Mechanisms explaining transitions between tonic and phasic firing in neuronal populations as predicted by a low dimensional firing rate model

Several firing patterns experimentally observed in neural populations have been successfully correlated to animal behavior. Population bursting, hereby regarded as a period of high firing rate followed by a period of quiescence, is typically observed in groups of neurons during behavior. Biophysical membrane-potential models of single cell bursting involve at least three equations. Extending such models to study the collective behavior of neural populations involves thousands of equations and can be very expensive computationally. For this reason, low dimensional population models that capture biophysical aspects of networks are needed. \noindent The present paper uses a firing-rate model to study mechanisms that trigger and stop transitions between tonic and phasic population firing. These mechanisms are captured through a two-dimensional system, which can potentially be extended to include interactions between different areas of the nervous system with a small number of equations. The typical behavior of midbrain dopaminergic neurons in the rodent is used as an example to illustrate and interpret our results. \noindent The model presented here can be used as a building block to study interactions between networks of neurons. This theoretical approach may help contextualize and understand the factors involved in regulating burst firing in populations and how it may modulate distinct aspects of behavior.Comment: 25 pages (including references and appendices); 12 figures uploaded as separate file

Biodistribution and Pharmacokinetics of O-Palmitoyl Tilisolol, a Lipophilic Prodrug of Tilisolol, after Intravenous Administration in Rats

The purpose of this study was to modify the biodistribution and pharmacokinetics of tilisolol, a β-blocker, using the palmitoyl prodrug approach. After intravenous administration of tilisolol and O-palmitoyl tilisolol in rats, drug concentrations were determined in blood, bile, urine, and several tissues. The concentration-time profiles of tilisolol and O-palmitoyl tilisolol were analyzed pharmacokinetically. The blood concentrations of O-palmitoyl tilisolol after intravenous administration of O-palmitoyl tilisolol were about 10-fold higher than those of tilisolol after intravenous administration of tilisolol. The biliary excretion rates of O-palmitoyl tilisolol and tilisolol after intravenous administration of O-palmitoyl tilisolol were about 10- to 100-fold larger than those of tilisolol after intravenous administration of tilisolol. In addition, the hepatic uptake clearance of O-palmitoyl tilisolol after intravenous administration of O-palmitoyl tilisolol was 3.6-fold higher than that of tilisolol after the intravenous administration of tilisolol. In the in vitro experiments, it was demonstrated that the distribution ratios between blood cells and plasma (blood/plasma) of O-palmitoyl tilisolol and tilisolol was 95.7 and 55.5%, respectively. These findings suggest that O-palmitoyl tilisolol exists as a binding form with biological components, especially blood cells, in systemic circulation. In conclusion, the palmitoyl prodrug approach is useful as a drug delivery system to deliver the parent drug to the liver

Contribution to the Study of the Mass Reduction of Stones by Some Medicinal Plants

ABSTRACT: The cystine calculi's, consisting primarily of amino acids, is considered the rarest stones with a prevalence of 1% with adults and 10% with the gallstone child. Its treatment is difficult because of its resistance to extracorporeal lithotripsy and its frequent recurrence. Drug treatments used until now, based on citrate are effective, but often poorly tolerated. Morocco is one of the countries that has been using, for a long time, traditional medicine based on natural plants to treat many diseases including stones. Material and methods: In 1L saline solution containing 9 g / L of NaCl and boiled, is introduced 5 g of plant extract powder. The powder is left soaked for 15 minutes and then filtered. A specific installation that resembles the urinary circuit was conducted in the laboratory. As a result, the cystine stone is placed in a tube then undergoes a steady flow through a dynamic circuit, the solution laden with extract for eight weeks; as an effective time to treat gallstones. [1] Every two weeks, the calculations are removed and dried for 16 hours at a temperature of 40 ° C. The same assembly was carried out for two other witnesses solutions to correct the loss mass (Dissolution Rate): The first is a solution of Potassium Citrate of 3 mmol / L and the second is NaCl of 9 g / L. Results: After eight weeks, the loss mass is about (61,43±11,12) % with. ( HHL ) , (63,75±10,95) % to ( OFI ) , (66,83±11,12) % to (AVL ) and (72,46±11,07) % to ( SZM ), while the loss of mass in the presence of witnesses solutions is (20,23±3,12) %for potassium citrate ( C Pot ) and (18,38±5,32) %for the saline solutions

Indications and results of renal biopsy in children: A single-center experience from Morocco

The contribution of renal biopsy (RB) is of major importance in the management of many renal diseases in children. Specific indications for performing biopsy in children include steroid-resistant nephrotic syndrome (NS) and secondary nephropathies. The aim of our study was to report the common histological varieties of kidney diseases in children in Morocco. In this retrospective and descriptive study, we included all renal biopsies performed in patients under 16 years in the Department of Pediatrics of Hassan II University Hospital, Fez, Morocco from July 2009 to December 2013. Biopsy samples without glomeruli and those with less than five glomeruli or repeat biopsies on the same patient were excluded from our study. We performed 112 RBs during this period; the average age at the time of RB was 10.05 ± 4 years and the sex-ratio was 1.07. The indications for RB were NS with hematuria and/or renal failure (RF) in 32.1%, active urinary sediment in 21.4%, isolated NS in 15.2%, RF in 13.4% and steroid-resistant NS in 10.7% of cases. Primary nephropathies represented 59.8% of cases, with a predominance of minimal change disease (MCD) seen in 40.2% of the cases. Secondary nephropathies accounted for 27.7% of the cases, with a predominance of lupus nephritis (11.6%), followed by Henoch-Schonlein purpura nephritis (6.2% of cases) and post-streptococcal glomerulonephritis (3.6%). There was one case of hepatitis B virus-associated membranous glomerulonephritis. Chronic glomerulonephritis accounted for 12.5% of the cases. Vascular and tubulo-interstitial nephritis were rare. Our study confirmed that primary glomerular nephropathy was the most common renal disease in children. The most common lesion was MCD. Secondary nephropathies were less frequent, with a predominance of lupus nephritis

Corrélations entre la dysfonction sexuelle et le profil clinicobiologique de l’insuffisant rénal en hémodialyse

Objectif: Etudier les corrélations entre la dysfonction sexuelle et le profil clinicobiologique de l’insuffisant rénal chronique en hémodialyse (HD) au CHU Hassan II de Fès, Maroc Matériel et méthodes: Nous avons réalisé une étude transversale descriptive et analytique à propos de 73 patients incluant les malades des deux sexes âgés de plus de 18 ans et suivis pour insuffisance rénale chronique (IRC) en stade d’HD. Une recherche de dysfonction sexuelle ainsi que l’étude de paramètres cliniques: âge, comorbidités, durée d’HD, néphropathie initiale et biologiques: taux d’hémoglobine, ferritine, LH, FSH, prolactine, œstradiol et testostérone ont été réalisés. Résultats: L’âge moyen de nos malades était de 45,5+/-1,5 ans avec une médiane de 45 ans. Environ 56% des malades étaient de sexe masculin. La néphropathie diabétique (11 cas, 15%) et la néphroangiosclérose (14 cas, 19,2%) étaient les néphropathies initiales les plus fréquentes. La durée moyenne de dialyse était 101,9+/-6,17mois. La fréquence de la dysfonction sexuelle était de 78% tous grades confondus. Les patients présentant une dysfonction sexuelle avaient un âge plus avancé, un début de dialyse plus ancien et des troubles hormonaux significativement plus marqués que les patients sans dysfonction sexuelle. La téstostéronémie était basse chez 32 patients et a été significativement plus bas chez les hommes présentant des troubles sexuels (p = 0,020). Les concentrations de l’estradiol n’étaient pas liées à la dysfonction sexuelle chez les femmes (p = 0,345). Conclusion: Certains facteurs cliniques et perturbations biologiques peuvent aider à la compréhension de l’étiopathogénie de ces troubles. Une approche globale peut être proposée basée sur une optimisation des facteurs intervenants. Notre étude souligne l’intérêt d’une surveillance clinique, biologique et hormonale de ces patients