Publications by authors named "Ashish Asthana"

15 Publications

  • Page 1 of 1

A miniaturized push-pull-perfusion probe for few-second sampling of neurotransmitters in the mouse brain.

Lab Chip 2019 04;19(8):1332-1343

BIOS - Microdevices for Chemical Analysis group, MESA+ Institute for Nanotechnology, Techmed Centre, University of Twente, Hallenweg 15, 7522 NH Enschede, The Netherlands.

Measuring biomolecule concentrations in the brain of living animals, in real time, is a challenging task, especially when detailed information at high temporal resolution is also required. Traditionally, microdialysis probes are used that generally have sampling areas in the order of about 1 mm2, and provide information on concentrations with a temporal resolution of at least several minutes. In this paper, we present a novel miniaturized push-pull perfusion sampling probe that uses an array of small 3 μm-wide sampling channels to sample neurotransmitters at a typical recovery rate of 61%, with a reduced risk of clogging. The added feature to segment the dialysate inside the probe into small water-in-decane droplets enables the detection of concentrations with a temporal resolution of a few seconds. Here we used the probe for in vivo recordings of neurotransmitter glutamate released upon electrical stimulation in the brain of a mouse to demonstrate the feasibility of the probe for real-time neurochemical brain analysis.
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http://dx.doi.org/10.1039/c8lc01137kDOI Listing
April 2019

How efficacious are , , Guduchi extracts and chlorhexidine as intracanal disinfectants? A comparative study.

Ayu 2017 Jan-Jun;38(1-2):70-75

Department of Microbiology, Subharti Medical College, Meerut, Uttar Pradesh, India.

Introduction: In endodontics, despite careful instrumentation and antimicrobial irrigation, root canals still harbor cultivable microorganisms. Such cases require intra canal medicament that eliminates the microbial inhabitants from the canals. Recent trend advocates the use of herbal extracts due to easy availability, cost-effectiveness, low toxicity, and lack of microbial resistance. Hence, in the present study, , , and extracts were used as intracanal medicaments.

Aim: This study aimed to evaluate and compare the antibacterial efficacy of , , extracts, and chlorhexidine against , when used as intracanal medicaments.

Materials And Methods: One hundred and twenty-five extracted human teeth, inoculated with , were divided into four experimental groups and a control group ( = 25 in each group). The experimental groups were treated with chlorhexidine, , , and extracts and their antibacterial property was evaluated by estimating microbial counting (CFU/ml).

Results: The reduction in bacterial count for chlorhexidine, , , and groups was 60.76%, 51.98%, 37.73%, and 34.93%, respectively. Statistically significant difference in reduction of bacterial count was observed in all the groups, when compared with the control group.

Conclusion: Among all the herbal extracts, was found to be the most potent medicament followed by and . However, chlorhexidine was found to be at epic.
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http://dx.doi.org/10.4103/ayu.AYU_72_16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5954265PMC
June 2018

Evaluation of phenotypic tests for detection of Klebsiella pneumoniae carbapenemase and metallo-beta-lactamase in clinical isolates of Escherichia coli and Klebsiella species.

Indian J Pathol Microbiol 2015 Jan-Mar;58(1):31-5

Department of Microbiology, Subharti Medical College, Swami Vivekanand Subharti University, Meerut, Uttar Pradesh, India.

Context: Carbapenemase production is an important mechanism responsible for carbapenem resistance.

Aims: Phenotypic detection and differentiation of types of carbapenemase in carbapenem resistant Enterobacteriaceae is important for proper infection control and appropriate patient management.

Settings And Design: We planned a study to determine the occurrence of Class A Klebsiella pneumoniae carbapenemase (KPC type) and Class B Metallo-β-lactamase (MBL type) carbapenemase in hospital and community.

Materials And Methods: Clinical isolates of Escherichia coli and Klebsiella species and simultaneously evaluate different phenotypic methods for detection of carbapenemases.

Results: It was observed that 20.72% clinical isolates of E. coli and Klebsiella spp. were resistant to carbapenem on screening of which, 14.64% were E. coli and 29.69% were Klebsiella spp. Using phenotypic confirmatory tests the occurrence of carbapenemase production was found to be 87.01% in E. coli and 91.51% in Klebsiella spp. using both modified Hodge test (MHT) and combined disk test (CDT) using imipenem-ethylenediaminetetraacetic acid.

Conclusions: Both MBL and KPC type carbapenemases were seen among clinical isolates of E. coli and Klebsiella spp. CDT is simple, rapid and technically less demanding procedure, which can be used in all clinical laboratories. Supplementing MHT with CDT is reliable phenotypic tests to identify the class A and class B carbapenemase producers.
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http://dx.doi.org/10.4103/0377-4929.151168DOI Listing
August 2015

C-Reactive Protein (CRP) and its Association with Periodontal Disease: A Brief Review.

J Clin Diagn Res 2014 Jul 20;8(7):ZE21-4. Epub 2014 Jul 20.

Assistant Professor, Department of Microbiology, Subharti Medical College, Swami Vivekanand Subharti University , Meerut, U.P., India .

Periodontal disease is a chronic infection of the gums characterised by a loss of attachment between the tooth and bone, and bone loss. C-reactive protein (CRP) elevation is a part of the acute phase response to acute and chronic inflammation. Many epidemiological studies have shown that serum CRP levels were elevated in patients with chronic periodontitis. CRP levels increase to hundreds of μg/ml within hours following infection. It out-performs erythrocyte sedimentation rate (ESR) in terms of responsiveness and specificity for inflammation. While CRP elevation is suggestive of inflammation or infection in the appropriate clinical context, it can also occur with obesity and renal dysfunction. Conversely, a lack of CRP elevation in inflammation may be seen with hepatic failure, as well as during flares of conditions such as systemic lupus erythematosus.
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http://dx.doi.org/10.7860/JCDR/2014/8355.4646DOI Listing
July 2014

Extended spectrum beta lactamase producing Proteus penneri: a rare missed pathogen?

Indian J Pathol Microbiol 2014 Jul-Sep;57(3):489-91

Department of Microbiology, Subharti Medical College, Swami Vivekanand Subharti University, Meerut, Uttar Pradesh, India.

Indole negative Proteus species are invariably incorrectly identified as Proteus mirabilis, often missing out isolates of Proteus penneri. We report a case of extended spectrum beta lactamase producing and multidrug-resistant P. penneri isolated from pus from pressure sore of a patient of road traffic accident. Correct and rapid isolation and identification of such resistant pathogen are important as they are significant nosocomial threat.
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http://dx.doi.org/10.4103/0377-4929.138791DOI Listing
April 2015

Genotype MTBDR plus assay for molecular detection of rifampicin and isoniazid resistance in Mycobacterium tuberculosis.

Indian J Pathol Microbiol 2014 Jul-Sep;57(3):423-6

Department of Microbiology, Subharti Medical College, Swami Vivekanand Subharti University, Meerut, Uttar Pradesh, India.

Aim: This study was performed for the rapid identification of Mycobacterium tuberculosis complex and its resistance to rifampicin and isoniazid, directly from the sputum samples of pulmonary tuberculosis patients.

Materials And Methods: A commercially available genotype MTBDR plus assay was used for the identification and detection of mutations in Mycobacterial isolates. A total of 100 sputum samples of pulmonary tuberculosis patients were analyzed by using the genotype MTBDR plus assay. The MTBDR plus assay is designed to detect the mutations in the hotspot region of rpoB gene, katG and regulatory region of inhA gene.

Results: The genotype MTBDR plus assay detected 22% multidrug resistant (MDR), 2% rifampicin (RMP) monoresistant and 1% isoniazid (INH) monoresistant isolates. In 22 MDR isolates, the codons most frequently involved in RMP-associated mutations were codon 531 (54.55%), 516 (31.82%) and 526 (13.63%), and 90.90% of MDR isolates showed KatG S315T mutations and 9.1% showed inhA C-15T mutations associated with INH resistance.

Conclusion: The new genotype MTBDR plus assay represents a rapid, reliable tool for the detection of MDR-TB, wherein results are obtained in 5 h allowing early and appropriate treatment, which is essential to cut the transmission path and reduce the spread of MDR-TB. The genotype MTBDR plus assay can readily be included in a routine laboratory work for the early diagnosis and control of MDR-TB.
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http://dx.doi.org/10.4103/0377-4929.138738DOI Listing
April 2015

Multifunctional superhydrophobic polymer/carbon nanocomposites: graphene, carbon nanotubes, or carbon black?

ACS Appl Mater Interfaces 2014 Jun 20;6(11):8859-67. Epub 2014 May 20.

Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ‡Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zurich , Zurich 8092, Switzerland.

Superhydrophobic surfaces resisting water penetration into their texture under dynamic impact conditions and offering simultaneously additional functionalities can find use in a multitude of applications. We present a facile, environmentally benign, and economical fabrication of highly electrically conductive, polymer-based superhydrophobic coatings, with impressive ability to resist dynamic water impalement through droplet impact. To impart electrical conductivity, the coatings were prepared by drop casting suspensions with loadings of different kinds of carbon nanoparticles, namely, carbon black (CB), carbon nanotubes (CNT), graphene nanoplatelets (GNP) and their combinations, in a fluoropolymer dispersion. At 50 wt % either CB or CNT, the nanocomposite coatings resisted impalement by water drops impacting at 3.7 m/s, the highest attainable speed in our setup. However, when tested with 5 vol % isopropyl alcohol-water mixture, i.e., a lower surface tension liquid posing a stiffer challenge with respect to impalement, only the CB coatings retained their impalement resistance behavior. GNP-based surfaces featured very high conductivity ∼1000 S/m, but the lowest resistance to water impalement. The optimal performance was obtained by combining the carbon fillers. Coatings containing CB:GNP:polymer = 1:1:2 showed both excellent impalement resistance (up to 3.5 m/s with 5 vol % IPA-water mixture drops) and electrical conductivity (∼1000 S/m). All coatings exhibited superhydrophobic and oleophilic behavior. To exemplify the additional benefit coming from this property, the CB and the optimal, combined CB/GNP coatings were used to separate mineral oil and water through filtration of their mixture.
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http://dx.doi.org/10.1021/am501649wDOI Listing
June 2014

Evaluation of phenotypic tests for the detection of AmpC beta-lactamase in clinical isolates of Escherichia coli.

Indian J Pathol Microbiol 2013 Apr-Jun;56(2):135-8

Department of Microbiology, Subharti Medical College, Meerut, Uttar Pradesh, India.

Background: AmpC beta lactamases are cephalosporinases that confer resistance to a wide range of beta lactam drugs thereby causing serious therapeautic problem. As there are no CLSI guidelines for detection of AmpC mediated resistance in Gram negative clinical isolates and it may pose a problem due to misleading results, especially so in phenotypic tests. Although cefoxitin resistance is used as a screening test, it does not reliably indicate AmpC production.

Materials And Methods: We planned a study to determine the occurrence of AmpC beta lactamase in hospital and community, clinical isolates of Escherichia coli and simultaneously evaluate different phenotypic methods for detection of AmpC beta lactamases.

Results: It was observed that 82.76% isolates were ESBL positive and 59% were cefoxitin screen positive. Using phenotypic confirmatory tests the occurrence of Amp C beta lactamases was found to be 40% and 39% by inhibitor based method using boronic acid (IBM) and modified three dimensional test (M3D) respectively.

Conclusion: Both the test showed concordant result. Co-production was observed in 84.62% isolates Screening of ESBL and Amp C can be done in routine clinical microbiology laboratory using aztreonam and IBM respectively as it is a simple, rapid and technically less demanding procedure which can be used in all clinical laboratories.
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http://dx.doi.org/10.4103/0377-4929.118686DOI Listing
April 2014

Neonatal candidemia: a changing trend.

Indian J Pathol Microbiol 2012 Jan-Mar;55(1):132-3

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http://dx.doi.org/10.4103/0377-4929.94900DOI Listing
August 2012

Maxillary osteomyelitis by mucormycosis: report of four cases.

Int J Infect Dis 2011 Jan 18;15(1):e66-9. Epub 2010 Nov 18.

Department of Microbiology, Subharti Medical College, Swami Vivekanand Subharti University, Meerut 250 005, UP, India.

Mucormycosis is a fungal infection commonly affecting structures in the head and neck, such as the air sinuses, orbits, and the brain. Common predisposing factors include diabetes mellitus and immunosuppression. We describe our clinical experience with four cases of mucormycosis of the maxillary antrum associated with uncontrolled diabetes mellitus managed at our centre. Early diagnosis and prompt treatment can significantly reduce the mortality and morbidity of this lethal fungal infection.
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http://dx.doi.org/10.1016/j.ijid.2010.09.003DOI Listing
January 2011

Physician accessories: doctor, what you carry is every patient's worry?

Indian J Pathol Microbiol 2010 Oct-Dec;53(4):711-3

Department of Microbiology, Subharti Medical College, Swami Vivekanand Subharti University, Meerut - 250 002, UP, India.

Background: Nosocomial infections are on the rise worldwide and many a times they are carried by the health care personnel. Accessories used by physicians and healthcare personnel can be a potential source of nosocomial infection.

Materials And Methods: We designed a survey with the aim to investigate the prevalence of microbial flora of accessories such as pens, stethoscopes, cell phones and white coat used by the physicians working in a tertiary care hospital.

Observations: It was observed that 66% of the pens, 55% of the stethoscopes, 47.61% of the cell phones and 28.46% of the white coats used by the doctors were colonized with various microorganisms. Staphylococcus spp. was the predominant isolate followed by Escherichia coli. Methicillin resistance in Staphylococcus aureus was also found, which was a matter of concern.

Conclusions: Awareness of appropriate hand hygiene is important in order to prevent potential transmission to patients.
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http://dx.doi.org/10.4103/0377-4929.72047DOI Listing
February 2011

Underwater sustainability of the "Cassie" state of wetting.

Langmuir 2009 Oct;25(20):12120-6

Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560 012, India.

A rough hydrophobic surface when immersed in water can result in a "Cassie" state of wetting in which the water is in contact with both the solid surface and the entrapped air. The sustainability of the entrapped air on such surfaces is important for underwater applications such as reduction of flow resistance in microchannels and drag reduction of submerged bodies such as hydrofoils. We utilize an optical technique based on total internal reflection of light at the water-air interface to quantify the spatial distribution of trapped air on such a surface and its variation with immersion time. With this technique, we evaluate the sustainability of the Cassie state on hydrophobic surfaces with four different kinds of textures. The textures studied are regular arrays of pillars, ridges, and holes that were created in silicon by a wet etching technique, and also a texture of random craters that was obtained through electrodischarge machining of aluminum. These surfaces were rendered hydrophobic with a self-assembled layer of fluorooctyl trichlorosilane. Depending on the texture, the size and shape of the trapped air pockets were found to vary. However, irrespective of the texture, both the size and the number of air pockets were found to decrease with time gradually and eventually disappear, suggesting that the sustainability of the "Cassie" state is finite for all the microstructures studied. This is possibly due to diffusion of air from the trapped air pockets into the water. The time scale for disappearance of air pockets was found to depend on the kind of microstructure and the hydrostatic pressure at the water-air interface. For the surface with a regular array of pillars, the air pockets were found to be in the form of a thin layer perched on top of the pillars with a large lateral extent compared to the spacing between pillars. For other surfaces studied, the air pockets are smaller and are of the same order as the characteristic length scale of the texture. Measurements for the surface with holes indicate that the time for air-pocket disappearance reduces as the hydrostatic pressure is increased.
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http://dx.doi.org/10.1021/la902679cDOI Listing
October 2009

External ophthalmomyiasis caused by Oestrus ovis: a rare case report from India.

Korean J Parasitol 2009 Mar 12;47(1):57-9. Epub 2009 Mar 12.

Department of Microbiology, Subharti Medical College, Meerut, Uttar Pradesh, India.

Myiasis of different organs has been reported off and on from various regions in the world. We report a human case of external ophthalmomyiasis caused by the larvae of a sheep nasal botfly, Oestrus ovis, for the first time from Meerut city in Western Uttar Pradesh, India. A 25-year-old farmer presented with severe symptoms of conjunctivitis. The larvae, 3 in number, were observed in the bulbar conjunctiva, and following removal the symptoms of eye inflammation improved within a few hours.
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http://dx.doi.org/10.3347/kjp.2009.47.1.57DOI Listing
March 2009

Beta-lactamase producing Pseudomonas aeruginosa in hospitalised patients.

Indian J Pathol Microbiol 2005 Oct;48(4):530-3

Department of Microbiology, Subharati Medical College, Delhi-Haridwar by Pass Road, Meerut.

Beta lactamase continues to be the leading cause of resistance to beta lactam antibiotics in gram-negative bacteria. A total of 50 clinical isolates of Pseudomonas aeruginosa were studied to determine the prevalence of ESBL production in hospital strains and also to study their susceptibility to various other antimicrobial agents. ESBL production was observed in a total of 18/50 (36%) of cases. Most of the ESBL positive isolates showed resistance to 3rd generation cephalosporins including multidrug resistance (MDR) to antibiotics like piperacillin, nalidixic acid, ciprofloxacin, levofloxacin, gentamicin and tobramycin. The ESBL producers however showed good susceptibility to drugs like meropenem, gatifloxacin and amikacin.
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October 2005
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