Oblikovanje i vrednovanje plutajućih uljnih mikrozrnaca loratadina s produljenim zadržavanjem u želucu

Gastro retentive controlled release system of loratadine was formulated to increase the residence time in stomach and to modulate the release behaviour of the drug. Oil entrapped floating microbeads prepared by emulsion gelation method were optimized by 23 factorial design and a polymer ratio of 2.5:1.5 (pectin: sodium alginate) by mass, 15% (m/v) of oil (mineral oil or castor oil) and 0.45 mol L-1 calcium chloride solution were selected as the optimized processing conditions for the desired buoyancy and physical stability. In vitro drug release in fed state conditions demonstrated sustained release of loratadine for 8 h that best fitted the Peppas model with n < 0.45. The ethylcellulose coating on microbeads optimized by 22 factorial design resulted in controlled release formulation of loratadine that provided zero-order release for 8 h.U radu je opisana priprava plutajućih mikrozrnaca za kontrolirano oslobađanje loratadina metodom želiranja emulzije. Mikrozrnca sadrže ulja, a njihovo zadržavanje u želucu je produljeno. Priprava mikrozrnaca je optimirana 23 faktorijalnim dizajnom. Pripravci optimalne sposobnosti plutanja i stabilnosti dobiveni su uz omjer masa pektina i natrijevog alginata 2,5:1,5, udio mineralnog ulja ili ulja kastora 15% (m/v) i koncentraciju kalcijevog klorida 0,45 mol L1. Iz tih se mikrozrnaca loratadin oslobađa in vitro tijekom 8 h, a oslobađanje slijedi Peppasov model ako je n < 0,45. Mikrozrnca presvučena etilcelulozom optimirana 22 faktorijalnim dizajnom slijede kinetiku nultog reda tijekom 8 h

Delamination of pipeline steels: determination of an anisotropic cleavage criterion

Cette étude concerne l’effet de l’anisotropie de la rupture par clivage appliquée à deux tôles d’acier faiblement allié, ferrito-bainitiques, pour gazoducs. La rupture de la tôle par délaminage est étudiée en fonction de la microstructure et du chargement mécanique, afin d’optimiser les propriétés de ces aciers et notamment leur résilience mesurée par essais Battelle et Charpy. Des essais mécaniques ont été effectués sur des mini-éprouvettes axisymétriques entaillées, dimensionnées à cette intention et prélevées dans les directions principales de la tôle, y compris dans la direction travers court. Des essais de traction ont permis de tracer une courbe de transition ductile-fragile sur ces éprouvettes entaillées, dans une gamme de températures comprise entre +20°C et -140°C. Les mécanismes de rupture et les sites d’amorçage de la rupture par clivage ont été identifiés au microscope électronique à balayage. L’analyse mécanique de ces essais a été menée aux différentes températures, le comportement mécanique étant identifié sur éprouvettes lisses sollicitées dans les mêmes directions que les éprouvettes entaillées. Des simulations par éléments finis des essais sur éprouvettes entaillées ont été effectuées afin d’analyser les champs de contrainte et de déformation à rupture et d’en extraire une valeur de contrainte critique de clivage, en fonction de la direction de sollicitation. L’impact du modèle de comportement choisi (critère de plasticité isotrope ou non) sur la valeur de la contrainte critique de clivage a été évalué. Le critère de rupture proposé tient compte des paramètres microstructuraux des aciers étudiés

Priprava i in vitro karakterizacija mikrosfera amoksicilina dobivenih metodom sušenja sprejom

The purpose of the present study was to design mucoadhesive chitosan microspheres containing amoxycillin. Chitosan microspheres with a small particle size and good sphericity were prepared by a spray-drying method followed by chemical treatment with a chemical crosslinking agent (glutaraldehyde). Parameters affecting the extent of crosslinking were the crosslinking time and the concentration of the crosslinker agent. Crosslinked spray-dried chitosan microspheres were analyzed for their morphological aspects, particle size, drug entrapment efficiency, swelling percent and in vitro drug release. Batch M4 with a drug polymer ratio of 1:2, dissolved in minimum concentration of acetic acid solution treated with glutraldehyde, was found to be optimal giving controlled drug release for 10 h. It was found that both the increase of glutaraldehyde concentration and crosslinking duration decreased the swelling capacity of chitosan microspheres. This could be directly correlated to drug release from the microspheres.Cilj ovog rada bio je priprava mukoadhezivnih kitozanskih mikrosfera amoksicilina. Mikrosfere male veličine čestica i dobre sferičnosti pripravljene su metodom sušenja sprejom, te obradom s glutaraldehidom kao sredstvom za umrežavanje. Stupanj umrežavanja ovisio je o vremenu umrežavanja i koncentraciji sredstva za umrežavanje. Umreženim kitozanskim mikrosferama određen je oblik, veličina čestica, količina uklopljenog lijeka, postotak bubrenja i in vitro oslobađanje ljekovite tvari. Pripravak M4 s optimalnim svojstvima i kontroliranim oslobađanjem amoksicilina tijekom 10 sati pripravljen je pomoću smjese polimera omjera 1:2 otopljenih u razrijeđenoj octenoj kiselini, te umreženih pomoću glutraldehida. Povećanje koncentracije glutaraldehida i trajanja umrežavanja smanjuje sposobnost bubrenja kitozanskih mikrosfera, što je u izravnoj korelaciji s oslobađanjem lijeka iz mikročestica

Are social norms associated with smoking in French university students? A survey report on smoking correlates

<p>Abstract</p> <p>Background</p> <p>Knowledge of the correlates of smoking is a first step to successful prevention interventions. The social norms theory hypothesises that students' smoking behaviour is linked to their perception of norms for use of tobacco. This study was designed to test the theory that smoking is associated with perceived norms, controlling for other correlates of smoking.</p> <p>Methods</p> <p>In a pencil-and-paper questionnaire, 721 second-year students in sociology, medicine, foreign language or nursing studies estimated the number of cigarettes usually smoked in a month. 31 additional covariates were included as potential predictors of tobacco use. Multiple imputation was used to deal with missing values among covariates. The strength of the association of each variable with tobacco use was quantified by the inclusion frequencies of the variable in 1000 bootstrap sample backward selections. Being a smoker and the number of cigarettes smoked by smokers were modelled separately.</p> <p>Results</p> <p>We retain 8 variables to predict the risk of smoking and 6 to predict the quantities smoked by smokers. The risk of being a smoker is increased by cannabis use, binge drinking, being unsupportive of smoke-free universities, perceived friends' approval of regular smoking, positive perceptions about tobacco, a high perceived prevalence of smoking among friends, reporting not being disturbed by people smoking in the university, and being female. The quantity of cigarettes smoked by smokers is greater for smokers reporting never being disturbed by smoke in the university, unsupportive of smoke-free universities, perceiving that their friends approve of regular smoking, having more negative beliefs about the tobacco industry, being sociology students and being among the older students.</p> <p>Conclusion</p> <p>Other substance use, injunctive norms (friends' approval) and descriptive norms (friends' smoking prevalence) are associated with tobacco use.</p> <p>University-based prevention campaigns should take multiple substance use into account and focus on the norms most likely to have an impact on student smoking.</p

Beleid bij acute hepatitis C en bij prikaccidenten met hepatitis-C-viruspositief bloed

Acute hepatitis C is rarely diagnosed, in part because of its usually subclinical course. Infection with the hepatitis C virus (HCV) has a high chronicity rate, 70-90%. The risk of infection after a needlestick accident with HCV positive blood is 3-10%. There are no efficacious preventive measures regarding HCV infection but treatment with the antiviral drug interferon alpha during the acute phase of the disease has shown to significantly reduce the risk of subsequent chronic infection. It is advised to evaluate individuals who were exposed to infected blood by a needlestick accident regarding HCV transmission, and to offer interferon treatment to them in case they become HCV positive, as demonstrated with a positive serum HCV-RNA tes

Polychlorinated biphenyls in marine sediments from the southern North Sea and Scheldt estuary: A ten-year study of concentrations, patterns and trends

The paper reports the concentrations and patterns of CBs in sediments of the Belgian part of the southern North Sea and the Scheldt estuary for the period 1991-2001. The long-term analytical performance was well within the quality assurance boundaries set at the outset of the study and is consistent with the state of the art for this type of analysis. The CB concentrations (given as the median of the sum of IUPAC Nos 28, 52, 101, 118, 138, 153 and 180) vary between 0.1 ?g kg-1 and 50 ?g kg-1 dry weight in the total sediment and it could be demonstrated that CB patterns in the fine fraction of the sediment were closely similar throughout the investigated area. Isolation of the fine fraction (<63 ?m) by sieving can be regarded as a physical normalisation to reduce the differences in sediment granulometric composition. It allows for a better understanding of CB distribution and patterns and improves the trend analysis. A significant downward trend could not be found at any of the stations, which suggests that CB levels have not been changing in the area of interest in the past decade

Literatuuroverzicht en economische evaluatie: Haemophilus type b-vaccin

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