Occurrence of <i>N</i>-Acyl Homoserine Lactones in Extracts of Bacterial Strain of <i>Pseudomonas aeruginosa</i>and in Sputum Sample Evaluated by Gas Chromatography–Mass Spectrometry

This study presents a fast, accurate and sensitive technique using gas chromatography-mass spectrometry (GC-MS) for the identification and quantification of N-acyl homoserine lactones (AHLs) in the extracts of bacterial strain of Pseudomonas aeruginosa and sputum sample of a cystic fibrosis patient. This method involves direct separation and determination of AHLs by using GC-MS as simultaneous separation and characterization of AHLs were possible without any prior derivatiza-tion. Electron ionization resulted in a common fragmentation pattern with the most common fragment ion at m/z 143 and other minor peaks at 73, 57 and 43. The limit of detection for N-butanoyl, N-hexanoyl, N-octanoyl, N-decanoyl, N-dodecanoyl and N-tetradecanoyl homoserine lactones was 2.14, 3.59, 2.71, 2.10, 2.45 and 2.34 μg/L, respectively. The presence of AHLs in the culture of P. aeruginosa strain and spu-tum of a cystic fibrosis patient was achieved in selected ion monitoring (SIM) mode by using the prominent fragment at m/z 143.

Rare earth(La)and metal ion(Pb)substitution induced structural and multiferroic properties of bismuth ferrite

In this study,bulk samples of multiferroic with compositional formula,BiFeO3 and Bi_(0.825)A_(0.175)FeO_(3)(A=La,Pb),were synthesized by solid state reaction route.X-ray diffraction(XRD)along with the Rietveld refinement revealed the distorted rhombohedral(R3c)structure for pristine BiFeO3 and Bi0.825La0.175FeO3 and tetragonal(P4/mmm)for Bi_(0.825)Pb_(0.175)FeO_(3)ceramic.To support the structural results,bond length between atoms for both of the compounds was calculated.A change in Raman mode position in BiFeO3(BFO)has been observed with La and Pb substitution from Raman scattering measurements and also recommended a structural change with rare earth and metal ion substitution at Bi site.From the frequency dependent dielectric constant and dielectric loss plots,a decrease in dielectric values with increase in frequency was observed for both of the samples.For microelectronic devices,porous ceramics with lower value of dielectric constant are most useful.Thus,further studies are also needed to carefully tune the magnetoelectric properties and structural distortion after La/Pb substitution in BFO.

A comparative study to evaluate the effect of limited access dressing on diabetic ulcers

Aim:Emerging evidence favors the important role of antioxidants,matrix metalloproteinases(MMPs),and nitric oxide(NO)in the healing of diabetic wounds.There is a lack of substantial evidence regarding the effects of negative pressure on antioxidants,MMPs and NO in chronic wounds associated with diabetes.Methods:A total of 55 type 2 diabetic patients with leg ulcers were divided into 2 groups:a limited access dressing(LAD)group(n=27)and a conventional dressing group(n=28).Levels of hydroxyproline,total protein,MMP-2 and MMP-9,NO and antioxidants including reduced glutathione(GSH)and the oxidative biomarker malondialdehyde(MDA)were measured in the granulation tissue at days 0 and 10.Changes in levels between the LAD and conventional groups were determined by the Student’s t-test.Results:After 10 days of treatment,the LAD vs.conventional dressing group showed increase in the levels of hydroxyproline(mean±standard deviation=55.2±25.1 vs.29.2±1,P<0.05),total protein(12.8±6.5 vs.8.34±3.2,P<0.05),NO(1.13±0.52 vs.0.66±0.43,P<0.05),GSH(7.0±2.4 vs.6.6±2.2,P<0.05)and decrease in MMP-2(0.47±0.33 vs.0.62±0.30,P<0.05),MMP-9(0.32±0.20 vs.0.53±0.39,P<0.05)and MDA(6.8±2.3 vs.10.4±3.4,P<0.05).Conclusion:When compared to conventional dressings,LAD induces biochemical changes by significantly increasing the levels of hydroxyproline,total protein,NO and antioxidants levels,and significantly reducing MMPs(MMP-2 and MMP-9)and an oxidative biomarker in diabetic wounds.These biochemical changes are thought to favor diabetic wound healing.