Fluorescence properties of Phycocyanin and Phycocyanin-human serum albumin complex

In this work, the fluorescence properties of Phycocyanin (PC) and the corresponding quenching effects are investigated in attendance of human serum albumin (HSA). At first, PC is excited at 532 nm using CW SHG Nd:YAG laser, then the emission wavelength, Stokes shift, quantum yield, extinction constant and self-quenching coefficient are obtained based on the modified Beer-Lambert equation. It is shown that a notable red shift appears in terms of PC concentration. According to the fluorescence spectra, the addition of HSA in PC solution leads to a significant reduction in the fluorescence signal via quenching events, however a lucid blue shift takes place in the same time. Stern-Volmer formalism is used to determine the quenching constant (K_S), the number of binding sites (n) between PC and HSA as well as the association constant K_a for the purpose of facile transportation to the target in the context of drug delivery. Eventually, temperature dependent coefficients and corresponding spectral shifts are investigated over a wide range of temperatures at a couple of distinct PC concentrations to attest the dominant static quenching takes place. The rate of conjugate formations elevates at low temperatures leading to a certain blue shift. Furthermore, large K_S is measured in the course of signal reduction, particularly at low PC populations. In fact, PC conjugation to HSA is essential interaction to enhance chemo drug transportation. Here, at the body temperature, the quenching coefficient decreases to facilitate the drug release. Moreover, the spectral shift of fluorescence emission can be useful for simultaneous monitoring and drug delivery treatment.

Validity testing of classroom community scale in virtual environment learning: A cross sectional study

Background

Fostering a Sense of Classroom Community is considered to be associated with the reduction of student's dropout rate in an online environment. Many scales have been developed to measure sense of community in online and traditional learning, and Rovai's Classroom Community Scale has been widely used. This study was designed to examine the psychometric properties and the theoretical structure of the Classroom Community Scale.

Materials and methods

A total of 215 postgraduate virtual students responded to the Classroom Community Scale. A measurement model was evaluated using confirmatory factor analysis to determine the adequacy of goodness-of-fit to sample data.

Results

The confirmatory factor analysis provided valid data that the Classroom Community Scale with a two-factor structure is a valid scale with adequate model fit. Connectedness and learning subscales were also valid and reliable. Overall, the results supported the high reliability, face and content validity of all items of the scale.

Conclusions

The 20 item Classroom Community Scale provides a valid and reliable scale to measure sense of community among postgraduate medical education students.

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The Persian version of CCS is a psychometrically sound scale to measure SCC in virtual environment.

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It is a valuable assessment tool that can be used for various purposes: (1) to measure SCC in online learning; (2) to measure the efficacy of courses designed to promote online classroom community; (3) to reduce feelings of isolation experienced in online learning, (4) to create classroom and school environments that promote community learning, and (5) to enhance student satisfaction, learning, and persistence in virtual environments.

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Fostering a sense of classroom community (SCC), would reduce students dropout rate in the online environment.

Molecular basis of Bombay phenotype in Mashhad, Iran: identification of a novel FUT1 deletion

BACKGROUND AND OBJECTIVES

Bombay phenotype is characterized by the lack of H substance both on red blood cell (RBC) surface and in body secretions. Mutations of fucosyltransferase 1 (FUT1) and fucosyltransferase 2 (FUT2) genes are resulted in this rare phenotype.

MATERIALS AND METHODS

Five unrelated patients were tested by hemagglutination and adsorption/elution techniques for the presence of ABH antigens. The saliva specimens were analysed by hemagglutination inhibition method. The exons 6 and 7 of ABO gene were sequenced to determine ABO genotype. The coding fragments of FUT1 and FUT2 were amplified and sequenced by specific primers.

RESULTS

Serologic investigation confirmed Bombay phenotype in all individuals. FUT1 molecular analysis revealed a novel large deletion. Also two novel homozygous mutations were detected; one was a missense mutation (392T>C, L131P) and the other a three nucleotide deletion (668_670delACT, Y224del). FUT2 sequencing showed one reported null allele (428G>A, W143X) and one homozygous deletion of FUT2.

CONCLUSION

Although FUT2 deletion has been reported, this is the first report of FUT1 deletion. Finding two FUT1 novel alleles in Iranian people is indicative of mutation diversity in this gene.

In vitro effects of several surface preparation methods on shear bond strength of orthodontic brackets to caries-like lesions of enamel

AIM

The aim of this study was to evaluate the efficiency of several surface preparation methods for improving shear bond strength of brackets to demineralised enamel.

STUDY DESIGN

in vitro study. Eighty premolars were selected and divided into 5 groups. Group 1 served as the control, while the remaining 4 groups were immersed in a demineralising solution (pH 4.8) for 12 weeks. In groups 1 (control) and 2 (demineralised/control) conventional acid etching was used. In group 3, a solution of 5% sodium hypochlorite (NaOCl) was applied on enamel surface for one minute after acid etching. The brackets in group 4 were bonded with Transbond Plus self-etching primer, and group 5 underwent treatment with a 2% sodium fluoride (NaF) gel, which was applied on the enamel surface for 4 minutes before etching. Shear bond strength (SBS) and adhesive remnant index (ARI) were determined in all groups, and surface morphology was examined under scanning electron microscope (SEM).

RESULTS

The mean SBS of acid-etched demineralised enamel was significantly lower than that of acid-etched sound enamel (p<0.05). Treatment of caries-like lesions with 5% NaOCl or self-etching primer failed to improve the bond strength. After NaF treatment and acid etching of demineralised enamel, both type 1 and type 2 etching patterns were observed and the resulting SBS was comparable to that of sound enamel (p>0.05).

CONCLUSION

The application of 2% NaF on enamel caries before bracket bonding is an effective way for enhancing the bond strength.

An investigation of the tylosis with oesophageal cancer (TOC) locus in Iranian patients with oesophageal squamous cell carcinoma

Oesophageal cancer is one of the ten leading causes of cancer mortality worldwide. Earlier loss of heterozygosity (or allelic imbalance) studies have implicated regions on chromosomes 3p, 5q, 9p, 13q, 17p, 17q, and 18q in the development of sporadic oesophageal cancer and recent data have linked the familial tylosis with oesophageal cancer (TOC) gene-containing region on chromosome 17q25 with this cancer. We have studied allelic imbalance (AI) at microsatellite markers both closely linked to and distant from the TOC gene locus in 60 sporadic squamous cell oesophageal cancers from Iran and have investigated the most likely candidate gene by mutation analysis in these tumours. Forty-four out of these 60 samples (73%) show allelic imbalance at one or more loci within or adjacent to the TOC minimal region, while the highest incidence of AI was observed at the D17S2244 and D17S2246 loci (almost 70% AI in informative cases), correlating with the TOC minimal region. Analysis of the coding regions of a candidate gene in these tumours failed to show an equivalently high incidence of mutation, although two mutations and one polymorphism were observed. These data support and extend previous observations that the TOC region of chromosome 17q25 may be involved in the aetiology of the sporadic form of oesophageal cancer from a number of different geographical populations and suggest that the causative gene may be epigenetically silenced rather than mutated.

Medicinal used plants from India: analysis of the essential oils of Sphaeranthus indicus flowers, roots and stems with leaves

The essential oils of flowers, roots and herb (stems with leaves) of Sphaeranthus indicus Kurz. (Asteraceae) from southern India were investigated by gas chromatographic-spectroscopic (GC-FID and GC-MS) and olfactoric methods to identify those compounds responsible for the characteristic odor as well as partly for the folk medicinal use of this plant. More than 95 volatiles were found to be constituents of the three essential S. indicus oils with following composition of main components: flower oil: β-eudesmol (21.4%), 2,5-dimethoxy-p-cymene (16.2%), β-caryophyllene (7.8%), τ-cadinol (7.2%). caryophyllene oxide (6.9%) and α-eudesmol (4.5%); root oil: 2,5-dimethoxy-pcymene (28.3%), τ-cadinol (25.3%), (2)-arteannuic alcohol (10.1 %), β-maaliene (3.9%) and caryophyllene oxide (3.1%); herb oil: 2,5-dimethoxy-p-cymene (27.0%), τ-cadinol (12.5%), β-eudesmol (9.1 %), α-eudesmol (7.0%) and caroyphyllene oxide (4.7%). In addition, the odor impressions of the samples are described and the possible use of the essential Sphaeranthus indicus oils in medicinal, cosmetic and food flavoring discussed.