/kg/day for 14 days. Rats were killed on day 15, blood samples were collected for hematology and clinical chemistry determinations, and tissues, including lymph nodes, spleens, livers, and kidneys, were subjected to pathologic examinations. The toxicity profiles of the four oligodeoxynucleotides were very similar, but differed in magnitude. In terms of the severity of the abnormalities caused by the oligodeoxynucleotides, the order was MBO 2 > PS oligo > self-stabilized oligo > MBO 1. Alterations in hematology parameters included thrombocytopenia, anemia, and neutropenia. Abnormalities in clinical chemistry parameters observed with PS oligo or MBO 2 were dose-dependent elevation of liver transaminases and reduction of the levels of alkaline phosphatase, albumin, and total protein. In addition, MBO 2 caused elevation of the total bilirubin level in male rats at the 30 mg/kg dose. No major alterations in hematology or clinical chemistry were observed in rats receiving MBO 1 or self-stabilized oligo. Dose-dependent enlargements of spleen, liver, and kidney were observed, especially in rats receiving PS oligo and MBO 2. Pathologic studies showed a generalized hyperplasia of the reticuloendothelial (RE) system in the tissues examined. Alterations in the spleen were mainly RE cell hyperplasia and hematopoietic cell proliferation. In addition to RE cell hyperplasia, lymph nodes showed necrosis, hepatocytes showed cytologic alterations and necrosis, and kidneys showed renal tubule regeneration. The severity of pathologic changes observed was oligodeoxynucleotide dependent, in the order of MBO 2 > PS oligo > self-stabilized oligo > MBO 1.

Receptor specificity and trigemino-vascular inhibitory actions of a novel 5-HT1B/1D receptor partial agonist, 311C90 (zolmitriptan)

1. 311C90 (zolmitriptan zomig: (S)-4[[3-[2-(dimethylamino)ethyl]-1H-indol-5-yl]methyl]-2-oxazolidinone) is a novel 5-HT1B/1D receptor agonist with proven efficacy in the acute treatment of migraine. Here, we describe the receptor specificity of the drug and its actions on trigeminal-evoked plasma protein extravasation into the dura mater of the anaesthetized guinea-pig. 2. At the "5-HT1B-like' receptor mediating vascular contraction (rabbit saphenous vein), the compound was a potent (p[A50] = 6.79 +/- 0.06) partial agonist achieving 77 +/- 4% of the maximum effect to 5-hydroxytryptamine (5-HT). In the same experiments, sumatriptan (p[A50] = 6.48 +/- 0.04) was half as potent as 311C90 and produced 97 +/- 2% of the 5-HT maximum effect. Studies in which receptor inactivation methods were used to estimate the affinity (pKA) and efficacy relative to 5-HT (tau rel) for each agonist confirmed that 311C90 exhibits higher affinity than sumatriptan (pKA = 6.63 +/- 0.04 and 6.16 +/- 0.03, respectively) and that both drugs are partial agonists relative to 5-HT (tau rel = 0.61 +/- 0.03 and 0.63 +/- 0.10, respectively, compared to 5-HT = 1.0). 3. Consistent with its effects in rabbit saphenous vein, 311C90 also produced concentration-dependent contractions of primate basilar artery and human epicardial coronary artery rings. In basilar artery, agonist potency (p[A50] = 6.92 +/- 0.07) was similar to that demonstrated in rabbit saphenous vein, again being 2-3 fold higher than for sumatriptan (p[A50] = 6.46 +/- 0.03). Both agonists produced about 50% of the maximum response obtained with 5-HT in the same preparations. In rings of human coronary artery, the absolute potency of 311C90 and sumatriptan was higher than in primate basilar artery (p[A50] = 7.3 +/- 0.1 and 6.7 +/- 0.1, respectively), but maximum effects relative to 5-HT were lower (37 +/- 8% and 35 +/- 7%, respectively). In both types of vessel, the inability of 5-HT1B/1D agonists to achieve the same maximum as the endogenous agonist 5-HT is explained by the additional presence of 5-HT2A receptors. 4. 311C90 displayed high affinity at human recombinant 5-HT1D (formerly 5-HT1D alpha) and 5-HT1B (formerly 5-HT1D beta) receptors in transfected CHO-K1 cell membranes (pIC50 values = 9.16 +/- 0.12 and 8.32 +/- 0.09, respectively). In intact cells, the drug produced concentration-dependent inhibition of forskolin-stimulated adenylyl cyclase (p[A50] = 9.9 and 9.5, respectively) achieving the same maximum effect as 5-HT. Excepting human recombinant 5-HT1A and 5-ht1F receptors at which the drug behaved as an agonist with modest affinity (pIC50 = 6.45 +/- 0.11 and 7.22 +/- 0.12, respectively), 311C90 exhibited low, or no detectable affinity (pKi or pKB < or = 5.5) at numerous other monoamine receptors, including other 5-HT receptor subtypes. 5. When administered to anaesthetized guinea-pigs ten minutes before unilateral electrical stimulation of the trigeminal ganglion (1.2 mA, 5 Hz, 5 ms, 5 min), 311C90 (3-30 micrograms kg-1, i.v.) caused a dose-dependent inhibition of [125I]-albumin extravasation within the ipsilateral dura mater. At the same doses, the drug also produced dose-dependent falls in cranial vascular conductance (32.3 +/- 7.5% at 30 micrograms kg-1), as measured in the ear by laser doppler flowmetry. 6. These results show that 311C90, a novel member of the 5-HT1B/1D agonist drug class, exhibits a high degree of pharmacological specificity. Its potent partial agonist action at "5-HT1B-like' receptors in intracranial arteries, coupled with potent agonism at 5-HT1D and 5-HT1B receptors and an ability to inhibit neurogenic plasma protein extravasation in the dura, are consistent with its utility as an effective acute treatment for migraine.

Biochemical and molecular characterization of acetylcholinesterase from the hagfish Myxine glutinosa

To obtain information about the evolution of the cholinesterases, we investigated the cholinesterase activity of an agnathan vertebrate, the hagfish Myxine glutinosa. On the basis of evidence from enzymology, pharmacology, and molecular biology, we conclude that the cholinesterase activity is due to acetylcholinesterase (AChE). The enzyme hydrolyzes acetylthiocholine preferentially and exhibits substrate inhibition. The hydrolysis of both acetylthiocholine and butyrylthiocholine are inhibited in parallel by cholinesterase inhibitors, with the AChE-specific drug BW284c51 being the most potent; however, this drug and propidium, a peripheral anionic site ligand, are much weaker inhibitors of the hagfish enzyme than of Torpedo AChE. We used sequential extraction, collagenase digestion, and velocity sedimentation on sucrose gradients to determine that the AChE from the skeletal muscle of the hagfish is present in both globular and asymmetric forms. We also used the polymerase chain reaction with degenerate oligonucleotide probes and genomic DNA to obtain a 1 kb gene fragment for hagfish AChE. The enzyme has an acyl binding site typical of other vertebrate AChE, but lacks two aromatic residues implicated in the function of the peripheral anionic subsite. We discuss the relevance of our findings to the evolution of the cholinesterases in the vertebrates.

Characterization of a 5-HT1B receptor on CHO cells: functional responses in the absence of radioligand binding

1. Chinese hamster ovary (CHO) cells have been reported to be devoid of 5-HT receptors and have frequently been used as hosts for the expression of cloned 5-HT receptors. Unexpectedly, 5-HT was found to induce profound inhibition of forskolin-stimulated cyclic AMP production in these cells and the aim of this study was to classify the 5-HT receptor involved. 2. In CHO(dhfr-) cells 5-HT was a potent agonist and caused 80-100% inhibition of forskolin stimulated cyclic AMP production. A study using several 5-HT1 receptor agonists revealed the following potencies (p[A50]): RU24969 (9.09 +/- 0.17) > 5-carboxamidotryptamine (8.86 +/- 0.20) > 5-HT (8.07 +/- 0.05) > CP-93,129 (7.74 +/- 0.10) > sumatriptan (5.93 +/- 0.04). All five agonists achieved a similar maximum effect. Irreversible receptor alkylation studies yielded a pKA estimate of 7.04 +/- 0.34 for 5-HT. 3. The 5-HT1A/1B antagonist, (+/-)-cyanopindolol (4-100 nM), caused parallel rightward shifts of the 5-HT concentration-effect curve with no change in asymptote. Schild analysis yielded a pKB estimate of 8.69 +/- 0.09 (Schild slope 1.13 +/- 0.10). (+/-)-Cyanopindolol actually behaved as a partial agonist with an intrinsic activity of 0.2-0.5 and a p[A50] of 8.55. 4. 5-HT (0.01-10 microM) also elicited a concentration-dependent increase in intracellular [Ca2+] in CHO(dhfr-) cells thus demonstrating that dual coupling is not a phenomenon restricted to systems in which there is overexpression of transfected receptors. 5. This agonist and antagonist profile is consistent with the presence of a 5-HT1B receptor. 8-OH-DPAT (1 microM) and renzapride (3 microM) were without effect on forskolin-stimulated cyclic AMP production and ketanserin (0.3 microM) did not antagonize the inhibition produced by 5-HT, thus excluding the involvement of 5-HT1A, 5-HT4, and 5-HT2 receptors. 6. The possibility that expression of a 5-HT1B receptor was associated with the dhfr- mutation was excluded since RU24969, 5-HT and CP-93,129 were also potent agonists in unmutated, CHO-K1 cells: p[A50] 9.03 +/- 0.03, 8.34 +/- 0.05, 7.69 +/- 0.07 respectively, and (+/-)-cyanopindolol (0.1 microM) shifted the 5-HT curve to the right and yielded a pA2 estimate of 8.70 +/- 0.06. 7. Little or no specific binding of [3H]-5-HT (0.1-200 nM) or of the high affinity ligand [125I]-iodocyanopindolol (0.01-3 nM) to CHO(dhfr-) cell membranes could be detected. 5-HT also failed to elicit any increase in the binding of [35S]-GTP gamma S to CHO membranes. 8. In conclusion, cultured CHO cells express 5-HT1B receptors which are negatively coupled to adenylyl cyclase and positively coupled to increases in intracellular calcium. The absence of radioligand binding was unexpected in view of the high potency of 5-HT and the partial agonist activity of the normally 'silent' competitive antagonist, (+/-)-cyanopindolol. This implies very efficient receptor-effector coupling of a low density of 5-HT1B receptors. Clearly, the absence of detectable radioligand binding cannot be assumed to mean the absence of receptors capable of eliciting a significant functional response.

Synthesis of Hexahydrocyclopentimidazol-2-(1H)-one derivatives displaying selective DP-receptor agonist properties

The rationale for investigating conformationally restricted analogues of BW245C as DP-receptor ligands and the syntheses of three such racemic bicyclic imidazolidinone analogues are described. Compounds 7 (BW587C), 8 (BW480C85), and 9 (BW572C85) were found to be potent inhibitors of human platelet aggregation and selective DP-receptor agonists in washed platelet and jugular vein isolated tissue assays.

Cloning and characterisation of the rabbit 5-HT1D alpha and 5-HT1D beta receptors

The genes encoding the rabbit 5HT1D alpha and 5HT1D beta receptors have been cloned. The deduced amino acid sequence of these receptors shows 91-92% amino acid sequence identity with their human homologues, and similar high sequence identity with homologues from other species. The receptors were transiently expressed in COS-7 cells and exhibit a pharmacological profile closely resembling their human homologues, including a higher affinity of ketanserin for the 5-HT1D alpha subtype. However, sumatriptan had a lower affinity for both the rabbit receptors compared to their human counterparts. This may be accounted for by differences between the primary amino acid sequences of these species homologues.

Improving asthma documentation in a paediatric emergency department

OBJECTIVE

To improve documentation for children presenting to the Emergency Department (ED) of The Children's Hospital with acute asthma.

METHODOLOGY

In phase I, the documentation process was analysed using a standard total quality management (TQM) approach to identify specific problems leading to poor documentation. Fifty-two medical records of children presenting over a 3 week period were reviewed for nursing and medical documentation. A set of minimum criteria, consistent with the Paediatric Asthma Management Plan, were established for documentation by both medical and nursing staff. Following dissemination and education, compliance with documentation was evaluated and compared to an asthma survey performed in the ED in 1991. In phase II, a specific proforma for medical assessment was developed and 80 medical records of children presenting over a 3 week period were reviewed. Fifty-two (65%) with completed proformas were evaluated. The outcome measure was the documentation rate for minimum criteria established by TQM process.

RESULTS

In phase I, nursing compliance with documentation ranged from 46% for signs of respiratory distress to 83% for a past history of asthma and 100% for pulse rate. Doctors were similarly poor at documenting essential elements such as severity (31%), palpable pulsus paradoxus (29%), the child's usual doctor (46%) and follow-up arrangements (21-56%). In phase II, the documentation of the severity of acute asthma (42%) and of the child's usual doctor (42%) remained poor but there were statistically significant improvements in documentation of interval medications, palpable pulsus paradoxus, respiratory rate, pre-treatment oximetry, education, follow-up arrangements and communication letters.

CONCLUSION

The process of TQM has proved valuable in improving some aspects of documentation of children presenting to ED with acute asthma. It remains to be shown whether improved documentation will result in improved outcome.

Selective prostaglandin D2 receptor stimulation elicits ocular hypotensive effects in rabbits and cats

The effects of the selective prostaglandin D2 (DP) receptor agonists, 572C85 ((+/-)-5-(3-carboxypropylthio)-1-(2-cyclohexyl-2-hydroxyethyl- amino)hexahydrocyclopenta(d)imidazol-2(1H)-one) and 192C86 ((+/-)-5-(3-carboxypropylthio)-1-(2-cyclohexyl-2-hydroxyethylidene - amino)-3-ethylhexahydrocyclopenta(d)imidazol-2(1H)-one), were determined on intraocular pressure regulation in rabbits and cats. 572C85 (50 micrograms) in rabbits maximally lowered intraocular pressure by 4.3 mm Hg, and significantly for 4 h compared to control. In cats 572C85 had a similar effect. 192C86 (50 micrograms) reduced intraocular pressure by 2.8 mm Hg for 2 h in rabbits. Following exposure to the specific DP receptor antagonist, BW A868C ((+/-)-3-benzyl-5-(6-carboxyhexyl)-1-(2-cyclohexyl-2-hydroxyethylamin o)- hydantoin; 50 micrograms), which had no effect on intraocular pressure by itself, 572C85 (50 micrograms) did not reduce intraocular pressure in rabbits and cats. The intraocular pressure lowering effect of the mixed DP and EP receptor agonist, BW245C (5-(6-carboxyhexyl)-1-(3-cyclohexyl-3-hydroxypropyl)-hydantoin; 50 micrograms), in cats was suppressed by only 64% by BW A868C (50 micrograms). These results clearly show that the DP receptors in rabbit and cat eyes are involved in intraocular pressure regulation. However, under baseline conditions DP receptor activity does not contribute to this regulation.

Patronizing the young: forms and evaluations

Exploratory work indicated that Californian undergraduates were frequently, and irritatingly, patronized by older adults in a variety of ways. In a follow-up, using multidimensional scaling procedures, three distinct clusters representing young adults' own conceptions of patronizing speech emerged ("non-listening," "disapproving," and "parental"). In the main study, young adults were provided with a single vignette of a short conversation between an older and younger person. Eight versions of this vignette were devised independently varying elder's age (40- vs. 70-years) and speech style (neutral vs. non-listening vs. disapproving vs. parental). Participants were required to evaluate both vignette-targets. As expected, the patronizing elders were negatively perceived. An evaluative hierarchy differentiated between the three patronizing forms, and in ways that differed depending on the nature of the judgmental task. Content analyses of open-ended data also revealed interesting differences in interpretive responses to the various vignette conditions.

Platelet glycoprotein IIb-IIIa and size are increased in acute myocardial infarction

Platelet aggregation, which plays an important role in acute myocardial infarction (AMI), is mediated by fibrinogen binding to the platelet membrane glycoprotein (GP)IIb-IIIa (CD41). This study measured the relative number of GPIIb-IIIa complexes on platelets from patients immediately following AMI (n = 14) compared with those from controls (n = 14). Flow cytometry was used to demonstrate that there were, on average, 20% more GPIIb-IIIa complexes on platelets after AMI compared with controls. Platelet size was also 7% greater in AMI and it is known that larger platelets are more reactive. Since platelet size and protein content are determined at thrombopoiesis the majority of these platelets must have been circulating prior to AMI. Larger platelets, with more GPIIb-IIIa may, therefore, be causally related to AMI.

Cyclic-AMP-dependent Ca2+ influx elicited by prostaglandin D2 in freshly isolated nonchromaffin cells from bovine adrenal medulla

We previously reported that prostaglandin D2 (PGD2) specifically elevates intracellular cyclic AMP in nonchromaffin cells isolated from bovine adrenal medulla (Biochim. Biophys. Acta (1989) 1011, 75-80). Here we again found that PGD2 increased intracellular Ca2+ concentration ([Ca2+]i) in freshly isolated nonchromaffin cells and investigated the cellular mechanisms of PGD2-induced [Ca2+]i increase using the Ca2+ indicator fura-2 and a fluorescence microscopic imaging system. Treatment of the cells with PGD2 receptor agonists BW245C and ZK110841 resulted in both marked stimulation of cyclic AMP formation and an increase in [Ca2+]i. The [Ca2+]i response was also induced by bypassing of the receptor with forskolin, a direct activator of adenylate cyclase, but not by PGE2 or PGF2 alpha both of which are devoid of the ability to generate cyclic AMP in the cells. These cyclic AMP and [Ca2+]i responses induced by PGD2 were completely blocked by the PGD2 receptor antagonist BWA868C. The time-course of cyclic AMP production stimulated by PGD2 coincided with that of the [Ca2+]i increase. While the Ca(2+)-mobilizing hormone bradykinin stimulated a rapid inositol phosphate accumulation in nonchromaffin cells, PGD2 did not stimulate it significantly. Removal of extracellular Ca2+ markedly reduced the Ca2+ response to PGD2 in magnitude and duration, but did not alter the peak [Ca2+]i response to bradykinin. These results demonstrate that PGD2 receptor activation induces the increase in [Ca2+]i via cyclic AMP mainly by increasing the Ca2+ influx from the outside, unlike inositol trisphosphate which causes release of Ca2+ from internal stores.

The effect of a prostaglandin DP-receptor partial agonist (192C86) on platelet aggregation and the cardiovascular system in healthy volunteers

1. PGD2 (DP)-receptors mediate inhibition of platelet aggregation and vasodilatation. If receptor reserve were greater on platelets it might be possible to separate these effects. To determine whether such a difference in receptor reserve exists, we have examined the effects of a highly selective DP-receptor partial agonist 192C86 on platelet aggregation and the cardiovascular system in healthy volunteers. 2. Using an open, dose-escalating study design, four male volunteers received constant rate intravenous infusions of 192C86 for up to 60 min. Ex vivo platelet aggregation to ADP and collagen in platelet-rich plasma (PRP) and whole blood (WB) was studied at baseline, after 15, 30 and 60 min of each infusion and at 180 min post-infusion. Heart rate (HR), systolic and diastolic (DBP) blood pressure were measured at frequent intervals. Adverse experiences were monitored by checklist. Facial flushing was assessed by the volunteer using a visual analogue scale, by an observer using a numerical scale and by full-face colour photographs. Blood was taken for assay of plasma 192C86 concentrations by radio-immunoassay (r.i.a.). 3. 192C86 (0.007-0.058 micrograms kg-1 min-1) inhibited platelet aggregation to ADP and collagen both in PRP and WB in a dose-dependent manner. However, this was always accompanied by a decrease in DBP, increase in HR and facial flushing. Plasma concentrations of 192C86 were at or below the limits of sensitivity of the r.i.a. (0.5 ng ml-1). 4. The highest infusion rate was stopped after 20 min due to symptomatic hypotension on standing.(ABSTRACT TRUNCATED AT 250 WORDS)

Classification of platelet and vascular prostaglandin D2 (DP) receptors: estimation of affinities and relative efficacies for a series of novel bicyclic ligands. With an appendix on goodness-of-fit analyses

1. The DP receptors located on platelets and vasculature were examined in a human washed platelet preparation and in isolated rings of rabbit external jugular vein. 2. A series of eight novel bicyclic compounds were studied for their effects in the two assays. Seven produced agonism, inhibition of aggregation or vascular relaxation, and one compound was 'silent' in both assays. 3. The operational model of agonism (Black & Leff, 1983) was fitted simultaneously to concentration-effect curve data for the seven agonist compounds. The affinity and efficacy estimates so obtained were tested for similarity between the two tissues by analysis of variance, showing that the model could be fitted to both sets of data by assuming the same relative affinity and efficacy values. However, absolute affinity estimates were consistently lower in the vascular preparation. 4. Analysis of two of the seven agonists as antagonists was also possible. This provided pKB estimates which supported the agonist affinity estimates. The eighth compound was also analysed as an antagonist. It, like the other seven, demonstrated a difference in affinity between the two tissues. 5. The results of this study support the view that platelet and vascular DP receptors are similar, assuming that the systematic difference in affinity estimates for the series of compounds between the two tissues is the consequence of receptor micro-environment and/or accessory binding site differences.

Intergenerational talk and communication with older people

A program of research conducted within an anti-agism paradigm demonstrates that young people process and respond to the speech of older people in stereotypical ways. Such conclusions result from studies using a variety of research methods. Experimental studies demonstrate that older-sounding speech triggers age schematic responses and that young people tend to use agist strategies of information seeking and compliance gaining from older people, while interactive studies explore how stereotypes and age identities are co-produced by young and old people in conversation. We use lifespan and intercultural perspectives to argue that the communicative patterns we observe in our studies are in some senses and contexts counterproductive in both the long and short term, in that they can reproduce negative attitudes toward aging as well as inhibit successful aging.

Inotropic polyazapentalene sulmazole analogues

Aryl substituted 1H-imidazo[1,2-a]imidazole 8, imidazo[2,1-b]thiazole 9, 1,4-dihydroimidazo[4,5-d]imidazole 11, and 1(2),4-dihydroimidazo[4,5-c]pyrazoles 12-17 have been prepared. An X-ray crystallographic study confirmed the structure of 8 and showed this analogue to exist as the 1H-tautomer. These heterocycles were evaluated as inotropic agents and analogues 12, 15, and 17 found to display inotropic properties which were less potent in vitro, but more potent in vivo, than those of sulmazole. Structure-activity relationships are discussed.

Inhibition of endothelium-dependent vasorelaxation by arginine analogues: a pharmacological analysis of agonist and tissue dependence

1. Isolated rings of rabbit external jugular vein (RbJV) and rat thoracic aorta (RA) were used to study the effect of the NO synthase inhibitor L-NG-nitroarginine methyl ester (L-NAME) on muscarinic and 5-hydroxytryptamine (5-HT) receptor-stimulated, endothelium-dependent vascular relaxations. 2. In RbJV relaxations produced by the endothelial 5-HT receptor agonist alpha-methyl-5-HT were potently and non-surmountably inhibited by L-NAME (10 microM), whereas acetylcholine relaxations in this tissue were unaffected by this concentration of inhibitor. By contrast, acetylcholine relaxations in RA were virtually abolished by 10 microM L-NAME. In each case an equivalent concentration of D-NAME was without effect on agonist-induced relaxations. 3. The different effect of L-NAME on acetylcholine relaxations in RbJV and RA was not due to muscarinic receptor differences. Affinity estimates for acetylcholine (pKA = 6.12 +/- 0.09; 6.09 +/- 0.08 respectively) and for 4-diphenyl-acetoxy-N-methylpiperidine methobromide (4-DAMP, pKB = 9.01 +2- 0.012; 9.24 +/- 0.16 respectively) indicated that the receptors in both tissues belong to the same M3 class. Tissue differences resulting from the release of a cyclo-oxygenase product or a glibenclamide-sensitive K(+)-channel-linked hyperpolarizing factor were also ruled out by selective inhibition of these pathways. 4. When phenoxybenzamine was used to reduce the efficacy of acetylcholine in RbJV so that it behaved as a partial agonist in this tissue, L-NAME (10 microM) now produced non-surmountable inhibition of relaxation responses. In untreated tissues the same concentration of L-NAME also profoundly inhibited responses produced by butyrylcholine and pilocarpine, both of which behave as partial agonists at the M3 receptor in RbJV. 5. A simple model was developed which describes the theoretical behaviour of receptor-stimulated synthesis and release of NO. The model predicts that competitive inhibition of NO formation results in parallel displacements of the agonist response curve in the case of high efficacy agonist, but right-shift with concomitant depression of the curve maximum in the case of low efficacy agonists. Simulations based on the model showed reasonable agreement with the experimental data. 6. It is concluded that analogues of L-arginine demonstrate tissue- and agonist-dependence in terms of their ability to inhibit receptor-mediated events involving the liberation of NO. This behaviour can reflect differences in agonist efficacy in the receptor systems being studied, a possibility that should be ruled out before apparent resistance to inhibition is taken as evidence for the involvement of heterogeneous endothelium-derived relaxing factors (EDRFs).

Type-1 and type-2 astrocytes are distinct targets for prostaglandins D2, E2, and F2 alpha

Accumulating evidence has revealed that astrocytes are potential targets for various neurotransmitters. Here we investigated the effects of prostaglandins (PGs) on signal transduction in purified primary cultures of rat type-1 and type-2 astrocytes. PGF2 alpha, PGD2, and 9 alpha,11 beta-PGF2, a metabolite of PGD2 and a stereoisomer of PGF2 alpha, evoked a rapid rise in the intracellular Ca2+ concentration ([Ca2+]i) in type-1, but not in type-2, astrocytes. STA2, a stable analogue of thromboxane A2, was less effective, and PGE2 showed little effect. The PG-induced rise in [Ca2+]i was not blocked by an antagonist of either PGD2 receptor or thromboxane A2 receptor. PGF2 alpha and 9 alpha,11 beta-PGF2 stimulated rapid formation of inositol trisphosphate followed by inositol bisphosphate and inositol monophosphate. On the other hand, PGE2 increased the intracellular level of cyclic AMP in type-2 astrocytes, rather than in type-1 astrocytes. The potency of PGs for cyclic AMP formation was in the following order: PGE2 greater than PGE1 greater than or equal to STA2 much greater than iloprost, a stable analogue of PGI2. PGD2 and PGF2 alpha had no effect on cyclic AMP formation. These results demonstrate that type-1 astrocytes preferentially express PGF2 alpha receptors, the activation of which leads to phosphoinositide metabolism and [Ca2+]i elevation, whereas type-2 astrocytes possess PGE receptors that are linked to cyclic AMP formation.

Information-seeking triggered by age

Age labels may lead to the seeking of age-stereotypic information from target individuals. Using Carver and de la Garza's information-seeking procedure (which asked respondents to judge the relative importance of various kinds of information they would glean from drivers involved in an automobile accident for assigning accident responsibility), but extending it to a wider life span (16 to 91 years of age) and to both genders, we generalized earlier findings to a similar undergraduate sample (n = 437) in another country. Also demonstrated for the first time is the fact that ageist information-seeking across the life span was independent of the driver's gender, the participant's age, and the participant's gender. Specifically, participants wanted to know from younger drivers about their driving conduct (whether they had been drunk and speeding), and from older drivers about their capacity for driving (mental competence, vision, and health). The seeking of environmental information (car safety and road conditions) did not vary with the age of driver in any systematic way.

A comparative study of the prostanoid receptor profile of 9 alpha 11 beta-prostaglandin F2 and prostaglandin D2

1. The aim of this study was to determine the receptor profile of 9 alpha 11 beta-prostaglandin F2 (PGF2) and compare it with that of its parent, prostaglandin D2 (PGD2). The experiments were designed to overcome the problems associated with the presence of multiple prostanoid receptor sub-types in most tissues; the lack of selective antagonists for each receptor means that conclusions regarding efficacy at FP and EP2 receptors must remain provisional. 2. At DP receptors in human platelets and rabbit jugular vein, PGD2 was a full agonist, p[A50] 7.02 +/- 0.09 and 6.60 +/- 0.12 respectively. 9 alpha 11 beta-PGF2 was approximately 30-60 fold less potent than PGD2. 3. 9 alpha 11 beta-PGF2 was a full agonist in the FP receptor containing preparation, cat iris sphincter (p [A50] 7.35 +/- 0.09) comparable in potency to PGD2 (p[A50] 7.15 +/- 0.19). Likewise the two prostanoids showed similar potency at the TP receptor in guinea-pig aorta (9 alpha 11 beta-PGF2 p[A50] 6.00 +/- 0.07; PGD2 6.24 +/- 0.08). 4. 9 alpha 11 beta-PGF2 and PGD2 had efficacy but low potency at EP1 receptors (guinea-pig oesophageal muscularis mucosa) and demonstrated 2000-3000 fold lower potency than PGE2 (p[A50] 8.35 +/- 0.09). Similarly, in the EP2 receptor-containing preparation, cat trachea, 9 alpha 11 beta-PGF2 was 3500 fold less potent and PGD2 700 fold less potent than PGE2 (p[A50] 8.06 +/- 0.26). 5. 9 alpha 11 beta-PGF2 and PGD2 (10 microM) were without affinity at the IP receptors on human platelets and had no agonist action in the EP3 receptor containing preparation, guinea-pig vas deferens. 6. 9 alpha 11 beta,-PGF2 is a major metabolite of PGD2 in vivo and this conversion clearly represents an inactivation step since 9 alpha 11 beta-PGF2 is of considerably lower potency than PGD2 at DP receptors. However, it is of similar potency to PGD2 at TP, FP, EP1 and EP2 receptors and it may, therefore, contribute to the biological effects which follow PGD2 administration or endogenous synthesis; its actions at these receptors are likely to be similar to those of PGD2 itself.

Inotropic "A" ring substituted sulmazole and isomazole analogues

A series of "A" ring substituted sulmazole and isomazole analogues have been prepared and evaluated as inotropic agents. pKA's, protonation sites, and log P values were measured for selected compounds and their electronic properties were calculated. No simple correlation between inotropic activity and pKA, protonation site, or log P value was observed. However, in vitro inotropism did correlate with the calculated charge density of the "B" ring imidazo nitrogen atom. The 6-position of sulmazole appeared to be the most tolerant toward substituents, the 6-amino derivative 7 being a more potent inotrope than sulmazole itself. 4-Methoxyisomazole 13 had comparable in vivo inotropic properties to those of isomazole.

Cardiotonic 'C' ring modified isomazole analogues

Isomazole analogues which have achiral electron withdrawing substituents at the 4'-position and analogues with heterocyclic 'C' rings have been synthesized and evaluated as inotropic agents. It was found that pyridyl could replace phenyl in the 'C' ring without loss of activity. The 4'-methylsulphonyl, -cyano, -carboxamido, and acetyl analogues had similar inotropic potencies to Isomazole whilst displaying superior cardiovascular profiles in in vivo studies.

Estimation of agonist affinity and efficacy by direct, operational model-fitting

A few years ago Black and Leff (1983) presented a theoretical model for agonist action that can be fitted directly to experimental agonist concentration-effect data in order to estimate affinities and relative efficacies of agonists. The model has been successfully applied to data obtained using experimental designs commonly employed in pharmacologic experiments. This article describes the methodology used to fit the model equations to data for full and partial agonists, shows how affinity and efficacy estimates are calculated for these values, and shows how experimental design influences these calculations.

The classification of prostaglandin DP-receptors in platelets and vasculature using BW A868C, a novel, selective and potent competitive antagonist

1. BW A868C, a novel compound, behaved as a simple competitive antagonist in a human washed platelet aggregation assay. Anti-aggregatory concentration-effect curves to BW 245C were displaced in a parallel manner. The shifts accorded with a Schild plot slope of unity and a pKB of 9.26. 2. Inhibition of platelet aggregation by prostaglandin D2 (PGD2) was antagonized with a similar potency, as were the relaxation effects of BW 245C and PGD2 in the rabbit jugular vein. BW A868C can, therefore, be classified as a DP-receptor antagonist. 3. Actions of BW A868C at other prostaglandin receptors (IP, EP1, EP2, TP and FP) were excluded at concentrations up to 1,000 times higher than the DP-receptor affinity. 4. Analyses of BW 245C- and PGD2-mediated effects were complicated by additional agonist receptor interactions which were revealed by BW A868C. In rabbit jugular vein a resistant phase of agonism was detectable, indicating that both agonists exerted effects through another receptor (possibly EP2). Also, PGD2, in addition to its anti-aggregatory effect on platelets, demonstrated a pro-aggregatory action in the presence of BW A868C. 5. The contractile effects of PGD2 in guinea-pig tracheal strips were resistant to 10 microM BW A868C indicating that they were not mediated through DP-receptors. 6. To our knowledge this is the first account of a well-classified competitive antagonist at the DP-receptor. Its potency and selectivity make it an important new tool in prostanoid receptor classification and identification.

Qualitative real-time cross-sectional echocardiographic imaging of the human fetus during the second half of pregnancy

In this study, we used high-resolution echocardiographic systems to investigate how early in pregnancy normal fetal cardiac anatomy could be noninvasively evaluated. Over a 2-year period, 84 of 88 fetuses were successfully imaged (27 were studied serially). Postnatal images of 73 were obtained during the newborn period. Estimated fetal age varied at initial examination from 19-41 weeks (mean +/- 0.5 weeks [+/- SEM]) of pregnancy. Estimated fetal weight using an ultrasound algorithm varied from 500-3100 g (mean 1580 +/- 80 g [+/- SEM]). To evaluate fetal cardiac anatomy, we reproduced commonly used cross-sectional views of the heart. The four-chamber and the short-axis great artery views have been most successful for cardiac evaluation in the fetus. These views could be obtained in 96% and 95% of the patients, respectively. With these views, cardiac chamber and valve structures, as well as two great arteries, could be imaged in detail. The ascending and descending aorta, as well as the aortic arch and vessels to the arms and head, were visualized in 87% of examinations, and the inferior and superior venae cavae were visualized in 76%. In two of three RH fetuses, changes in cardiac chambers compatible with hydrops fetalis were demonstrated. We examined all fetuses after birth and verified clinically (or noninvasively) that no cardiac malformations were present. It appears, however, that the diagnosis of major congenital heart defects should be possible before birth.