RPR 119990, a novel alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid antagonist: synthesis, pharmacological properties, and activity in an animal model of amyotrophic lateral sclerosis.

Alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate receptor antagonists are of potential interest for the treatment of certain acute and chronic neurodegenerative diseases, including amyotrophic lateral sclerosis. Here, we describe the synthesis and pharmacological properties of 9-carboxymethyl-4-oxo-5H,10H-imidazo[1,2-a]indeno[1,2-e]pyrazin-2-phosphonic acid (RPR 119990). The compound displaced [3H]AMPA from rat cortex membranes with a K(i) of 107 nM. In oocytes expressing human recombinant AMPA receptors, RPR 119990 depressed ion flux with a K(B) of 71 nM. The antagonist properties of this compound were confirmed on rat native AMPA receptors in cerebella granule neurons in culture and in hippocampal slices where it antagonized electrophysiological responses with IC50 values of 50 and 93 nM, respectively. RPR 119990 antagonized hippocampal evoked responses in vivo, demonstrating brain penetration at active concentrations. RPR 119990 is a potent anticonvulsant in the supramaximal electroshock in the mouse with an ED50 of 2.3 mg/kg 1 h post s.c. administration, giving it a workably long action. Pharmacokinetic studies show good passage into the plasma after subcutaneous administration, whereas brain penetration is low but with slow elimination. This compound was found active in a transgenic mouse model of familial amyotrophic lateral sclerosis (SOD1-G93A) where it was able to improve grip muscle strength and glutamate uptake from spinal synaptosomal preparations, and prolong survival with a daily dose of 3 mg/kg s.c.

Infarto renal como forma de presentación de una estenosis mitral / Renal infarction as presentation of a mitral stenosis

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[Prevalence of IgG antibodies against Cytomegalovirus in patients with angiographically demonstrated coronary atherosclerosis]. / Prevalencia de anticuerpos IgG frente a Citomegalovirus en pacientes con aterosclerosis coronaria demostrada angiográficamente.

BACKGROUND: Over the past 25 years the potential role of herpesvirus and particularly Cytomegalovirus as a factor which contribute to atherogenesis, and more recently in restenosis, has been investigated. OBJECTIVES: To determine the rate of Cytomegalovirus seropositivity in patients with angiographically demonstrated Coronary Artery Atherosclerosis. PATIENTS AND METHODS: The subjects were all adult patients undergoing coronary angiography at the Hospital Virgen de la Salud, Toledo between February, 1997 and May, 1998. From each patient, blood was drawn and collected to be assayed. Also we collected the data from sex, age, classic risk factors for coronary artery disease (hypertension, hypercholesterolemia, diabetes and cigarette smoking) and catheterization. Data from 437 patients who underwent cardiac catheterization were collected. There was 349 (82.3%) patients who underwent catheterization because of Ischemic Heart Disease. SEROLOGIC ASSAYS: Serum IgG antibodies to cytomegalovirus were measured quantitatively with EIA, VIDAS, (bioMérieux). As recommended by the manufacturer a titer over 6 was considered positive. RESULTS: There was 115 female and 319 males. Patients were 24-86 years old. Data from catheterization showed that 113 patients (26%) have no lesions on coronaryography and 321 patients (74%) have Coronary Artery Disease (CAD). The rate of Cytomegalovirus-seropositive was 97.1% in patients with lesions and 98.2% in those without lesions. CONCLUSIONS: There is a high rate of antibodies positive for Cytomegalovirus in the population, in patients with Ischemic Heart Disease and with coronary artery disease as in those without lesions in the coronarigraphy. Our conclusion is that if Cytomegalovirus could have any role in the building of proliferating ateheromas and in view of seroepidemiological studies some other factors must be implicated in the development of plaque growth.

[An adrenaline-induced vasospasm as the form of presentation of variant angina]. / Vasoespasmo inducido por adrenalina como forma de presentación de una angina variante.

A 41-year-old-man without previous ischemic heart disease, developed a severe anaphylactic reaction. After administration of epinephrine (0.5 mg) the patient complained of chest pain. The electrocardiogram showed an elevation of ST segment in inferior leads. Myocardial necrosis was ruled out. Coronary arteriography disclosed normal coronary arteries. Eight months later, the patient developed severe chest pain during physical activity. ST elevation was again seen in inferior leads. ECG changes disappeared, when sublingual nitroglycerin was administered. A diagnosis of vasospastic angina was made. Exercise test was negative, during treatment with calcium-blocking agents. The patient subsequently remain free of symptoms taking medication. The physiological mechanisms of vasospastic angina and precipitating factors are discussed.

Glutamate uptake is decreased tardively in the spinal cord of FALS mice.

This study examined high affinity Na+-dependent uptake of glutamate in synaptosomal preparations from spinal cord in mice that express a dominant mutation of human copper/zinc superoxide dismutase (SOD1) and represent an animal model of amyotrophic lateral sclerosis (ALS). Their muscle strength was also monitored by a grip traction test throughout their lifespan. The high affinity Na+-dependent uptake of [3H]glutamate was decreased between 120 and 150 days of age. A marked and significant decrease in Vmax (-40.2%; p < 0.001) on whole spinal cord synaptosomes was observed at 150 days, with no change in Km. This significant decrease was reached a week before the animals died (157.2 +/- 2.2 days) and corresponded to a considerable fall in muscle strength (25% loss between 120 and 140 days, p < 0.001). The FALS mouse model therefore reproduces the decrease in glutamate uptake reported in humans suffering from sporadic or familial ALS. These results are discussed in terms of a possible tardive involvement of glutamate uptake deficiency in human ALS.

The mechanism of action of zopiclone.

The mechanism of action of the cyclopyrrolone hypnotic drug zopiclone involves allosteric modulation of the GABAA receptor. Zopiclone displaces the binding of [(3)H]-flunitrazepam with an affinity of 28 nM, and enhances the binding of the channel blocker [(35)S]-TBPS. The binding of zopiclone, unlike that of hypnotic benzodiazepines, is not facilitated by GABA. Zopiclone does not distinguish between GABAA receptors containing different alpha-subunits (BZ(1) and BZ(2) phenotype). Studies with protein-modifying agents (eg diethylpyrocarbonate) and photoaffinity labelling suggest that cyclopyrrolones bind to a domain on the GABAA receptor different from the benzodiazepine binding domain. The consequence of this interaction with the GABAA receptor is to potentiate responses to GABA, as can be demonstrated by electrophysiological methods. Subchronic treatment of mice with high doses of zopiclone does not produce the changes in sensitivity of the GABAA receptor that are observed with hypnotic benzodiazepines.

RP 59037 and RP 60503: anxiolytic cyclopyrrolone derivatives with low sedative potential. interaction with the gamma-aminobutyric acidA/benzodiazepine receptor complex and behavioral effects in the rodent.

This study describes the pharmacological properties of two novel cyclopyrrolone derivatives, RP 59037 [2-(7-chloro-2-naphthyridin-1,8-yl)-3-(5- methyl-2-oxohexyl)isoindolin-1-one] and RP 60503 [2-(7-chloro-2-naphthyridin-1,8-yl)isoindolin-1-yl-4- acetamidobutyrate], in the rodent. These compounds possess high affinity for the benzodiazepine binding site on the gamma-aminobutyric acidA receptor in rat cerebrocortical membranes with Ki values of 0.98 nM (RP 59037) and 1.16 nM (RP 60503). Neither compound discriminates between the putative benzodiazepine BZ1 and BZ2 binding site subtypes present in the rat cerebellum and hippocampus, respectively. Both compounds protect mice against pentylenetetrazole-induced seizures with ID50 values of 0.21 mg.kg-1 p.o. (RP 59037) and 5.96 mg.kg-1 p.o. (RP 60503). The two compounds displayed a restricted anticonvulsant profile compared to diazepam and, in this respect, resembled the pyrazoloquinoline partial agonist, CGS 9896. RP 59037 and RP 60503 were active in two rat models predictive of anxiolytic drug action, a modified Geller-Seifter conflict paradigm (minimal effective dose, 0.33 mg.kg-1 p.o. for RP 59037 and 5 mg.kg-1 p.o. for RP 60503) and the elevated plus maze (minimal effective dose, 0.33 mg.kg-1 p.o. for RP 59037 and 5 mg.kg-1 p.o. for RP 60503). Only very low activities were observed in tests of sedative or myorelaxant effects (ED50 > 50 mg.kg-1 p.o.). It is concluded that the two cyclopyrrolones possess a dissociated behavioral profile, displaying potent anxiolytic and anticonvulsant properties with little or no sedative or myorelaxant effects. Although both compounds appear to be partial agonists at their allosteric recognition site on the gamma-aminobutyric acidA receptor, RP 60503 seems to be more dissociated than RP 59037, which would be compatible with it having lower intrinsic activity. This difference is reflected in a higher receptor occupancy requirement for activity, and a smaller modulatory effect on the binding of t-[35S]butylbicyclophosphothionate.

Inhibition by riluzole of electrophysiological responses mediated by rat kainate and NMDA receptors expressed in Xenopus oocytes.

The effects of riluzole, an anticonvulsant and neuroprotective compound, on excitatory amino acid-evoked currents were studied in Xenopus laevis oocytes injected with mRNA from rat whole brain or cortex. Responses to kainic acid were blocked by riluzole (IC50 = 167 microM) as well as by the quinoxalinedione antagonists 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX: IC50 = 0.21 microM) and 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline (NBQX: IC50 = 0.043 microM). Riluzole was somewhat more potent at blocking responses to N-methyl-D-aspartic acid (NMDA: IC50 = 18.2 microM); the competitive NMDA receptor antagonist 2-amino-phosphonovaleric acid (2-APV) yielded an IC50 of 6.1 microM in this system. The inhibition by both riluzole and 2-APV was reversible and did not appear to be use dependent, unlike that of the channel blocker MK-801 ([+]-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclohepten-5,10-imine maleate). It was impossible to demonstrate an interaction of riluzole with any of the known ligand recognition sites on either the kainate or the NMDA receptor in radioligand binding studies. These results suggest a direct but non-competitive action of riluzole on ionotropic glutamate receptors.

A rapid filtration assay for the glycine binding site on the NMDA receptor in rat cortical membranes using [3H]dichlorokynurenic acid.

A filtration binding assay using [3H]dichlorokynurenic acid to label the glycine binding site on the N-methyl-D-aspartic acid receptor has been evaluated on rat cortical membranes. This ligand binds to a single population of binding sites following mass action kinetics with a KD of 29 nM and a capacity of 5.73 pmol (mg protein)-1. The pharmacological specificity of the binding site is identical to that previously reported for this binding site using [3H]glycine as a radioligand. Agonists showed lower affinity and antagonists higher affinity when [3H]dichlorokynurenic acid was used compared with [3H]glycine. The higher affinity of [3H]dichlorokynurenic acid compared with [3H]glycine make it the more suitable compound with which to label the glycine site.

Ascitic fluid polymorphonuclear cell count and serum to ascites albumin gradient in the diagnosis of bacterial peritonitis.

The analysis of ascitic fluid has been complicated by several recently reported new tests. To simplify this assessment, we evaluated nine parameters prospectively and simultaneously in blood and ascitic fluid from 285 patients with ascites to determine which were the most reliable for immediate diagnosis of the etiology of the ascites and of its complications. Subjects were first divided into four groups: sterile cirrhotic ascites (n = 201), spontaneous bacterial peritonitis (n = 41), malignant ascites (n = 34), and miscellaneous ascites (n = 9). An ascitic fluid polymorphonuclear count greater than 500/microliters was the test with the greatest accuracy (96%) for the diagnosis of spontaneous bacterial peritonitis. Neither the most precise cutoff values for ascitic fluid pH (less than 7.32) and ascitic fluid lactate (greater than 32 mg/dl), nor their respective blood-ascitic fluid gradients (greater than 0.11 and less than -20 mg/dl) were more reliable indexes of spontaneous bacterial peritonitis, mainly due to the decreased ascitic fluid pH and increased ascitic fluid lactate observed in malignant ascites, tuberculous peritonitis, and pancreatic ascites. A blood-ascitic fluid albumin gradient less than 1.1 g/dl was the most accurate parameter for the diagnosis of malignant ascites (diagnostic efficacy, 93%). Therefore, the etiologic analysis of ascitic fluid might be simplified and the single practice of two tests, ascitic fluid polymorphonuclear cell count and blood-ascitic fluid albumin gradient, provides immediately useful information.

Evidence that temporary complete occlusion of splenic vessels prevents massive embolization and sudden death associated with intrasplenic hepatocellular transplantation.

It has been reported elsewhere that liver cell suspensions injected at several locations retain some proper hepatic functions, significantly improve the survival rate of rats with different models of acute fulminant hepatic injury, correct some congenital enzyme deficiency diseases, and improve liver function in cirrhotic animals. Among several locations, the splenic parenchyma has been shown to be the most suitable place for hepatocellular transplantation. Unfortunately, infusion of cells into the splenic pulp is not without risk. In fact, portal hypertension and hepatic embolizations have been described after intrasplenic transplantation of hepatocytes or pancreatic islets or fragments. In addition, pulmonary hepatocyte embolizations have been observed in rats with spontaneous (unpublished observations) or surgically induced portosystemic shunts. In this work, we evaluate the efficacy of temporary occlusion of splenic vessels to prevent hepatic and pulmonary embolizations after liver cell transplantation into the spleen in portal hypertension cirrhotic rats with portosystemic shunts.

Circadian rhythm in the membrane of circulating human blood cells: microviscosity and number of benzodiazepine binding sites. A search for regulation by plasma ions, nucleosides, proteins or hormones.

Circadian rhythms in both the number of peripheral type binding sites for benzodiazepines in platelet membranes and the microviscosity of the erythrocyte membrane were demonstrated in 7 healthy men. Neither variable appeared to be linked to each other, or regulated by the plasma concentrations of total or free cortisol, testosterone, potassium, magnesium, calcium, cAMP, cGMP or proteins or by the erythrocytic concentration of magnesium or potassium or by the plasma cAMP:cGMP ratio or by the ratio of intra-erythrocyte:plasma concentrations of potassium or magnesium. A highly significant negative correlation was found between the microviscosity of the erythrocyte membrane and the activity of the membrane-bound enzyme, methyltransferase I. Such a correlation was validated both on raw data and on 24 hr-means (r = 0.84; P less than 0.01). A circadian rhythm in the activity of this enzyme was also demonstrated. Moreover, a highly significant correlation was also found between plasma transcortin concentration (TRC) and microviscosity (r = 0.50, P less than 0.01), and between TRC and methyltransferase I activity (r = 0.61, P less than 0.01). Such findings may constitute clues towards the understanding of the regulation of the circadian rhythm in the fluidity of the red blood cell membrane in man and guide future steps with regard to the role of this rhythm upon the availability of drug binding sites at the cell surface.