Detection of SARS-CoV-2 antibodies using commercial assays and seroconversion patterns in hospitalized patients

Objectives

SARS-CoV-2 antibody assays are needed for serological surveys and as a complement to molecular tests to confirm COVID-19. However, the kinetics of the humoral response against SARS-CoV-2 remains poorly described and relies on the performance of the different serological tests.

Methods

In this study, we evaluated the performance of six CE-marked point-of-care tests (POC) and three ELISA assays for the diagnosis of COVID-19 by exploring seroconversions in hospitalized patients who tested positive for SARS-CoV-2 RNA.

Results

Both the ELISA and POC tests were able to detect SARS-CoV-2 antibodies in at least half of the samples collected seven days or more after the onset of symptoms. After 15 days, the rate of detection rose to over 80% but without reaching 100%, irrespective of the test used. More than 90% of the samples collected after 15 days tested positive using the iSIA and Accu-Tell® POC tests and the ID.Vet IgG ELISA assay. Seroconversion was observed 5 to 12 days after the onset of symptoms. Three assays suffer from a specificity below 90% (EUROIMMUN IgG and IgA, UNscience, Zhuhai Livzon).

Conclusions

The second week of COVID-19 seems to be the best period for assessing the sensitivity of commercial serological assays. To achieve an early diagnosis of COVID-19 based on antibody detection, a dual challenge must be met: the immunodiagnostic window period must be shortened and an optimal specificity must be conserved.

Joint analysis of BICEP2/keck array and Planck Data

We report the results of a joint analysis of data from BICEP2/Keck Array and Planck. BICEP2 and Keck Array have observed the same approximately 400  deg^{2} patch of sky centered on RA 0 h, Dec. -57.5°. The combined maps reach a depth of 57 nK deg in Stokes Q and U in a band centered at 150 GHz. Planck has observed the full sky in polarization at seven frequencies from 30 to 353 GHz, but much less deeply in any given region (1.2  μK deg in Q and U at 143 GHz). We detect 150×353 cross-correlation in B modes at high significance. We fit the single- and cross-frequency power spectra at frequencies ≥150  GHz to a lensed-ΛCDM model that includes dust and a possible contribution from inflationary gravitational waves (as parametrized by the tensor-to-scalar ratio r), using a prior on the frequency spectral behavior of polarized dust emission from previous Planck analysis of other regions of the sky. We find strong evidence for dust and no statistically significant evidence for tensor modes. We probe various model variations and extensions, including adding a synchrotron component in combination with lower frequency data, and find that these make little difference to the r constraint. Finally, we present an alternative analysis which is similar to a map-based cleaning of the dust contribution, and show that this gives similar constraints. The final result is expressed as a likelihood curve for r, and yields an upper limit r_{0.05}<0.12 at 95% confidence. Marginalizing over dust and r, lensing B modes are detected at 7.0σ significance.

Amatoxins in wood-rotting Galerina marginata

Amatoxins, bicyclic octapeptide derivatives responsible for severe hepatic failure, are present in several Basidiomycota species belonging to four genera, i.e. Amanita, Conocybe, Galerina and Lepiota. DNA studies for G. autumnalis, G. marginata, G. oregonensis, G. unicolor and G. venenata (section Naucoriopsis) determined that these species are the same, supporting the concept of Galerina marginata complex. These mostly lignicolous species are designated as white-rot fungi having a broad host range and capable of degrading both hardwoods and softwoods. Twenty-seven G. marginata basidiomes taken from different sites and hosts (three sets) as well as 17 A. phalloides specimens (three sets) were collected in French locations. The 44 basidiomes were examined for amatoxins and phallotoxins using high-performance liquid chromatography. Toxinological data for the wood-rotting G. marginata and the ectomycorrhizal A. phalloides species were compared and statistically analyzed. The acidic and neutral phallotoxins were not detected in any G. marginata specimen, whereas the acidic (β-Ama) and neutral (α-Ama and γ-Ama) amanitins were found in all basidiomes from either Angiosperms or Gymnosperms hosts. The G. marginata amatoxin content varied from 78.17 to 243.61 μg.mg(-1) of fresh weight and was elevated significantly in one set out of three. The amanitin amounts from certain Galerina specimens were higher than those from some A. phalloides basidiomes. Relationship between the amanitin distribution and the chemical composition of substrate was underlined and statistically validated for the white-rot G. marginata. Changes in nutritional components from decayed host due to enzymatic systems and genetic factors as well as environmental conditions seem to play a determinant role in the amanitin profile. Variability noticed in the amanitin distribution for the white-rot G. marginata basidiomes was not observed for the ectomycorrhizal A. phalloides specimens.

Determination of fosmidomycin in human serum and urine by capillary electrophoresis

A capillary electrophoresis method with direct UV detection was developed for the determination of fosmidomycin, a promising new anti-malarial drug, in human serum and urine. Optimization of the separation parameters resulted in a buffer system adjusted to pH 10.8 containing a cationic reagent and an organic modifier. Under these conditions, the migration time of fosmidomycin was 5.2 min with serum and 7.4 min with urine samples. Validation of the method revealed good recoveries, precision and accuracy. The limit of quantification was 0.5 microg/ml in serum and 10 microg/ml in urine. The determination of fosmidomycin in serum was linear over a range of 0.1-150 microg/ml. Short and long-term stability tests resulted in no significant loss of fosmidomycin. The described technique will provide a fast and accurate analytical method for future pharmacokinetic studies.

The effect of rifampin on the pharmacokinetics of vinorelbine in the micropig

BACKGROUND

Vinorelbine has been shown to be metabolised by CYP3A4 in vitro. To evaluate the impact of CYP3A in the disposition of vinorelbine in vivo, we compared the kinetics of the alkaloid given intravenously alone and combined with rifampin, a potent CYP3A inducer, in the micropig.

ANIMALS AND METHODS

Four healthy Yucatan micropigs, about 20 kg, received a first infusion of vinorelbine (0.5 mg/kg). During the next week they were injected rifampin (600 mg daily) and a second vinorelbine infusion (0.5 mg/kg) on the 7th day of rifampin dosing. Serum concentrations of vinorelbine and rifampin were measured by high performance liquid chromatography.

RESULTS

The mean peak concentrations of vinorelbine were 274.2 ng/ml (Standard Deviation or SD: 90) and 458 ng/ml (SD: 448), the mean areas under the serum concentration-time curve were 8,344 ng.min.ml-1 (SD: 2,604) and 14,093 ng/ml.min-1 (SD: 10,000) and the total clearances were 1.146 l/min (SD: 0.333) and 1.003 l/min (SD: 0.714) when the Catharanthus alkaloid was given alone or was combined with rifampin, respectively.

CONCLUSION

We did not observe an increase in vinorelbine elimination by rifampin related to a CYP3A induction in an animal model physiologically close to humans. Although the number of animals was small, these results suggest that CYP3A metabolism constitutes a minor pathway of elimination of intravenous vinorelbine in the micropig.

Moxifloxacin efficacy and vitreous penetration in a rabbit model of Staphylococcus aureus endophthalmitis and effect on gene expression of leucotoxins and virulence regulator factors

Bacterial endophthalmitis is a serious complication of ocular surgery and of eye trauma; the leading causative organisms are Staphylococcus aureus strains. Tissue damage is due both to the host inflammatory response and to toxin synthesis by bacteria. Systemic treatment remains difficult because most antibiotics show poor ocular penetration. Moxifloxacin (MXF), a novel fluoroquinolone, was evaluated for its penetration into the vitreous of normal rabbit eyes and of eyes of rabbits infected for 24 h with methicillin-susceptible and methicillin-resistant S. aureus (MSSA and MRSA) following a single intravenous administration of 5 or 20 mg/kg. MXF penetration was rapid and efficient regardless of the dose, ranging from 28 to 52%. An inflammatory state of the vitreous significantly increased penetration after the 20-mg/kg dose, with penetration reaching 52%. Concentrations determined in the vitreous cavity following a 20-mg/kg administration showed a 3.5-fold decrease of the bacterial density within 5 h for MSSA (MIC, 0.125 micro g/ml) and a 1.6-fold decrease for MRSA (MIC, 4 micro g/ml) strains, respectively. By using a semiquantitative reverse transcription-PCR method, the expression of luk-PV and hlgCB, but not hlgA, encoding staphylococcal leukotoxins, was detected in the vitreous without MXF treatment. A slight decrease in the expression of leucotoxins and sarA, agr, and sigB virulence regulatory factors was observed 1 h following the administration of 5 mg of MXF per kg.

[Sinusal penetration of amoxicillin-clavulanic acid. Formulation 1 g./125 mg., twice daily versus formulation 500 mg./125 mg., three times daily]

INTRODUCTION

In order to meet the evolution of pneumococcus resistance to beta-lactam antibiotics, a new formulation of amoxicillin (AMX) and clavulanic acid (CA), with twice as much AMX (1 g/125 mg vs. 500 mg/125 mg) was developed for the treatment of acute pneumonia in patients at risk. This formulation can also be used in the treatment of acute maxillary sinusitis using a 1 g/125 mg regimen twice-daily.

OBJECTIVES

Compare the sinusal penetration of AMX and CA (1 g/125 mg twice-daily vs. 500 mg/125 mg three times a day) when administered at both regimens to demonstrate equivalent pharmacokinetic and pharmacodynamic behaviour of the former when compared to the latter.

METHODS

Concentrations of AMX and CA were measured in the anterior ethmoid, maxillary, posterior ethmoid sinus and in the middle nasa concha in 62 patients undergoing surgery for nasosinusal polyps. Patients randomised in two groups corresponding to 2 oral regimens, received either 1 g/125 mg twice a day or 500 mg/125 mg three times a day for 4 days. The last dose in both groups was administered 1 h 30, 3, 5 or 8 hrs prior to surgery. Serum samples were taken simultaneously to tissue samples. AMX and CA were measured by high performance liquid chromatography. Exogenous and above all endogenous blood contamination were taken into account with the hematocrit as well as blood and tissue haemoglobin concentrations. Comparisons of tissue concentrations were made for each sampling time, according to values obtained for a specific tissue with both doses on one hand, and on the other to values obtained with a specific dose in different tissues. The calculated pharmacodynamic parameters, which are considered to be predictive for bacteriological and clinical efficacy, result directly from tissue concentrations of AMX. tissue inhibitory quotients (IQtissue = Tissue concentration/MIC). time above MICs for serum and tissue concentrations (T > MIC).

RESULTS

As regards AMX, whatever the dose, at 1 h 30 and at 3 hrs, tissue concentrations did not differ significantly whatever the tissue studied (from 1.1 to 2.5 micrograms/g). Conversely, at 5 and 8 hrs, they were greater than after the 1 g/125 mg regimen given twice-daily (0.06-0.7 vs. 0.7-1.8 micrograms/g). If we consider a given dose, the comparison between the various tissues showed identical concentrations in the four tissues studied at each sampling time, except in two cases with the dose of 500 mg/125 mg 3 times a day. T > MIC for serum and tissue showed higher values than those required for AMX/pneumococcus association (40-50%) with, nevertheless, greater tissue values for the 1 g/125 mg dose given twice-daily when MIC was of 1 microgram/ml (40-52% vs. 50-66%). The maximum tissue inhibitory quotients were also greater with the twice-daily 1 g/125 mg dose, when calculated with MIC 50 or 90 of S. Pneumoniae, H. influenzae, M. catarrhalis or S. pyogenes. As for CA, concentrations were equivalent for both doses at each sampling time and greater than those required in vitro during respectively 4 and 5 hours for beta-lactamases H. influenzae and M. catarrhalis.

DISCUSSION-CONCLUSION

A least an equivalence between both dose regimens was observed, with occasionally a superiority of the twice-daily 1 g/125 mg dose, in terms of pharmacokinetics, tissue penetration and pharmacodynamics for both AMX and CA. This new regimen therefore appears more appropriate for the treatment of acute maxillary sinusitis in adults.

Gastric penetration of amoxicillin in a human Helicobacter pylori-infected xenograft model

The delivery of antibiotics into Helicobacter pylori-infected human stomachs is still poorly understood. Human embryonic gastric xenografts in nude mice have recently been proposed as a new model for the study of H. pylori infection. Using this model, we compared the penetration of amoxicillin, after intraperitoneal administration of a dose of 20 mg/kg of body weight, into the gastric mucosae of infected and uninfected xenografts. The concentrations of this drug in serum and superficial gastric mucosae were determined at 20 min and 1 and 3 h after injection. Ten mice with H. pylori-infected grafts (n = 5) or uninfected grafts (n = 5) were studied. Mucosal samples were obtained by cryomicrotomy. The concentrations in serum were similar to those obtained in the serum of humans after oral administration of 1 g of amoxicillin. The mean area under the tissue concentration-versus-time curve from 0 to 3 h obtained for mice with infected grafts was significantly higher than that obtained for the animals with uninfected grafts (P = 0.01). These results suggest that the penetration of amoxicillin into the superficial gastric mucosa may be substantially increased in the case of H. pylori infection. Thus, human xenografts in nude mice represent a new, well-standardized model for investigation of systemic delivery of drugs into H. pylori-infected gastric mucosa.

Food and nutrient intake outside the home of 629 French people of fifteen years and over

OBJECTIVE

This study was conducted to assess nutrient intake outside the home of 629 people representative of the French population.

SUBJECTS

The study population consisted of 629 people aged 15 years and over. They were recruited in a randomized way with two levels (town and household).

METHOD

Food intake outside the home was assessed by self-completed estimated record for 7 d. Individuals referred to photographs to estimate portions. Nutrient intake has been calculated for energy, protein, carbohydrate, fat and some minerals (calcium, phosphorus, magnesium, iron).

RESULTS

Lunches and dinners eaten out are on average too rich in protein (20% of the energy), too high in fat (40-43% of the energy) and do not contain enough carbohydrate. The percentage of energy from sugars varies between 11% for lunch and 30% for breakfast. Mean intake of nutrients by beverages drunk outside the home decrease with the age of consumers.

CONCLUSION

This study shows that foods and drinks consumed outside the home in France are on average too rich in fat and protein.

Pre-Main-Sequence Star Candidates in the Bar of the Large Magellanic Cloud

Candidate pre-main-sequence stars were observed in the bar of the Large Magellanic Cloud during the search for dark matter in the galactic halo. Seven blue stars of apparent visual magnitude 15 to 17 had irregular photometric variations and hydrogen emission lines in their optical spectra, which suggested that these stars are pre-main-sequence stars of about 10 solar masses. These stars are slightly more massive and definitely more luminous than are Herbig AeBe pre-main-sequence stars in our own galaxy. Continued observations of these very young stars from another galaxy, which are probably at the pre-hydrogen-burning stage, should provide important clues about early stages of star formation.

Photoaffinity labeling of peripheral-type benzodiazepine-binding sites

The use of a novel photoaffinity label for the peripheral-type benzodiazepine-binding site is described. This compound, PK 14105, has high affinity (4 nM) and selectivity for cardiac benzodiazepine-binding sites. Under ultraviolet light, PK 14105 couples covalently to an 18,000-Da membrane protein which apparently corresponds to the (or a part of the) cardiac benzodiazepine-binding site. Since covalent attachment of PK 14105 totally precludes the binding of other ligands to this binding site, it is suggested that, during ultraviolet irradiation, this compound inserts covalently into the binding domain of the peripheral-type benzodiazepine-binding site.

Partial purification and pharmacology of peripheral-type benzodiazepine receptors

This report describes the results obtained with a new photoaffinity ligand for the "peripheral-type" benzodiazepine binding site (PBS), using a digitonin solubilized preparation from rat heart or adrenals. The specific binding activity of the solubilized adrenal preparation is higher than 50 pmol/mg protein, with binding properties and pharmacological specificity identical to the membrane bound PBS. The apparent molecular weight of the solubilized PBS, determined by gel filtration is 215 KDa. The photoaffinity ligand (PK 14105) is a nitrophenyl derivative of PK 11195, which attaches covalently and specifically to all the PBS when cardiac membranes are irradiated with this compound under ultraviolet light. After photolabelling with [3H]PK 14105 and solubilization in SDS of heart or adrenal membranes, gel electrophoresis indicates the existence of a single protein band whose molecular weight (18 KDa) is unaltered by incubation with sulphydryl-reducing or protein cross-linking agents. This molecule seems to be a low molecular weight, acidic protein. Diethylpyrocarbonate decreases partially (60%) the binding of [3H]PK 11195 without affecting [3H] RO5-4864 binding, which implies a vital histidine residue in the binding domain of [3H]-PK 11195. Treatment with phospholipase A2 or mellitin, a stimulant of endogenous PLA2, led to a selective loss of [3H] RO5-4864 binding with no change in the binding of [3H]PK 11195. Such differences between a benzodiazepine ligand and an isoquinoline ligand suggest that these compounds may induce, on binding, different conformational changes in the PBS, which is compatible with the hypothesis that RO5-4864 and PK 11195 may be an agonist and an antagonist respectively at the PBS.

Stereoselective inhibition of the binding of [3H]PK 11195 to peripheral-type benzodiazepine binding sites by a quinolinepropanamide derivative

The specific binding of [3H]PK 11195 to the peripheral-type benzodiazepine binding site is inhibited by the l-enantiomer of N,N-diethyl-alpha-methyl-2-phenyl-4-quinolinepropanamide ((-)Q1) but not by its d-enantiomer ((+)Q1). (-)Q1 inhibited [3H]PK 11195 binding to several rat tissues with an IC50 of less than 10 nM whereas (+)Q1 was at least 500 times less potent. This stereoselectivity was observed in all the tissues tested (brain, heart, kidney and adrenals). The same stereoselectivity was found for the displacement of the binding of [3H]PK 11195 in vivo, where (-)Q1 had an ID50 between 4-15 mg/kg and (+)Q1 was completely inactive at all doses tested (i.e. up to 40 mg/kg). Neither isomer had appreciable affinity for central-type benzodiazepine binding sites ([3H]diazepam) nor for voltage-sensitive calcium channels ([3H]PN 200210 and [3H]verapamil).

4-Amino-6-chloro-2-piperazinopyrimidines with selective affinity for alpha 2-adrenoceptors

A series of 4-amino-6-chloro-2-piperazinopyrimidines were synthesized and evaluated for their ability to interact with alpha 1- and alpha 2-adrenoceptors in vitro in binding assays using [3H]WB-4101, [3H]clonidine, and [3H]idazoxan as radioligands. Some compounds were also tested as inhibitors of [3H]spiroperidol binding. Several members of this series showed high and selective affinity for alpha 2-adrenoceptors. The nature of the 4-amino substituent seems to be the most critical factor in determining the potency at these receptors.

PK 11195, an antagonist of peripheral type benzodiazepine receptors, modulates Bay K8644 sensitive but not beta- or H2-receptor sensitive voltage operated calcium channels in the guinea pig heart

In a partially depolarized guinea pig papillary muscle preparation, BAY K8644 stimulated voltage-operated calcium channels, promoting slow action potentials; this effect was dose-dependent over a concentration range of 3 X 10(-7) M to 3 X 10(-6) M. Isoproterenol and histamine also induced slow action potentials by stimulating beta or H2 receptors, respectively. PK 11195, the antagonist of peripheral type benzodiazepine receptors, inhibited the effect of BAY K8644, but not those of histamine or isoproterenol. Moreover, PK 11195 "dose-dependently" antagonized the ability of RO5-4864 to inhibit the slow action potentials elicited by barium chloride. Thus, in the heart, PK 11195, an antagonist of peripheral type benzodiazepine receptors, can modulate voltage-operated calcium channels when they are activated directly, but not when they are activated by stimulation of neurotransmitter receptors.

Modulation of voltage-operated, but not receptor-operated, calcium channels in the rabbit aorta by PK 11195, an antagonist of peripheral-type benzodiazepine receptors

We compared the effects of PK 11195, an antagonist of peripheral benzodiazepine receptors, on contractions of rabbit aorta by activation of either voltage-operated calcium channels (VOC) using BAY K 8644 (a calcium "agonist") and KCl or receptor-operated channels (ROC) using phenylephrine and B-HT 920, (alpha 1- and alpha 2-adrenoceptor agonist, respectively). In partially depolarized muscle strips, BAY K 8644 induced contractions that were noncompetitively inhibited by PK 11195 (pD'2 = 5.6 +/- 0.15). The effect of this calcium agonist was also antagonized by nitrendipine (competitively) and by yohimbine (noncompetitively), while prazosin was inactive. Contractions induced by KCl were inhibited by nitrendipine and, weakly, by PK 11195. Contractions induced by phenylephrine and B-HT 920 were inhibited competitively by prazosin and yohimbine and noncompetitively by nitrendipine, while PK 11195 was ineffective. It is concluded that PK 11195 behaves as an antagonist of VOC activated by BAY K 8644 and to a lesser extent by KCl depolarization but not of ROC coupled to alpha 1- and alpha 2-receptors.

PK 11195, an antagonist of peripheral benzodiazepine receptors, reduces ventricular arrhythmias during myocardial ischemia and reperfusion in the dog

PK 11195, an antagonist of peripheral type benzodiazepine receptors, in doses from 5 to 25 mg/kg i.d. protected in a dose-dependent manner dogs against both early and delayed ventricular arrhythmias induced by 20 min ischemia and against ventricular fibrillation following reperfusion. Thus, peripheral-type benzodiazepine receptors might represent a novel target in the treatment of angina and cardiac ischemia.

Opposite effects of two ligands for peripheral type benzodiazepine binding sites, PK 11195 and RO5-4864, in a conflict situation in the rat

The effects of two drugs acting at the peripheral type benzodiazepine binding sites, PK 11195 and RO5-4864, were examined in shock-induced suppression of drinking in rats. These two compounds have opposite effects : RO5-4864 (3.1-1205 mg/kg i.p.) enhanced whereas PK 11195 (25-50 mg/kg i.p.) decreased the punished responding, and PK 11195 (6.25 mg/kg, a dose which did not alter the punished responding) blocked the proconflict action of RO5-4864 (6.25 and 12.5 mg/kg). The effects of RO5-4864 and PK 11195 were not antagonized by RO15-1788, a selective antagonist of the central benzodiazepine site. In addition, PK 11195 (6.25 mg/kg) did not reverse the proconflict effect of two beta-carbolines : beta-CEE and FG 7142. AS picrotoxin did not change the punished responding, these data imply that the effects of RO5-4864 and PK 11195 on the one hand and those of chlordiazepoxide and beta-carbolines on the other hand are differentially mediated and suggest that the peripheral type benzodiazepine binding sites are involved in this conflict model.

Electrophysiological and pharmacological evidence that peripheral type benzodiazepine receptors are coupled to calcium channels in the heart

PK 11195, an antagonist of the peripheral type benzodiazepine receptor, does not affect either the duration of the action potential or the tension of the guinea pig papillary muscle. However, it antagonized the effects of the calcium channel blockers, nitrendipine, verapamil, diltiazem, and of BAY K8644, a calcium channel agonist in this heart preparation. On the other hand, PK 11195 does not change the increase in the action potential duration provoked by the potassium channel blocker tetraethylammonium. RO5-4864, an agonist of the peripheral type benzodiazepine receptor, decreased the tension of the guinea pig papillary muscle. The effect was reversed by increasing extracellular Ca2+ concentrations up to 4 mM. These results suggest that in the heart the peripheral type benzodiazepine receptors are coupled to calcium channels.

Characterization of solubilized "peripheral type" benzodiazepine binding sites from rat adrenals by using [3H]PK 11195, an isoquinoline carboxamide derivative

"Peripheral type" benzodiazepine binding sites have been solubilized with digitonin. Binding site density for the solubilized material is increased 1.7 times compared to membranes. A decrease in the affinity for [3H]-PK 11195 (a new ligand for the peripheral type benzodiazepine binding sites) was also observed. Pharmacological specificity of displacing agents was conserved during solubilization. The apparent molecular weight determined by gel filtration was 215,000 +/- 20,000. The high Bmax value of the solubilized preparation (greater than 50 pmole/mg protein) makes it advantageous as the starting point for a purification procedure.

[Right intraventricular tumors. Apropos of a case]

The authors report a case of right ventricular tumour in a 16 year old girl who presented with dyspnoea on effort, chest pain on exertion and loss of consciousness. The diagnosis was made on the basis of abnormal right intraventricular echoes on two dimensional echocardiography and was confirmed by angiography. The patient was operated with success. Histology revealed a mesenchymoma, a benign tumour, but whose infiltrating nature calls for a reserved prognosis. The echocardiogram can be used for regular post-operative surveillance. The young patient is well after 18 months' follow-up.

Pharmacological evidence that PK 8165 behaves as a partial agonist of brain type benzodiazepine receptors

PK 8165, a new quinoline derivative, has a good affinity for brain type benzodiazepine binding sites and an anticonflict activity in the Vogel Test. However, contrarily to classical benzodiazepines (BZ) this compound is devoid of anticonvulsant and sedative properties. As biochemical studies suggested that PK 8165 is a partial agonist for BZ receptors, its interactions with convulsant, sedative and muscle relaxant properties of diazepam (DZ) were investigated. PK 8165 potentiates (12.5 to 50 mg/kg i.p.) the antagonistic effect of DZ on M.E.S.-induced seizures and footshock-induced fighting in mice. Moreover, PK 8165 potentiates in the same dose range the muscle relaxant and hypnotic effects of DZ in mice. These potentiations are specific since PK 8165 does not interfere with phenobarbital and mebubarbital effects in M.E.S. and righting reflex in mice. Also, PK 8165's anticonflict activity (punished drinking in thirsty rats) is antagonized by RO15-1788, a specific antagonist of centrally active BZ.

Histidine modification with diethylpyrocarbonate induces a decrease in the binding of an antagonist, PK 11195, but not of an agonist, RO5-4864, of the peripheral benzodiazepine receptors

[3H]PK 11195 binding to peripheral type benzodiazepine binding sites in kidney membranes is inhibited by the histidine blocking agent diethylpyrocarbonate. This reagent irreversibly decreases the Bmax for [3H]PK 11195 without affecting the affinity. By contrast binding of [3H]RO5-4864 is not affected by diethylpyrocarbonate treatment. However RO5-4864 can protect in a concentration dependent manner the [3H]PK 11195 binding site from diethylpyrocarbonate whereas clonazepam and RO15-1788 are not active. These results suggest that PK 11195 and RO5-4864 interact with different conformational states of the receptors that RO5-4864. This is in agreement with our previous hypothesis that PK 11195 is an antagonist and RO5-4864 an agonist at the "peripheral type" benzodiazepine receptors.

Electrophysiological and pharmacological characterization of peripheral benzodiazepine receptors in a guinea pig heart preparation

RO5-4864 decreased in a dose-dependent manner, from 3 X 10(-9) M to 3 X 10(-6) M, the duration of intracellular action potential and the contractility in a guinea pig preparation. Diazepam was less effective and clonazepam inactive. The effects of RO5-4864 were GABA-independent and antagonized by PK 11195 but not by the selective antagonist of the brain type benzodiazepine receptors RO15-1788. These results show the pharmacological relevance of peripheral type benzodiazepine binding sites at the cardiac level.

Characterization of peripheral type benzodiazepine binding sites in human and rat platelets by using [3H]PK 11195. Studies in hypertensive patients

Peripheral type benzodiazepine binding sites have been studied in human and rat platelets and platelet membranes by using PK 11195 (1-(2-chlorophenyl)-N-methyl-N-(1-methyl propyl)-3-isoquinolinecarboxamide) as a ligand. [3H]PK 11195 binding to the intact cells and membranes is saturable, with a high affinity and presents the pharmacological specificity corresponding to the peripheral binding sites (PK 11195 greater than RO5-4864 greater than diazepam greater than clonazepam). [3H]PK 11195 affinity is not affected by cell lysis, but there is a loss of binding capacity, contrarily to RO5-4864 whose affinity is greatly diminished. For this reason [3H]RO5-4864 binding can only be demonstrated in intact cells. Furthermore opposite to RO5-4864, PK 11195 affinity is not decreased by increasing temperatures. No difference was found between binding parameters (KD and Bmax) for [3H]PK 11195 between normotensive and hypertensive subjects. The very high binding capacity of human and rat platelets (Bmax greater than pmole/10(8) cells) makes them a good biological model for studying the physiological significance of "peripheral type" benzodiazepine binding sites.

Autoradiographic localization of peripheral benzodiazepine binding sites in the cat brain with [3H]PK 11195

"Peripheral type" benzodiazepine binding sites were labelled in cat brain membranes by using [3H]PK 11195. This ligand binds to the "peripheral type" binding sites in a reversible, specific and saturable manner. Cat brain binding sites density (congruent to 6 pmol/mg prot.) was higher than in the rat. Pharmacological specificity was demonstrated by the potency order of displacing agents: PK 11195 greater than RO5-4864 greater than dipyridamole greater than diazepam greater than clonazepam. A similar characterization was performed in slide mounted brain sections where [3H]PK 11195 also labelled the "peripheral type" benzodiazepine binding sites. The high percentage of specific binding (80%) at 1 nM of [3H]PK 11195 made possible the autoradiographic studies on binding sites distribution. These sites were heterogeneously distributed in the grey matter and absent in white matter. Visual, auditory and other specific sensory relay stations were highly labelled. The blood pressure regulating nuclei, the vestibulo-cerebellar and the extrapyramidal motor system also presented a very high binding density. As previously described in the rat brain, choroid plexus was also strongly labelled by [3H]PK 11195 in the cat.

Opposite effects of an agonist, RO5-4864, and an antagonist, PK 11195, of the peripheral type benzodiazepine binding sites on audiogenic seizures in DBA/2J mice

Two compounds with high affinity for the "peripheral type" benzodiazepine binding sites, PK 11195 (an isoquinoline derivative) and RO5-4864 (a benzodiazepine derivative) can modify the sensitivity of DBA/2J mice to audiogenic seizures. RO5-4864 (1-15 mg/kg) facilitates in a dose-dependent manner the audiogenic seizures and PK 11195 (2-5 mg/kg) antagonizes the RO5-4864 effects. At these doses PK 11195 alone does not modify the sensitivity to audiogenic seizures, but at doses between 20-80 mg/kg it protects DBA/2J mice against audiogenic seizures. By contrast PK 11195 is inactive against the facilitation of audiogenic seizures by ethyl-beta-carboline-3-carboxylate (a brain benzodiazepine receptor inverse agonist) and against the seizure elicited in absence of noise stimuli by RO5-4864 at doses between 20-40 mg/kg. These results suggest that facilitation by RO5-4864 of the audiogenic seizures and its antagonism by PK 11195 are mediated by the peripheral type benzodiazepine binding sites and agree with the thermodynamic analysis of the binding data which suggested that RO5-4864 might be an agonist and PK 11195 an antagonist. The good correlation between pharmacological effects and the occupancy degree of the binding sites as measured by the displacement of the "in vivo" [3H]-PK 11195 binding give an additional support to binding sites mediated effects.

[Clinical study of the action of dobutamine in acute cardiac insufficiency]

78 patients were treated with dobutamine for a severe episode of heart failure at a mean dose of 9.51 micrograms . kg-1 . min-1 for an average of 5 days. 59 of these patients had ischaemic heart disease, including 34 with recent infarcts. The monitoring of treatment was essentially clinical, consisting of repeated measurement of the heart rate, the systolic and diastolic blood pressure and the diuresis. A haemodynamic survey was performed in only 25 cases. 48 patients were improved. 24 of these patients had no clinical or radiological signs of heart failure at the end of the treatment. Dobutamine significantly increases the blood pressure (97.7 +/- 24.9 to 105.8 +/- 21 mm Hg), the diuresis and the cardiac index (2.02 +/- 0.51 to 2.52 +/- 0.54 l . min-1 . m-2) and it significantly decreases the mean capillary pressure (25.36 +/- 6.20 to 21.03 +/- 6.94 mm Hg). The tolerance was very satisfactory, particularly in terms of the heart rate, ventricular excitability and the progression of the coronary disease. This clinical study confirms the value of dobutamine in the treatment of severe heart failure, either alone or in combination with vasodilators. The authors do not believe tha haemodynamic monitoring is essential at the doses used, which means that dobutamine could be used more widely in these indications.

In vivo labelling in several rat tissues of 'peripheral type' benzodiazepine binding sites

'Peripheral type' benzodiazepine binding sites in several rat tissues were labelled by intravenous injection of [3H]PK 11195 and [3H] RO5 -4864. Binding was saturable in all tissues studied and regional distribution paralleled the in vitro binding. A similar potency order of displacing compounds was found in vivo and in vitro PK 11195 greater than PK 11211 greater than RO5 -4864 greater than diazepam greater than dipyridamole greater than clonazepam. These results demonstrate the feasibility of using this technique to examine the effects of pharmacological manipulation on the binding sites in their native state. However some properties (broader maximum during time course, higher percentage of particulate binding in the brain and independence of temperature) make [3H]PK 11195 the most suitable ligand for this kind of studies.

The 5-hydroxytryptamine-releasing properties of two epimer quinoline derivatives

Two epimer quinoline derivatives, PK 5078 and PK 7059, have been shown to be potent at releasing 5-HT from blood platelets. Moreover PK 5078 was also a potent and selective inhibitor of the uptake of 5-HT, being about 20 times as active as clomipramine. Both drugs, like p-chloroamphetamine, released 5-HT but did not inhibit MAO-A. Whilst p-chloroamphetamine seemed to be active on the cytoplasmic pool of 5-HT and reserpine on the vesicular pool, PK 5078 and PK 7059 were effective first on the vesicular pool and then on the cytoplasmic pool. The quinoline derivatives were devoid of the typical side-effects of amphetamine-like drugs, i.e. hyperactivity, anorexia and group toxicity. For these reasons PK 5078 and PK 7059 can be considered to be a new type of selective 5.HT-releasing drug.

Labelling of "peripheral-type" benzodiazepine binding sites in the rat brain by using [3H]PK 11195, an isoquinoline carboxamide derivative: kinetic studies and autoradiographic localization

PK 11195 [1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide] is a new ligand for the "peripheral-type" benzodiazepine binding sites, chemically unrelated to benzodiazepines. It displaces with a very high potency (IC50 congruent to 10(-9) M) [3H]-RO5-4864 (a benzodiazepine which specifically labels the peripheral-type sites) from its binding sites. [3H]PK 11195 binds to a membrane fraction from rat brain cortex and rat olfactory bulb in a saturable and reversible manner with a very high affinity (KD = 10(-9) M). The number of maximal binding sites was ten times greater in the olfactory bulb than in the brain cortex. The order of potency of several compounds as displacers at 25 degrees C (PK 11195 greater than RO5-4864 greater than diazepam greater than dipyridamole greater than clonazepam) demonstrates that [3H]PK 11195 binds to the peripheral-type benzodiazepine binding sites. The KD value for the [3H]PK 11195 binding is not affected by temperature changes, whereas RO5-4864 and diazepam affinities decrease with increasing temperatures. Autoradiographic images of [3H]PK 11195 binding to rat brain sections show that binding sites are mainly localized in the olfactory bulb, median eminence, choroid plexus, and ependyma. This ligand could be a useful tool to elucidate the physiological and pharmacological relevance of these binding sites.

"Peripheral type" benzodiazepine binding sites in rat adrenals: binding studies with [3H]PK 11195 and autoradiographic localization

PK 11195 [1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinec arboxamide] is a compound chemically unrelated to benzodiazepines with a high affinity for the "peripheral type" binding sites for benzodiazepines (Le Fur et al., 1983a). [3H]PK 11195 binds to the adrenal membranes with a high affinity (KD congruent to 3 nM) in a specific, reversible and GABA-independent manner. Binding is also characterized by very high Bmax (34 pmol/mg protein). These binding sites are the "peripheral type" benzodiazepine binding sites as demonstrated by the potency order of displacement of the [3H]PK 11195 bound: PK 11195 greater than R05-4864 greater than diazepam greater than dipyridamole greater than clonazepam. The biochemical characteristic of the binding to rat adrenal sections has also been studied. In these conditions the affinity for [3H]PK 11195 is ten times smaller, but the potency order of displacing agents was the same, demonstrating the identity of the section binding sites. Using tritium sensitive film these sites have been visualized in adrenal sections. [3H]PK 11195 binding sites are localized in the adrenal cortex with some spare labelling in the medulla.

Differentiation between two ligands for peripheral benzodiazepine binding sites, [3H]RO5-4864 and [3H]PK 11195, by thermodynamic studies

The [3H]PK 11195, 1-(2-chlorophenyl)-N-methyl-N-(1-methyl-propyl)-3-isoquinolinecarboxamide, binding sites in rat cardiac membranes are saturable, with high affinity, specific GABA-independent and correspond to the peripheral type of benzodiazepine. The order of potency of displacing agents was: PK 11195 greater than RO5-4864 greater than dipyridamole greater than diazepam greater than clonazepam. The Bmax obtained with [3H]PK 11195 was equivalent of the Bmax obtained with [3H]RO5-4864 in the same experimental conditions. However thermodynamic analysis indicates that the [3H]PK 11195 binding was entropy driven whereas the [3H]RO5-4864 binding was enthalpy driven. Consequently PK 11195 might be an antagonist of these binding sites and RO5-4864 an agonist or a partial agonist. The simultaneous use of both drugs might help to elucidate the physiological relevance of peripheral benzodiazepine binding sites.

Peripheral benzodiazepine binding sites: effect of PK 11195, 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxamide. I. In vitro studies

[3H] RO5-4864 binding sites have been characterized in kidney, heart, brain, adrenals and platelets in the rat. In all these organs the following order of potency in the RO5-4864 displacement was found: RO5-4864 greater than diazepam greater than clonazepam indicating that they correspond to the "peripheral type" of benzodiazepine binding sites. PK 11195, an isoquinoline carboxamide derivative, displaces [3H] RO5-4864 from its binding sites in all the organs. PK 11195 was as potent as RO5-4864 in the platelets, heart, adrenals, kidney and several brain regions (midbrain, hypothalamus, medulla + pons and hippocampus. However it was 5 to 10 times more effective in cortex and striatum. In conclusion PK 11195 might represent a new tool to elucidate the physiological relevance of "peripheral type" benzodiazepine binding sites and might help to discriminate the hypothetical subclasses of these binding sites.

Peripheral benzodiazepine binding sites: effect of PK 11195, 1-(2-chlorophenyl)-N-methyl-(1-methylpropyl)-3 isoquinolinecarboxamide. II. In vivo studies

Peripheral type of benzodiazepine binding sites were labelled in the kidney, the heart and the brain with [3H] RO5-4864 following intravenous injection in mice. The regional distribution of this in vivo binding parallels the in vitro binding: heart and kidney were more labelled than brain. Benzodiazepine potencies in reducing [3H] RO5-4864 binding in vivo parallel relative affinities for [3H] RO5-4864 binding sites in isolated organs membranes: RO5-4864 greater than diazepam greater than clonazepam. PK 11195 a new compound, chemically unrelated to benzodiazepines, which is a potent inhibitor of [3H] RO5-4864 in vitro is also very effective (more than RO5-4864) after I.P. injection and oral administration. These results emphasize the feasibility of using this technique to examine the effects on various pharmacological and physiological manipulations of these binding sites in vivo. Moreover the fact that PK 11195 binds to these sites in vivo might indicate that this compound could help to elucidate the physiological relevance of the peripheral type of benzodiazepine binding sites.

1-[4-(2-ter-butyl-quinolyl)]-3-(4-piperidyl)propanol (PK 10139): a new potent and long-acting antiarrhythmic agent

PK 10139 is a new synthetic quinoline antiarrhythmic agent 10 times more potent and at least 2 to 3 times longer acting than quinidine sulfate. In the dog, the near 100% active dose (1.5 mg/kg i.v.) completely converted to sinus rhythm ouabain-induced ventricular tachycardia for over 30 min. The efficacy of this compound against multifocal beats induced by two-stage ligation of the left coronary artery (Harris) in the conscious dog was demonstrated after i.v. and oral administration with no peripheral and central nervous system side effects after the higher effective dose contrary to quinidine. In the anesthetized dog, PK 10139 like quinidine, increased atrial, atrioventricular nodal and ventricular refractory periods as determined with the programmed extrastimulus technique. PK 10139 also increased electrical stimulus threshold and intracardiac conduction times evaluated by measurement of A-H nodal conduction time, H-V conduction time and QRS interval as seen with all the class I antiarrhythmic agents. Thus, PK 10139 is a much more potent and long-acting agent than quinidine, with better tolerance.

Fluorogenic labeling of organophosphate pesticides with dansyl chloride. Application to residue analysis by high-pressure liquid chromatography and thin-layer chromatography

The analysis of some organophosphorus pesticides by fluorogenic labeling with dansyl chloride (5-dimethylaminonaphthalene--l-sulfonyl chloride) was investigated. The pesticides were hydrolysed in sodium hydroxide to the corresponding phenols. The reaction of dansyl chloride with the phenols was accomplished in a two-phase system. The resulting fluorescent derivatives were separated and analysed quantitatively by in situ thin-layer chromatography (TLC) and high-pressure liquid chromatography (HPLC). As little as 10-25 ng/spot of pesticide was detected by both TLC and HPLC.