Publications by authors named "Rachna Dave"

11 Publications

  • Page 1 of 1

Improving allergy skin testing proficiency.

Ann Allergy Asthma Immunol 2019 07 5;123(1):108-109. Epub 2019 Apr 5.

Department of Pediatrics, University of Tennessee Health Science Center and Le Bonheur Children's Hospital, Memphis, Tennessee. Electronic address:

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http://dx.doi.org/10.1016/j.anai.2019.04.001DOI Listing
July 2019

A fence that eats the weed: Alginate lyase immobilization on ultrafiltration membrane for fouling mitigation and flux recovery.

Chemosphere 2016 Dec 17;165:144-151. Epub 2016 Sep 17.

Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam, Tamil Nadu 603 102, India; Homi Bhabha National Institute, Anushaktinagar, Mumbai, India. Electronic address:

Polysaccharide fouling poses a significant challenge in the widespread application of membrane filtration for water purification. In order to mitigate the problem, a polysaccharide-degrading enzyme alginate lyase (Alg L; EC 4.2.2.3) was successfully immobilized on cellulose acetate ultrafiltration membrane using a dead-end filtration unit. Attenuated total reflectance Fourier transform infrared microscopy confirmed covalent linkage of the Alg L to the membrane. HPLC and Alg L activity studies confirmed that Alg L in immobilized form was enzymatically active. Even after 21 d, Alg L in immobilized form retained 80% of its original activity, compared to its free counterpart, which retained only 20% of its original activity. In fouling experiments using tap water containing 50 mg L alginate, a simple backwash could remove the fouling on Alg L immobilized membrane, but not that on the control membrane. Atomic force microscopic analysis and bright field microscopic images of the fouled test membrane after backwash showed significant removal of fouling, while fouling on the control membrane remained largely intact. The immobilized Alg L remained active even after 10 runs of fouling-backwash cycle. The present antifouling technology using immobilized enzyme is suitable for keeping ultrafiltration membranes clean without the use of toxic chemical biocides.
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http://dx.doi.org/10.1016/j.chemosphere.2016.09.017DOI Listing
December 2016

Protein as chemical cue: non-nutritional growth enhancement by exogenous protein in Pseudomonas putida KT2440.

PLoS One 2014 12;9(8):e103730. Epub 2014 Aug 12.

Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam, India.

Research pertaining to microbe-microbe and microbe-plant interactions has been largely limited to small molecules like quorum sensing chemicals. However, a few recent reports have indicated the role of complex molecules like proteins and polysaccharides in microbial communication. Here we demonstrate that exogenous proteins present in culture media can considerably accelerate the growth of Pseudomonas putida KT2440, even when such proteins are not internalized by the cells. The growth enhancement is observed when the exogenous protein is not used as a source of carbon or nitrogen. The data show non-specific nature of the protein inducing growth; growth enhancement was observed irrespective of the protein type. It is shown that growth enhancement is mediated via increased siderophore secretion in response to the exogenous protein, leading to better iron uptake. We highlight the ecological significance of the observation and hypothesize that exogenous proteins serve as chemical cues in the case of P.putida and are perceived as indicator of the presence of competitors in the environment. It is argued that enhanced siderophore secretion in response to exogenous protein helps P.putida establish numerical superiority over competitors by way of enhanced iron assimilation and quicker utilization of aromatic substrates.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0103730PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4130607PMC
April 2015

Comparing segmented ASL perfusion of vascular territories using manual versus semiautomated techniques in children with sickle cell anemia.

J Magn Reson Imaging 2015 Feb 8;41(2):439-46. Epub 2014 Jan 8.

Department of Radiological Sciences, St Jude Children's Research Hospital, Memphis, Tennessee, USA.

Purpose: Elevated cerebral blood flow (CBF) in sickle cell anemia (SCA) is an adaptive pathophysiologic response associated with decreased vascular reserve and increased risk for ischemia. We compared manual (M) and semiautomated (SA) vascular territory delineation to facilitate standardized evaluation of CBF in children with SCA.

Materials And Methods: ASL perfusion values from 21 children were compared for gray matter and white matter (WM) in vascular territories defined by M and SA delineation. SA delineated CBF was compared with clinical and hematologic variables acquired within 4 weeks of the MRI.

Results: CBF measurements from M (MCA 82 left, 79 right) and SA (MCA 81 left, 81 right) delineated territories were highly correlated (R = 0.99, P < 0.0001). Bland-Altman plots had close-fitting limits of agreement of -1.8 to -3.5 lower limit and 0 to 1.8 upper limit. SA vascular territory delineation was comparable to the expert delineation with a kappa index of 0.62-0.85 and was considerably faster. Median territorial CBF values did not differ by gender or age. WM perfusion in the posterior cerebral artery territories was positively correlated with degree of hemolysis (R = 0.58, P = 0.01 left, 0.73, P < 0.001 right) and negatively correlated with hemoglobin (R = -0.48; P = 0.03 left; -0.47; P = 0.04 right) and hemoglobin F (R = -0.42; P = .09 left; -0.47; P = 0.049 right).

Conclusion: We established the validity of the SA method, which in our experience was much faster than the M method for delineation of vascular territories. Associations between CBF and hematologic variables may demonstrate pathophysiologic changes that contribute to clinical variation in CBF.
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http://dx.doi.org/10.1002/jmri.24559DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4528912PMC
February 2015

Pumping iron to keep fit: modulation of siderophore secretion helps efficient aromatic utilization in Pseudomonas putida KT2440.

Microbiology (Reading) 2014 Jul 17;160(Pt 7):1393-1400. Epub 2014 Apr 17.

Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre, Kalpakkam 603 102, India.

Studies of biotechnology applications of Pseudomonas putida KT2440 have been predominantly focused on regulation and expression of the toluene degradation (TOL) pathway. Unfortunately, there is limited information on the role of other physiological factors influencing aromatic utilization. In this report, we demonstrate that P. putida KT2440 increases its siderophore secretion in response to the availability of benzyl alcohol, a model aromatic substrate. It is argued that accelerated siderophore secretion in response to aromatic substrates provides an iron 'boost' which is required for the effective functioning of the iron-dependent oxygenases responsible for ring opening. Direct evidence for the cardinal role of siderophores in aromatic utilization is provided by evaluation of per capita siderophore secretion and comparative growth assessments of wild-type and siderophore-negative mutant strains grown on an alternative carbon source. Accelerated siderophore secretion can be viewed as a compensatory mechanism in P. putida in the context of its inability to secrete more than one type of siderophore (pyoverdine) or to utilize heterologous siderophores. Stimulated siderophore secretion might be a key factor in successful integration and proliferation of this organism as a bio-augmentation agent for aromatic degradation. It not only facilitates efficient aromatic utilization, but also provides better opportunities for iron assimilation amongst diverse microbial communities, thereby ensuring better survival and proliferation.
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http://dx.doi.org/10.1099/mic.0.079277-0DOI Listing
July 2014

Endogenously triggered electrospun fibres for tailored and controlled antibiotic release.

J Biomater Sci Polym Ed 2013 11;24(11):1305-19. Epub 2013 Jan 11.

Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, Bhabha Atomic Research Centre Facilities, Kalpakkam, 603 102, India.

The study was aimed at assessing the potential of enzyme-embedded antibiotic-releasing polycaprolactone (PCL)-based electrospun fibres for tunable drug delivery. This was attempted by incorporation of gentamicin sulphate (GS) in the biocompatible polymer (PCL) matrix, with the degradation of the matrix being ensured by co-impregnating a polymer-degrading enzyme (lipase). Single phase solutions were obtained by hydrophobic ion pairing of GS and surfactant coating of lipase with an anionic surfactant, docusate sodium salt Aerosol OT (AOT). By electrospinning the solution, we could produce PCL fibres containing 11% (w/w) GS-AOT and 28 U (w/w) lipase-AOT. However, sustained release of GS was not obtained. FESEM analysis showed that the fibres did not undergo the expected degradation. Subsequent experiments with unmodified lipase gave satisfactory results; the polymer underwent degradation displaying characteristic perforations in the fibres, suggestive of 'endo-attack'. By modulating the concentrations of lipase (1 to 28 U, w/w), we could obtain GS release rates that varied from 0.53 to 32 mg/ml/d. Accordingly, the lifetime of the fibres could be tuned (10 h to 25 days). The fibres showed excellent antibacterial activity against Staphylococcus aureus throughout their lifetime.
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http://dx.doi.org/10.1080/09205063.2012.757725DOI Listing
November 2013

Biomedical evaluation of a novel nitrogen oxides releasing wound dressing.

J Mater Sci Mater Med 2012 Dec 22;23(12):3097-106. Epub 2012 Sep 22.

Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, 603 102, India.

Chronic wounds are a major cause for both suffering and economical losses. Management of chronic non-healing wounds requires multipronged approach. They are polymicrobial and agonizing for the patient due to associated pain. Moist dressing providing antimicrobial action is a highly desirable chronic wound management option. Here we report a hydrogel based dressing that possesses the antimicrobial properties of acidified sodium nitrite and the homeostatic property of a hydrogel. The dressing was developed by combining citric acid cross-linked cotton gauze and sodium nitrite loaded gelatin. The cotton gauze was cross-linked with citric acid by pad-dry-curing in presence of nano-titania catalyst. The cotton gauze-gelatin hydrogel combination was gamma-irradiated and freeze-dried. At the time of application, the freeze-dried dressing is wetted by sodium nitrite solution. The dressing has a fluid uptake ability of 90 % (w/v) and the water vapour evaporation rate was estimated to be 2,809 ± 20 g/m(2)/day. The dressing showed significant antimicrobial activity against both planktonic and biofilm forms and was effective during consecutive re-uses. Cytotoxicity study showed inhibition of fibroblasts, but to a lesser extent than clinically administered concentrations of antiseptic like povidone iodine. Storage at 37 °C over a 3 month period resulted in no significant loss of its antimicrobial activity.
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http://dx.doi.org/10.1007/s10856-012-4766-4DOI Listing
December 2012

The impact of yoga upon female patients suffering from hypothyroidism.

Complement Ther Clin Pract 2011 Aug 18;17(3):132-4. Epub 2010 Dec 18.

Department of Psychology, Barkatullah University, Bhopal 462026, Madhya Pradesh, India.

Objective: To study the effect of yoga on the quality of life of female hypothyroid patients.

Design: The WHO Quality of Life Scale(22) was used to assess the quality of life of 20 female hypothyroid patients. Subjects attended one hour yoga sessions daily for a period of one month. A pretest-post-test research design was used for data analysis.

Results: Patients' quality of life scores following the yoga program were greater than scores obtained prior to undertaking yoga (p < 0.01). Patients also reported significant improvement in their perception of the overall quality of life and of their health post yoga intervention.

Conclusions: It can be concluded that yoga is valuable in helping the hypothyroid patients to manage their disease-related symptoms. Yoga may be considered as supportive or complementary therapy in conjunction with medical therapy for the treatment of hypothyroid disorder.
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http://dx.doi.org/10.1016/j.ctcp.2010.11.004DOI Listing
August 2011

Novel biocatalytic polymer-based antimicrobial coatings as potential ureteral biomaterial: preparation and in vitro performance evaluation.

Antimicrob Agents Chemother 2011 Feb 6;55(2):845-53. Epub 2010 Dec 6.

Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, India.

Catheters and other indwelling devices placed inside human body are prone to bacterial infection, causing serious risk to patients. Infections associated with implants are difficult to resolve, and hence the prevention of bacterial colonization of such surfaces is quite appropriate. In this context, the development of novel antimicrobial biomaterials is currently gaining momentum. We describe here the preparation and antibacterial properties of an enzyme-embedded polycaprolactone (PCL)-based coating, coimpregnated with the antibiotic gentamicin sulfate (GS). The enzyme uses PCL itself as substrate; as a result, the antibiotic gets released at a rate controlled by the degradation of the PCL base. In vitro drug release studies demonstrated sustained release of GS from the PCL film throughout its lifetime. By modulating the enzyme concentration in the PCL film, we were able to vary the lifetime of the coating from 33 h to 16 days. In the end, the polymer is completely degraded, delivering the entire load of the antibiotic. The polymer exhibited antibacterial properties against three test isolates: Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Foley urinary catheters coated with the modified polymer exhibited sustained in vitro release of GS over a 60-h period. The results suggest that the antibiotic-plus-enzyme-loaded polymer can be used as tunable self-degrading antimicrobial biomaterial coating on catheters.
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http://dx.doi.org/10.1128/AAC.00477-10DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3028754PMC
February 2011

Competition triggers plasmid-mediated enhancement of substrate utilisation in Pseudomonas putida.

PLoS One 2009 Jun 26;4(6):e6065. Epub 2009 Jun 26.

Biofouling and Biofilm Processes Section, Water and Steam Chemistry Division, BARC Facilities, Kalpakkam, India.

Competition between species plays a central role in the activity and structure of communities. Stable co-existence of diverse organisms in communities is thought to be fostered by individual tradeoffs and optimization of competitive strategies along resource gradients. Outside the laboratory, microbes exist as multispecies consortia, continuously interacting with one another and the environment. Survival and proliferation of a particular species is governed by its competitive fitness. Therefore, bacteria must be able to continuously sense their immediate environs for presence of competitors and prevailing conditions. Here we present results of our investigations on a novel competition sensing mechanism in the rhizosphere-inhabiting Pseudomonas putida KT2440, harbouring gfpmut3b-modified Kan(R) TOL plasmid. We monitored benzyl alcohol (BA) degradation rate, along with GFP expression profiling in mono species and dual species cultures. Interestingly, enhanced plasmid expression (monitored using GFP expression) and consequent BA degradation were observed in dual species consortia, irrespective of whether the competitor was a BA degrader (Pseudomonas aeruginosa) or a non-degrader (E. coli). Attempts at elucidation of the mechanistic aspects of induction indicated the role of physical interaction, but not of any diffusible compounds emanating from the competitors. This contention is supported by the observation that greater induction took place in presence of increasing number of competitors. Inert microspheres mimicking competitor cell size and concentration did not elicit any significant induction, further suggesting the role of physical cell-cell interaction. Furthermore, it was also established that cell wall compromised competitor had minimal induction capability. We conclude that P. putida harbouring pWW0 experience a competitive stress when grown as dual-species consortium, irrespective of the counterpart being BA degrader or not. The immediate effect of this stress is a marked increase in expression of TOL, leading to rapid utilization of the available carbon source and massive increase in its population density. The plausible mechanisms behind the phenomenon are hypothesised and practical implications are indicated and discussed.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0006065PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2698150PMC
June 2009

Influence of dimethyl sulfoxide on extracellular enzyme production by Pleurotus ostreatus.

Biotechnol Lett 2006 May;28(9):651-5

Department of Biology, Dowling College, NY 11769, USA.

Dimethyl sulfoxide (DMSO) is commonly used as a co-solvent to dissolve poorly water-soluble biologically active agents to assess their biological activities such as for enzyme induction. The question addressed was whether DMSO can be assumed to be an inert co-solvent. The influence of DMSO on the production of extracellular enzymes by Pleurotus ostreatus was investigated. DMSO functioned as either an inducer or a repressor, depending on the enzyme studied. The production of laccase and endo-1,4-beta-xylanase increased by 29 and 250%, respectively, in presence of DMSO. However, DMSO repressed the activities of manganese peroxidase, beta-glucosidase, beta-xylanase, and endo-1,4-beta-glucanase by 30, 33, 99 and 16%, respectively. These results raise concerns about the interpretation of bioactivity measurements when DMSO is assumed to function as an inert co-solvent to solubilize water-insoluble molecules.
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http://dx.doi.org/10.1007/s10529-006-0031-6DOI Listing
May 2006