Drug Permeability - Best Practices for Biopharmaceutics Classification System (BCS)-Based Biowaivers: A workshop Summary Report

The workshop "Drug Permeability - Best Practices for Biopharmaceutics Classification System (BCS) Based Biowaivers" was held virtually on December 6, 2021, organized by the University of Maryland Center of Excellence in Regulatory Science and Innovation (M-CERSI), and the Food and Drug Administration (FDA). The workshop focused on the industrial, academic, and regulatory experiences in generating and evaluating permeability data, with the aim to further facilitate implementation of the BCS and efficient development of high-quality drug products globally. As the first international permeability workshop since the BCS based biowaivers was finalized as the ICH M9 guideline, the workshop included lectures, panel discussions, and breakout sessions. Lecture and panel discussion topics covered case studies at IND, NDA, and ANDA stages, typical deficiencies relating to permeability assessment supporting BCS biowaiver, types of evidence that are available to demonstrate high permeability, method suitability of a permeability assay, impact of excipients, importance of global acceptance of permeability methods, opportunities to expand the use of biowaivers (e.g. non-Caco-2 cell lines, totality-of-evidence approach to demonstrate high permeability) and future of permeability testing. Breakout sessions focused on 1) in vitro and in silico intestinal permeability methods; 2) potential excipient effects on permeability and; 3) use of label and literature data to designate permeability class.

Plastic waste recycling: existing Indian scenario and future opportunities

This review article aims to suggest recycling technological options in India and illustrates plastic recycling clusters and reprocessing infrastructure for plastic waste (PW) recycling in India. The study shows that a majority of states in India are engaged in recycling, road construction, and co-processing in cement kilns while reprocessing capabilities among the reprocessors are highest for polypropylene (PP) and polyethylene (PE) polymer materials. This review suggests that there are key opportunities for mechanical recycling, chemical recycling, waste-to-energy approaches, and bio-based polymers as an alternative to deliver impact to India's PW problem. On the other hand, overall, polyurethane, nylon, and polyethylene terephthalate appear most competitive for chemical recycling. Compared to conventional fossil fuel energy sources, polyethylene (PE), polypropylene (PP), and polystyrene are the three main polymers with higher calorific values suitable for energy production. Also, multi-sensor-based artificial intelligence and blockchain technology and digitization for PW recycling can prove to be the future for India in the waste flow chain and its management. Overall, for a circular plastic economy in India, there is a necessity for a technology-enabled accountable quality-assured collaborative supply chain of virgin and recycled material.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13762-022-04079-x.

Monitoring characteristics and genotoxic effects of engineered nanoparticle-protein corona

Engineered nanoparticles (ENPs) possess different physical and chemical properties compared to their bulk counterparts. These unique properties have found application in various products in the area of therapeutics, consumer goods, environmental remediation, optical and electronic fields. This has also increased the likelihood of their release into the environment thereby affecting human health and ecosystem. ENPs, when in contact with the biological system have various physical and chemical interactions with cellular macromolecules including proteins. These interactions lead to the formation of protein corona around the ENPs. Consequently, living systems interact with the protein-coated ENP rather than with a bare ENP. This ENP-protein interaction influences uptake, accumulation, distribution and clearance and thereby affecting the cytotoxic and genotoxic responses. Although there are few studies which discussed the fate of ENPs, there is a need for extensive research in the field of ENPs, to understand the interaction of ENPs with biological systems for their safe and productive application.

Synthesis and characterization of multifunctional gold nanoclusters for application in radiation therapy

Gold nanoparticles, because of their high radiation absorption coefficient and efficient generation of secondary photoelectrons, have been predicted to enhance therapeutic efficacy in radiation therapy. However, high dose for effective treatment limits their use. We have synthesized multifunctional gold nanoclusters (GNCs) that can be used for imaging and radiation therapy. The designed GNCs have been characterized for their physicochemical properties, biocompatibility, and their radiation dose enhancement potential on PC3 cell lines.

Synthesis of biocompatible iron oxide nanoparticles as a drug delivery vehicle

Over the last decade, there has been growing interest in developing novel nanoparticles (NPs) for biomedical applications. A safe-by-design approach was used in this study to synthesize biocompatible iron oxide NPs. The size of the particles obtained was ~100 nm. Although these NPs were significantly (P<0.05) internalized in MCF-7 (human breast adenocarcinoma cell line) cells, no adverse effect was observed in the cells as assessed by cytotoxicity assays (neutral red uptake and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) and cell cycle analysis. Our data demonstrate the potential of iron oxide NPs as a biocompatible carrier for targeted drug delivery.

Synthesis and in vitro studies of PLGA-DTX nanoconjugate as potential drug delivery vehicle for oral cancer

Advances in nanotechnology have led to the design of multifunctional nanoparticles capable of cellular imaging, targeted drug delivery, and diagnostics for early cancer detection. We synthesized poly(lactic-co-glycolic acid) nanoparticles encapsulating a model radiosensitizing drug docetaxel accomplishing localized in situ delivery of the sensitizer to the tumor site. The synthesized nanoparticles have been characterized for their physicochemical properties. The in vitro cytotoxicity of drug-loaded nanoparticles has been studied on human tongue carcinoma cell line SCC-9 (ATCC-CRL-1629).

Impact of Stress on Type 2 Diabetes Mellitus Management

BACKGROUND

Type 2 diabetes mellitus (T2DM) is one among the major health and socioeconomic problems worldwide. It is, however, not a somatic illness for which just symptomatic treatment will suffice. Stress is an important factor in not only causing diabetes onset or exacerbation, but also in hampering proper treatment by interfering with the treatment adherence of patients. Hence, it becomes important for physicians to acquaint themselves with the effects of stress on T2DM in order to ensure proper treatment of the latter.

OBJECTIVE

Documentation of effect of stress on the management of T2DM.

SUBJECTS AND METHODS

The research was a cross-sectional study on the patients attending Sri Muthukumaran Medical College, Hospital and Research Institute, Mangadu. A total of 400 people, who werepre-established diabetic patients of the hospital of age greater than 30 years, were chosen for the study. The stress levels of the patients were assessed with the Perceived Stress Scale (PSS) and treatment adherence using a questionnaire prepared exclusively for the study. Based on the data, a statistical relationship was framed between the degree of control (treatment adherence) and the stress levels of the patients.

RESULTS

The FBS levels were a direct reflection of the stress levels (P<0.05). Stress had a major impact on treatment adherence among the diabetic subjects: Increased levels of stress decreased the adherence (P<0.001). The glycemic index (HbA_1C level) was found to be linked to both treatment adherence and stress. Increased adherence kept it at bay (P<0.05) while stress proved abysmal to glycemic control.

CONCLUSION

T2DM is the result of an interplay between various factors; environmental, psychiatric and somatic. Hence, a holistic treatment approach is required, one that involves stress management, education and mental health awareness along with pharmacological treatment, to fully control the disease.

Zinc oxide nanoparticle induced age dependent immunotoxicity in BALB/c mice

Zinc oxide (ZnO) nanoparticles (NPs) have potential applications in cosmetics, food packaging and biomedicine but concerns regarding their safety need to be addressed. In the present study, the immunotoxic potential of ZnO NPs was evaluated in different ages of BALB/c mice after sub-acute exposure. The cytokine release, immunophenotyping, distribution of ZnO NPs and ultrastructural changes were assessed. A significant (p < 0.05) change in the CD4- and CD8-cells, levels of IL-6, IFN-γ and TNF-α and reactive oxygen species were observed in aged mice. In juvenile mice, increase in reactive oxygen species and IL-6 and TNF-α levels was observed with no significant changes in adult mice. A significant (p < 0.05) increase in the expression levels of mitogen activated protein kinase (MAPK) cascade proteins such as phospho-ERK1/2, phospho-JNK and phospho-p38 were also induced in aged mice. Collectively, our results indicate that the aged mice are more susceptible to ZnO NP induced immunotoxicity.

Laboratory Scale Microbial Food Chain To Study Bioaccumulation, Biomagnification, and Ecotoxicity of Cadmium Telluride Quantum Dots

The increasing applications of engineered nanomaterials (ENMs) in consumer products warrant a careful evaluation of their trophic transfer and consequent ecological impact. In the present study, a laboratory scale aquatic microbial food chain was established using bacteria (Escherichia coli (E. coli)) as a prey and ciliated protozoan (Paramecium caudatum) as a predator organism to determine the impact of cadmium telluride quantum dots (CdTe QDs). We observed that 29% of bacterivory potential of paramecium was lost, including an ∼12 h delay in doubling time on exposure to 25 mg/L CdTe QD (∼4 nm) as compared to control. The fluorescence based stoichiometric analysis revealed that 65% of the QDs bioaccumulated when paramecia were exposed to 25 mg/L QDs at 24 h. There was a significant (p < 0.05) increase in cellular cadmium (Cd) concentration at 24 h (306 ± 192 mg/L) as compared to 1 h (152 ± 50 mg/L). Moreover, the accumulation of Cd in E. coli (147 ± 25 mg/L) at 1 h of exposure to 25 mg/L QDs transferred 1.4 times higher Cd (207 ± 24 mg/L; biomagnification factor = 1.4) to its predator, paramecium.

Heteroagglomeration of zinc oxide nanoparticles with clay mineral modulates the bioavailability and toxicity of nanoparticle in Tetrahymena pyriformis

The extensive use of zinc oxide nanoparticles (ZnO NPs) in cosmetics, sunscreens and healthcare products increases their release in the aquatic environment. The present study explored the possible interaction of ZnO NPs with montmorillonite clay minerals in aqueous conditions. An addition of ZnO NPs on clay suspension significantly (p<0.05) increases the hydrodymic size of clay particles from 1652±90nm to 2158±13nm due to heteroagglomeration. The electrokinetic measurements showed a significant (p<0.05) difference in the electrophoretic mobilities of bare (-1.80±0.03μmcm/Vs) and ZnO NPs-clay association (-1.37±0.03μmcm/Vs) that results to the electrostatic interaction between ZnO NPs and clay particles. The attenuated total reflectance Fourier transform infrared spectroscopy analysis of ZnO NPs-clay association demonstrated the binding of ZnO NPs with the Si-O-Al region on the edges of clay particles. The increase in size of ZnO NPs-clay heteroagglomerates further leads to their sedimentation at 24h. Although, the stability of ZnO NPs in the clay suspension was decreased due to heteroagglomeration, but the bioavailability and toxicity of ZnO NPs-clay heteroagglomerates in Tetrahymena pyriformis was enhanced. These observations provide an evidence on possible mechanisms available in natural environment that can facilitate nanoparticles entry into the organisms present in lower trophic levels of the food web.

Montmorillonite clay alters toxicity of silver nanoparticles in zebrafish (Danio rerio) eleutheroembryo

An exponential development in the use of silver nanoparticles (AgNPs) in consumer products has accelerated their release in aquatic environment. As the AgNPs enters into the aquatic systems, their fate may change due to interactions with abiotic (e.g. clay particles) or biotic factors. The abundantly present clay particles are expected to more prone for interaction with nanoparticles in aquatic systems. In the present study, it is demonstrated that AgNPs interacts with clay particles and forms heteroagglomerates. Furthermore, an impact on toxicity potential of AgNPs after interactions with clay particles was assessed by using zebrafish eleutheroembryos (72 h post hatching) as an in vivo model. The mortality rate of zebrafish eleutheroembryos was higher in case of exposure to AgNPs-clay complexes (pH 4.0 and 7.0) as compared to bare AgNPs. In addition, at earlier time points, the eleutheroembryos expressed higher levels of morphological changes in tail, yolk and pericardia, but the edema in yolk sac was followed by cell death. It can be concluded from the observations made in the present study that the inorganic colloids in the aquatic matrices can alter the fate and toxicity potential of nanoparticles.

Can CuO nanoparticles lead to epigenetic regulation of antioxidant enzyme system?

Copper has been used from ancient time in various applications. Scientists have exploited its means of exposure and consequences to living organisms. The peculiar property of nanomaterials that is a high surface to volume ratio has increased the range of application in products. Copper oxide nanoparticles (CuO NPs) are widely used in industrial applications such as semiconductor devices, gas sensor, batteries, solar energy converter, microelectronics, heat transfer fluids and consumer products. In contrast, acute toxicity of CuO NPs has also been reported. Subsequently, human and environmental health may be at a high risk. Their frequent use can also contaminate ecosystems. Therefore, the toxicity of CuO NPs needs to be thoroughly understood. In this review, we have tried to discuss the recent facts and mechanism that have been explored for CuO NPs-induced toxicity at a cellular, in vivo and ecotoxicological level. Accordingly, the main cause for induction of toxicity by CuO NPs is the generation of reactive oxygen species (ROS) followed by the mitochondrial destruction that leads to apoptosis via the intrinsic pathway or under the condition such as hypoxia cell on exposure to CuO NPs may commit to necrosis. Moreover, CuO NPs also result in activation of MAPK pathways, ERKs and JNK/SAPK thus play an important role in the activation of AP-1. Furthermore, CuO NPs also leads to up-regulation of p53 and caspase three genes. Therefore, careful measures are required to explore omic technology to understand the molecular mechanism of the deleterious effects caused by CuO NPs. Copyright © 2016 John Wiley & Sons, Ltd.

Natural water as the test medium for Ag and CuO nanoparticle hazard evaluation: An interlaboratory case study

Engineered nanoparticles (NPs) have realistic potential of reaching natural waterbodies and of exerting toxicity to freshwater organisms. The toxicity may be influenced by the composition of natural waters as crucial NP properties are influenced by water constituents. To tackle this issue, a case study was set up in the framework of EU FP7 NanoValid project, performing an interlaboratory hazard evaluation of NPs in natural freshwater. Ag and CuO NPs were selected as model NPs because of their potentially high toxicity in the freshwater. Daphnia magna (OECD202) and Danio rerio embryo (OECD236) assays were used to evaluate NP toxicity in natural water, sampled from Lake Greifen and Lake Lucerne (Switzerland). Dissolution of the NPs was evaluated by ultrafiltration, ultracentrifugation and metal specific sensor bacteria. Ag NP size was stable in natural water while CuO NPs agglomerated and settled rapidly. Ag NP suspensions contained a large fraction of Ag(+) ions and CuO NP suspensions had low concentration of Cu(2+) ions. Ag NPs were very toxic (48 h EC50 1-5.5 μg Ag/L) to D. magna as well as to D. rerio embryos (96 h EC50 8.8-61 μg Ag/L) in both standard media and natural waters with results in good agreement between laboratories. CuO NP toxicity to D. magna differed significantly between the laboratories with 48 h EC50 0.9-11 mg Cu/L in standard media, 5.7-75 mg Cu/L in Lake Greifen and 5.5-26 mg Cu/L in Lake Lucerne. No toxicity of CuO NP to zebrafish embryos was detected up to 100 mg/L independent of the medium used. The results show that Ag and CuO NP toxicity may be higher in natural water than in the standard media due to differences in composition. NP environmental hazard evaluation can and should be carried out in natural water to obtain more realistic estimates on the toxicity.

Exploring the potential reservoirs of non specific TEM beta lactamase (bla(TEM)) gene in the Indo-Gangetic region: A risk assessment approach to predict health hazards

The emergence of antimicrobial resistant bacteria is an important public health and environmental contamination issue. Antimicrobials of β-lactam group accounts for approximately two thirds, by weight, of all antimicrobials administered to humans due to high clinical efficacy and low toxicity. This study explores β-lactam resistance determinant gene (blaTEM) as emerging contaminant in Indo-Gangetic region using qPCR in molecular beacon format. Quantitative Microbial Risk Assessment (QMRA) approach was adopted to predict risk to human health associated with consumption/exposure of surface water, potable water and street foods contaminated with bacteria having blaTEM gene. It was observed that surface water and sediments of the river Ganga and Gomti showed high numbers of blaTEM gene copies and varied significantly (p<0.05) among the sampling locations. The potable water collected from drinking water facility and clinical settings exhibit significant number of blaTEM gene copies (13±0.44-10200±316 gene copies/100mL). It was observed that E.crassipes among aquatic flora encountered in both the rivers had high load of blaTEM gene copies. The information on prevalence of environmental reservoirs of blaTEM gene containing bacteria in Indo-Gangetic region and risk associated will be useful for formulating strategies to protect public from menace of clinical risks linked with antimicrobial resistant bacteria.

Multiplex PCR based genotypic characterization of pathogenic vancomycin resistant Enterococcus faecalis recovered from an Indian river along a city landscape

BACKGROUND

Enterococci are normal commensals of human gut, but vancomycin-resistant enterococci (VRE) are a severe threat to human health. Antimicrobial-resistant enterococci have been reported previously from Indian surface waters. However, the presence of antimicrobial resistance and virulence markers in Enterococcus faecalis, the most dominant enterococci is yet to be investigated.

OBJECTIVES

The goal of this study was to analyse concentration of enterococci and distribution of antimicrobial resistance and virulence markers in E. faecalis isolates from river waters along an important north Indian city landscape.

METHODS

We enumerated enterococci in river water samples (n = 60) collected from five sites across the Lucknow city landscape using the most probable number and membrane-filtration methods. The antimicrobial sensitivity profile of E. faecalis isolate was generated with the Kirby-Bauer antimicrobial disc diffusion assay. The multiplex PCR was used for genotypic characterization of vancomycin-resistance and virulence in E. faecalis isolates.

RESULTS

Enterococci density (p < 0.0001) increased from up-to-down-stream sites. Multiplex PCR based genotypic characterization has shown a significant distribution of virulence-markers gelE, ace or efaA in the E. faecalis isolates (p < 0.05). The range of antimicrobial-resistance varied from 5 to 12 in the landscape with the frequency of vancomycin-resistant E. faecalis (VRE) ranging from 22 to 100 %.

CONCLUSION

The occurrence of pathogenic VRE in river Gomti surface water is an important health concern. The observed high background pool of resistance and virulence in E. faecalis in river waters has the potential to disseminate more alarming antimicrobial resistance in the environment and poses serious health risk in developing countries like India as VRE infections could lead to increased cost of healthcare.

Cell cycle dependent cellular uptake of zinc oxide nanoparticles in human epidermal cells

Metal oxide nanoparticles (NPs), including zinc oxide (ZnO) NPs have shown success for use as vehicles for drug delivery and targeting gene delivery in many diseases like cancer. Current anticancer chemotherapeutics fail to effectively differentiate between cancerous and normal cells. There is an urgent need to develop novel drug delivery system that can better target cancer cells while sparing normal cells and tissues. Particularly, ZnO NPs exhibit a high degree of cancer cell selectivity and induce cell death, oxidative stress, interference with the cell cycle progression and genotoxicity in cancerous cells. In this scenario, effective cellular uptake of NP seems to be crucial, which is shown to be affected by cell cycle progression. In the present study, the cytotoxic potential of ZnO NPs and the effect of different cell cycle phases on the uptake of ZnO NPs were examined in A431 cells. It is shown that the ZnO NPs led to cell death and reactive oxygen species generation and were able to induce cell cycle arrest in S and G2/M phase with the higher uptake in G2/M phase compared with other phases.

Q-PCR Based Culture-Independent Enumeration and Detection of Enterobacter: An Emerging Environmental Human Pathogen in Riverine Systems and Potable Water

The availability of safe and pristine water is a global challenge when large numbers of natural and anthropogenic water resources are being depleted with faster rate. The remaining water resources are severely contaminated with various kinds of contaminants including microorganisms. Enterobacter is one of the fecal coliform bacteria of family Enterobacteriaceae. Enterobacter was earlier used as an indicator bacterium along with other fecal Coliforms namely Escherichia coli, Citrobacter, and Klebsiella, but it is now known to cause various diseases in human beings. In this study, we have collected 55 samples from potable water and riverine system and proved their presence using their conserved sequences of 16S rRNA and 23S rRNA genes with the help of SYBR green real-time PCR, which showed very high specificity for the detection of Enterobacter. The Enterobacter counts in potable water were found to 1290 ± 32.89 to 1460 ± 39.42 cfu/100 ml. The Enterobacter levels in surface water were 1.76 × 10(4) ± 492, 1.33 × 10(4) ± 334, 1.15 × 10(4) ± 308, 2.56 × 10(4) ± 802, 2.89 × 10(4) ± 962, 8.16 × 10(4) ± 3443 cfu/100 ml; the levels of Enterobacter contamination associated with hydrophytes were 4.80 × 10(4) ± 1804, 3.48 × 10(4) ± 856, 8.50 × 10(4) ± 2074, 8.09 × 10(4) ± 1724, 6.30 × 10(4) ± 1738, 3.68 × 10(4) ± 949 cfu/10 g and the Enterobacter counts in sediments of the river, were 2.36 × 10(4) ± 703, 1.98 × 10(4) ± 530, 9.92 × 10(4) ± 3839, 6.80 × 10(4) ± 2230, 8.76 × 10(4) ± 3066 and 2.34 × 10(4) ± 732 cfu/10 g at the sampling Site #1, Site #2, Site #3, Site #4, Site #5, and Site #6, respectively. The assay could be used for the regular monitoring of potable water and other water reservoirs to check waterborne outbreaks.

DNA assembled metal nanoclusters: synthesis to novel applications

In this review, we have discussed the emergence of promising environmental-benign DNA assembled fluorescent metal nanoclusters and their unique electronic structures, unusual physical and chemical properties.

Nanotechnology in Disease Diagnostic Techniques

Currently the major research highlights of bioengineering and medical technology are directed towards development of improved diagnostic techniques to screen complex diseases. Screening requirements are to identify the cause of illnesses, monitor improvement or progression of the state of diseases such as cancer, cardiovascular or neurodegenerative diseases. Nanotechnology enables the manipulation of materials at nanoscale and has shown potential to enhance sensitivity, selectivity and lower the cost of a diagnosis. The causative biomolecules (DNA, proteins) can be detected by red-shifted absorbance of gold nanoparticles or alteration in the conductance of a nanowire or nanotubes, and deflection of a micro or nano-cantilever. Several types of nanomaterials such as metals, metal-oxides and quantum dots have shown ample advantages over traditional diagnosis, intracellular labeling and visualization of target cells/tissues. Nanotechnology has also opened several avenues which could be further developed to enable enhanced visualization of tissues, cells, DNA and proteins over a point-of-care device. Protein or gene chips created using nanomaterials could further be integrated into a convenient nano-fluidic device for better disease diagnosis.

Fluorescent magnesium nanocomplex in a protein scaffold for cell nuclei imaging applications

For the first time, we report a facile strategy for the synthesis of ultra-fine blue-green emitting fluorescent magnesium nanoparticles–protein complex (MgNC) which shows excellent photo stability and also stain cell nuclei with high specificity.

Isolation and classification of a soil actinomycete capable of sulphur-specific biotransformation of dibenzothiophene, benzothiophene and thianthrene

AIM

To isolate actinomycete spp with the ability to desulphurize sulphur-containing heterocyclic compounds present in petroleum.

METHODS AND RESULTS

Enrichment cultures were set up to select and isolate sulphur heterocycle metabolizing soil micro-organisms. Screening of the microbial isolates for the desulphurization property led to isolation of R3. The isolate was characterized by PCR screening of 16S rRNA genes and classical taxonomic investigations. HPLC analysis of the desulphurization assays with R3 showed ~85% transformation of dibenzothiophene (270 μmol l(-1)), present as the sole sulphur source in basal salt medium, in 4 days. Production of the desulphurized dibenzothiophene metabolite, 2-hydroxybiphenyl, was confirmed by GC/MS analyses. GC/MS analyses also established the ability of R3 to transform benzothiophene to benzothiophene-1-oxide and benzothiophene-1, 1-dioxide, and thianthrene to thianthrene-5-oxide. PCR primers computed based on the desulphurization operon (dszABC) of Rhodococcus erythropolis IGTS8 yielded the predicted amplification products with R3 genomic DNA as template. Southern hybridization and restriction endonuclease digestion profiles indicated that R3 amplicons were homologous to dsz AB.

CONCLUSIONS

The enrichment method used in this study yielded an environmental isolate with the ability to transform multiple sulphur heterocycles. The isolate R3 has taxonomic proximity to the Oerskovia sp, order Actinomycetales. The isolate R3 selectively removes sulphur from dibenzothiophene yielding 2-hydroxybiphenyl and sulphate. R3 also transforms benzothiophene and thianthrene in a sulphur-targeted manner. The desulphurization genes in R3 bear similarity to those in R. erythropolis IGTS8.

SIGNIFICANCE AND IMPACT OF THE STUDY

The actinomycetes present in soil can remove sulphur from different sulphur heterocycle substrates and have potential as biodesulphurization catalysts.

Quantification of Salmonella Typhi in water and sediments by molecular-beacon based qPCR

A molecular-beacon based qPCR assay targeting staG gene was designed for specific detection and quantification of S. Typhi and validated against water and sediment samples collected from the river Ganga, Yamuna and their confluence on two days during Mahakumbha mela 2012-2013 (a) 18 December, 2012: before six major religious holy dips (Makar Sankranti, Paush Poornima, Mauni Amavasya, Basant Panchami, Maghi Poornima and Mahashivratri) (b) 10 February, 2013: after the holy dip was taken by over 3,00,00,000 devotees led by ascetics of Hindu sects at Sangam on 'Mauni Amavasya' (the most auspicious day of ritualistic mass bathing). The assay could detect linearly lowest 1 genomic equivalent per qPCR and is highly sensitive and selective for S. Typhi detection in presence of non specific DNA from other bacterial strains including S. Paratyphi A and S. Typhimurium. It has been observed that water and sediment samples exhibit S. Typhi. The mass holy dip by devotees significantly affected the water and sediment quality by enhancing the number of S. Typhi in the study area. The qPCR developed in the study might be helpful in planning the intervention and prevention strategies for control of enteric fever outbreaks in endemic regions.

Mechanism of uptake of ZnO nanoparticles and inflammatory responses in macrophages require PI3K mediated MAPKs signaling

The inflammatory responses after exposure to zinc oxide nanoparticles (ZNPs) are known, however, the molecular mechanisms and direct consequences of particle uptake are still unclear. Dose and time-dependent increase in the uptake of ZNPs by macrophages has been observed by flow cytometry. Macrophages treated with ZNPs showed a significantly enhanced phagocytic activity. Inhibition of different internalization receptors caused a reduction in uptake of ZNPs in macrophages. The strongest inhibition in internalization was observed by blocking clathrin, caveolae and scavenger receptor mediated endocytic pathways. However, FcR and complement receptor-mediated phagocytic pathways also contributed significantly to control. Further, exposure of primary macrophages to ZNPs (2.5 μg/ml) caused (i) significant enhancement of Ras, PI3K, (ii) enhanced phosphorylation and subsequent activation of its downstream signaling pathways via ERK1/2, p38 and JNK MAPKs (iii) overexpression of c-Jun, c-Fos and NF-κB. Our results demonstrate that ZNPs induce the generation of reactive nitrogen species and overexpression of Cox-2, iNOS, pro-inflammatory cytokines (IL-6, IFN-γ, TNF-α, IL-17 and regulatory cytokine IL-10) and MAPKs which were found to be inhibited after blocking internalization of ZNPs through caveolae receptor pathway. These results indicate that ZNPs are internalized through caveolae pathway and the inflammatory responses involve PI3K mediated MAPKs signaling cascade.

Determination of viable Salmonellae from potable and source water through PMA assisted qPCR

Resource constrained countries identified as endemic zones for pathogenicity of Salmonella bear an economic burden due to recurring expenditure on medical treatment. qPCR used for Salmonella detection could not discriminate between viable and nonviable cells. Propidium monoazide (PMA) that selectively penetrates nonviable cells to cross-link their DNA, was coupled with ttr gene specific qPCR for quantifying viable salmonellae in source/potable waters collected from a north Indian city. Source water (raw water for urban potable water supply) and urban potable water exhibited viable salmonellae in the range of 2.1×10(4)-2.6×10(6) and 2-7160CFU/100mL, respectively. Potable water at water works exhibited DNA from dead cells but no viable cells were detected. PMA assisted qPCR could specifically detect low numbers of live salmonellae in Source and potable waters. This strategy can be used in surveillance of urban potable water distribution networks to map contamination points for better microbial risk management.

Surfactant mediated enhanced biodegradation of hexachlorocyclohexane (HCH) isomers by Sphingomonas sp. NM05

Environmental biodegradation of several chlorinated pesticides is limited by their low solubility and sorption to soil surfaces. To mitigate this problem we quantified the effect of three biosurfactant viz., rhamnolipid, sophorolipid and trehalose-containing lipid on the dissolution, bioavailability, and biodegradation of HCH-isomers in liquid culture and in contaminated soil. The effect of biosurfactants was evaluated through the critical micelle concentration (CMC) value as determined for each isomer. The surfactant increased the solubilization of HCH isomers by 3-9 folds with rhamnolipid and sophorolipid being more effective and showing maximum solubilization of HCH isomers at 40 μg/mL, compared to trehalose-containing lipid showing peak solubilization at 60 μg/mL. The degradation of HCH isomers by Sphingomonas sp. NM05 in surfactant-amended liquid mineral salts medium showed 30% enhancement in 2 days as compared to degradation in 10 days in the absence of surfactant. HCH-spiked soil slurry incubated with surfactant also showed around 30-50% enhanced degradation of HCH which was comparable to the corresponding batch culture experiments. Among the three surfactants, sophorolipid offered highest solubilization and enhanced degradation of HCH isomers both in liquid medium and soil culture. The results of this study suggest the effectiveness of surfactants in improving HCH degradation by increased bioaccessibility.

Bio-capture of S. Typhimurium from surface water by aptamer for culture-free quantification

In this study, a DNA aptamer was used to bio-capture Salmonella enterica serovar Typhimurium from surface water collected from highly endemic zone prior to culture-free detection through Molecular-Beacon based real-time PCR assay targeting invA gene. The assay could detect S. Typhimurium cells (1 CFU/PCR or 100 CFU/ml) selectively captured by serovar specific DNA aptamer. The observations indicate that all the water samples (n=40) collected from the river Gomti were contaminated by S. Typhimurium (31400-1 × 10(7) CFU/100 ml). The pre-analytical step in the form of serovar specific DNA aptamer based bio-capture of the bacterial cell was found to enhance the sensitivity of the florescent probe based real-time PCR assay during detection of S. Typhimurium in environmental samples exhibiting natural PCR inhibitors and high background bacterial flora. The assay could be used for the regular monitoring of surface waters for forecasting and management of non-typhoidal Salmonellosis in south Asia.

Engineered ZnO and TiO(2) nanoparticles induce oxidative stress and DNA damage leading to reduced viability of Escherichia coli

Extensive use of engineered nanoparticle (ENP)-based consumer products and their release into the environment have raised a global concern pertaining to their adverse effects on human and environmental health. The safe production and use of ENPs requires improvement in our understanding of environmental impact and possible ecotoxicity. This study explores the toxicity mechanism of ZnO and TiO(2) ENPs in a gram-negative bacterium, Escherichia coli. Internalization and uniform distribution of characterized bare ENPs in the nano range without agglomeration was observed in E. coli by electron microscopy and flow cytometry. Our data showed a statistically significant concentration-dependent decrease in E. coli cell viability by both conventional plate count method and flow cytometric live-dead discrimination assay. Significant (p<0.05) DNA damage in E. coli cells was also observed after ENP treatment. Glutathione depletion with a concomitant increase in hydroperoxide ions, malondialdehyde levels, reactive oxygen species, and lactate dehydrogenase activity demonstrates that ZnO and TiO(2) ENPs induce oxidative stress leading to genotoxicity and cytotoxicity in E. coli. Our study substantiates the need for reassessment of the safety/toxicity of metal oxide ENPs.

Contamination of potable water by enterotoxigenic Escherichia coli: qPCR based culture-free detection and quantification

Tourists visiting to endemic zones may acquire Enterotoxigenic Escherichia coli (ETEC) infection resulting into diarrhea due to consumption of contaminated potable waters. In this study, a qPCR assay (SYBR Green), targeting LT1 and ST1 genes was designed to quantify ETEC in potable waters derived from civic water supply. The assay could detect lowest 1CFU/PCR targeting LT1/ST1 gene from ten-fold diluted culture of the reference strain (E. coli MTCC 723) and is ten-fold more sensitive than the conventional PCR. The quantification of the ETEC in potable waters collected from civic supply of a major city of the northern India exhibiting high flow of tourists reveals that all the sites that ran along sewage line were contaminated by the ETEC. Contamination was due to percolation of sewage. The assay could be used for the regular monitoring of potable water in places exhibiting heavy flow of tourists to prevent ETEC induced diarrhea.

Identification of environmental reservoirs of nontyphoidal salmonellosis: aptamer-assisted bioconcentration and subsequent detection of salmonella typhimurium by quantitative polymerase chain reaction

In this study, identification of environmental reservoirs of Salmonella enterica subsp. enterica serovar Typhimurium (abbreviated as Salmonella Typhimurium) in sediments, water, and aquatic flora collected from the Ganges River (Ganges riverine material) was carried out by adopting a two-step strategy. Step 1 comprised a selective serovar-specific capture of Salmonella Typhimurium from potential reservoirs. Step 2 involved culture-free detection of selectively captured Salmonella Typhimurium by ttr gene-specific molecular beacon (MB) based quantitative polymerase chain reaction (q-PCR). The ttr gene-specific MB designed in this study could detect 1 colony-forming unit (cfu)/PCR captured by serovar-specific DNA aptamer. Sediments, water, and aquatic flora collected from the Ganges River were highly contaminated with Salmonella Typhimurium. The preanalytical step in the form of serovar-specific DNA aptamer-based biocapture of bacterial cells was found to enhance the sensitivity of the fluorescent probe in the presence of nonspecific DNA . Information about the presence of environmental reservoirs of Salmonella Typhimurium in the Ganges River region may pave the way for forecasting and management of nontyphoidal salmonellosis in south Asia.

Study of K-line radiation of thick titanium produced in collisions of keV electrons

The characteristic K-line yields Y(E₀) of a pure thick titanium (Z=22) element target are measured for 8-18 keV electron impact and compared with the simulation calculations using PENELOPE code. A fair agreement between experiment and simulation results is found within the existing experimental uncertainty of measurements. The ratio F of indirectly produced characteristic Ti K X-ray yield to its total (directly+indirectly) yield is determined by employing an approximate analytical formulation of Hanson and Cowan (Hanson, H.P., Cowan, D.J., 1961. Phys. Rev. 124, 22-26). It is found that F changes strongly with impact energy E₀ for normal angle of incidence in contrast to a mild change predicted by the simulation calculations. Furthermore, experimental and simulation results for peak to effective continuum ratio R of Ti K-line are compared and discussed for the energy range of impact of the present investigation.

A flow cytometric method to assess nanoparticle uptake in bacteria

Toxicity of engineered nanomaterials (ENMs), such as metal oxides, has been of concern among environmental and health scientists. For ecotoxicity studies of ENMs, it is important to assess nanoparticle uptake and correlate it with the cellular response. However, due to nonavailability of adequate methods for assessing cellular uptake of ENMs, there is a lack of information in this important area. In the present study, a method has been developed using flow cytometry, which allows for rapid detection of ENM internalization in live bacteria under different experimental conditions for several generations. Our data demonstrate significant internalization of Zinc oxide (ZnO) and Titanium (IV) oxide (TiO(2) ) nanoparticles (NPs) in Escherichia coli in a dose-dependent manner. ZnO NPs treatment exhibited a significant increase in the intensity of side scatter (SSC) with liver-S9 fraction (76, 94, and 181% increase) rather than without S9 (10.5, 24.5, and 125.9% increase) at 10, 40, and 80 μg/ml concentrations, respectively. This was due to the protein coating of NPs by the S9 fraction. A similar response was also observed on exposure to TiO(2) NPs (139 and 203% with S9 and 128 and 198% without S9). In a multigeneration study, this new method was able to detect the presence of ENMs in E. coli up to four generations. Our data demonstrate that this method can be used for assessing the uptake of ENMs in bacteria and provides a handle to toxicologists for ecotoxicity studies of economically important ENMs to ensure safer products in the market.

Chromium oxide nano-particles induce stress in bacteria: probing cell viability

In this study, viability of an environmentally relevant bacterium, Escherichia coli exposed to 0-100 microg/mL chromium oxide nanoparticles (Cr2O3, Nps) for 120 min in Luria Bertani broth was evaluated by Propidium monoazide (PMA) assisted Q-PCR and standard plate count (SPC) method. Viable count for E. coli grown in Cr2O3, Nps amended medium was more by PMA assisted Q-PCR than SPC. Thus, the observations made in this study suggest that the inclusion of PMA assisted Q-PCR for viability assessment in Nps toxicity studies will provide the real count for the viable cells comprising of both viable and viable but not culturable (VBNC) cells.

C60-fullerene binds with the ATP binding domain of human DNA topoiosmerase II alpha

C60-fullerene has promising biological applications, such as drug delivery, biosensors, diagnosis and theraupetics. Despite of these applications, several in vitro studies have also reported the DNA damaging potential of this nanomaterial. Though, very little is known about the mechanism involved behind the fullerene mediated DNA damage. Our study was aimed at identifying the binding site of fullerene in the ATP binding domain of human topoisomerase II alpha, a major enzyme involved in maintaining DNA topology. In silico studies of fullerene with the enzyme demonstrated that it can interact with the active site residues of this enzyme through hydrophobic, pi-stacking and van der Waals interactions and could inhibit the activity of this enzyme.