Utilisation des interactions stériques de la 5-tert-butylproline pour mimer la structure secondaire peptidique

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal

Detection of Listeria pathogens by gradient/constant denaturing gel electrophoresis

Listeriosis is a serious, but preventable disease, and the virulence factor of this disease is produced only by the two pathogenic species L. monocytogenes and L. ivanovii in humans and/or animals. In this study, we used both denaturing gradient gel electrophoresis (DGGE) and constant denaturing gel electrophoresis (CDGE) as molecular methods combined with Polymerase Chain Reaction (PCR) for the detection and identification of Listeria pathogens on 543 samples of raw milk collected from all Syrian provinces. The two methods are based on the PCR amplification of a fragment of the InlC gene (virulence gene) from the studied Listeria species and on the analysis of the PCR products ob-tained by DGGE/CDGE. Based on the differences present in the sequences amplified, it was possible to obtain species-specific DGGE/CDGE migration that allowed fast and easy identification of the virulence and pathogenicity of L. monocytogenes and L. ivanovii in humans and/or animals, in order to reduce the incidence of Listeria bacteria in the environment and foods and to prevent the occur-rence of listeriosis in animal and human hosts

Trans−cis Switching Mechanisms in Proline Analogues and Their Relevance for the Gating of the 5-HT3 Receptor

Trans-cis isomerization of a proline peptide bond is a potential mechanism to open the channel of the 5-HT3 receptor. Here, we have used the metadynamics method to theoretically explore such a mechanism. We have determined the free energy surfaces in aqueous solution of a series of dipeptides of proline analogues and evaluated the free energy difference between the cis and trans isomers. These theoretical results were then compared with data from mutagenesis experiments, in which the response of the 5-HT3 receptor was measured when the proline at the apex of the M2-M3 transmembrane domain loop was mutated. The strong correlation between the experimental and the theoretical data supports the existence of a trans-cis proline switch for opening the 5-HT3 receptor ion channel

A GENERALIZATION OF D’ALEMBERT, JENSEN AND QUADRATIC FUNCTIONAL EQUATIONS ON SEMIGROUPS

A GENERALIZATION OF D’ALEMBERT, JENSEN AND QUADRATIC FUNCTIONAL EQUATIONS ON SEMIGROUP

In vitro leaves and twigs antimicrobial properties of Psidium guajava L. (Myrtaceae)

The current study aimed to investigate antimicrobial activity of methanol, ethanol, acetone, ethyl acetate and hot water (leaves and twigs fractions) Psidium guajava L. crude extracts against three bacteria and two fungi pathogens. Antimicrobial activity expressed by disc-diffusion assay (zone of inhibitions - ZIs), activity index (AI) and minimum inhibitory concentration (MICs) that were measured as reported in many investigations. Based upon the estimated ZIs, AI and MICs values, hot water twigs <1 cm diameter extract was the most potent against all tested microorganisms. The MICs value ranged between 4 and 7.2 mg/ml for bacteria, while, it was between 14.5 and 37.3 mg/ml for fungi. Moreover, ethyl acetate had the lowest antimicrobial activity compared to the other tested solvents. From the results obtained herein, it could be concluded that P. guajava serve as antibacterial and antifungal agent

In vitro leaves and twigs antimicrobial properties of Psidium guajava L. (Myrtaceae)

S u m m a r y The current study aimed to investigate antimicrobial activity of methanol, ethanol, acetone, ethyl acetate and hot water (leaves and twigs fractions) Psidium guajava L. crude extracts against three bacteria and two fungi pathogens. Antimicrobial activity expressed by disc-diffusion assay (zone of inhibitions -ZIs), activity index (AI) and minimum inhibitory concentration (MICs) that were measured as reported in many investigations. Based upon the estimated ZIs, AI and MICs values, hot water twigs &lt;1 cm diameter extract was the most potent against all tested microorganisms. The MICs value ranged between 4 and 7.2 mg/ml for bacteria, while, it was between 14.5 and 37.3 mg/ml for fungi. Moreover, ethyl acetate had the lowest antimicrobial activity compared to the other tested solvents. From the results obtained herein, it could be concluded that P. guajava serve as antibacterial and antifungal agent

Przeciwdrobnoustrojowe właściwości liści i gałązek Pisidium guajava L (Myrtaceae)

The current study aimed to investigate antimicrobial activity of methanol, ethanol, acetone, ethyl acetate and hot water (leaves and twigs fractions) Psidium guajava L. crude extracts against three bacteria and two fungi pathogens. Antimicrobial activity expressed by disc-diffusion assay (zone of inhibitions - ZIs), activity index (AI) and minimum inhibitory concentration (MICs) that were measured as reported in many investigations. Based upon the estimated ZIs, AI and MICs values, hot water twigs <1 cm diameter extract was the most potent against all tested microorganisms. The MICs value ranged between 4 and 7.2 mg/ml for bacteria, while, it was between 14.5 and 37.3 mg/ml for fungi. Moreover, ethyl acetate had the lowest antimicrobial activity compared to the other tested solvents. From the results obtained herein, it could be concluded that P. guajava serve as antibacterial and antifungal agent.Celem niniejszych badań było oznaczenie aktywności przeciwdrobnoustrojowej ekstraktu metanolowego, etanolowego, acetonowego oraz uzyskanego za pomocą octanu etylu i gorącej wody z liści i gałązek Pisidium guajava L. wobec trzech bakterii i dwóch grzybów chorobotwórczych. Aktywność przeciwdrobnoustrojową określano za pomocą krążków bibułowych (strefa zahamowania – ZIs), indeksu aktywności (AI) oraz najmniejszego stężenia hamującego (MICs). Na podstawie przeprowadzonych badań stwierdzono, że największą aktywnością, biorąc pod uwagę wszystkie zastosowane metody, odznaczał się ekstrakt uzyskany za pomocą gorącej wody z gałązek o średnicy <1 cm. W metodzie MICs dawał on w odniesieniu do wszystkich testowanych drobnoustrojów strefę zahamowania o średnicy powyżej 1 cm. Wartość wskaźnika MICs waha się w geranicach od 4 do7,2 mg/ml w przypadku bakterii oraz od 14,5 do 37,3 mg/ml dla badanych grzybów. Ponadto wykazano, że najniższą aktywność przeciwdrobnoustrojową wykazywał ekstrakt otrzymany przy użyciu octanu etylu. Przedstawione wyniki badań wskazują, że P. guajava może być uważana za roślinę o właściwościach przeciwbakteryjnych i przeciwgrzybiczych