Searching for rare diseases in PubMed: a blind comparison of Orphanet expert query and query based on terminological knowledge.

BACKGROUND: Despite international initiatives like Orphanet, it remains difficult to find up-to-date information about rare diseases. The aim of this study is to propose an exhaustive set of queries for PubMed based on terminological knowledge and to evaluate it versus the queries based on expertise provided by the most frequently used resource in Europe: Orphanet. METHODS: Four rare disease terminologies (MeSH, OMIM, HPO and HRDO) were manually mapped to each other permitting the automatic creation of expended terminological queries for rare diseases. For 30 rare diseases, 30 citations retrieved by Orphanet expert query and/or query based on terminological knowledge were assessed for relevance by two independent reviewers unaware of the query's origin. An adjudication procedure was used to resolve any discrepancy. Precision, relative recall and F-measure were all computed. RESULTS: For each Orphanet rare disease (n = 8982), there was a corresponding terminological query, in contrast with only 2284 queries provided by Orphanet. Only 553 citations were evaluated due to queries with 0 or only a few hits. There were no significant differences between the Orpha query and terminological query in terms of precision, respectively 0.61 vs 0.52 (p = 0.13). Nevertheless, terminological queries retrieved more citations more often than Orpha queries (0.57 vs. 0.33; p = 0.01). Interestingly, Orpha queries seemed to retrieve older citations than terminological queries (p < 0.0001). CONCLUSION: The terminological queries proposed in this study are now currently available for all rare diseases. They may be a useful tool for both precision or recall oriented literature search.

[Benefits and usability of a pharmaceutical record in medical practice. A survey of hospital doctors and pharmacists (MATRIX study)]. / Intérêt et utilisabilité du dossier pharmaceutique en pratique médicale. Enquête auprès de médecins et pharmaciens hospitaliers (étude MATRIX).

BACKGROUND: To evaluate the impact of the pharmaceutical patient record use in emergency, geriatric and anaesthesia and intensive care departments, an experimentation was launched in 2013 in 55 hospitals. The purpose of the study was to assess the opinions of physicians and pharmacists about the benefits and usability of the patient pharmaceutical record. METHODS: An e-mailed self-administered questionnaire was sent to all the pharmacists, anaesthesiologists, geriatricians and emergency physicians of the 55 hospitals involved in the patient pharmaceutical record experimentation. The questionnaire assessed the usability of the patient pharmaceutical record using the "System Usability Scale", as well as its use, its benefits and limitations perceived in clinical practice, and overall user satisfaction. Questionnaires were collected from November 2014 to January 2015. RESULTS: Ninety-six questionnaires were collected, from 47 hospitals, representing 86% of the hospitals involved in the experimentation. The patient pharmaceutical record was effectively operational in 36 hospitals. Data from 73 questionnaires filled by physicians and pharmacists with potential experience with the patient pharmaceutical record were used for evaluation. Forty-two respondents were pharmacists (57%) and 31 were physicians (43%), including 13 geriatricians, 11 emergency physicians and 7 anaesthesiologists. Patient pharmaceutical record overall usability score was 62.5 out of 100. It did not vary with the profession or seniority of the respondent. It was positively correlated with the frequency of use. More than half of respondents reported that they never or uncommonly used the patient pharmaceutical record. The length of access to data period was considered as insufficient. Main obstacles to more utilization of the patient pharmaceutical record were the lack of information about the dosage of dispensed drugs, the low number of patients in possession of their health card and the low number of patients with an activated patient pharmaceutical record. CONCLUSION: Two years after the beginning of the experiment aiming to broaden the access to the patient pharmaceutical record to physicians, these first evaluation results are encouraging. The evaluation of the consequences of the access to the patient pharmaceutical record for physicians remains necessary.

Physician satisfaction with transition from CPOE to paper-based prescription.

INTRODUCTION: In January 2015, Rouen University Hospital's information system experienced serious issues. It was necessary to rapidly switch from the computerized provider order entry (CPOE) system towards a paper-based order entry (PBOE) system. This was an opportunity to evaluate prescriber opinion on the two provider order entry (POE) systems. METHODS: All residents were asked to fill an augmented version of the POE satisfaction and usage survey for both POE systems. The results were compared to identify the strengths and weaknesses of each system. RESULTS: Fifty-one respondents had used the CPOE system and the PBOE system. Overall, satisfaction was higher with PBOE than CPOE (odds ratio (OR)=3.74; p<0.001). Usability (OR=4.00; p<0.001), reliability (OR=8.54; p<0.001), time consumption (OR=0.50; p<0.05 - survey statement was formulated negatively), and communication with nurses (OR=14.27; p<0.0001) reached statistically better agreement. The more experience with CPOE the more residents were disillusioned with the reliability (OR=6.55; p<0.01), the usability (OR=5.68; p<0.01) and the patient safety (OR=0.27; p<0.05 - survey statement was formulated negatively) of CPOE. Although safety issues were reported for both systems, the causes were different; PBOE imposed frequent rewriting of the order while CPOE lack of usability might be unsafe. Another important issue with both POE systems was time consumption. CONCLUSION: Residents did not report any increase in safety issues with the rapid switch from CPOE to PBOE. They even seemed more satisfied with the rollback to paper, which remains a possible degraded mode in case of health information technology collapse.

Some Innovative Approaches for Public Health and Epidemiology Informatics.

OBJECTIVES: Summarize excellent current research published in 2015 in the field of Public Health and Epidemiology Informatics. METHODS: The complete 2015 literature concerning public health and epidemiology informatics has been searched in PubMed and Web of Science, and the returned references were reviewed by the two section editors to select 14 candidate best papers. These papers were then peer-reviewed by external reviewers to allow the editorial team an enlightened selection of the best papers. RESULTS: Among the 1,272 references retrieved from PubMed and Web of Science, three were finally selected as best papers. The first one presents a language agnostic approach for epidemic event detection in news articles. The second paper describes a system using big health data gathered by a statewide system to forecast emergency department visits. The last paper proposes a rather original approach that uses machine learning to solve the old issue of outbreak detection and prediction. CONCLUSIONS: The increasing availability of data, now directly from health systems, will probably lead to a boom in public health surveillance systems and in large-scale epidemiologic studies.

Asymmetric hemoglobin hybrids.

We have investigated the functional properties of hemoglobin (Hb) valency hybrids, and specifically whether it makes a difference if the oxidized subunits are on the same dimer (asymmetric hybrid) or not. CO recombination kinetics were used to probe the allosteric equilibrium of tetramers with two oxidized subunits. Asymmetric hybrids were prepared by mixing HbCO with a large excess of cyano-metHb; dimer exchange occurs in the order of seconds, producing a population of fully liganded [dimer-CO/dimer-CN] hybrids; these hybrids could then be photolysed to study CO rebinding to the doubly liganded [dimer-deoxy/dimer-CN] species. Before mixing, the HbCO samples typically show 30 to 50% slow phase, characteristic of deoxy (or T-state) Hb. Addition of HbCN to these samples decreased the slow fraction. The higher the ratio of HbCN to HbCO, the less slow phase was observed, with about 5% slow phase at a ratio of 10:1. This would indicate that the photoproduct [deoxy-dimer/ dimer-CN] is not predominantly in the low-affinity (T-state) conformation. We did not observe the difference between asymmetric and symmetric hybrids expected from published studies. The difference between the present flash photolysis results and the published equilibrium studies could be due to a kinetic factor: if the conversion to the T-state is slow after photolysis, then the biomolecular kinetics will reflect the pre-flash conditions of fully liganded (R-state) hemoglobin.

Synthesized allosteric effectors of the hemoglobin molecule: a possible mechanism for improved erythrocyte oxygen release capability in hemoglobinopathy H disease.

Patients with the nondeletion genotype of hemoglobinopathy H (HbH or beta4) disease have higher proportions of HbH and more severe tissue hypoxia than patients with the deletion genotype. Because these patients' red blood cells (RBCs) contain mainly two Hb species, HbH and HbA, the high proportion of HbA can be exploited by lowering its oxygen affinity; this would probably increase oxygen delivery to the RBCs and improve the patients' clinical phenotype. Allosteric effectors that induce a low-affinity Hb may be useful in this regard. We investigated the effect of a bezafibrate derivative, RSR-4, on the oxygen affinity of RBCs and purified hemolysates containing HbA and HbH. This allosteric effector crosses RBC membranes and binds reversibly to the alpha-chains of deoxy-Hb, decreasing hemoglobin oxygen affinity. The blood used was obtained from a patient with HbH disease (alphaTSaudi homozygote) whose HbH level was 33.5% as measured by high-performance liquid chromatography. Oxygen binding studies were performed in RBCs and purified hemolysates. RBCs incubated in the presence of 500 microM RSR-4 (2-[[[(3,5-dichloroanilino)-carbonyl]methyl]phenoxy]-2-methylpropi onic acid) in standard conditions (pH 7.4, 0.14 M NaCl, 37 degrees C) displayed an increase in their P50 value from 14.5 to 35.2 mm Hg. Oxygen binding studies in purified stripped hemolysates (pH 7.2, 0.1 M NaCl, 25 degrees C) showed that addition of both 500 microM RSR-4 and 1 mM of 2,3 diphosphoglycerate (DPG) led to an 11-fold decrease in oxygen affinity, whereas the addition of the natural effector DPG or RSR-4 alone produced a 2.7- and 5.7-fold decrease, respectively. In both cases, the oxygen equilibrium curves (OECs) were biphasic due to the presence of the noncooperative, high-oxygen-affinity HbH (beta4) component. After addition of RSR-4, the lower part of the OEC (corresponding to HbH) was not shifted compared with the upper part (corresponding to HbA). These results were confirmed by kinetic studies of CO recombination. Both experiments demonstrated that RSR-4 does not affect beta4 Hb. Our findings provide an experimental model for lowering the oxygen affinity of HbA in HbH-containing cells and suggest that the oxygen delivery capability of the latter would be thereby improved.

Toward a formalization of the process to select IMIA Yearbook best papers.

BACKGROUND: Each year, the International Medical Informatics Association Yearbook recognizes significant scientific papers, labelled as "best papers", published the previous year in the subfields of biomedical informatics that correspond to the different section topics of the journal. For each section, about fifteen pre-selected "candidate" best papers are externally peer-reviewed to select the actual best papers. Although based on the available literature, little is known about the pre-selection process. OBJECTIVE: To move toward an explicit formalization of the candidate best papers selection process to reduce variability in the literature search across sections and over years. METHODS: A methodological framework is proposed to build for each section topic specific queries tailored to PubMed and Web of Science citation databases. The two sets of returned papers are merged and reviewed by two independent section editors and citations are tagged as "discarded", "pending", and "kept". A protocolized consolidation step is then jointly conducted to resolve conflicts. A bibliographic software tool, BibReview, was developed to support the whole process. RESULTS: The proposed search strategy was fully applied to the Decision Support section of the 2013 edition of the Yearbook. For this section, 1124 references were returned (689 PubMed-specific, 254 WoS-specific, 181 common to both databases) among which the 15 candidate best papers were selected. CONCLUSIONS: The search strategy for determining candidate best papers for an IMIA Yearbook's section is now explicitly specified and allows for reproducibility. However, some aspects of the whole process remain reviewer-dependent, mostly because there is no characterization of a "best paper".

Tetramer-dimer equilibrium of oxyhemoglobin mutants determined from auto-oxidation rates.

One of the main difficulties with blood substitutes based on hemoglobin (Hb) solutions is the auto-oxidation of the hemes, a problem aggravated by the dimerization of Hb tetramers. We have employed a method to study the oxyHb tetramer-dimer equilibrium based on the rate of auto-oxidation as a function of protein concentration. The 16-fold difference in dimer and tetramer auto-oxidation rates (in 20 mM phosphate buffer at pH 7.0, 37 degrees C) was exploited to determine the fraction dimer. The results show a transition of the auto-oxidation rate from low to high protein concentrations, allowing the determination of the tetramer-dimer dissociation coefficient K4,2 = [Dimer] 2/[Tetramer]. A 14-fold increase in K4,2 was observed for addition of 10 mM of the allosteric effector inositol hexaphosphate (IHP). Recombinant hemoglobins (rHb) were genetically engineered to obtain Hb with a lower oxygen affinity than native Hb (Hb A). The rHb alpha2beta2 [(C7) F41Y/(G4) N102Y] shows a fivefold increase in K4,2 at pH 7.0, 37 degrees C. An atmosphere of pure oxygen is necessary in this case to insure fully oxygenated Hb. When this condition is satisfied, this method provides an efficient technique to characterize both the tetramer-dimer equilibrium and the auto-oxidation rates of various oxyHb. For low oxygen affinity Hb equilibrated under air, the presence of deoxy subunits accelerates the auto-oxidation. Although a full analysis is complicated, the auto-oxidation studies for air equilibrated samples are more relevant to the development of a blood substitute based on Hb solutions. The double mutants, rHb alpha2beta2 [(C7) F41Y/(G4) N102A] and rHb alpha2beta2 [(C7) F41Y/(E10) K66T], show a lower oxygen affinity and a higher rate of oxidation than Hb A. Simulations of the auto-oxidation rate versus Hb concentration indicate that very high protein concentrations are required to observe the tetramer auto-oxidation rate. Because the dimers oxidize much more rapidly, even a small fraction dimer will influence the observed oxidation rate.

Two mutations in recombinant Hb beta F41(C7)Y, K82 (EF6)D show additive effects in decreasing oxygen affinity.

Based on the properties of two low oxygen affinity mutated hemoglobins (Hb), we have engineered a double mutant Hb (rHb beta YD) in which the beta F41Y substitution is associated with K82D. Functional studies have shown that the Hb alpha 2 beta 2(C7)F41Y exhibits a decreased oxygen affinity relative to Hb A, without a significantly increased autooxidation rate. The oxygen affinity of the natural mutant beta K82D (Hb Providence-Asp) is decreased due to the replacement of two positive charges by two negative ones at the main DPG-binding site. The functional properties of both single mutants are interesting in the view of obtaining an Hb-based blood substitute, which requires: (1) cooperative oxygen binding with an overall affinity near 30 mm Hg at half saturation, at 37 degrees C, and in the absence of 2,3 diphosphoglycerate (DPG), and (2) a slow rate of autooxidation in order to limit metHb formation. It was expected that the two mutations were at a sufficient distance (20 A) that their respective effects could combine to form low oxygen affinity tetramers. The double mutant does display additive effects resulting in a fourfold decrease in oxygen affinity; it can insure, in the absence of DPG, an oxygen delivery to the tissues similar to that of a red cell suspension in vivo at 37 degrees C. Nevertheless, the rate of autooxidation, 3.5-fold larger than that of Hb A, remains a problem.

Activation of dopamine D4 receptor inhibits an L-type calcium current in cerebellar granule cells.

The functions of the D4 receptor, a newly cloned D2-like receptor, as well as the identity of cells expressing it, are still poorly defined. Using quantitative polymerase chain reaction we detected the messenger RNA of the D4, but not other D2-like receptor, in cultured granule cells from neonatal rat cerebellum. In these neurons, dopamine reduced high-voltage-activated calcium current, with a pharmacology corresponding to that of the D4 receptor. The response declined from one to three days, when calcium currents were mostly sensitive to nifedipine, to 15 days, when nifedipine-insensitive calcium currents were also present and D4 receptor messenger RNA had declined. The dopamine response was abolished after pretreatment of the cells by pertussis toxin, was potentiated and made irreversible by infusion of guanosine 5'-O-(3-thiotriphosphate) but persisted in the presence of cyclic AMP and isobutylmethylxanthine. These results indicate the presence in the neonatal cerebellum of a functional D4 receptor inhibiting an L-type calcium current, an action involving a Gi/Go protein but independent from adenylate cyclase inhibition.

Phenotypical characterization of neurons expressing the dopamine D3 receptor in the rat brain.

We have established the cellular distribution of the dopamine D3 receptor using tritiated 7-hydroxy-N-N-di-n-propyl-2-aminotetralin and a complementary RNA probe to visualize autoradiographically the protein in binding studies and the gene transcripts by in situ hybridization, respectively. Studies with these two markers confirm the restricted expression of the D3 receptor in few brain areas, i.e. mainly the ventral striatal complex, the substantia nigra-ventral tegmental area and the cerebellum. In nucleus accumbens, the D3 receptor was mainly expressed in medium-sized neurons of the rostral pole and ventromedial shell subdivisions, but not of the core or septal pole, i.e. accumbal subdivisions expressing the D2 receptor. In the ventromedial shell, about 60% of the D3 receptor-expressing neurons were neurotensin neurons, presumably projecting to the ventral pallidum. In the islands of Calleja, both D3 receptor binding and messenger RNA were abundant in the entire population of granule cells. These cells are known to make sparse contacts with dopaminergic axons and also to express the D1 receptor. In the mesencephalon, low levels of D3 messenger RNA were detected in few dopamine neurons of substantia nigra pars lateralis and ventral tegmental area. In addition, some D3 receptor binding but not messenger RNA was detected in medial substantia nigra and lateral ventral tegmental area, where the receptor is presumably located presynaptically on afferents. In the archicerebellum, Purkinje cell perikarya in lobules 9 and 10 expressed the D3 receptor messenger RNA, whereas binding sites were found in the molecular layer, where corresponding dendrites but no known dopaminergic projection from mesencephalon are found. The occurrence of D3 receptor gene expression in some brain areas receiving low dopamine innervation supports the hypothesis that this receptor may mediate non-synaptic actions of dopamine.

Multiple dopamine receptors: the D3 receptor and actions of substances of abuse.

Our knowledge of dopamine receptor diversity has markedly increased during the past few years as a result of discovery of five distinct genes, splice variants and polymorphic receptors. The genes can be classified in two subfamilies: the intronless genes that encode the D1 and D5 receptors positively linked to adenylyl cyclase and genes with introns that encode the two isoforms of the D2 receptor and the D3 and D4 receptors. The various dopamine receptor subtypes can be distinguished by their sequence, intracellular signalling systems, pharmacology and localisation. The localisation of the D3 receptor in the shell of nucleus accumbens suggests its participation in brain reward circuits and actions of substances of abuse.

Schizophrenia and the cannabinoid receptor type 1 (CB1): association study using a single-base polymorphism in coding exon 1.

Abuse of cannabis is frequent among the young and is suspected to precipitate schizophrenia in vulnerable subjects. Cannabinoid receptor (CB1) is particularly concentrated in dopamine-modulated areas of the nervous system. An association between an AAT polymorphism of the CB1 gene and intravenous drug abuse has been previously reported, but not with schizophrenia. In a French Caucasian population, we compared the distribution of a single-base polymorphism revealed by MspI within the first exon of the CB1 gene in patients with schizophrenia (n = 102) and ethnic- and gender-matched controls (n = 63). No significant difference was seen in the allele or genotype distribution between the whole sample of schizophrenic patients and controls. However, we found a borderline lack of allele g and a significant lack of gg genotype in the non-substance-abusing patients compared to substance-abusing patients, the latter being similar to the controls. These results are the first report of an significant association between CB1 receptor and a subtype of schizophrenia. Studies are needed to confirm and further explore the precise role of the cannabinoid system in schizophrenia.

Dopamine D3 receptor gene: organization, transcript variants, and polymorphism associated with schizophrenia.

DNA fragments from a genomic library were used to establish the partial structure of the human dopamine D3 receptor gene (DRD3). Its coding sequence contains 6 exons and stretches over 40,000 base pairs. The complete DRD3 transcript and three shorter variants, in which the second and/or third exon are deleted, were detected in similar proportions in brains from four controls and three psychiatric patients. The Msp I polymorphism was localized in the fifth intron of the gene, 40,000 base pairs downstream the Bal I polymorphism and a PCR-based method was developed for genotyping this polymorphism. The distribution of the Msp I and Bal I genotypes were not independent in 297 individuals (chi 2 = 10.5, df = 4, P = 0.03), but only a weak association was found between allele 1 of the Bal I polymorphism and allele 2 of the Msp I polymorphism (chi 2 = 3.99, df = 1, P = 0.04). The previously reported association between homozygosity at both alleles of the Bal I polymorphism and schizophrenia was presently maintained in an extended sample, comprising 119 DSM-III-R chronic schizophrenics and 85 controls (chi 2 = 5.3, df = 1, P = 0.02) and found more important in mal than in females. The presence of the Bal I allele 2 is associated with an early age at onset, particularly in males (df = 35, t value = 2.6, P = 0.014). In the same sample, allelic frequencies, genotype counts, and proportion of homozygotes for the Msp I polymorphism did not differ between schizophrenics and controls (chi 2 = 0.06, df = 1, P = 0.80, chi 2 = 0.22, df = 1, P = 0.90 and chi 2 = 0.16, df = 1, P = 0.69, respectively). The large distance of the Msp I polymorphism from the Bal I polymorphism and its localization in the 3' part of the gene may explain the discrepant results obtained with the two polymorphisms.

Endogenous histamine induces c-fos expression within paraventricular and supraoptic nuclei.

Thioperamide, an H3-receptor antagonist that enhances endogenous histamine release, induced c-fos mRNA expression and Fos-like immunoreactivity in magnocellular neurones of rat supraoptic and paraventricular nuclei. This response was prevented as a result of blockade of the H1 receptor, indicating that endogenous histamine is able to activate these magnocellular neurones via stimulation of this receptor.

A functional test identifies dopamine agonists selective for D3 versus D2 receptors.

The functional potency of a series of dopamine agonists for increasing mitogenesis, measured by incorporation of [3H]thymidine, was established in transfected cell lines expressing human D2 or D3 receptors. The functional selectivity of agonists markedly differs from their binding selectivity. (+)7-OH-DPAT, pramipexole, quinerolane and PD 128,907, the most D3 receptor-selective compounds in binding studies, were 7, 15, 21 and 54 times more potent, respectively, at the D3 than at the D2 receptor in the functional test. Bromocriptine displayed a 10-fold functional selectivity toward the D2 receptor. The known behavioural actions of D3 selective agonists support a role for the D3 receptor in motor inhibitions, which should be taken into account for the treatment of motor dysfunctions by dopamine agonists.

The preferential dopamine D3 receptor ligand, (+)-UH232, is a partial agonist.

In a NG 108 15 hybrid cell line stably expressing a recombinant dopamine D3 receptor, (+)-UH 232 (cis-(+)-1S,2R)-5-methoxy-1-methyl-2-(di-n- propylamino)tetralin), a partially selective D3 receptor ligand, stimulates mitogenesis, as measured by incorporation of [3H]thymidine, with an EC50 of 7.6 nM and a maximal increase corresponding to 23% of the response elicited by quinpirole, a full agonist. This effect was antagonised by nafadotride, a D3 receptor-selective antagonist. (+)-UH 232 also antagonised quinpirole-induced mitogenesis with a Ki value of 9.4 nM. (+)-UH 232 (1 microM) inhibited by 22% the forskolin-induced accumulation of cAMP, whilst the inhibition by quinpirole (100 nM) was 53%. These results indicate that (+)-UH 232 is a partial agonist at the D3 receptor with an intrinsic activity of 0.2-0.4.

Functional coupling of the human dopamine D3 receptor in a transfected NG 108-15 neuroblastoma-glioma hybrid cell line.

Transfection of a human dopamine D3 receptor cDNA in a neuroblastoma-glioma hybrid cell line (NG 108-15) provided clonal cell lines stably expressing up to 600 fmol per mg protein of [125I]iodosulpiride binding sites. Dopamine and several agonists distinguished two receptor-affinity states in membranes. In the case of dopamine, the high-affinity state (Ki = 0.9 nM, 30% of total binding) was completely converted into a low-affinity state (Ki = 57 nM) in the presence of 10 microM guanosine-5'-O-(3-thiotriphosphate). In addition to these two sites, a site with a very low affinity for dopamine was evidenced in whole cells. The dopamine D3 receptor mediated two responses: c-fos activation, as measured by the appearance of Fos-like immunoreactivity, and increased mitogenesis, as measured by incorporation of [3H]thymidine. The Fos-like immunoreactivity appeared within 30 min, lasted 2 h and was blocked by the partially selective dopamine D3 receptor compound (+)-UH 232 (cis-(+)-5-methoxy-1-methyl-2-(di-n-propylamino)tetralin). The mitogenic effect, which occurred after a lag time (over 2 h stimulation), was produced with subnanomolar potency and full intrinsic activity by several compounds previously identified as dopamine D2 receptor agonists, e.g. quinpirole, (+)-7-OH-DPAT ((+)-7-hydroxy-2-(di-n-propylamino)tetralin) and RU 24926 (N-n-propyl-di-beta(3-hydroxyphenyl)-ethylamine), and was reversibly blocked by (+)-UH 232 (Ki = 9 nM). Talipexole (B-HT 920, 5-allyl-2-amino-5,6,7,8-tetrahydro-4H-thiazolo[4,5-d]azepin) was identified as a partial agonist at the dopamine D3 receptor. Dopamine D3 receptor-mediated mitogenesis was potentiated by a phorbol ester and was abolished by pretreatment with pertussis toxin. A mitogenic effect of same amplitude was elicited by bradykinin or carbachol, both acting through constitutive receptors. Bradykinin markedly activated inositol phosphate turnover, and had no effect on forskolin-stimulated cyclic AMP accumulation. Carbachol inhibited forskolin-stimulated cyclic AMP accumulation and had no effect on inositol-phosphate turnover. Quinpirole had no effect on any of these second messenger pathways. Thus, in transfected NG 108-15 cells, the dopamine D3 receptor is coupled to a pertussis toxin-sensitive G protein and mediates two possibly unrelated biological effects, through initial biochemical events that remain to be identified.

The dopamine D3 receptor and schizophrenia: pharmacological, anatomical and genetic approaches.

Antipsychotic drug therapy mainly rests on the use of antagonists of dopamine D2-like (D2, D3 and D4) receptors, for which all clinically active compounds have high affinity. The D3 receptor has a restricted expression in brain limbic areas, associated with cognitive functions and motivated behavior. D3 selective agonists and antagonists reveal an inhibitory role on motor behaviors for the D3 receptor, opposite to that of the D2 receptor. An opposing role for D2 and D3 receptors is also suggested by the contrasted effects of D2/D3 antagonists on neurotensin expression in discrete subdivisions of nucleus accumbens, where D2 and D3 receptors are selectively expressed. Tolerance to the motor but not to the therapeutic effects of neuroleptics is observed after repeated administration, which upregulates the D2, but not the D3 receptor in animals. In genetic association studies, an excess of homozygosity for both alleles of the BalI polymorphism at the D3 receptor gene was found in schizophrenic patients, suggesting that this gene may have subtle influence on the liability to develop schizophrenia. These results suggest the D3 receptor as an important target for antipsychotic drug action, and D3 receptor selective antagonists as promising therapeutic agents.

Thermodynamics of Na+ binding to coagulation serine proteases.

The sodium binding to serine proteases triggers a conformational change in the proteins that enhances the catalytic activity of the enzymes. The interaction of the cation with the protein is mediated by the hydrogen-bonding network of water molecules that embed the Na+ site. We pointed out the crucial role of the insertion loop 186a-d and the I16-D194 ion pair in the stabilization of sodium binding pocket in thrombin. This paper contributes to better explain the molecular mechanism of sodium binding for different serine proteases leading to the identification of the structural changes necessary to engineer a functional Na+ site and regulate catalytic activity in serine proteases.