Role of reactant concentration and identity of added cation in controlling emission from post-synthetically modified terbium incorporated zinc sulfide nanoparticles: an avenue for the detection of lead(ii) cations

This work reports the photophysical properties of 1-thioglycerol capped hydrophilic terbium cation incorporated (doped) zinc sulfide [Zn(Tb)S] nanoparticles, which have been post-synthetically modified using Pb²⁺ [Zn(Tb)S/Pb] under ambient conditions with [Zn(Tb)S] : [Pb²⁺] = 1 : 10⁻⁵–1 : 10, essentially providing a scenario with low to heavy co-doping and ultimately the possibility of forming a material of different chemical identity. The effects of selected concentrations of [Zn(Tb)S] : [Mⁿ⁺] = 1 : 1 and 1 : 10⁻² have also been evaluated for the post-synthetic addition of Hg²⁺, Cd²⁺, Ca²⁺, Mg²⁺, Na⁺ and K⁺. The broad zinc sulfide nanoparticle and sharp Tb³⁺ emission have different dependence on the relative reactant concentration, with cation identity playing a significant role. The underlying photophysical processes have been rationalized based on the interplay among the (i) cation exchange, (ii) modification of the structural properties of the nanoparticles without necessarily exchanging the cations and (iii) emission enhancement of terbium dopants. In cases where Tb³⁺ emission is apparent, all the nanoparticles studied demonstrate an optical antenna effect, thus accessing a lower Tb³⁺ concentration regime compared to in bulk environments. The results presented provide an avenue for the detection of heavy metal ions in general and Pb²⁺ in particular, with a limit of detection that is at least in the range of sub-ppm, using either the broad ZnS or sharp Tb³⁺ emission, respectively. This strategy provides an avenue to combine (i) the extremely sensitive and easily accessible analytical technique of photoluminescence spectroscopy, (ii) post-synthetic modification reactions in semiconductor nanoparticles that can be performed with less experimental demand, (iii) time-gated measurement related to the longer luminescence lifetime of terbium cations and (iv) the simultaneous use of broad ZnS nanoparticle and sharp Tb³⁺ emission from the same assembly, helping eliminate false positive results.

Reactant concentration and the identity of the added cation control the emission in post-synthetically modified terbium incorporated zinc sulfide nanoparticles.     

Evaluation of chemopreventive potentials of ethanolic extract of Ruta graveolens against A375 skin melanoma cells in vitro and induced skin cancer in mice in vivo

OBJECTIVE: Chemopreventive approach with natural products, particularly plants and plant-derived ones, is receiving increasing attention for their effective role against cancer without any palpable side effects. In this study, efficacy of ethanolic extract of Ruta graveolens(RG) on skin melanoma cells(A375) in vitro and on 7,12-dimethylbenz(a)anthracene(DMBA)-induced skin cancer in vivo has been tested in Swiss albino mice.METHODS: Studies on cell viability, apoptosis and autophagy induction were conducted in vitro. To check apoptosis, assays like alteration in mitochondrial membrane potential, annexin V-fluorescein isothiocyanate/propidium iodide assay and immunoblot were performed. Fluorescence microscopic and immunoblot assays were performed to confirm autophagy induction. The effects of RG were determined by evaluating body weight, tumor incidence, tumor volume and tumor burden in mice. Enzymatic and non-enzymatic antioxidant status was assessed. The role of some relevant signaling proteins was also analyzed.RESULTS: RG caused death of A375 cells through induction of caspase 3-mediated apoptosis and Beclin-1-associated autophagy. Moreover, RG administration(75 mg/kg body weight) which showed no acute or chronic toxicity, showed significant reduction in the skin tumor burden of DMBA-painted mice. RG also demonstrated potent anti-lipid peroxidative and antioxidant functions during the course of skin cancer induction by DMBA.CONCLUSION: Chemopreventive potential of RG was demonstrated from overall results of this study, indicating its possible use in therapeutic formulation of an effective drug to treat skin cancer.     

Latent variable models for gene–environment interactions in longitudinal studies with multiple correlated exposures

Many existing cohort studies designed to investigate health effects of environmental exposures also collect data on genetic markers. The Early Life Exposures in Mexico to Environmental Toxicants project, for instance, has been genotyping single nucleotide polymorphisms on candidate genes involved in mental and nutrient metabolism and also in potentially shared metabolic pathways with the environmental exposures. Given the longitudinal nature of these cohort studies, rich exposure and outcome data are available to address novel questions regarding gene–environment interaction (G × E). Latent variable (LV) models have been effectively used for dimension reduction, helping with multiple testing and multicollinearity issues in the presence of correlated multivariate exposures and outcomes. In this paper, we first propose a modeling strategy, based on LV models, to examine the association between repeated outcome measures (e.g., child weight) and a set of correlated exposure biomarkers (e.g., prenatal lead exposure). We then construct novel tests for G × E effects within the LV framework to examine effect modification of outcome–exposure association by genetic factors (e.g., the hemochromatosis gene). We consider two scenarios: one allowing dependence of the LV models on genes and the other assuming independence between the LV models and genes. We combine the two sets of estimates by shrinkage estimation to trade off bias and efficiency in a data‐adaptive way. Using simulations, we evaluate the properties of the shrinkage estimates, and in particular, we demonstrate the need for this data‐adaptive shrinkage given repeated outcome measures, exposure measures possibly repeated and time‐varying gene–environment association. Copyright © 2014 John Wiley & Sons, Ltd.     

Mediastinal hydatid disease: an unusual presentation

Hydatid disease is a significant health problem in endemic areas. While occurrence of the cysts in the liver and lung is common, mediastinal localisation is extremely rare. We report the case of a 35-year-old male who presented with a painless swelling on the right side of the neck and features of superior vena caval obstruction. Chest radiography and computed tomography (CT) suggested a cyst in the right upper lobe, extending into the right supraclavicular region as well as another cyst in the left lung. Thoracotomy revealed that the right-sided cyst was actually mediastinal in location and had herniated through the thoracic inlet compressing the superior vena cava (SVC). Both cysts were removed in two separate operations and symptoms of SVC compression subsided after removal of the right-sided cyst. Histopathology was consistent with a hydatid disease.     

Understanding the role of stimulation in reflexology: development and testing of a robotic device

Reflexology is a common choice of women with breast cancer as supportive care during treatment. It involves stimulation of specific locations of the feet called reflexes using a specialised walking motion with the thumb of the reflexologist. Reflexology has shown potential for the successful management of cancer and treatment-related symptoms and improvement in physical functioning; however to date, the mechanism of action for these improvements is unknown. One confounder to the study of reflexology is the 'human factor'. To study the effects of the stimulation of the reflexes independent of the 'human factor', there is a need for an alternative method for the delivery of reflexology. The objective of this work was to design and create a robotic reflexology device that would deliver a breast cancer-specific reflexology protocol to the feet of patients. A prototype robotic reflexology device was developed and tested for feasibility, safety and acceptability with breast cancer survivors (n= 13), and preliminary efficacy in symptom management and enhanced functional status with a sample of women undergoing chemotherapy for breast cancer (n= 13). Safety, feasibility and acceptability were established, and significant improvements from pre- to post-device-delivered reflexology were seen in symptom severity among women on chemotherapy.     

Foreign Body Aspiration: Demographic Trends and Foreign Bodies Posing a Risk

This study was done to find out modern demographic trends of aspiration and different foreign bodies posing a risk. For this study, 94 patients with suspected foreign body aspiration (FBA) were selected. Detailed history, especially age, suspected Foreign body (FB) and mode of onset were noted and a thorough clinical examination was done. X-ray chest and neck, antero-posterior and lateral view was the only investigation done in all. Rigid bronchoscopy under general anaesthesia was done in all the cases of suspected FBA for diagnostic cum therapeutic purpose. Among 94 patients 70.2% i.e. 66 were within 5 years of age and most were within 2–3 years of age. Rigid bronchoscopy was done in all the cases and foreign body was successfully retrieved in 78.7% of cases. Bronchoscopy was negative in the rest of the cases. The Most common site of lodgment was the right bronchus followed by the left bronchus, the trachea and other sites. Vegetables were the most common FBs as they were found in 26 cases. Whistles from small plastic toys were the single most common FB(15). Other foreign bodies were small plastic and metallic parts, safety pins, jewellery etc. Children under 5 years of age are at greatest risk of FBA. Different vegetables and whistles of low grade toys are the most commonly aspirated FB. Detailed history is most important for diagnosis. X-ray is not a reliable tool for diagnosis. Bronchoscopy should be done whenever a foreign body is suspected in the airway.     

Electroglottographic Parameterization of the Effects of Gender, Vowel and Phonatory Registers on Vocal Fold Vibratory Patterns: An Indian Perspective

In-depth study on laryngeal biomechanics and vocal fold vibratory patterns reveal that a single vibratory cycle can be divided into two major phases, the closed and open phase, which is subdivided into opening and closing phases. Studies reveal that the relative time course of abduction and adduction, which in turn is dependent on the relative relaxing and tensing of the vocal fold cover and body, to be the determining factor in production of a particular vocal register like the modal (or chest), falsetto, glottal fry registers. Studies further point out Electroglottography to be particularly suitable for the study of vocal vibratory patterns during register changes. However, to date, there has been limited study on quantitative parameterization of EGG wave form in vocal fry register. Moreover, contradictory findings abound in literature regarding effects of gender and vowel types on vocal vibratory patterns, especially during phonation at different registers. The present study endeavors to find out the effects of vowel and gender differences on the vocal fold vibratory patterns in different registers and how these would be reflected in standard EGG parameters of Contact Quotient (CQ) and Contact Index (CI), taking into consideration the Indian sociolinguistic context. Electroglottographic recordings of 10 young adults (5 males and 5 females) were taken while the subjects phonated the three vowels /a/,/i/,/u/ each in two vocal registers, modal and vocal fry. Obtained raw EGG were further normalized using the Derived EGG algorithm and theCQ and CI values were derived. Obtained data were subject to statistical analysis using the 3-way ANOVA with gender, vowel and vocal register as the three variables. Post-hoc Dunnett C multiple comparison analysis were also performed. Results reveal that CQ values are significantly higher in vocal fry than modal phonation for both males and females, indicating a relatively hyperconstricted vocal system during vocal fry. The males have significantly greater CQ values than females both at modal and vocal fry phonations which indicate that the males are predisposed to greater vocal fold constriction. Females demonstrated no significant increase in CI values in vocal fry state; and in some cases actually decrease in the CI values which suggest an inherently distinct vocal fold physiological adjustment from that in males. No vowel effects were found in any conditions. Perturbation values (CQP and CIP) are significantly more in vocal fry register than in modal register, and the increase was more in case of females than males. The findings give strong evidence to certain hypotheses in literature regarding effects of vowel, gender and phonatory register on vocal fold vibratory patterns.