Active targeted nanoparticles: Preparation, physicochemical characterization and in vitro cytotoxicity effect

In this study, the folate decorated biodegradable poly (lactide-co-glycolide) (PLGA) nanoparticles were developed for tumor targeting of anticancer agents. Due to the overexpression of the folate receptor on tumor surface, the folate has been efficiently employed as a targeting moiety for various anticancer agents to avoid their non-specific attacks on normal tissues and also to increase their cellular uptake within target cells. Folate conjugate PLGA was synthesized successfully and its chemical structure was evaluated by FTIR, DSC and (1)HNMR spectroscopy. PLGA-folate nanoparticles (PLGA-Fol NPs) were prepared by nanoprecipitation method, adopting PLGA as a drug carrier, folic acid as a targeting ligand and 9-nitrocampthotecin as a model anticancer drug. The average size and encapsulation efficiency of the prepared PLGA-Fol NPs were found to be around 115 ± 12 nm and 57%, respectively. In vitro release profile indicated that nearly 85% of the drug was released in 50 h. The in vitro intracellular uptakes of PLGA-Fol NPs showed greater cytotoxicity on cancer cell lines compared to non-folate mediated carriers.

Encapsulation in PLGA-PEG enhances 9- nitro-camptothecin cytotoxicity to human ovarian carcinoma cell line through apoptosis pathway

Ovarian cancer is the fifth leading cause of the cancer-related death among women. 9-nitrocamptothecin (9-NC) is a water-insoluble derivative of camptothecin used for the treatment of patients with advanced ovarian cancer. Previous studies showed that the encapsulation of 9-NC in poly (lactic-co-glycolic acid, PLGA) nanoparticles increased the cytotoxic effect of the drug on different cancer cell lines. In the present study, the cytotoxic effects of 9-NC, 9-NC-loaded PLGA and PLGA-polyethylene glycol (PLGA-PEG) nanoparticles with varying degree of PEG (5, 10, and 15%) were evaluated on human ovarian carcinoma cell line. Furthermore, the mode of cell death induced by 9-NC and the optimized 9-NC-loaded PLGA-PEG nanoparticles on A2780 cell line were investigated. 9-NC incorporating nanoparticles were prepared by nanopercipitation method and their physicochemical characteristics were evaluated using standard methods. The results showed that activation of caspase-3 and -9 significantly increased by free 9-NC and PLGA-PEG loaded nanoparticles in A2780 cells. In contrast to the free drug which increased the activation of caspase-8, 9-NC-loaded PLGA-PEG nanoparticles did not alter the activation of caspase-8. Collectively, it appears that apoptosis induced by 9-NC incorporated in PLGA-PEG 5% occurred through the activation of caspase-9 rather than activation of caspase-8 which is the mediator of extrinsic pathway. Moreover, our results confirmed that 9-NC in nanoparticles at the level of gene expression potentiated down-regulation of Bcl-2, up regulation of Bax, and Smac/DIABLO leading to a decrease in mitochondrial membrane potential. Taken together, our results showed that 9-NC incorporated in PLGA-PEG 5% nanoparticles is able to induce apoptosis in A2780 human ovarian carcinoma cells and has the potential for the treatment of ovarian carcinoma.

Acute and subchronic toxicological evaluation of Stachys lavandulifolia aqueous extract in Wistar rats

Stachys lavandulifolia (S. lavandulifolia) is a plant that has been widely used as an herbal medicine in Iran. Unfortunately, despite the prevalent medicinal uses of the plant, there are no reports on the possible toxic effects of S. lavandulifolia. In the present study the potential toxicity of S. lavandulifolia after acute and subchronic administration in rats was evaluated. Rats were orally treated with single doses of S. lavandulifolia aqueous extract and screened for signs of toxicity two weeks after administration. In the sub-chronic toxicity study, S. lavandulifolia was administered for 45 days. Mortality, clinical signs, body weight changes were assayed during the study. After 45 days animals were sacrificed and hematological and biochemical parameters, as well as weight of some organs were measured. All of the rats treated with different concentrations of water extracts of S. lavandulifolia were alive for all 14 days of observation. No hematological changes were observed a part from significant increase in WBC and neutrophils counts. Moreover, serum aspartate aminotransferase (AST) and creatinine significantly increased. Histopathological examinations showed fatty change, degeneration of hepatocytes and renal glomerular atrophy in the male rats. In the female rats, atrophy of hepatocytes and dilatation of sinusoids in liver, hyperemia and degeneration of renal epithelium mostly in cortical region were observed. Based on the results of this study no observed adverse effect level (NOAEL) of the total aqueous extract of S. lavandulifolia considered to be 250 and 100 mg/kg/day for the male and female rats, respectively.

Spectrophotometric study of complex formations between 1-(2-pyridylazo)-2-naphthol (PAN) and some metal ions in organic solvents and the determination of thermodynamic parameters

The complexation reactions between Ni(2+), Co(2+) and Zn(2+) metal ions with PAN in methanol (MeOH), acetonitrile (AN) and dimethyl sulfoxide (DMSO) were studied using a spectrophotometric method. The stability constants of the resulting complexes were determined from computer fitting absorbance mole-ratio data. The results revealed that the stability constants of complexes are varying in order of Ni(2+)<Zn(2+)<Co(2+) for all solvents. The values of the thermodynamic parameters (ΔH°, ΔS° and ΔG°) for complexation reactions were obtained from the temperature dependence of the stability constants.

The academic environment: the students' perspective

Dental education is regarded as a complex, demanding and often stressful pedagogical procedure. Undergraduates, while enrolled in programmes of 4-6 years duration, are required to attain a unique and diverse collection of competences. Despite the major differences in educational systems, philosophies, methods and resources available worldwide, dental students' views regarding their education appear to be relatively convergent. This paper summarizes dental students' standpoint of their studies, showcases their experiences in different educational settings and discusses the characteristics of a positive academic environment. It is a consensus opinion that the 'students' perspective' should be taken into consideration in all discussions and decisions regarding dental education. Moreover, it is suggested that the set of recommendations proposed can improve students' quality of life and well-being, enhance their total educational experience and positively influence their future careers as oral health physicians. The 'ideal' academic environment may be defined as one that best prepares students for their future professional life and contributes towards their personal development, psychosomatic and social well-being. A number of diverse factors significantly influence the way students perceive and experience their education. These range from 'class size', 'leisure time' and 'assessment procedures' to 'relations with peers and faculty', 'ethical climate' and 'extra-curricular opportunities'. Research has revealed that stress symptoms, including psychological and psychosomatic manifestations, are prevalent among dental students. Apparently some stressors are inherent in dental studies. Nevertheless, suggested strategies and preventive interventions can reduce or eliminate many sources of stress and appropriate support services should be readily available. A key point for the Working Group has been the discrimination between 'teaching' and 'learning'. It is suggested that the educational content should be made available to students through a variety of methods, because individual learning styles and preferences vary considerably. Regardless of the educational philosophy adopted, students should be placed at the centre of the process. Moreover, it is critical that they are encouraged to take responsibility for their own learning. Other improvements suggested include increased formative assessment and self-assessment opportunities, reflective portfolios, collaborative learning, familiarization with and increased implementation of information and communication technology applications, early clinical exposure, greater emphasis on qualitative criteria in clinical education, community placements, and other extracurricular experiences such as international exchanges and awareness of minority and global health issues. The establishment of a global network in dental education is firmly supported but to be effective it will need active student representation and involvement.