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Halder P, Pal U, Ganguly A, Ghosh P, Malakar MG, Guha N, Gami C, Ghosh S. Impact of COVID-19 Pandemic on Psychosocial Attributes of Indian Families Bearing Child With Down Syndrome: A Survey by Trisomy 21 Research Society (T21RS), Indian Chapter. Asia Pac J Public Health 2024:10105395241240954. [PMID: 38519483 DOI: 10.1177/10105395241240954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2024]
Affiliation(s)
- Pinku Halder
- Cytogenetics and Genomics and Down Syndrome Research Unit, Department of Zoology, University of Calcutta, Kolkata, India
- ICM Institute for Brain and Spinal Cord, Hôpital Pitié, Paris, France
| | - Upamanyu Pal
- Cytogenetics and Genomics and Down Syndrome Research Unit, Department of Zoology, University of Calcutta, Kolkata, India
| | - Agnish Ganguly
- Cytogenetics and Genomics and Down Syndrome Research Unit, Department of Zoology, University of Calcutta, Kolkata, India
| | - Papiya Ghosh
- Department of Zoology, Bijoykrishna Girls' College, Howrah, India
| | | | - Nitasha Guha
- Central Kolkata Welfare Association for Persons with Down Syndrome, Kolkata, India
| | - Chaitali Gami
- Central Kolkata Welfare Association for Persons with Down Syndrome, Kolkata, India
| | - Sujay Ghosh
- Cytogenetics and Genomics and Down Syndrome Research Unit, Department of Zoology, University of Calcutta, Kolkata, India
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Halder P, Pal U, Ganguly A, Ghosh P, Ray A, Sarkar S, Ghosh S. Understanding etiology of chromosome 21 nondisjunction from gene × environment models. Sci Rep 2021; 11:22390. [PMID: 34789805 PMCID: PMC8599692 DOI: 10.1038/s41598-021-01672-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 11/02/2021] [Indexed: 11/09/2022] Open
Abstract
Maternal risk factors and their interactions with each other that associate chromosome 21 nondisjunction are intriguing and need incisive study to be resolved. We determined recombination profile of nondisjoined chromosome 21 and maternal genotypes for four selected polymorphic variants from the folate regulators genes stratifying the women according to the origin of segregation error and age at conception. We conducted association study for genotype and maternal addiction to smokeless chewing tobacco, usually chopped tobacco leaves or paste of tobacco leaves with the incidence of Down syndrome birth. Additionally, we designed various logistic regression models to explore the effects of maternal genotype, maternal habit of smokeless chewing tobacco, maternal age at conception and all possible interactions among them on chromosome 21 nondisjunction. We found folate regulator gene mutations are associated with maternal meiosis II error. Regression models revealed smokeless chewing tobacco and folate polymorphic/mutant risk genotype interact with each other to increase the risk of reduced and single peri-centromeric recombination events on chromosome 21 that nondisjoined at meiosis II in the oocytes and the effect is maternal age independent. We inferred maternal folate polymorphic/mutant risk genotypes and habit of smokeless chewing tobacco interact with each other and increase the risk of meiosis II error in oocytes in maternal age-independent manner.
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Affiliation(s)
- Pinku Halder
- Cytogenetics and Genomics Research Unit, Department of Zoology, University of Calcutta, Kolkata, West Bengal, India
| | - Upamanyu Pal
- Cytogenetics and Genomics Research Unit, Department of Zoology, University of Calcutta, Kolkata, West Bengal, India
| | - Agnish Ganguly
- Cytogenetics and Genomics Research Unit, Department of Zoology, University of Calcutta, Kolkata, West Bengal, India
| | - Papiya Ghosh
- Department of Zoology, Bijoy Krishna Girls' College (Affiliated to University of Calcutta), Howrah, West Bengal, India
| | - Anirban Ray
- Department of Zoology, Bangabasi Morning College (Affiliated to University of Calcutta), Kolkata, West Bengal, India
| | - Sumantra Sarkar
- Department of Paediatric Medicine, Diamond Harbour Government Medical College and Hospital, Diamond Harbour, West Bengal, India
| | - Sujay Ghosh
- Cytogenetics and Genomics Research Unit, Department of Zoology, University of Calcutta, Kolkata, West Bengal, India.
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Halder P, Pal U, Paladhi P, Dutta S, Paul P, Pal S, Das D, Ganguly A, IshitaDutta, SayarneelMandal, Ray A, Ghosh S. Evaluation of potency of the selected bioactive molecules from Indian medicinal plants with M Pro of SARS-CoV-2 through in silico analysis. J Ayurveda Integr Med 2021; 13:100449. [PMID: 34054246 PMCID: PMC8139275 DOI: 10.1016/j.jaim.2021.05.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 04/12/2021] [Accepted: 05/05/2021] [Indexed: 12/12/2022] Open
Abstract
Background The recent outbreak of novel SARs CoVid-2 across the globe and absence of specific drug against this virus lead the scientific community to look into some alternative indigenous treatments. India as a hub of ayurvedic and medicinal plants can shed light on its treatment using specific active bio-molecules from these plants. Objectives Keeping our herbal resources in mind we were interested to inquire whether some phytochemicals from Indian spices and medicinal plants can be used as alternative therapeutic agents in contrast to synthetic drugs. Materials and methods We used in-silico molecular docking approach to test whether bioactive molecules of herbal origin such as Hyperoside, Nimbaflavone, Ursolic acid, 6-gingerol, 6-shogaol& 6-paradol, Curcumin, Catechins&Epigallocatechin, α-Hederin, Piperine could bind and potentially block theMproenzyme of Sars-CoV-2 virus. Results Ursolic acid showed the highest docking score (-8.7 kcal/mol) followed by Hyperoside (-8.6kcal/mol), α-Hederin (-8.5 kcal/mol) and Nimbaflavone (-8.0kcal/mol). Epigallocatechin, Catechins, and Curcumin also exhibited high binding affinity (Docking score -7.3, -7.1 and -7.1 kcal/mol) with the Mpro. Rest of the tested phytochemicals exhibited moderate binding and inhibitory effects. Conclusion This finding provides a basis for biochemical assay on Sars-CoV-2 virus.
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Affiliation(s)
- Pinku Halder
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - Upamanyu Pal
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - Pranab Paladhi
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - Saurav Dutta
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - Pallab Paul
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - Samudra Pal
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - Debasmita Das
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - Agnish Ganguly
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - IshitaDutta
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - SayarneelMandal
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
| | - Anirban Ray
- Department of Zoology, Bangabasi Morning College (affiliated to University of Calcutta), Kolkata, West Bengal, India, Pincode: 700009
| | - Sujay Ghosh
- Cytogenetics& Genomics Research Unit, Department of Zoology; University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), 35 Ballygunge Circular Road, Kolkata, WestBengal, India,Pincode: 700019
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Pal U, Halder P, Ray A, Sarkar S, Datta S, Ghosh P, Ghosh S. The etiology of Down syndrome: Maternal MCM9 polymorphisms increase risk of reduced recombination and nondisjunction of chromosome 21 during meiosis I within oocyte. PLoS Genet 2021; 17:e1009462. [PMID: 33750944 PMCID: PMC8021012 DOI: 10.1371/journal.pgen.1009462] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 04/01/2021] [Accepted: 03/03/2021] [Indexed: 11/21/2022] Open
Abstract
Altered patterns of recombination on 21q have long been associated with the nondisjunction chromosome 21 within oocytes and the increased risk of having a child with Down syndrome. Unfortunately the genetic etiology of these altered patterns of recombination have yet to be elucidated. We for the first time genotyped the gene MCM9, a candidate gene for recombination regulation and DNA repair in mothers with or without children with Down syndrome. In our approach, we identified the location of recombination on the maternal chromosome 21 using short tandem repeat markers, then stratified our population by the origin of meiotic error and age at conception. We observed that twenty-five out of forty-one single nucleotide polymorphic sites within MCM9 exhibited an association with meiosis I error (N = 700), but not with meiosis II error (N = 125). This association was maternal age-independent. Several variants exhibited aprotective association with MI error, some were neutral. Maternal age stratified characterization of cases revealed that MCM9 risk variants were associated with an increased chance of reduced recombination on 21q within oocytes. The spatial distribution of single observed recombination events revealed no significant change in the location of recombination among women harbouring MCM9 risk, protective, or neutral variant. Additionally, we identified a total of six novel polymorphic variants and two novel alleles that were either risk imparting or protective against meiosis I nondisjunction. In silico analyses using five different programs suggest the risk variants either cause a change in protein function or may alter the splicing pattern of transcripts and disrupt the proportion of different isoforms of MCM9 products within oocytes. These observations bring us a significant step closer to understanding the molecular basis of recombination errors in chromosome 21 nondisjunction within oocytes that leads to birth of child with Down syndrome. We studied MCM9 variations in the genome of women with a Down syndrome child by stratifying the women based on MCM9 genotypes, meiotic error group, and their age of conception. We identified polymorphisms are associated with reduced recombination and nondisjunction of chromosome 21 at the meiosis I stage of oogenesis in a maternal age-independent manner. But these variants do not affect the position of chiasma formation. In Silico analyses revealed the presence of MCM9 variants that may cause alteration in protein function due to amino acid substitution. We also identified splice variants in MCM9. We hypothesize that the polymorphisms in MCM9 predispose women to experience reduced recombination on chromosome 21 in oocytes at meiosis I, which ultimately leads to the birth of a child with Down syndrome.
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Affiliation(s)
- Upamanyu Pal
- Cytogenetics and Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath Palit Siksha Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
| | - Pinku Halder
- Cytogenetics and Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath Palit Siksha Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
| | - Anirban Ray
- Department of Zoology, Bangabasi Morning College (affiliated to University of Calcutta), Kolkata, West Bengal, India
| | - Sumantra Sarkar
- Department of Paediatric Medicine, Institute of Post Graduate Medical Education and Research (IPGMER), Bhowanipore, Kolkata, West Bengal, India
- Department of Paediatric Medicine, Diamond Harbour Government Medical College & Hospital, Diamond Harbour, West Bengal, India
| | - Supratim Datta
- Department of Paediatric Medicine, Institute of Post Graduate Medical Education and Research (IPGMER), Bhowanipore, Kolkata, West Bengal, India
| | - Papiya Ghosh
- Department of Zoology, Bijoykrishna Girls’ College (Affiliated to University of Calcutta), Howrah, West Bengal, India
| | - Sujay Ghosh
- Cytogenetics and Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath Palit Siksha Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
- * E-mail:
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Klouwens MJ, Trentelman JJ, Ersoz JI, Nieves Marques Porto F, Sima R, Hajdusek O, Thakur M, Pal U, Hovius JW. Investigating BB0405 as a novel Borrelia afzelii vaccination candidate in Lyme borreliosis. Sci Rep 2021; 11:4775. [PMID: 33637813 PMCID: PMC7910573 DOI: 10.1038/s41598-021-84130-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 02/01/2021] [Indexed: 01/20/2023] Open
Abstract
BB0405 is a surface exposed Borrelia burgdorferi protein and its vaccination protected mice against B. burgdorferi infection. As BB0405 is highly conserved across different B. burgdorferi sensu lato species, we investigated whether vaccination with recombinant BB0405 or through intradermal bb0405 DNA tattoo vaccination could provide protection against different Borrelia species, specifically against Borrelia afzelii, the predominant B. burgdorferi sensu lato genospecies causing Lyme borreliosis across Eurasia. We immunized C3H/HeN mice with recombinant BB0405 or with a codon-optimized bb0405 DNA vaccine using the pVAC plasmid and immunized corresponding control groups mice with only adjuvant or empty vectors. We subsequently subjected these immunized mice to a tick challenge with B. afzelii CB43-infected Ixodes ricinus nymphs. Upon vaccination, recombinant BB0405 induced a high total IgG response, but bb0405 DNA vaccination did not elicit antibody responses. Both vaccine formulations did not provide protection against Borrelia afzelii strain CB43 after tick challenge. In an attempt to understand the lack of protection of the recombinant vaccine, we determined expression of BB0405 and showed that B. afzelii CB43 spirochetes significantly and drastically downregulate the expression of BB0405 protein at 37 °C compared to 33 °C, where as in B. burgdorferi B31 spirochetes expression levels remain unaltered. Vaccination with recombinant BB0405 was previously shown to protect against B. burgdorferi sensu stricto. Here we show that vaccination with either recombinant BB0405 (or non-immunogenic bb0405 DNA), despite being highly conserved among B. burgdorferi sl genospecies, does not provide cross-protection against B. afzelii, mostly likely due to downregulation of this protein in B. afzelii in the mammalian host.
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Affiliation(s)
- M J Klouwens
- Department of Internal Medicine, Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands. .,Division of Infectious Diseases, Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands. .,Amsterdam Multidisciplinary Lyme Borreliosis Center, Academic Medical Center, Amsterdam, The Netherlands.
| | - J J Trentelman
- Department of Internal Medicine, Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - J I Ersoz
- Department of Internal Medicine, Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - F Nieves Marques Porto
- Department of Internal Medicine, Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - R Sima
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | - O Hajdusek
- Biology Centre, Institute of Parasitology, Czech Academy of Sciences, Ceske Budejovice, Czech Republic
| | - M Thakur
- Department of Veterinary Medicine, University of Maryland, College Park and Virginia- Maryland Regional College of Veterinary Medicine, College Park, MD, USA
| | - U Pal
- Department of Veterinary Medicine, University of Maryland, College Park and Virginia- Maryland Regional College of Veterinary Medicine, College Park, MD, USA
| | - J W Hovius
- Department of Internal Medicine, Center for Experimental and Molecular Medicine, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.,Division of Infectious Diseases, Department of Internal Medicine, Academic Medical Center, Amsterdam, The Netherlands.,Amsterdam Multidisciplinary Lyme Borreliosis Center, Academic Medical Center, Amsterdam, The Netherlands
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Halder P, Pal U, Ray A, Sarkar S, Dutta S, Ghosh S. Polymorphisms of folate metabolism regulators increase risk of meiosis II nondisjunction of chromosome 21 in oocyte. Meta Gene 2019. [DOI: 10.1016/j.mgene.2019.100606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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Katla S, Karmakar B, Tadi SRR, Mohan N, Anand B, Pal U, Sivaprakasam S. High level extracellular production of recombinant human interferon alpha 2b in glycoengineered Pichia pastoris: culture medium optimization, high cell density cultivation and biological characterization. J Appl Microbiol 2019; 126:1438-1453. [PMID: 30776176 DOI: 10.1111/jam.14227] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 02/13/2019] [Accepted: 02/14/2019] [Indexed: 12/18/2022]
Abstract
AIMS The present study was aimed at design of experiments (DoE)- and artificial intelligence-based culture medium optimization for high level extracellular production of a novel recombinant human interferon alpha 2b (huIFNα2b) in glycoengineered Pichia pastoris and its characterization. METHODS AND RESULTS The artificial neural network-genetic algorithm model exhibited improved huIFNα2b production and better predictability compared to response surface methodology. The optimized medium exhibited a fivefold increase in huIFNα2b titre compared to the complex medium. A maximum titre of huIFNα2b (436 mg l-1 ) was achieved using the optimized medium in the bioreactor. Real-time capacitance data from dielectric spectroscopy were utilized to model the growth kinetics with unstructured models. Biological characterization by antiproliferative assay proved that the purified recombinant huIFNα2b was biologically active, exhibiting growth inhibition on breast cancer cell line. CONCLUSIONS Culture medium optimization resulted in enhanced production of huIFNα2b in glycoengineered P. pastoris at both shake flask and bioreactor level. The purified huIFNα2b was found to be N-glycosylated and biologically active. SIGNIFICANCE AND IMPACT OF THE STUDY DoE-based medium optimization strategy significantly improved huIFNα2b production. The antiproliferative activity of huIFNα2b substantiates its potential scope for application in cancer therapy.
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Affiliation(s)
- S Katla
- BioPAT Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - B Karmakar
- BioPAT Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - S R R Tadi
- BioPAT Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - N Mohan
- BioPAT Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - B Anand
- MAB Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - U Pal
- Molecular Endocrinology Lab, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
| | - S Sivaprakasam
- BioPAT Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, India
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Ray A, Oliver TR, Halder P, Pal U, Sarkar S, Dutta S, Ghosh S. Risk of Down syndrome birth: Consanguineous marriage is associated with maternal meiosis-II nondisjunction at younger age and without any detectable recombination error. Am J Med Genet A 2018; 176:2342-2349. [PMID: 30240118 DOI: 10.1002/ajmg.a.40511] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 05/17/2018] [Accepted: 07/26/2018] [Indexed: 01/10/2023]
Abstract
Consanguineous marriage was examined as a risk factor for Down syndrome birth. We genotyped Down syndrome family trios using short tandem repeat markers on 21q-to interpret the parental and meiotic stage of origin of errors as well as to record recombination profile along long arm of chromosome 21. We then compared nonconsanguineous (N = 811) group with-the consanguineous (N =157) marriages. We report for the first time that consanguineous marriage is associated with an increased risk for nondisjunction of chromosome 21 in oocytes-during the second meiotic division. We observed the absence of recombination more frequently in younger mothers in nonconsanguineous meiosis I cases. This was in contrast to an equal distribution of nonrecombinant cases across the age categories in the meiosis I consanguineous group. Moreover, the non-consanguineous group exhibited preferential telomeric recombination in meiosis I error among younger women and centromeric recombination in meiosis II errors in older women. In contrast, the consanguineous group exhibited medially placed recombination events in both meiosis I and meiosis II nondisjunction errors. Additionally, we recorded reduced maternal age at conception in the-consanguineous group. These findings suggest novel risk factors associated that increase the risk of chromosome 21 nondisjunction in the families with consanguinity.
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Affiliation(s)
- Anirban Ray
- Cytogenetics & Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
| | | | - Pinku Halder
- Cytogenetics & Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
| | - Upamanyu Pal
- Cytogenetics & Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
| | - Sumantra Sarkar
- Department of Pediatric Medicine, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
| | - Supratim Dutta
- Department of Pediatric Medicine, Institute of Post Graduate Medical Education and Research, Kolkata, West Bengal, India
| | - Sujay Ghosh
- Cytogenetics & Genomics Research Unit, Department of Zoology, University of Calcutta, Taraknath-Palit-Siksha-Prangan (Ballygunge Science College Campus), Kolkata, West Bengal, India
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Bogireddy NKR, Pal U, Gomez LM, Agarwal V. Size controlled green synthesis of gold nanoparticles using Coffea arabica seed extract and their catalytic performance in 4-nitrophenol reduction. RSC Adv 2018; 8:24819-24826. [PMID: 35542117 PMCID: PMC9082294 DOI: 10.1039/c8ra04332a] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 06/29/2018] [Indexed: 11/21/2022] Open
Abstract
Well crystalline gold nanoparticles (AuNPs) of different sizes were fabricated using sundried Coffea arabica seed (CAS) extract at room temperature by controlling the pH of the green extract. The size, shape and crystallinity of the nanoparticles have been studied using electron microscopy and X-ray diffraction. The presence of phenolic groups (revealed through FT-IR studies) from the CAS extract are responsible both for the reduction of Au ions and stabilization of the formed AuNPs. The efficiency of the CAS extract mediated green synthesis technique for the production of AuNPs has been compared to the conventional chemical Turkevich technique, which not only uses a toxic reductant such as NaBH4, but also operates around the boiling point of water. It has been observed that the CAS extract mediated synthesis process produces relatively bigger AuNPs at similar pH values of the reaction mixture in comparison to the AuNPs produced in the Turkevich process. Although the AuNPs synthesized using CAS extract are relatively larger and polydisperse in nature, their catalytic efficiencies for the degradation of an aromatic nitro compound (4-nitrophenol) are found to be comparable to the chemically fabricated AuNPs. Probable mechanisms associated with the formation of AuNPs and their size control in the CAS extract mediated green synthesis process have been discussed. Size dependent catalytic activity of AuNPs synthesized at room temperature from Coffea arabica seed extract.![]()
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Affiliation(s)
- N. K. R. Bogireddy
- Centro de Investigacion en Ingenieria y Ciencias Aplicadas
- UAEM
- Cuernavaca
- México
| | - U. Pal
- Instituto de Física
- Benemérita Universidad Autónoma de Puebla
- Puebla Pue
- Mexico
| | - L. Martinez Gomez
- Universidad Nacional Autonoma de Mexico
- Instituto de Ciencias Fisicas
- Cuernavaca
- 62210 Mexico
| | - V. Agarwal
- Centro de Investigacion en Ingenieria y Ciencias Aplicadas
- UAEM
- Cuernavaca
- México
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Sahare P, Ayala M, Vazquez-Duhalt R, Pal U, Loni A, Canham LT, Osorio I, Agarwal V. Enhancement of Peroxidase Stability Against Oxidative Self-Inactivation by Co-immobilization with a Redox-Active Protein in Mesoporous Silicon and Silica Microparticles. Nanoscale Res Lett 2016; 11:417. [PMID: 27650291 PMCID: PMC5030200 DOI: 10.1186/s11671-016-1605-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 08/31/2016] [Indexed: 06/06/2023]
Abstract
The study of the stability enhancement of a peroxidase immobilized onto mesoporous silicon/silica microparticles is presented. Peroxidases tend to get inactivated in the presence of hydrogen peroxide, their essential co-substrate, following an auto-inactivation mechanism. In order to minimize this inactivation, a second protein was co-immobilized to act as an electron acceptor and thus increase the stability against self-oxidation of peroxidase. Two heme proteins were immobilized into the microparticles: a fungal commercial peroxidase and cytochrome c from equine heart. Two types of biocatalysts were prepared: one with only covalently immobilized peroxidase (one-protein system) and another based on covalent co-immobilization of peroxidase and cytochrome c (two-protein system), both immobilized by using carbodiimide chemistry. The amount of immobilized protein was estimated spectrophotometrically, and the characterization of the biocatalyst support matrix was performed using Brunauer-Emmett-Teller (BET), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared (FTIR) analyses. Stability studies show that co-immobilization with the two-protein system enhances the oxidative stability of peroxidase almost four times with respect to the one-protein system. Thermal stability analysis shows that the immobilization of peroxidase in derivatized porous silicon microparticles does not protect the protein from thermal denaturation, whereas biogenic silica microparticles confer significant thermal stabilization.
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Affiliation(s)
- P. Sahare
- Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autónoma del Estado de México, Av. Univ. 1001, Col. Chamilpa, Cuernavaca, Morelos 62209 Mexico
| | - M. Ayala
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, Cuernavaca, 62210 Morelos Mexico
| | - R. Vazquez-Duhalt
- Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de Mexico, Km. 107, Carretera Tijuana-Ensenada, Apdo. Postal 14, CP 22800 Ensenada, Baja California Mexico
| | - U. Pal
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - A. Loni
- pSiMedica Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ UK
| | - L. T. Canham
- pSiMedica Ltd, Malvern Hills Science Park, Geraldine Road, Malvern, Worcestershire WR14 3SZ UK
| | - I. Osorio
- Facultad de Química, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - V. Agarwal
- Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autónoma del Estado de México, Av. Univ. 1001, Col. Chamilpa, Cuernavaca, Morelos 62209 Mexico
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Lizama-Tzec FI, García-Rodríguez R, Rodríguez-Gattorno G, Canto-Aguilar EJ, Vega-Poot AG, Heredia-Cervera BE, Villanueva-Cab J, Morales-Flores N, Pal U, Oskam G. Influence of morphology on the performance of ZnO-based dye-sensitized solar cells. RSC Adv 2016. [DOI: 10.1039/c5ra25618f] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The relation between the morphological and textural properties and the performance of ZnO-based dye-sensitized solar cells is explored using ZnO materials prepared by a sonochemical method as a function of pH.
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Affiliation(s)
| | | | | | | | | | | | - J. Villanueva-Cab
- Instituto de Física
- Benemérita Universidad Autónoma de Puebla
- Puebla
- México
| | - N. Morales-Flores
- Centro de Investigación en Dispositivos Semiconductores
- ICUAP
- Benemérita Universidad Autónoma de Puebla
- Puebla
- México
| | - U. Pal
- Instituto de Física
- Benemérita Universidad Autónoma de Puebla
- Puebla
- México
| | - G. Oskam
- Department of Applied Physics
- CINVESTAV-IPN
- Mérida
- México
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Pal U, Saha S, Samantaray ΒK, Chaudhuri AK, Banerjee HD. X-ray and electron microscopic determination of Debye characteristic temperature, stacking fault energy and other microstructural parameters in zinc telluride films. Z KRIST-CRYST MATER 2015. [DOI: 10.1524/zkri.1990.193.14.33] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Mendoza-Dorantes T, Pal U, Vega-Acosta J, Márquez-Beltrán C. Encapsulation and surface charge manipulation of organic and inorganic colloidal substrates by multilayered polyelectrolyte films. Colloids Surf A Physicochem Eng Asp 2013. [DOI: 10.1016/j.colsurfa.2013.05.027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Suput M, Delucas R, Pati S, Ye G, Pal U, Powell IV AC. Solid oxide membrane technology for environmentally sound production of titanium. ACTA ACUST UNITED AC 2013. [DOI: 10.1179/174328508x290911] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Ruiz Peralta MDL, Pal U, Zeferino RS. Photoluminescence (PL) quenching and enhanced photocatalytic activity of Au-decorated ZnO nanorods fabricated through microwave-assisted chemical synthesis. ACS Appl Mater Interfaces 2012; 4:4807-4816. [PMID: 22939243 DOI: 10.1021/am301155u] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ZnO nanorods decorated with gold nanoparticles of ~20 nm average size were fabricated by microwave-assisted chemical synthesis. For the surface-attached growth of metal nanoparticles, the ZnO nanostructures were first functionalized by sodium citrate and then the metal ions were reduced under microwave heating. While the incorporation of gold nanoparticles at the surface seen to quench both the band edge and visible emissions of the ZnO nanostructures, it enhances the degradation rate of Rhodamine 6G up to 3 folds under UV emission. The mechanisms of citrate functionalization, growth of Au nanoparticles on the surface of the oxide nanostructures, luminescence emission quenching, and enhanced photocatalytic activity of the composite nanostructures have been discussed.
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Affiliation(s)
- Ma De Lourdes Ruiz Peralta
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla, Pue. 72570, Mexico
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Peralta MDLR, Serrano JG, Pal U. Morphology Defined ZnO Nanostructures Through Microwave Assisted Chemical Synthesis: Growth Mechanism, Defect Structure, and Emission Behaviours. ACTA ACUST UNITED AC 2012. [DOI: 10.1166/asl.2012.1998] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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González A, Herrera M, Valenzuela J, Escobedo A, Pal U. Cathodoluminescence evaluation of defect structure in hydrothermally grown ZnO:Sb nanorods. J Nanosci Nanotechnol 2011; 11:5526-5531. [PMID: 21770214 DOI: 10.1166/jnn.2011.3424] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Cathodoluminescence emission of hydrothermally grown antimony doped ZnO nanostructures with different antimony doping (2.5, 4.8, and 11.8 at%) was studied in a scanning electron microscope (CL-SEM). Incorporation of antimony results in formation of mostly nanorods with low aspect ratio together with some Sb-rich nanoparticles. Transmissibn electron microscopy (TEM) of the Sb-doped samples revealed delaminated {10-10} planes produced by antimony surface segregation. CL spectra of the as-grown samples revealed well defined emission bands centered at 3.2, 2.74 and 2.0 eV, attributed to excitonic recombination, and the so-called blue and yellow emissions, respectively. It was observed that the intensity of the blue emission depends strongly on antimony content, suggesting the formation of point defects on Sb doping. While the yellow emission red-shifted after thermal annealing, either in argon or oxygen atmosphere, the intensity of the blue band decreases considerably; such behavior is explained through the reduction of the population of Zn(i) defects.
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Affiliation(s)
- A González
- Posgrado en Física de Materiales, Centro de Investigación Científica y de Educación Superior de Ensenada, Apartado Postal 2732, Ensenada, B. C. 22860, México
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Pal M, Pal U, Chernov V, Meléndrez R, Barboza-Flores M. Thermoluminescence and optically stimulated luminescence properties of beta-irradiated TiO2:Yb nanoparticles. J Nanosci Nanotechnol 2009; 9:1851-1857. [PMID: 19435049 DOI: 10.1166/jnn.2009.369] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The thermoluminescence (TL) and optically stimulated luminescenece (OSL) response of TiO2:Yb nanoparticles are studied. After beta irradiation, the materials developed a significant TL/OSL signal associated to several localized trapping states around 360-620 K. The OSL signal is mainly due to the releasing of trapped charges in the low temperature (360 and 460 K) trapping states. A computer glow curve deconvolution procedure was used to determine the activation energies and kinetic order of the TL processes.
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Affiliation(s)
- M Pal
- Posgrado en Ingeniería y Ciencias Aplicadas, UAEM-CIICAP Cuernavaca, Morelos, México
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Escobedo Morales A, Aceves R, Pal U, Zhang JZ. Low temperature photoluminescence characteristics of chemically synthesized indium doped zinc oxide nanostructures. J Nanosci Nanotechnol 2008; 8:6538-6544. [PMID: 19205237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Photoluminescence (PL) emission and excitation (EPL) spectra of un-doped and indium (1%) doped 1D zinc oxide nanostructures are studied at different temperatures. The nanostructures reveal a blue emission band attributed to localized donor states. Indium doping enhances the blue emission. While at low temperatures (< 50 K) PL spectra are dominated by the emission attributed to the recombination of excitons bound to neutral donors (D(0),X), at higher temperatures (>100 K), defect related emissions in the visible range dominate over the excitonic emission. Temperature dependence measurements on the doped sample reveal that (D(0),X) emission energies obey the Varshni's formula with fitting constants alpha = 8.4 +/- 0.3 x 10(-4) eV/K and beta = 650 +/- 40 K. The (D(0),X) emission intensity decays exponentially with temperature.
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Affiliation(s)
- A Escobedo Morales
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, CP 72570, Puebla, Pue., México
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González-Carrazco A, Herrera-Zaldívar M, Pal U. Studies of point defect formation and self-compensation in indium doped ZnO nanorods by STM and STS. J Nanosci Nanotechnol 2008; 8:6598-6602. [PMID: 19205247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The effect of indium doping on the point defect formation in ZnO nanostructures is studied by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) techniques. While the incorporation of a donor dopant like indium should increase the n-type conductivity of ZnO nanostructures, it has been found that formation of V(Zn) native acceptors in heavily doped ZnO nanostructures produces self-compensation effect, creating acceptor states in their band gap. Presence of both donor and acceptor states in heavily indium doped ZnO nanostructures are probed and identified. The mechanism of formation of such donor and acceptor states is discussed.
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Affiliation(s)
- A González-Carrazco
- Centro de Ciencias de la Materia Condensada, Universidad Nacional Autónoma de México, Apdo. Postal 2681, C.P. 22800, Ensenada, Baja California, México
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Escobedo Morales A, Pal U, Herrera Zaldivar M. Incorporation of Sb in ZnO nanostructures through hydrothermal process. J Nanosci Nanotechnol 2008; 8:6551-6557. [PMID: 19205239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Incorporation of dopants in optoelectronic semiconductor nanostructures has been a matter of great interest in recent times. While such doping has been performed almost routinely using physical methods, use of low-cost chemical techniques for that purpose is still rare. We incorporated antimony in zinc oxide (ZnO) nanostructures through a low temperature hydrothermal method. In as-grown nanostructures, antimony remains partially in Sb2O3 phase. On thermal annealing at 500 degrees C, it dissociates and antimony incorporates into ZnO mainly by substituting zinc from the crystal lattice. Incorporation of Sb drastically modifies the morphology of the ZnO nanostructures. While incorporation of Sb in low concentration promotes the formation of uniform prismatic ZnO nanorods probably due to catalytic effect, high concentration of Sb causes the formation of rounded shaped nanoparticles due to high interfacial compressive stress. Incorporated Sb in the ZnO nanostructures remains inhomogeneously distributed. The optical band gap of the ZnO nanostructures increases a bit for lightly doped samples but it decreases for heavy doping.
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Affiliation(s)
- A Escobedo Morales
- Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, C.P. 72570, Puebla, Pue., Mexico
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Sathyamoorthy R, Sudhagar P, Chandramohan S, Pal U. Size effect on the physical properties of CdS thin films prepared by integrated physical-chemical approach. J Nanosci Nanotechnol 2008; 8:6481-6486. [PMID: 19205226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Using an integrated physical-chemical approach, nanocrystalline cadmium sulfide (CdS) thin films were prepared by evaporating chemically synthesized CdS nanorods. Both the CdS nanorods and nanocrystalline thin films exhibited hexagonal wurtzite structure. Chemically synthesized CdS nanorods of about 7 nm average diameter were flexible, frequently folded to have elliptical cage linked chain structures and aggregate to form nanorod bundles. The bandgap energy of the nanocrystalline CdS films suffered a blue shift of about 0.07 eV due to intermediate quantum confinement of charge carriers. The reaction atmosphere was found to have strong effects on the particle size control of the nanostructures. Room temperature photoluminescence (PL) spectra of the films revealed a broad emission at about 429 nm related to recombination of excitons and shallowly trapped electron-hole pairs, along with the near-band-edge emission. Influence of particle size and defects on the structural and optical properties of CdS nanorods and nanocrystalline thin films are discussed.
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Affiliation(s)
- R Sathyamoorthy
- PG and Research Department of Physics, Kongunadu Arts and Science College, Coimbatore 641029, India
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25
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Pal U, Zaldivar MH, Sathyamoorthy R, Manjuladevi V, Sudhagar P, Mohan SC, Senthilarasu S. Nanocrystalline CdSe thin films of different morphologies in thermal evaporation process. J Nanosci Nanotechnol 2008; 8:6474-6480. [PMID: 19205225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Cadmium selenide nanocrystalline thin films of quasi-spherical morphology are prepared by evaporating CdSe nanopowders on glass substrates. Slightly oval shaped CdSe particles of about 165 nm average size (in 2-D) could be assembled over glass substrates by controlling the film thickness. Morphologies like assembly of particles, interconnected particles with mosaic-like structures and thin films of smooth surfaces could be prepared simply by controlling film thickness. A mechanism for such morphological variations is proposed. Observed variation of band gap energy in the films is explained in terms of quantum confinement effect and substrate-film interface strain.
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Affiliation(s)
- U Pal
- Instituto de Física, Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla, Pue. 72570, Mexico
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26
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Pal U, Meléndrez R, Chernov V, Barboza-Flores M. Effect of Yb doping on the afterglow and thermoluminescent properties of ZnO nanophosphors. J Nanosci Nanotechnol 2008; 8:6513-6518. [PMID: 19205232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ZnO nanophosphors prepared by a glycol mediated chemical synthesis exhibit afterglow (AG) and thermoluminescence (TL) after excitation with beta rays. These properties, which are of great interest in dose assessment of ionizing radiation fields, could be appreciably modified by Yb doping. Concentration of 1, 2 and 5% diminished the AG and TL efficiency and modified the TL glow curve shape significantly. However, the 5% Yb doping concentration reduced the AG and TL fading behavior, improving the use of ZnO:Yb (5%) as potential TL ionizing radiation dosimeter.
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Affiliation(s)
- U Pal
- Instituto Física, Universidad Autónoma de Puebla, Apartado Postal J-48, Puebla 72570, México
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Kantam M, Chakravarti R, Pal U, Sreedhar B, Bhargava S. Selective Reduction of the Nitro Group Using Nanocyrstalline MgO-Stabilized Palladium(0). ACTA ACUST UNITED AC 2008. [DOI: 10.1055/s-2008-1078440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Xiong G, Pal U, Serrano JG, Ucer KB, Williams RT. Photoluminesence and FTIR study of ZnO nanoparticles: the impurity and defect perspective. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/pssc.200672164] [Citation(s) in RCA: 301] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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García-Serrano J, Herrera AM, Pérez-Moreno F, Valdez MA, Pal U. Synthesis of novel ionic polymers containing arsonic acid group. ACTA ACUST UNITED AC 2006. [DOI: 10.1002/polb.20807] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Sánchez-Ramírez JF, Jiménez Pérez JL, Cruz Orea A, Gutierrez Fuentes R, Bautista-Hernández A, Pal U. Thermal diffusivity of nanofluids containing Au/Pd bimetallic nanoparticles of different compositions. J Nanosci Nanotechnol 2006; 6:685-90. [PMID: 16573121 DOI: 10.1166/jnn.2006.124] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Colloidal suspensions of bimetallic Au/Pd nanoparticles were prepared by simultaneous reduction of the metal ions from their corresponding chloride salts with polymer (PVP) stabilizer. Thermal properties of water containing bimetallic nanoparticles with different nominal compositions (Au/Pd = 12/1, 5/1, 1/1, 1/5) were measured using the mode mismatched dual-beam thermal lens technique to determine the effect of particle composition on the thermal diffusivity of the nanofluids. The characteristic time constant of the transient thermal lens was estimated by fitting the experimental data to the theoretical expression for transient thermal lens. The thermal diffusivity of the nanofluids (water, containing Au/Pd bimetallic nanoparticles) is seen to be strongly dependent on the composition of the particles. The maximum diffusivity was achieved for the nanoparticles with highest Au/Pd molar ratio. A possible mechanism for such high thermal diffusivity of the nanofluids with bimetallic particles is given. UV-Vis spectroscopy, TEM and high-resolution electron microscopy (HREM) techniques were used to characterize the Au/Pd bimetallic nanoparticles.
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Liu HB, Pal U, Perez R, Ascencio JA. Structural Transformation of Au−Pd Bimetallic Nanoclusters on Thermal Heating and Cooling: A Dynamic Analysis. J Phys Chem B 2006; 110:5191-5. [PMID: 16539447 DOI: 10.1021/jp056060e] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Classical molecular dynamics simulation is used for structural thermodynamic and dynamic analysis of Au-Pd bimetallic clusters. It is observed that the Pd-core/Au-shell structure is the most stable, and can be formed through annealing of other structures such as Au-core/Pd-shell, eutecticlike, or solid solution. Depending on the starting temperature and initial composition, three-layer icosahedral nanorod, face-centered cubic (fcc) nanorod, and fcc cluster can be obtained on slow cooling. The three-layer icosahedral nanorod structure is not as stable as the Pd-core/Au-shell decahedron; however it is more stable than the solid-solution decahedron structure up to 400 K. Our findings provide valuable insight into catalysis using Au-Pd and other similar bimetallic clusters.
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Affiliation(s)
- H B Liu
- Programa de Investigación en Ductos, Materiales y Corrosión, Instituto Mexicano del Petróleo, Eje Central Lazaro Cardenas No. 152, Col. San Bartolo Atepehuacan, C.P.07730, México D.F., Mexico.
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Ascencio JA, Liu HB, Pal U, Medina A, Wang ZL. Transmission electron microscopy and theoretical analysis of AuCu nanoparticles: Atomic distribution and dynamic behavior. Microsc Res Tech 2006; 69:522-30. [PMID: 16732542 DOI: 10.1002/jemt.20321] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Though the application of bimetallic nanoparticles is becoming increasingly important, the local atomistic structure of such alloyed particles, which is critical for tailoring their properties, is not yet very clearly understood. In this work, we present detailed study on the atomistic structure of Au-Cu nanoparticles so as to determine their most stable configurations and the conditions for obtaining clusters of different structural variants. The dynamic behavior of these nanoparticles upon local heating is investigated. AuCu nanoparticles are characterized by high resolution transmission electron microscopy (HRTEM) and energy filtering elemental composition mapping (EFECM), which allowed us to study the internal structure and the elemental distribution in the particles. Quantum mechanical approaches and classic molecular dynamics methods are applied to model the structure and to determine the lowest energy configurations, the corresponding electronic structures, and understand structural transition of clusters upon heating, supported by experimental evidences. Our theoretical results demonstrate only the core/shell bimetallic structure have negative heat of formation, both for decahedra and octahedral, and energetically favoring core/shell structure is with Au covering the core of Cu, whose reverse core/shell structure is not stable and may transform back at a certain temperature. Experimental evidences corroborate these structures and their structural changes upon heating, demonstrating the possibility to manipulate the structure of such bimetallic nanoparticles using extra stimulating energy, which is in accordance with the calculated coherence energy proportions between the different configurations.
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Affiliation(s)
- J A Ascencio
- Programa de Investigación y Desarrollo de Ductos, Instituto Mexicano del Petroleo, Eje Central Lázaro Cárdenas No. 152, Col. San Bartolo Atepehuacan, C.P.07730, Mexico D.F., Mexico.
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Reza-San German C, Santiago P, Ascencio JA, Pal U, Pérez-Alvarez M, Rendón L, Mendoza D. Graphite-Incorporated MoS2 Nanotubes: A New Coaxial Binary System. J Phys Chem B 2005; 109:17488-95. [PMID: 16853236 DOI: 10.1021/jp052174e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Graphite-filled MoS2 nanotubes were synthesized by pyrolizing propylene inside MoS2 nanotubes prepared by a template-assisted technique. The large coaxial nanotubes were constituted of graphite sheets inserted between the MoS2 layers, forming the outer part, and coaxial multiwall carbon nanotubes intercalated with MoS2 inside. High-resolution electron microscopy (HREM) and electron energy loss spectroscopy techniques along with molecular dynamics simulation and quantum mechanical calculations were used to characterize the samples. The one-dimensional structures exhibit diverse morphologies such as long straight and twisted nanotubes with several structural irregularities. The interplanar spacing between the MoS2 layers was found to increase from 6.3 to 7.4 A due to intercalation with carbon. Simulated HREM images revealed the presence of mechanical strains in the carbon-intercalated MoS2 layers as the reason for obtaining these twisted nanostructures. The mechanism of formation of carbon-intercalated MoS2 tubular structures and their stability and electronic properties are discussed. Our results open up the possibility of using MoS2 nanotubes as templates for the synthesis of new one-dimensional binary-phase systems.
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Affiliation(s)
- C Reza-San German
- Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colon esq. Paseo Tollocan, Apartado Postal A-20, Toluca, C.P. 50120, México D.F., Mexico
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Abstract
ZnO nanostructures of different morphologies were grown in a controlled manner using a simple low-temperature hydrothermal technique. Controlling the content of ethylenediamine (soft surfactant) and the pH of the reaction mixture, nanoparticles, nanorods, and flowerlike ZnO structures could be synthesized at temperatures 80-100 degrees C with excellent reproducibility. High-resolution electron microscopy revealed the well crystalline nature of all the nanostructures with preferential growth along the [002] direction for linear structures. Photoluminescence spectra of the as-grown nanostructures revealed oxygen-vacancy-related defects in them, which could be reduced by air annealing at 250 degrees C. Possible mechanisms for the variation of morphology with synthesis parameters are discussed.
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Affiliation(s)
- U Pal
- Instituto de Física, Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla, Pue. 72570, Mexico.
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Santiago P, Rendón L, Reza-San Germán C, Pal U. HAADF imaging: an effective technique for the study of nonhomogeneous nanostructures. J Nanosci Nanotechnol 2005; 5:1172-6. [PMID: 16108445 DOI: 10.1166/jnn.2005.139] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Atomic number contrast (Z-contrast) imaging using high-angle annular dark field (HAADF) detector, along with high resolution electron microscopy (HREM), is used to study the nanostructured metal, semiconductor, mixed oxide, and soft matter composites of inhomogeneous nature. A comparison between the HREM and HAADF images for the analysis of crystal structure, defects, and compositional inhomogenity in those nanostructures has been made. While the HREM technique is efficient in determining bulk crystallinity and defect structures, the HAADF imaging technique is superior in determining the surface inhomogenity, defect structures in the interior of the nanostructures, even at atomic resolution. The efficiency of the HAADF imaging technique in determining the surface inhomogenity and defect structures is demonstrated for the Au-Pt bimetallic clusters, CdSe nanofibers and nanowires, Nb16W18O94 mixed oxide, and polystyrene-mormorillonite clay nanocomposites.
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Affiliation(s)
- P Santiago
- Instituto de Física, Universidad Nacional Autónoma de Mexico, Apartado postal 20-365, Mexico DF, Mexico
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Esparza R, Ascencio JA, Rosas G, Sánchez Ramírez JF, Pal U, Perez R. Structure, stability and catalytic activity of chemically synthesized Pt, Au, and Au-Pt nanoparticles. J Nanosci Nanotechnol 2005; 5:641-7. [PMID: 16004132 DOI: 10.1166/jnn.2005.r074] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Small (1-5 nm) metallic nanoparticles of Pt, Au, and Au/Pt of different nominal compositions in colloidal form were synthesized by a chemical reduction method using polymer (PVP) as protecting agent. Analytical techniques like HREM and UV-vis spectroscopy have been used to characterize the morphology and structural properties of these small particles. Theoretical simulations based on molecular dynamical have been used to interpret the experimental structural results and analyze the macroscopic properties like stability and catalytic selectivity of these nanoparticles based on the morphology and atomic distribution in the clusters.
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Affiliation(s)
- R Esparza
- Instituto de Investigaciones Metalúrgicas, UMSNH, Edificio U. Ciudad Universitaria, Morelia, Michoacan 58000, Mexico
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Pal U, Santiago P, Chavez J, Ascencio JA. Structure and growth mechanism study of Wurtzite CdSe nanorods grown by solvothermal techniques. J Nanosci Nanotechnol 2005; 5:609-14. [PMID: 16004127 DOI: 10.1166/jnn.2005.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Hexagonal cadmium selenide nanorods 32-170 nm in length and 12-28 nm in diameter were grown by a solvothermal technique by reacting cadmium chloride and selenium powders in ethylenediamine at 140 degrees C. Using electron microscopy, the shape, size, and crystal structure of the nanorods were determined. A detailed microscopy analysis revealed that the nanorods grow through the coalescence of very small particles or fiberlike structures of the compound. The size, shape and strain structures in the nanorods are defined by their growth mechanism.
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Affiliation(s)
- U Pal
- Instituto de Fisica, Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla, Pue. 72570, Mexico
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Velumani S, Castaneda H, Pal U, Chavez JA, Sebastian PJ, Ascencio JA. Structural and electrochemical characterization of sputter-deposited nitrided NiCr alloys. J Solid State Electrochem 2005. [DOI: 10.1007/s10008-004-0587-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Abstract
There are printed artistic documents where text lines of a single page may not be parallel to each other. These text lines may have different orientations or the text lines may be curved shapes. For the optical character recognition (OCR) of these documents, we need to extract such lines properly. In this paper, we propose a novel scheme, mainly based on the concept of water reservoir analogy, to extract individual text lines from printed Indian documents containing multioriented and/or curve text lines. A reservoir is a metaphor to illustrate the cavity region of a character where water can be stored. In the proposed scheme, at first, connected components are labeled and identified either as isolated or touching. Next, each touching component is classified either straight type (S-type) or curve type (C-type), depending on the reservoir base-area and envelope points of the component. Based on the type (S-type or C-type) of a component two candidate points are computed from each touching component. Finally, candidate regions (neighborhoods of the candidate points) of the candidate points of each component are detected and after analyzing these candidate regions, components are grouped to get individual text lines.
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Affiliation(s)
- U Pal
- Indian Statistical Institute, Kolkata-108, India.
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Rodríguez-López JL, Montejano-Carrizales JM, Pal U, Sánchez-Ramírez JF, Troiani HE, García D, Miki-Yoshida M, José-Yacamán M. Surface reconstruction and decahedral structure of bimetallic nanoparticles. Phys Rev Lett 2004; 92:196102. [PMID: 15169422 DOI: 10.1103/physrevlett.92.196102] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2003] [Indexed: 05/07/2023]
Abstract
We report on energetic surface reconstruction phenomena observed on bimetallic nanoparticle systems of AuPd and AuCu, similar to a resolidification effect observed during the cooling process in lead clusters. These binary alloy nanoparticles show the fivefold edges truncated, resulting in [100] facets on decahedral structures, an effect largely envisioned and reported theoretically, with no experimental evidence so far. We demonstrate experimentally as well as by computational simulations that this new eutectic structure is favored in such nanoalloy systems.
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Affiliation(s)
- J L Rodríguez-López
- Advanced Materials Department, IPICYT, Camino Presa San José 2055, 78216 San Luis Potosí, San Luis Potosí, Mexico
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Agrawal SC, Pal U. Viability of dried vegetative cells or filaments, survivability and/or reproduction under water and light stress, and following heat and UV exposure in some blue-green and green algae. Folia Microbiol (Praha) 2003; 48:501-9. [PMID: 14533482 DOI: 10.1007/bf02931332] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Vegetative cells in dried, mucilagenous mass of Gloeocapsa aeruginosa and Aphanothece nidulans, reticulum of Hydrodictyon reticulatum, mucilagenous mass of Chroococcus minor, and filaments of Oedogonium sp. and Scytonema hofmanni died within 1/2, 1/2, 1/2, 1, 3 and 6 h, respectively, while dried vegetative filaments of Phormidium foveolarum retained under similar storage conditions viability for 4 d. P. foveolarum tolerated 1 mol/L NaCl. The resistance to desiccation in P. foveolarum exhibited similar dependence as that to heat or UV light. The water stress imposed on growing algae either on high-agar solid media or in NaCl-containing liquid media reduced at various levels or altogether inhibited the survival of vegetative parts in all, the cell division in C. minor, G. aeruginosa and A. nidulans, formation of heterocyst and false branch in S. hofmanni, oogonium in Oedogonium sp., and daughter net in H. reticulatum. Heat or UV shock of any level also produced similar effects as that by water stress. P. foveolarum tolerated low light level of 10 and 2 mumol m-2 s-1 and no light longer than the rest of other algae studied. Tolerance of microalgal forms to water, heat or UV stress depends primarily upon cell-wall characteristics or cell-sap osmotic properties rather than their habitats, morphology and prokaryotic or eukaryotic nature.
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Affiliation(s)
- S C Agrawal
- Department of Botany, University of Allahabad, Allahabad, India
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Pal U, Sánchez-Ramírez JF, Gamboa SA, Sebastian PJ, Pérez R. Drastic improvement of electrical properties of Nafion® 112 membrane on impregnation of bimetallic Au/Pd nanoclusters. ACTA ACUST UNITED AC 2003. [DOI: 10.1002/pssc.200303847] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Pal U, Montgomery RR, Lusitani D, Voet P, Weynants V, Malawista SE, Lobet Y, Fikrig E. Inhibition of Borrelia burgdorferi-tick interactions in vivo by outer surface protein A antibody. J Immunol 2001; 166:7398-403. [PMID: 11390491 DOI: 10.4049/jimmunol.166.12.7398] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Borrelia burgdorferi outer surface protein (Osp) A is preferentially expressed by spirochetes in the Ixodes scapularis gut and facilitates pathogen-vector adherence in vitro. Here we examined B. burgdorferi-tick interactions in vivo by using Abs directed against OspA from each of the three major B. burgdorferi sensu lato genospecies: B. burgdorferi sensu stricto, Borrelia afzelii, and Borrelia garinii. Abs directed against B. burgdorferi sensu stricto (isolate N40) destroy the spirochete and can protect mice from infection. In contrast, antisera raised against OspA from B. afzelii (isolate ACA-1) and B. garinii (isolate ZQ-1) bind to B. burgdorferi N40 but are not borreliacidal against the N40 isolate. Our present studies assess whether these selected OspA Abs interfere with B. burgdorferi-tick attachment in a murine model of Lyme disease with I. scapularis. We examined engorged ticks that had fed on B. burgdorferi N40-infected scid mice previously treated with OspA (N40, ACA-1, ZQ-1, or mAb C3.78) or control Abs. OspA-N40 antisera or mAb C3.78 destroyed B. burgdorferi N40 within the engorged ticks. In contrast, treatment of mice with OspA-ACA-1 and OspA-ZQ-1 antisera did not kill B. burgdorferi N40 within the ticks but did effectively interfere with B. burgdorferi-I. scapularis adherence, thereby preventing efficient colonization of the vector. These studies show that nonborreliacidal OspA Abs can inhibit B. burgdorferi attachment to the tick gut, highlighting the importance of OspA in spirochete-arthropod interactions in vivo.
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MESH Headings
- Animals
- Anti-Bacterial Agents/administration & dosage
- Anti-Bacterial Agents/chemistry
- Anti-Bacterial Agents/metabolism
- Antibodies, Bacterial/administration & dosage
- Antibodies, Bacterial/chemistry
- Antibodies, Bacterial/metabolism
- Antibodies, Monoclonal/administration & dosage
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal/metabolism
- Antigens, Surface/genetics
- Antigens, Surface/immunology
- Antigens, Surface/metabolism
- Bacterial Outer Membrane Proteins/genetics
- Bacterial Outer Membrane Proteins/immunology
- Bacterial Outer Membrane Proteins/metabolism
- Bacterial Vaccines
- Binding Sites, Antibody/genetics
- Borrelia burgdorferi Group/genetics
- Borrelia burgdorferi Group/immunology
- Digestive System/immunology
- Digestive System/metabolism
- Digestive System/microbiology
- Epitopes/genetics
- Epitopes/metabolism
- Female
- Immune Sera/administration & dosage
- Immune Sera/chemistry
- Immune Sera/metabolism
- Injections, Intraperitoneal
- Injections, Subcutaneous
- Ixodes/anatomy & histology
- Ixodes/immunology
- Ixodes/metabolism
- Ixodes/microbiology
- Lipoproteins
- Lyme Disease/immunology
- Lyme Disease/prevention & control
- Lyme Disease Vaccines/genetics
- Lyme Disease Vaccines/immunology
- Lyme Disease Vaccines/metabolism
- Mice
- Mice, SCID
- Mutation
- Protein Structure, Tertiary/genetics
- Recombinant Proteins/immunology
- Recombinant Proteins/metabolism
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Affiliation(s)
- U Pal
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520. SmithKline Beecham Biologicals, Rixensart, Belgium
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Pal U, de Silva AM, Montgomery RR, Fish D, Anguita J, Anderson JF, Lobet Y, Fikrig E. Attachment of Borrelia burgdorferi within Ixodes scapularis mediated by outer surface protein A. J Clin Invest 2000; 106:561-9. [PMID: 10953031 PMCID: PMC380253 DOI: 10.1172/jci9427] [Citation(s) in RCA: 183] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Borrelia burgdorferi outer surface protein (Osp) A has been used as a Lyme disease vaccine that blocks transmission: OspA antibodies of immune hosts enter ticks during blood feeding and destroy spirochetes before transmission to the host can occur. B. burgdorferi produce OspA in the gut of unfed Ixodes scapularis ticks, and many spirochetes repress OspA production during the feeding process. This preferential expression suggests that OspA may have an important function in the vector. Here we show that OspA mediates spirochete attachment to the tick gut by binding to an I. scapularis protein. The binding domains reside in the central region and COOH-terminus of OspA. OspA also binds to itself, suggesting that spirochete-spirochete interactions may further facilitate adherence in the gut. OspA-mediated attachment in the tick provides a possible mechanism for how stage-specific protein expression can contribute to pathogenesis during the B. burgdorferi natural cycle.
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Affiliation(s)
- U Pal
- Section of Rheumatology, Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut 06520-8031, USA
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Abstract
Developmental alterations in the expression of glial fibrillary acidic protein (GFAP) and alpha-tubulin were examined at the level of mRNA and protein in human fetal brain between weeks 13-23 of gestation. Except for a transient increase at week 15, GFAP expression in the cytoskeletal (CSK) fraction was low until week 17, when it increased steadily to week 23, corresponding to the phase of glial proliferation. The developmental profile of alpha-tubulin in the CSK fraction displayed a biphasic pattern, with an initial rise between weeks 13-16 coinciding with the early phase of neuroblast multiplication, and a second rise between weeks 17-23 corresponding to the phase of glial proliferation. No significant difference in the spatial distribution of alpha-tubulin was found in different region of brain but GFAP expression varied with a higher level in cerebellum than that in cerebrum at late midgestation.
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Affiliation(s)
- U Pal
- Neurobiology Division, Indian Institute of Chemical Biology, Jadavpur, Calcutta
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Abstract
Automatic cell segmentation has various application potentials in cytometry and histometry. In this paper, an automatic cluster (touching) cell segmentation approach using the dominant contour feature points has been presented. Dominant feature points are the locations of indentation on the contour of the cluster. First, dominant feature points on the contour of the cluster are detected by distance profile. Next, using shape features of the cells, these feature points are selected for segmentation. We compared the results of the proposed method with manual segmentation and observed that the method has an overall accuracy about to 82%.
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Affiliation(s)
- U Pal
- GSF National Research Center for Environment and Health, Institute of Biomathematics and Biometry, Neuherberg, Germany
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Abstract
The effect of thyroid hormones (THs) on the expression of actin gene during fetal human brain development and the period of sensitivity to the hormones have been investigated. Developmental profile of actin in the cytoskeletal (CSK) and noncytoskeletal (non-CSK) fractions in the fetal cerebra showed a pronounced rise in the level of CSK actin at weeks 17-19. Northern blot analysis also revealed a sharp rise in the level of actin mRNA at weeks 16-18, temporally coinciding with the period of rise of THs and peak expression of TH receptors in the fetal brain. In organ cultures of weeks 13-23 fetal cerebra, THs elicited a general stimulation of CSK proteins at all ages studied with a preferential effect on actin at weeks 17-19. During this period, THs also stimulated the rate of synthesis of actin. Kinetics of induction of actin by TH in the non-CSK and CSK fractions in organ cultures of week 17 fetal cerebra showed an increased level of actin in both fractions within 1 h. Subsequently (at 5 and 18 h), induction was evident only in the insoluble CSK fraction, suggesting an effect of the hormone on the intracellular distribution of actin between the soluble non-CSK fraction and the insoluble CSK fraction. Correspondingly, in cultures of week 17 fetal cerebra, THs elicited an increase in actin mRNA level within 30 min of hormonal exposure. The overall results suggest that THs regulate the expression of actin gene by stimulating the rate of synthesis as well as intracellular distribution of actin during the mid phase of the second trimester of gestation.
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Affiliation(s)
- U Pal
- Neurobiology Division, Indian Institute of Chemical Biology, Calcutta, India
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