My Publications

Facile Plant Extract Mediated Eco-Benevolent Synthesis and Recent Applications of CaO-NPs: A State-of-the-art Review
May 2020    DOI: 10.33945/SAMI/JCR.2020.3.7
Trupti Pagar, Suresh K Ghotekar, Shreyas Pansambal, Bishnu P. Marasini

Ameliorating the sustainable and eco-accommodating routes for the procurable synthesis of nanoparticles (NPs) is a crucial aspect in the area of green nanotechnology. The known conventional routes for the production of NPs are complicated, noxious, expensive and not safer to human and environment. To overcome these threats, natural precursors such as biopolymers, plant, fungi, and bacteria have been used to fabricate the calcium oxide nanoparticles (CaO-NPs). The shape, size, and applications of the CaO-NPs are prominently affected by the reaction parameters under which they are synthesized. Moreover, the CaO-NPs synthesized by green approach have found potential applications in a wide spectrum of areas including, catalysis, bio-ceramics, additive in refractory, biodiesel production, adsorbent, antimicrobial agent, removal of Cr(VI) and trans esterification of oils. This research study discussed various plants and the different plant parts thathave been used for the synthesis of CaO-NPs. The protocol, characterization techniques, mechanism, and eco-benign synthesis of the CaO-NPs along with various recent applications were also discussed.

 Isolation and Characterization of Soil Myxobacteria from Nepal

publication date Dec 31, 2019 publication description Journal of Institute of Science and Technology, 24(2): 7-16
publication description Realizing myxobacteria as a potential source of antimicrobial metabolites, we pursued research to isolate myxobacteria showing antimicrobial properties. We have successfully isolated three strains (NR-1, NR-2, NR-3) using the Escherichia coli baiting technique. These isolates showed typical myxobacterial growth characteristics. Phylogenetic analysis showed that all the strains (NR-1, NR-2, NR-3) belong to the family Archangiaceae, suborder Cystobacterineae, and order Myxococcales. Furthermore, 16S rRNA gene sequence similarity searched through BLAST revealed that strain NR-1 showed the closest similarity (91.8 %) to the type strain Vitiosangium cumulatum (NR-156939), NR-2 showed (98.8 %) to the type of Cystobacter badius (NR-043940), and NR-3 showed the closest similarity (83.5 %) to the type of strain Cystobacter fuscus (KP-306730). All isolates showed better growth in 0.5-1 % NaCl and pH around 7.0, whereas no growth was observed at pH 9.0 and below 5.0. All strains showed better growth at 32° C and hydrolyzed starch, whereas casein was efficiently hydrolyzed by NR-1 and NR-2. Besides, preliminary antimicrobial tests from crude extracts showed activities against Gram-positive, Gram-negative bacteria, and fungi. Our findings suggest that the arcane soil habitats of Nepal harbor myxobacteria with the capability to produce diverse antimicrobial activities that may be explored to overcome the rapidly rising global concern about antibiotic resistance.

Extended spectrum β-lactamase producing uropathogenic Escherichia coli and the correlation of biofilm with antibiotics resistance in Nepal

publication date Dec 17, 2019 publication description BioMed Central Ltd
publication description Urinary tract infection (UTI) is one of the frequently diagnosed infectious diseases which is caused mainly by Escherichia coli. E. coli confers resistance against the two major classes of antibiotics due to the production of extended spectrum β-lactamase enzymes (ESBL), biofilm, etc. Biofilm produced by uropathogenic E. coli (UPEC) protects from host immune system and prevent entry of antimicrobial compounds. The main objective of this cross-sectional study was to determine the correlation of biofilm production and antibiotic resistance as well as to characterize the pgaA and pgaC genes responsible for biofilm formation among uropathogenic ESBL producing E. coli.

Glucose 6 phosphate dehydrogenase deficiency and hemoglobinopathy in South Western Region Nepal: a boon or burden
publication date Nov 8, 2019 publication description Springer
publication description The study was carried out to optimize the phenotypic method to characterize the sickle cell trait (SCT), sickle cell anemia (SCA), and β-thalassemia (β-TT) suspected sample from tharu community of South Western province-5, Nepal. SCT and SCA were further evaluated by genotypic method employing amplification refractory mutation system (ARMS PCR). Moreover, Glucose 6 phosphate dehydrogenase (G6PD) was estimated in those hemoglobinopathy to observe its prevalence. The accurate and reliable method can play an important role in reduction of morbidity and mortality rate.

The 100 suspected cases were subjected to phenotypic method adopting cellulose acetate electrophoresis and genotypic method using ARMS PCR which portraits (5%) SCA positive test showing HBS/HBS, (38%) SCT positive trait HBA/HBS and (36%) cases normal HBA/HBA. β-TT (21%) cases were confirmed by electropherogram. G6PD deficiency was observed in (40%) of SCA, (18.4%) of SCT, (4.8%) of β-TT and (2.8%) in normal cases. Increased G6PD were developed only in SCT (5.3%) and β-TT (4.8%). The study highlighted sickle cell disorder (SCD) and β-TT as the most common hemoglobinopathy coexisting with G6PD deficiency. Though hemoglobinopathy sometime could be protective in malaria but G6PD deficiency can cause massive hemolysis which may exacerbate the condition.

Challenges and Opportunity of in vitro Propagation of Paulownia tomentosa Steud for Commercial Production in Nepal
publication date 2016 publication description International Journal of Applied Sciences and Biotechnology

Evaluation of Antibacterial Activity of Some Traditionally Used Medicinal Plants against Human Pathogenic Bacteria
publication date Jan 16, 2015 publication description BioMed Research International
publication description The worldwide increase of multidrug resistance in both community- and health-care associated bacterial infections has impaired the current antimicrobial therapy, warranting the search for other alternatives. We aimed to find the in vitro antibacterial activity of ethanolic extracts of 16 different traditionally used medicinal plants of Nepal against 13 clinical and 2 reference bacterial species using microbroth dilution method. The evaluated plants species were found to exert a range of in vitro growth inhibitory action against the tested bacterial species, and Cynodon dactylon was found to exhibit moderate inhibitory action against 13 bacterial species including methicillin-resistant Staphylococcus aureus, imipenem-resistant Pseudomonas aeruginosa, multidrug-resistant Salmonella typhi, and S. typhimurium. The minimum inhibitory concentration (MIC) values of tested ethanolic extracts were found from 31 to >25,000 μg/mL. Notably, ethanolic extracts of Cinnamomum camphora, Curculigo orchioides, and Curcuma longa exhibited the highest antibacterial activity against S. pyogenes with a MIC of 49, 49, and 195 μg/mL, respectively; whereas chloroform fraction of Cynodon dactylon exhibited best antibacterial activity against S. aureus with a MIC of 31 μg/mL. Among all, C. dactylon, C. camphora, C. orchioides, and C. longa plant extracts displayed a potential antibacterial activity of MIC < 100 μg/mL.

Early onset Alzheimer’s Disease and its Pathogenesis
publication date 2015 publication description Nepal Med Coll J
publication description Prevalence of Alzheimer’s disease (AD) is significantly high in developed countries where life expectancy is relatively higher and its incidence is expected to increase over years. Etiology of this disease is complex; however, in a subtype called Early Onset Alzheimer’s Disease (EOAD) which manifests at age below 65 years, genes are the sole cause — mutations in APP, PSEN1 and PSEN2 genes. Currently, there is no effective cure for AD. Therefore, a thorough understanding of pathogenesis of AD is crucial for designing drug-development studies. However, our knowledge is only in the growing phase in this field. This paper briefly reviews the pathogenesis of EOAD

Clinical and microbiological observational study on AmpC β-lactamase-producing Enterobacteriaceae in a hospital of Nepal.
publication date Apr 2013 publication description Brazilian Journal of Infectious Diseases
publication description Brazilian Journal of Infectious Diseases, 17 (2), 256-259 doi:10.1016/j.bjid.2012.09.012

Limited information is available regarding AmpC β-lactamase (ABL)-producing Enterobacteriaceae compared to extended-spectrum β-lactamase-producing enterobacteria. Since ABL-producing organisms are often resistant to multiple antimicrobial agents, therapeutic options against these pathogens are limited. Among 230 clinical Enterobacteriaceae isolates, 64 (27.8%) were found to produce ABL in our study. Escherichia coli (83.9%) was a predominant pathogen, followed by Citrobacter freundii (5.2%). A significant proportion of ABL-producing isolates (81.3%) were found to be multidrug resistant against commonly used antibiotics. Univariate analysis showed that prior history of taking antibiotics (odds ratio [OR], 5.278; confidence interval [CI], 2.838–9.817; p < 0.001) and being inpatients (OR, 4.587; CI, 2.132–9.9; p < 0.001) were associated with ABL positivity. Regular antimicrobial resistance surveillance for ABL-producing Enterobacteriaceae is warranted for proper antimicrobial treatment strategy and policy making due to ABL-positive infections.

Nepal's Ancient Technologies Needs Revival to Ameliorate the Economy / NextGenVOICES 5 (6)
publication date Jan 4, 2013 publication description Science
publication description

DOI: 10.1126/science.339.6115.30

Stop Overuse of Antibiotics / NextGenVOICES 4 (15)
publication date Oct 5, 2012 publication description Science
publication description

DOI: 10.1126/science.338.6103.40

High prevalence of multidrug resistance in bacterial uropathogens from Kathmandu, Nepal
publication date 2012 publication description BMC Research Notes
publication description BMC Research Notes 2012, 5:38 doi:10.1186/1756-0500-5-38

The impact of Urinary Tract Infection (UTI) is worst in low-resource developing countries due to unaware of the UTIs caused by multidrug-resistant (MDR) pathogens and the possibility of transfer of MDR traits between them. Two hundred and nineteen bacterial isolates were recovered from 710 urine samples at Kathmandu Model hospital during the study period. All samples and isolates were investigated by standard laboratory procedures. Among the significant bacterial growth (30.8%, 219 isolates), 41.1% isolates were MDR. The most prevailing organism, E. coli (81.3%, 178 isolates) was 38.2% MDR, whereas second most common organism, Citrobacter spp. (5%, 11 isolates) was found 72.7% MDR. Extended-spectrum β-lactamase (ESBL) production was detected in 55.2% of a subset of MDR E. coli isolates. Among the 29 MDR E. coli isolates, plasmids of size ranging 2-51 kb were obtained with different 15 profiles. The most common plasmid of size 32 kb was detected in all of the plasmid-harbored E. coli strains. The majority of E. coli isolates investigated for the multidrug resistance transfer were able to transfer plasmid-mediated MDR phenotypes along with ESBL pattern with a frequency ranging from 0.3 × 10-7 to 1.5 × 10-7 to an E. coli HB101 recipient strain by conjugation. Most of the donor and recipient strain showed high levels of minimum inhibitory concentration (MIC) values for commonly-used antibiotics. The high prevalence of multidrug resistance in bacterial uropathogens was observed. Particularly, resistance patterns were alarmingly higher for amoxycillin, co-trimoxazole, flouroquinolones and third-generation cephalosporins, which necessitate the re-evaluation of first and second line therapies for UTI. In addition, conjugational co-transfer of MDR phenotypes with ESBL-positive phenotypes was observed in MDR E. coli.

Total Biomass Carbon Sequestration Ability Under the Changing Climatic Condition by Paulownia tomentosa Steud
publication description International Journal of Applied Sciences and Biotechnology
publication description The concentration of carbon dioxide (CO2) has risen continuously in atmosphere due to human induced activities, and has been considered the predominant cause of global climate change. Paulowina tomentosa Steud. (P. tomentosa), a multipurpose tree is popular around global market for its timber and its potential role in CO2 sequestration. In this study, the total biomass carbon of five years old and newly planted P. tomentosa has been estimated. The results indicated that the average total biomass carbon of five years old plant was found to be 4.52±0.53Kg C Year-1 per tree i.e. 9.04±1.06-ton C ha-1 Year-1 (assuming 2000 plants per hector). Likewise, the average total biomass carbon of newly planted P. tomentosa within 4 months was found to be 6.07±0.38 Kg in remote village area in Nepal. The estimated biomass carbon in one year of newly planted plants was found to be 18.21±1.14 Kg Year-1 i.e. 0.36-ton C ha-1 Year-1. These findings reveled that short rotational trees like P. tomentosa can be implemented in agroforestry system to reduce the green house emission in cities and emphasizes the carbon storage potential of agroforestry. In vitro micro propagation technique could be implemented to produce genetically uniform clone of P. tomentosa and can be applied in agroforestry system for the adaptation and to mitigate global climate change.

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