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Abstract
G-quadruplex (G4) binding proteins regulate important biological processes, but their interaction networks are poorly understood. We report the first use of G4 as a warhead of a proteolysis-targeting chimera (G4-PROTAC) for targeted degradation of a G4-binding protein (RHAU/DHX36). G4-PROTAC provides a new way to explore G4-protein networks and to develop potential therapeutics.
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Affiliation(s)
- Kiran M Patil
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
| | - Danielle Chin
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
| | - Hui Ling Seah
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
| | - Qi Shi
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
| | - Kah Wai Lim
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore.
| | - Anh Tuân Phan
- School of Physical and Mathematical Sciences, Nanyang Technological University, 637371, Singapore. .,NTU Institute of Structural Biology, Nanyang Technological University, 636921, Singapore
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2
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Tai Tay DJ, Song Y, Peng B, Toh TB, Hooi L, Kaixin Toh DF, Hong H, Tang SJ, Han J, Gan WL, Man Chan TH, Krishna MS, Patil KM, Maraswami M, Loh TP, Dan YY, Zhou L, Bonney GK, Kah-Hoe Chow P, Chen G, Kai-Hua Chow E, Le MT, Chen L. Targeting RNA Editing of Antizyme Inhibitor 1: a Potential Oligonucleotide-Based Antisense Therapy for Cancer. Mol Ther 2021; 29:3258-3273. [PMID: 33974998 PMCID: PMC8571177 DOI: 10.1016/j.ymthe.2021.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [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: 09/14/2020] [Revised: 03/29/2021] [Accepted: 05/05/2021] [Indexed: 11/26/2022] Open
Abstract
Dysregulated adenosine-to-inosine (A-to-I) RNA editing is implicated in various cancers. However, no available RNA editing inhibitors have so far been developed to inhibit cancer-associated RNA editing events. Here, we decipher the RNA secondary structure of antizyme inhibitor 1 (AZIN1), one of the best-studied A-to-I editing targets in cancer, by locating its editing site complementary sequence (ECS) at the 3′ end of exon 12. Chemically modified antisense oligonucleotides (ASOs) that target the editing region of AZIN1 caused a substantial exon 11 skipping, whereas ECS-targeting ASOs effectively abolished AZIN1 editing without affecting splicing and translation. We demonstrate that complete 2′-O-methyl (2′-O-Me) sugar ring modification in combination with partial phosphorothioate (PS) backbone modification may be an optimal chemistry for editing inhibition. ASO3.2, which targets the ECS, specifically inhibits cancer cell viability in vitro and tumor incidence and growth in xenograft models. Our results demonstrate that this AZIN1-targeting, ASO-based therapeutics may be applicable to a wide range of tumor types.
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Affiliation(s)
- Daryl Jin Tai Tay
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Yangyang Song
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Boya Peng
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117600; Department of Biomedical Sciences, School of Veterinary Medicine and Life Sciences, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - Tan Boon Toh
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; The N.1 Institute for Health (N.1), 28 Medical Dr, Singapore 117456
| | - Lissa Hooi
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - HuiQi Hong
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 2 Medical Drive, Singapore 117593
| | - Sze Jing Tang
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Jian Han
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Wei Liang Gan
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Tim Hon Man Chan
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Manikantha Maraswami
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Teck Peng Loh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Yock Young Dan
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; Division of Gastroenterology and Hepatology, National University Health System, Singapore 119228
| | - Lei Zhou
- Division of Gastroenterology and Hepatology, National University Health System, Singapore 119228
| | - Glenn Kunnath Bonney
- Division of Hepatobiliary and Liver Transplantation Surgery, National University Health System, Singapore 119228
| | - Pierce Kah-Hoe Chow
- Division of Surgical Oncology, National Cancer Centre Singapore, Singapore 169610; Department of Hepato-Pancreato-Biliary and Transplant Surgery, Singapore General Hospital, Singapore 169608; Duke-NUS Medical School, Singapore 169857
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore, 21 Nanyang Link, Singapore 637371
| | - Edward Kai-Hua Chow
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117600; The N.1 Institute for Health (N.1), 28 Medical Dr, Singapore 117456
| | - Minh Tn Le
- Department of Pharmacology, Yong Loo Lin School of Medicine, National University of Singapore, 16 Medical Drive, Singapore 117600; Department of Biomedical Sciences, School of Veterinary Medicine and Life Sciences, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong
| | - Leilei Chen
- Cancer Science Institute of Singapore, National University of Singapore, 14 Medical Drive, Singapore 117599; Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, 4 Medical Drive, Singapore 117594.
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3
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Ong AAL, Tan J, Bhadra M, Dezanet C, Patil KM, Chong MS, Kierzek R, Decout JL, Roca X, Chen G. RNA Secondary Structure-Based Design of Antisense Peptide Nucleic Acids for Modulating Disease-Associated Aberrant Tau Pre-mRNA Alternative Splicing. Molecules 2019; 24:molecules24163020. [PMID: 31434312 PMCID: PMC6720520 DOI: 10.3390/molecules24163020] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 08/14/2019] [Accepted: 08/19/2019] [Indexed: 12/18/2022] Open
Abstract
Alternative splicing of tau pre-mRNA is regulated by a 5' splice site (5'ss) hairpin present at the exon 10-intron 10 junction. Single mutations within the hairpin sequence alter hairpin structural stability and/or the binding of splicing factors, resulting in disease-causing aberrant splicing of exon 10. The hairpin structure contains about seven stably formed base pairs and thus may be suitable for targeting through antisense strands. Here, we used antisense peptide nucleic acids (asPNAs) to probe and target the tau pre-mRNA exon 10 5'ss hairpin structure through strand invasion. We characterized by electrophoretic mobility shift assay the binding of the designed asPNAs to model tau splice site hairpins. The relatively short (10-15 mer) asPNAs showed nanomolar binding to wild-type hairpins as well as a disease-causing mutant hairpin C+19G, albeit with reduced binding strength. Thus, the structural stabilizing effect of C+19G mutation could be revealed by asPNA binding. In addition, our cell culture minigene splicing assay data revealed that application of an asPNA targeting the 3' arm of the hairpin resulted in an increased exon 10 inclusion level for the disease-associated mutant C+19G, probably by exposing the 5'ss as well as inhibiting the binding of protein factors to the intronic spicing silencer. On the contrary, the application of asPNAs targeting the 5' arm of the hairpin caused an increased exon 10 exclusion for a disease-associated mutant C+14U, mainly by blocking the 5'ss. PNAs could enter cells through conjugation with amino sugar neamine or by cotransfection with minigene plasmids using a commercially available transfection reagent.
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Affiliation(s)
- Alan Ann Lerk Ong
- NTU Institute for Health Technologies (HeathTech NTU), Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Jiazi Tan
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Malini Bhadra
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Clément Dezanet
- University Grenoble Alpes/CNRS, Département de Pharmacochimie Moléculaire, ICMG FR 2607, UMR 5063, 470 Rue de la Chimie, F-38041 Grenoble, France
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore
| | - Mei Sian Chong
- Geriatic Education & Research Institute, 2 Yishun Central 2, Singapore 768024, Singapore
| | - Ryszard Kierzek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Jean-Luc Decout
- University Grenoble Alpes/CNRS, Département de Pharmacochimie Moléculaire, ICMG FR 2607, UMR 5063, 470 Rue de la Chimie, F-38041 Grenoble, France
| | - Xavier Roca
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371, Singapore.
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4
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Ong AAL, Toh DFK, Krishna MS, Patil KM, Okamura K, Chen G. Incorporating 2-Thiouracil into Short Double-Stranded RNA-Binding Peptide Nucleic Acids for Enhanced Recognition of A-U Pairs and for Targeting a MicroRNA Hairpin Precursor. Biochemistry 2019; 58:3444-3453. [PMID: 31318532 DOI: 10.1021/acs.biochem.9b00521] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Chemically modified short peptide nucleic acids (PNAs) recognize RNA duplexes under near physiological conditions by major-groove PNA·RNA-RNA triplex formation and show great promise for the development of RNA-targeting probes and therapeutics. Thymine (T) and uracil (U) are often incorporated into PNAs to recognize A-U pairs through major-groove T·A-U and U·A-U base triple formation. Incorporation of a modified nucleobase, 2-thiouracil (s2U), into triplex-forming oligonucleotides stabilizes both DNA and RNA triplexes. Thiolation of uracil causes a decrease in the dehydration energy penalty for triplex formation as well as a decrease in the pKa of the N3 atom, which may result in improved hydrogen bonding in addition to enhanced base stacking interactions, similar to the previously reported thiolation effect of pseudoisocytosine (J to L substitution). Here, we incorporated s2U into short PNAs, followed by binding studies of a series of s2U-modified PNAs. We demonstrated by nondenaturing polyacrylamide gel electrophoresis and thermal melting experiments that s2U and L incorporated into dsRNA-binding PNAs (dbPNAs) enhance the recognition of A-U and G-C pairs, respectively, in RNA duplexes in a position-independent manner, with no appreciable binding to the DNA duplex. Combining s2U and L modifications in dbPNAs facilitates enhanced recognition of dsRNAs and maintains selective binding to dsRNAs over ssRNAs. We further demonstrated through a cell-free assay the application of the s2U- and L-modified dbPNAs (8-mer, with a molecular mass of ∼2.3 kDa) in the inhibition of the pre-microRNA-198 maturation in a substrate-specific manner. Thus, s2U-modified dbPNAs may be generally useful for the enhanced and selective recognition of RNA duplexes and for the regulation of RNA functions.
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Affiliation(s)
- Alan Ann Lerk Ong
- NTU Institute for Health Technologies (HeathTech NTU), Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Drive , Singapore 637553.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Katsutomo Okamura
- Division of Biological Sciences , Nara Institute of Science and Technology , 8916-5 Takayama , Ikoma , Nara 630-0192 , Japan
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
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5
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Wang Y, Patil KM, Yan S, Zhang P, Guo W, Wang Y, Chen H, Gillingham D, Huang S. Nanopore Sequencing Accurately Identifies the Mutagenic DNA Lesion O
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‐Carboxymethyl Guanine and Reveals Its Behavior in Replication. Angew Chem Int Ed Engl 2019; 58:8432-8436. [DOI: 10.1002/anie.201902521] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Indexed: 01/13/2023]
Affiliation(s)
- Yu Wang
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Kiran M. Patil
- Department of ChemistryUniversity of Basel CH-4056 Basel Switzerland
| | - Shuanghong Yan
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Panke Zhang
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Weiming Guo
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Yuqin Wang
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Hong‐Yuan Chen
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Dennis Gillingham
- Department of ChemistryUniversity of Basel CH-4056 Basel Switzerland
| | - Shuo Huang
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
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6
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Wang Y, Patil KM, Yan S, Zhang P, Guo W, Wang Y, Chen H, Gillingham D, Huang S. Nanopore Sequencing Accurately Identifies the Mutagenic DNA Lesion O
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‐Carboxymethyl Guanine and Reveals Its Behavior in Replication. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201902521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Yu Wang
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Kiran M. Patil
- Department of ChemistryUniversity of Basel CH-4056 Basel Switzerland
| | - Shuanghong Yan
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Panke Zhang
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Weiming Guo
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Yuqin Wang
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Hong‐Yuan Chen
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
| | - Dennis Gillingham
- Department of ChemistryUniversity of Basel CH-4056 Basel Switzerland
| | - Shuo Huang
- School of Chemistry and Chemical EngineeringState Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life SciencesNanjing University 210023 China
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7
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Ong AAL, Toh DFK, Patil KM, Meng Z, Yuan Z, Krishna MS, Devi G, Haruehanroengra P, Lu Y, Xia K, Okamura K, Sheng J, Chen G. General Recognition of U-G, U-A, and C-G Pairs by Double-Stranded RNA-Binding PNAs Incorporated with an Artificial Nucleobase. Biochemistry 2019; 58:1319-1331. [PMID: 30775913 DOI: 10.1021/acs.biochem.8b01313] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Chemically modified peptide nucleic acids (PNAs) show great promise in the recognition of RNA duplexes by major-groove PNA·RNA-RNA triplex formation. Triplex formation is favored for RNA duplexes with a purine tract within one of the RNA duplex strands, and is severely destabilized if the purine tract is interrupted by pyrimidine residues. Here, we report the synthesis of a PNA monomer incorporated with an artificial nucleobase S, followed by the binding studies of a series of S-modified PNAs. Our data suggest that an S residue incorporated into short 8-mer dsRNA-binding PNAs (dbPNAs) can recognize internal Watson-Crick C-G and U-A, and wobble U-G base pairs (but not G-C, A-U, and G-U pairs) in RNA duplexes. The short S-modified PNAs show no appreciable binding to DNA duplexes or single-stranded RNAs. Interestingly, replacement of the C residue in an S·C-G triple with a 5-methyl C results in the disruption of the triplex, probably due to a steric clash between S and 5-methyl C. Previously reported PNA E base shows recognition of U-A and A-U pairs, but not a U-G pair. Thus, S-modified dbPNAs may be uniquely useful for the general recognition of RNA U-G, U-A, and C-G pairs. Shortening the succinyl linker of our PNA S monomer by one carbon atom to have a malonyl linker causes a severe destabilization of triplex formation. Our experimental and modeling data indicate that part of the succinyl moiety in a PNA S monomer may serve to expand the S base forming stacking interactions with adjacent PNA bases.
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Affiliation(s)
- Alan Ann Lerk Ong
- NTU Institute for Health Technologies (HeathTech NTU), Interdisciplinary Graduate School , Nanyang Technological University , 50 Nanyang Drive , Singapore 637553.,Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Zhenyu Meng
- Division of Mathematical Sciences, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Zhen Yuan
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Gitali Devi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Phensinee Haruehanroengra
- Department of Chemistry and The RNA Institute , University at Albany, State University of New York , 1400 Washington Avenue , Albany , New York 12222 , United States
| | - Yunpeng Lu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Kelin Xia
- Division of Mathematical Sciences, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
| | - Katsutomo Okamura
- Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore , Singapore , 117604.,School of Biological Sciences , Nanyang Technological University , 60 Nanyang Drive , Singapore , 639798
| | - Jia Sheng
- Department of Chemistry and The RNA Institute , University at Albany, State University of New York , 1400 Washington Avenue , Albany , New York 12222 , United States
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , Singapore 637371
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8
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Kesy J, Patil KM, Kumar SR, Shu Z, Yong HY, Zimmermann L, Ong AAL, Toh DFK, Krishna MS, Yang L, Decout JL, Luo D, Prabakaran M, Chen G, Kierzek E. A Short Chemically Modified dsRNA-Binding PNA (dbPNA) Inhibits Influenza Viral Replication by Targeting Viral RNA Panhandle Structure. Bioconjug Chem 2019; 30:931-943. [PMID: 30721034 DOI: 10.1021/acs.bioconjchem.9b00039] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
RNAs play critical roles in diverse catalytic and regulatory biological processes and are emerging as important disease biomarkers and therapeutic targets. Thus, developing chemical compounds for targeting any desired RNA structures has great potential in biomedical applications. The viral and cellular RNA sequence and structure databases lay the groundwork for developing RNA-binding chemical ligands through the recognition of both RNA sequence and RNA structure. Influenza A virion consists of eight segments of negative-strand viral RNA (vRNA), all of which contain a highly conserved panhandle duplex structure formed between the first 13 nucleotides at the 5' end and the last 12 nucleotides at the 3' end. Here, we report our binding and cell culture anti-influenza assays of a short 10-mer chemically modified double-stranded RNA (dsRNA)-binding peptide nucleic acid (PNA) designed to bind to the panhandle duplex structure through novel major-groove PNA·RNA2 triplex formation. We demonstrated that incorporation of chemically modified PNA residues thio-pseudoisocytosine (L) and guanidine-modified 5-methyl cytosine (Q) previously developed by us facilitates the sequence-specific recognition of Watson-Crick G-C and C-G pairs, respectively, at physiologically relevant conditions. Significantly, the chemically modified dsRNA-binding PNA (dbPNA) shows selective binding to the dsRNA region in panhandle structure over a single-stranded RNA (ssRNA) and a dsDNA containing the same sequence. The panhandle structure is not accessible to traditional antisense DNA or RNA with a similar length. Conjugation of the dbPNA with an aminosugar neamine enhances the cellular uptake. We observed that 2-5 μM dbPNA-neamine conjugate results in a significant reduction of viral replication. In addition, the 10-mer dbPNA inhibits innate immune receptor RIG-I binding to panhandle structure and thus RIG-I ATPase activity. These findings would provide the foundation for developing novel dbPNAs for the detection of influenza viral RNAs and therapeutics with optimal antiviral and immunomodulatory activities.
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Affiliation(s)
- Julita Kesy
- Institute of Bioorganic Chemistry, Polish Academy of Sciences , Noskowskiego 12/14 , 61-704 Poznan , Poland
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | | | - Zhiyu Shu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Hui Yee Yong
- Lee Kong Chian School of Medicine , Nanyang Technological University , EMB 03-07, 59 Nanyang Drive , 636921 , Singapore.,NTU Institute of Structural Biology , Nanyang Technological University , EMB 06-01, 59 Nanyang Drive , 636921 , Singapore.,School of Biological Sciences , Nanyang Technological University , 60 Nanyang Drive , 636921 , Singapore
| | - Louis Zimmermann
- Département de Pharmacochimie Moléculaire , University Grenoble Alpes, CNRS, ICMG FR 2607, UMR 5063 , 470 Rue de la Chimie , F-38041 Grenoble , France
| | - Alan Ann Lerk Ong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Lixia Yang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Jean-Luc Decout
- Département de Pharmacochimie Moléculaire , University Grenoble Alpes, CNRS, ICMG FR 2607, UMR 5063 , 470 Rue de la Chimie , F-38041 Grenoble , France
| | - Dahai Luo
- Lee Kong Chian School of Medicine , Nanyang Technological University , EMB 03-07, 59 Nanyang Drive , 636921 , Singapore.,NTU Institute of Structural Biology , Nanyang Technological University , EMB 06-01, 59 Nanyang Drive , 636921 , Singapore
| | - Mookkan Prabakaran
- Temasek Life Science Laboratory, 1 Research Link , National University of Singapore , 117604 , Singapore
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences , Nanyang Technological University , 21 Nanyang Link , 637371 , Singapore
| | - Elzbieta Kierzek
- Institute of Bioorganic Chemistry, Polish Academy of Sciences , Noskowskiego 12/14 , 61-704 Poznan , Poland
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9
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Räz MH, Sandell ES, Patil KM, Gillingham DG, Sturla SJ. High Sensitivity of Human Translesion DNA Synthesis Polymerase κ to Variation in O 6-Carboxymethylguanine Structures. ACS Chem Biol 2019; 14:214-222. [PMID: 30645109 DOI: 10.1021/acschembio.8b00802] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Carboxymethylation of DNA, including the formation of the DNA adduct O6-carboxymethylguanine ( O6-CMG), is associated with lifestyle factors, such as diet. It can impede replicative polymerases (Pols) and lead to replication fork stalling, or an alternative means for replication to proceed by translesion DNA synthesis (TLS). TLS requires specialized DNA Pols characterized by open and preformed active sites capable of preferential bypass of alkylated DNA adducts but that have high error rates, leading to mutations. Human TLS Pols can bypass O6-CMG with varying degrees of accuracy, but it is not known how the chemical structure of the O6-CMG adduct influences polymerase proficiency or fidelity. To better understand how adduct structure determines dNTP selection at lesion sites, we prepared DNA templates with a series of O6-CMG structural analogs and compared the primer extension patterns of Y- and X-family Pols in response to these modifications. The results indicate that the structure of the DNA adduct had a striking effect on dNTP selection by Pol κ and that an increased steric size influences the fidelity of Pol η, whereas Pol ι and β function were only marginally affected. To test the hypothesis that specific hydrogen bonding interactions between the templating base and the incoming dNTP are a basis of this selection, we modeled the structural analogs with incoming dNTP in the Pol κ active site. These data indicate that the base pairing geometry and stabilization by a dense hydrogen bonding network are important molecular features for dNTP incorporation, providing a basis for understanding error-free bypass of O6-CMG by Pol κ.
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Affiliation(s)
- Michael H. Räz
- Department of Health Sciences and Technology, ETH Zürich, Schmelzbergstrasse 9, 8092, Zürich, Switzerland
| | - Emma S. Sandell
- Department of Health Sciences and Technology, ETH Zürich, Schmelzbergstrasse 9, 8092, Zürich, Switzerland
| | - Kiran M. Patil
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Dennis G. Gillingham
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland
| | - Shana J. Sturla
- Department of Health Sciences and Technology, ETH Zürich, Schmelzbergstrasse 9, 8092, Zürich, Switzerland
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10
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Patil KM, Toh DFK, Yuan Z, Meng Z, Shu Z, Zhang H, Ong A, Krishna MS, Lu L, Lu Y, Chen G. Incorporating uracil and 5-halouracils into short peptide nucleic acids for enhanced recognition of A-U pairs in dsRNAs. Nucleic Acids Res 2018; 46:7506-7521. [PMID: 30011039 PMCID: PMC6125629 DOI: 10.1093/nar/gky631] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 06/09/2018] [Accepted: 07/03/2018] [Indexed: 01/16/2023] Open
Abstract
Double-stranded RNA (dsRNA) structures form triplexes and RNA-protein complexes through binding to single-stranded RNA (ssRNA) regions and proteins, respectively, for diverse biological functions. Hence, targeting dsRNAs through major-groove triplex formation is a promising strategy for the development of chemical probes and potential therapeutics. Short (e.g., 6-10 mer) chemically-modified Peptide Nucleic Acids (PNAs) have been developed that bind to dsRNAs sequence specifically at physiological conditions. For example, a PNA incorporating a modified base thio-pseudoisocytosine (L) has an enhanced recognition of a G-C pair in an RNA duplex through major-groove L·G-C base triple formation at physiological pH, with reduced pH dependence as observed for C+·G-C base triple formation. Currently, an unmodified T base is often incorporated into PNAs to recognize a Watson-Crick A-U pair through major-groove T·A-U base triple formation. A substitution of the 5-methyl group in T by hydrogen and halogen atoms (F, Cl, Br, and I) causes a decrease of the pKa of N3 nitrogen atom, which may result in improved hydrogen bonding in addition to enhanced base stacking interactions. Here, we synthesized a series of PNAs incorporating uracil and halouracils, followed by binding studies by non-denaturing polyacrylamide gel electrophoresis, circular dichroism, and thermal melting. Our results suggest that replacing T with uracil and halouracils may enhance the recognition of an A-U pair by PNA·RNA2 triplex formation in a sequence-dependent manner, underscoring the importance of local stacking interactions. Incorporating bromouracils and chlorouracils into a PNA results in a significantly reduced pH dependence of triplex formation even for PNAs containing C bases, likely due to an upshift of the apparent pKa of N3 atoms of C bases. Thus, halogenation and other chemical modifications may be utilized to enhance hydrogen bonding of the adjacent base triples and thus triplex formation. Furthermore, our experimental and computational modelling data suggest that PNA·RNA2 triplexes may be stabilized by incorporating a BrUL step but not an LBrU step, in dsRNA-binding PNAs.
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Affiliation(s)
- Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Zhen Yuan
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Zhenyu Meng
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Zhiyu Shu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Haiping Zhang
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Alan Ann Lerk Ong
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Manchugondanahalli S Krishna
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551
| | - Yunpeng Lu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
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11
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Puah RY, Jia H, Maraswami M, Toh DFK, Ero R, Yang L, Patil KM, Ong AAL, Krishna MS, Sun R, Tong C, Huang M, Chen X, Loh TP, Gao YG, Liu DX, Chen G. Selective Binding to mRNA Duplex Regions by Chemically Modified Peptide Nucleic Acids Stimulates Ribosomal Frameshifting. Biochemistry 2017; 57:149-159. [PMID: 29116759 DOI: 10.1021/acs.biochem.7b00744] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Minus-one programmed ribosomal frameshifting (-1 PRF) allows the precise maintenance of the ratio between viral proteins and is involved in the regulation of the half-lives of cellular mRNAs. Minus-one ribosomal frameshifting is activated by several stimulatory elements such as a heptameric slippery sequence (X XXY YYZ) and an mRNA secondary structure (hairpin or pseudoknot) that is positioned 2-8 nucleotides downstream from the slippery site. Upon -1 RF, the ribosomal reading frame is shifted from the normal zero frame to the -1 frame with the heptameric slippery sequence decoded as XXX YYY Z instead of X XXY YYZ. Our research group has developed chemically modified peptide nucleic acid (PNA) L and Q monomers to recognize G-C and C-G Watson-Crick base pairs, respectively, through major-groove parallel PNA·RNA-RNA triplex formation. L- and Q-incorporated PNAs show selective binding to double-stranded RNAs (dsRNAs) over single-stranded RNAs (ssRNAs). The sequence specificity and structural selectivity of L- and Q-modified PNAs may allow the precise targeting of desired viral and cellular RNA structures, and thus may serve as valuable biological tools for mechanistic studies and potential therapeutics for fighting diseases. Here, for the first time, we demonstrate by cell-free in vitro translation assays using rabbit reticulocyte lysate that the dsRNA-specific chemically modified PNAs targeting model mRNA hairpins stimulate -1 RF (from 2% to 32%). An unmodified control PNA, however, shows nonspecific inhibition of translation. Our results suggest that the modified dsRNA-binding PNAs may be advantageous for targeting structured RNAs.
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Affiliation(s)
| | | | | | | | - Rya Ero
- School of Biological Sciences, Nanyang Technological University , 60 Nanyang Drive, Singapore 637551
| | | | | | | | | | | | | | - Mei Huang
- School of Biological Sciences, Nanyang Technological University , 60 Nanyang Drive, Singapore 637551
| | | | | | - Yong-Gui Gao
- School of Biological Sciences, Nanyang Technological University , 60 Nanyang Drive, Singapore 637551
| | - Ding Xiang Liu
- School of Biological Sciences, Nanyang Technological University , 60 Nanyang Drive, Singapore 637551.,Guangdong Province Key Laboratory Microbial Signals & Disease Co, and Integrative Microbiology Research Centre, South China Agricultural University , Guangzhou 510642, Guangdong, People's Republic of China
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12
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Toh DFK, Patil KM, Chen G. Sequence-specific and Selective Recognition of Double-stranded RNAs over Single-stranded RNAs by Chemically Modified Peptide Nucleic Acids. J Vis Exp 2017:56221. [PMID: 28994801 PMCID: PMC5752312 DOI: 10.3791/56221] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
RNAs are emerging as important biomarkers and therapeutic targets. Thus, there is great potential in developing chemical probes and therapeutic ligands for the recognition of RNA sequence and structure. Chemically modified Peptide Nucleic Acid (PNA) oligomers have been recently developed that can recognize RNA duplexes in a sequence-specific manner. PNAs are chemically stable with a neutral peptide-like backbone. PNAs can be synthesized relatively easily by the manual Boc-chemistry solid-phase peptide synthesis method. PNAs are purified by reverse-phase HPLC, followed by molecular weight characterization by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF). Non-denaturing polyacrylamide gel electrophoresis (PAGE) technique facilitates the imaging of the triplex formation, because carefully designed free RNA duplex constructs and PNA bound triplexes often show different migration rates. Non-denaturing PAGE with ethidium bromide post staining is often an easy and informative technique for characterizing the binding affinities and specificities of PNA oligomers. Typically, multiple RNA hairpins or duplexes with single base pair mutations can be used to characterize PNA binding properties, such as binding affinities and specificities. 2-Aminopurine is an isomer of adenine (6-aminopurine); the 2-aminopurine fluorescence intensity is sensitive to local structural environment changes, and is suitable for the monitoring of triplex formation with the 2-aminopurine residue incorporated near the PNA binding site. 2-Aminopurine fluorescence titration can also be used to confirm the binding selectivity of modified PNAs towards targeted double-stranded RNAs (dsRNAs) over single-stranded RNAs (ssRNAs). UV-absorbance-detected thermal melting experiments allow the measurement of the thermal stability of PNA-RNA duplexes and PNA·RNA2 triplexes. Here, we describe the synthesis and purification of PNA oligomers incorporating modified residues, and describe biochemical and biophysical methods for characterization of the recognition of RNA duplexes by the modified PNAs.
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Affiliation(s)
- Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University;
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13
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Toh DFK, Devi G, Patil KM, Qu Q, Maraswami M, Xiao Y, Loh TP, Zhao Y, Chen G. Incorporating a guanidine-modified cytosine base into triplex-forming PNAs for the recognition of a C-G pyrimidine-purine inversion site of an RNA duplex. Nucleic Acids Res 2016; 44:9071-9082. [PMID: 27596599 PMCID: PMC5100590 DOI: 10.1093/nar/gkw778] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 08/24/2016] [Indexed: 12/11/2022] Open
Abstract
RNA duplex regions are often involved in tertiary interactions and protein binding and thus there is great potential in developing ligands that sequence-specifically bind to RNA duplexes. We have developed a convenient synthesis method for a modified peptide nucleic acid (PNA) monomer with a guanidine-modified 5-methyl cytosine base. We demonstrated by gel electrophoresis, fluorescence and thermal melting experiments that short PNAs incorporating the modified residue show high binding affinity and sequence specificity in the recognition of an RNA duplex containing an internal inverted Watson-Crick C-G base pair. Remarkably, the relatively short PNAs show no appreciable binding to DNA duplexes or single-stranded RNAs. The attached guanidine group stabilizes the base triple through hydrogen bonding with the G base in a C-G pair. Selective binding towards an RNA duplex over a single-stranded RNA can be rationalized by the fact that alkylation of the amine of a 5-methyl C base blocks the Watson-Crick edge. PNAs incorporating multiple guanidine-modified cytosine residues are able to enter HeLa cells without any transfection agent.
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Affiliation(s)
- Desiree-Faye Kaixin Toh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Gitali Devi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Kiran M Patil
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Qiuyu Qu
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Manikantha Maraswami
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Yunyun Xiao
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Teck Peng Loh
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Yanli Zhao
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
| | - Gang Chen
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371
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15
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Vij M, Natarajan P, Yadav AK, Patil KM, Pandey T, Gupta N, Santhiya D, Kumar VA, Fernandes M, Ganguli M. Efficient Cellular Entry of (r-x-r)-Type Carbamate–Plasmid DNA Complexes and Its Implication for Noninvasive Topical DNA Delivery to Skin. Mol Pharm 2016; 13:1779-90. [DOI: 10.1021/acs.molpharmaceut.5b00915] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Manika Vij
- Department
of Structural Biology, CSIR-Institute of Genomics and Integrative Biology, South
Campus, Mathura Road, New Delhi, India 110020
- Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, 2 Rafi Marg, New Delhi, India 110001
| | - Poornemaa Natarajan
- Department
of Structural Biology, CSIR-Institute of Genomics and Integrative Biology, South
Campus, Mathura Road, New Delhi, India 110020
| | - Amit K. Yadav
- CSIR-National Chemical Laboratory, Pune, Maharashtra, India 411008
| | - Kiran M. Patil
- CSIR-National Chemical Laboratory, Pune, Maharashtra, India 411008
| | - Tanuja Pandey
- Department
of Structural Biology, CSIR-Institute of Genomics and Integrative Biology, South
Campus, Mathura Road, New Delhi, India 110020
| | - Nidhi Gupta
- Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, New Delhi, India 110042
| | - Deenan Santhiya
- Delhi Technological University, Shahbad Daulatpur, Main Bawana Road, New Delhi, India 110042
| | | | | | - Munia Ganguli
- Department
of Structural Biology, CSIR-Institute of Genomics and Integrative Biology, South
Campus, Mathura Road, New Delhi, India 110020
- Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, 2 Rafi Marg, New Delhi, India 110001
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16
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Patil KM, Naik RJ, Rajpal, Fernandes M, Ganguli M, Kumar VA. Highly Efficient (R-X-R)-Type Carbamates as Molecular Transporters for Cellular Delivery. J Am Chem Soc 2012; 134:7196-9. [DOI: 10.1021/ja210026m] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kiran M. Patil
- Organic Chemistry
Division, National Chemical Laboratory,
Dr. Homi Bhabha Road,
Pune 411 008, India
| | - Rangeetha J. Naik
- Lab
No. 203, Institute of Genomics and Integrative Biology, Mall Road, Delhi
110 007, India
| | - Rajpal
- Lab
No. 203, Institute of Genomics and Integrative Biology, Mall Road, Delhi
110 007, India
| | - Moneesha Fernandes
- Organic Chemistry
Division, National Chemical Laboratory,
Dr. Homi Bhabha Road,
Pune 411 008, India
| | - Munia Ganguli
- Lab
No. 203, Institute of Genomics and Integrative Biology, Mall Road, Delhi
110 007, India
| | - Vaijayanti A. Kumar
- Organic Chemistry
Division, National Chemical Laboratory,
Dr. Homi Bhabha Road,
Pune 411 008, India
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17
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Charanya G, Patil KM, Narayanamurthy VB, Parivalavan R, Visvanathan K. Effect of foot sole hardness, thickness and footwear on foot pressure distribution parameters in diabetic neuropathy. Proc Inst Mech Eng H 2005; 218:431-43. [PMID: 15648667 DOI: 10.1243/0954411042632117] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [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: 11/18/2022]
Abstract
This paper presents details of the study undertaken to find the effects of foot sole hardness, thickness and footwear on walking-foot pressure distribution parameters (power ratio (PR)) in diabetic neuropathy. The foot sole hardness is characterized by Shore level. PR represents the ratio of high-frequency power to the total power in the power spectrum of the walking-foot pressure image distribution obtained from the optical pedobarograph. Spatial frequency distributions in the walking-foot pressure images were analysed to calculate the PR in each of the foot sole areas at different levels of foot sole sensation loss and mechanical and geometrical properties. The results show that the increase in PR in the upper foot sole Shore ranges (30-40) is 1.2-2.5 times the corresponding increase in lower Shore ranges (20-30) for some foot sole areas, implying a higher possibility of development of plantar ulcers when combined with deterioration of foot sole sensation. Plantar ulcers are found in feet with foot sole Shore values of 30, a sensation level of 45 mN and PR of 35; for Shore values of 40, sensation levels of 100 mN, with PR 52; and for Shore values above 40, sensation level > 100 mN with PR 58. Providing microcellular rubber insole footwear based on optimum hardness and thickness was found to be helpful in healing plantar ulcers in three to four weeks. Wearing preventive footwear for six months reduced hardness of the foot sole and PR values to near-normal values.
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Affiliation(s)
- G Charanya
- Biomedical Engineering Division, Department of Applied Mechanics, Indian Institute of Technology, Chennai, Madras-600036, India
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18
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Puri M, Patil KM, Balasubramanian V, Narayanamurthy VB. Texture analysis of foot sole soft tissue images in diabetic neuropathy using wavelet transform. Med Biol Eng Comput 2005; 43:756-63. [PMID: 16594303 DOI: 10.1007/bf02430954] [Citation(s) in RCA: 10] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The paper presents a new method of characterisation of texture changes in foot sole soft tissue ultrasound (US) images, as observed to occur in diabetic subjects, using wavelet transforms. US images of the soft tissue subcutaneous layer were taken with a 7.5 MHz linear transducer probe placed parallel to the skin surface. The foot sole hardness was characterised by Shore level. A 2D discrete wavelet transform was performed on the US images to extract features that encode the internal state of the foot sole soft tissue. The global energy feature computed at the output of each wavelet channel was found to achieve excellent delineation between the normal and the diabetic groups. An important finding was a strong correlation, in the order of 0.84 and above, between the feature values that reflect changes in the internal arrangement of the tissue, and the externally measurable hardening of the skin, characterised by the Shore levels, with the latter known to be high for diabetics. A comparison drawn between diabetic ulcer and non-ulcer groups established a change in the order of 122-311% in the textural parameter, as influenced by a corresponding 66.7-200% change in the respective Shore values. Thus US examination of foot sole soft tissue and its texture analysis may serve as sources of valuable information regarding the internal changes taking place with progressive hardening of the soft tissue and thereby help the clinician in taking appropriate preventive measures.
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Affiliation(s)
- M Puri
- Biomedical Engineering Division, Department of Applied Mechanics, Indian Institute of Technology, Madras
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Patil KM, Bodhankar SL. Simultaneous determination of lamotrigine, phenobarbitone, carbamazepine and phenytoin in human serum by high-performance liquid chromatography. J Pharm Biomed Anal 2005; 39:181-6. [PMID: 15927430 DOI: 10.1016/j.jpba.2005.02.045] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2004] [Revised: 01/30/2005] [Accepted: 02/25/2005] [Indexed: 11/16/2022]
Abstract
A simple reversed-phase high-performance liquid chromatography (HPLC) method was developed for the simultaneous estimation of the antiepileptic drugs (AEDs) lamotrigine (LTG), phenobarbitone (PB), carbamazepine (CBZ) and phenytoin (PHT) in human serum. The procedure involves extraction of the AEDs by mixing 200 microl of serum with 200mul of acetonitrile containing 10 microg/ml of pentobarbitone as internal standard (IS). After centrifugation, 10 microl of the supernatant was injected onto a NOVA PAK C-18 column (250 mm x 4.6mm, 5 microm Hypersil ODS) and eluted with a mobile phase consisting of phosphate buffer (10 mM)-methanol-acetonitrile-acetone in the ratio of 55:22:12:11 (v/v) adjusted to pH 7.0. A UV detector set at 210 nm was employed for detection. The AEDs were well resolved from the human serum constituents and the internal standard. The method can quantify LTG, PB, CBZ, and PHT at concentrations as low as 0.2 microg/ml. The method was quantitatively evaluated in terms of linearity, accuracy, precision, recovery, selectivity, sensitivity, and specificity. The method is simple, convenient, and suitable for the analysis of AEDs from human serum.
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Affiliation(s)
- K M Patil
- Department of Pharmacology, Bharati Vidyapeeth Deemed University, Poona College of Pharmacy, Pune, Maharashtra, India
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20
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Abstract
In diabetic neuropathic subjects, the hardness of foot sole soft tissue increases, and its thickness reduces, in different foot sole areas. Finite element analysis (FEA) of a three-dimensional two-arch model of the foot was performed to evaluate the effect of foot sole stresses on plantar ulcer development. Three sets of foot sole soft-tissue properties, i.e. isotropic (with control hardness value), diabetic isotropic (with higher hardness value) and anisotropic diabetic conditions, were simulated in the push-off phase, with decreasing foot sole soft-tissue thicknesses in the forefoot region, and the corresponding stresses were calculated. The results of the stress analyses for diabetic subject (anisotropic) foot models showed that, with non-uniformly increased hardness and decreased foot sole soft-tissue thickness, the normal and shear stresses at the foot sole increased (compared with control values) by 52.6% and 53.4%, respectively. Stress analyses also showed high ratios of gradients of normal and shear stresses of the order of 6.6 and 3.3 times the control values on the surface of the foot sole, and high relative values of stress gradients for normal and shear stresses of 6.25 and 4.35 times control values, respectively, between the foot sole surface and the adjacent inner layer of the foot sole, around a particular region of the foot sole with anisotropic properties. These ratios of high gradients and relative gradients of stresses due to changes in soft-tissue properties may be responsible for the development of plantar ulcers in diabetic neuropathic feet.
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Affiliation(s)
- V J Thomas
- Biomedical Engineering Division, Department of Applied Mechanics, Indian Institute of Technology, Madras, India
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21
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Prabhu KG, Patil KM, Srinivasan S. Diabetic feet at risk: a new method of analysis of walking foot pressure images at different levels of neuropathy for early detection of plantar ulcers. Med Biol Eng Comput 2001; 39:288-93. [PMID: 11465882 DOI: 10.1007/bf02345282] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [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: 10/24/2022]
Abstract
Studies were performed on a large number of diabetic patients with three levels of plantar sensation loss by analysing walking foot pressure images in the frequency domain. The feet of diabetic subjects were scanned over ten specified areas using Semmes-Weinstein's nylon monofilaments to determine quantitatively the three levels of neuropathy. A new parameter, the power ratio (PR, ratio of high frequency power to the total power in an image) was used to distinguish discretely between normal and diabetic feet in three levels of sensation loss. Analysis of results showed that the differences in PR values for diabetic feet (in all three levels of sensation loss) compared to normal feet were found to be highly significant (p<0.0005) in the areas of the foot where there was a high incidence of plantar ulcer formation, even at the early stage of neuropathy characterised by a sensation level of 45mN. This result could help in the early detection of plantar ulcer formation in the initial stage of sensation loss and may be utilised by orthopaedic surgeons to consider early corrective methods to protect these feet from further damage due to neuropathic ulcer formation.
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Affiliation(s)
- K G Prabhu
- Biomedical Engineering Department, MIT, Manipal, India
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22
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Patil KM, Jacob S. Mechanics of tarsal disintegration and plantar ulcers in leprosy by stress analysis in three dimensional foot models. Indian J Lepr 2000; 72:69-86. [PMID: 10935188] [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] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
This paper describes three dimensional two arch models of feet of a normal subject and two leprosy subjects, one in the early stage and the other in the advanced stage of tarsal disintegration, used for analysis of skeletal and plantar soft tissue stresses by finite element technique using NISA software package. The model considered the foot geometry (obtained from X-rays), foot bone, cartilages, ligaments, important muscle forces and sole soft tissue. The stress analysis is carried out for the foot models simulating quasi-static walking phases of heel-strike, mid-stance and push-off. The analysis of the normal foot model shows that highest stresses occur at push-off over the dorsal central part of lateral and medial metatarsals and dorsal junction of calcaneus and cuboid and neck of talus. The skeletal stresses, in early state leprosy with muscle paralysis and in the advanced stage of tarsal distintegration (TD), are higher than those for the normal foot model, by 24% to 65% and 30% to 400%, respectively. The vertical stresses in the soft tissue at the foot-ground interface match well with experimentally measured foot pressures and for the normal and leprosy subjects they are the highest in the push-off phase. In the leprosy subject with advanced TD, the highest soft tissue stresses and shear stresses (about three times the normal value) occur in push-off phase in the scar tissue region. The difference in shear stresses between the sole and the adjacent soft tissue layer in the scar tissue for the same subject is about three times the normal value. It is concluded that the high bone stresses in leprosy may be responsible for tarsal distintegration when the bone mechanical strength decreases due to osteoporosis and the combined effect of high value of footsole vertical stresses, shear stresses and the relative shear stresses between two adjacent soft tissue layers may be responsible for plantar ulcers in the neuropathic leprosy feet.
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Affiliation(s)
- K M Patil
- Department of Applied Mechanics, Indian Institute of Technology, Madras
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Bhatia MM, Patil KM. New on-line parameters for analysis of dynamic foot pressures in neuropathic feet of Hansen's disease subjects. J Rehabil Res Dev 1999; 36:264-72. [PMID: 10659809] [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] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
Pressures on the foot during walking are affected by the weight of the person and the walking velocity. It is also found that both the magnitude and duration of the dynamic foot pressures are important in ulcer formation in the neuropathic feet of persons with Hansen's disease (HD). Therefore, new parameters, Normalized Peak Pressure (NPP) and Pressure Contact Ratio (PCR), are calculated from dynamic foot pressure data in 10 defined areas of the feet of 52 nonimpaired controls and 108 persons with HD with different pathologies, using a long barograph that could accommodate at least two foot prints in one walking cycle. Statistical study of these new parameters, for various classes of HD subjects, shows significantly different mean values in the foot areas and hence could aid the clinician in better diagnosis and therapy planning. The second part of the article deals with on-line calculations and gray scale display of these parameter transforms for all the points on the plantar surfaces of both feet in a way that could help the clinician in quick analysis and better management and care of neuropathic feet.
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Affiliation(s)
- M M Bhatia
- Department of Applied Mechanics, Indian Institute of Technology, Madras
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Patil KM, Bhat MV, Bhatia MM, Narayanamurthy VB, Parivalavan R. New on-line methods for analysis of walking foot pressures in diabetic neuropathy. Front Med Biol Eng 1999; 9:49-62. [PMID: 10354909] [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] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
In this paper, studies are performed on a large number of diabetic patients belonging to different classes, using new on-line foot pressure parameters, i.e. normalized peak pressure (NPP) and pressure contact ratio (PCR), which include effects of the weight of the subject, velocity of walking and duration of high pressures in any region of the foot. A statistical study of the mean maximum value of these parameters in different plantar areas of the feet, for different classes of diabetic subjects, indicates distinguishing trends and hence could aid the clinician in better diagnosis and therapy planning. The NPP and PCR transforms calculated on-line (using specially developed software) help the clinician to quickly determine the heavily loaded foot areas that are potential sites of ulceration in insensitive feet and take the necessary action to prevent further damage to the foot sole.
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Affiliation(s)
- K M Patil
- Department of Applied Mechanics, IIT, Madras, India
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Ramakrishnan S, Sukhaswami MB, Patil KM, Eswaran C. Sequence data analysis reveals a relationship between LSR2, the recombinant fusion protein mimicing M. Leprae and VIF of bovine immunodeficiency virus (BIV). J Biomol Struct Dyn 1997; 15:605-9. [PMID: 9440006 DOI: 10.1080/07391102.1997.10508970] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In the course of computer simulation study looking for active sites for the interaction between MHC II and T7--a 12 residue long peptide of LSR2--a recombinant fusion protein mimicing the native bacillus M.Leprae--an interesting relationship between the antigenicity of LSR2 and VIF of BIF has come to light. Computer analysis study has revealed this stretch of residue from 36 to 48 of LSR2 is highly antigenic. The experimental observation seems to confirm the role of this 12 residue peptide in antibody response. In an effort to determine whether a significant sequence level relationship exists between this and any other known protein, the sequence homology of both protein and nucleic acid was studied. It is found that this 12 residue long peptide (T7) of LSR2 is homologous with Viral Infectivity Factor (VIF) of the Bovine Immunodeficiency Virus (BIV). Homology with translated nucleic acid sequence also indicate the same fact. The VIF gene which codes for this protein is known to be essential for ability of cell-free virus preparation to infect cells. These results lead to the question--whether this 12 residue long peptide which is common to both proteins play a role in their infectivity. Whether mutations in the peptide or elimination of this peptide from the protein and studying the effect of this on the diseases themselves may help in controlling them is another important question relevant to medical researchers.
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Abstract
This paper describes the design of a digital signal processor based system for a personal computer for EMG data acquisition to monitor muscle activity during gait and to estimate the power spectrum of the acquired data under normal and pathological conditions. It also gives the hardware details of the velocity meter which is used to monitor the muscle activity with speed of walking. Software has been developed for system initialization, data acquisition, processing of acquired data, and data display for five channels. The developed equipment will be useful to clinicians for enhancing the understanding of a patient's dynamic performance.
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Affiliation(s)
- G V Prasad
- Department of Applied Mechanics, Indian Institute of Technology, Madras, India
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Abstract
A two-dimensional model of the normal foot skeleton, which includes cartilages and ligaments, is used in this analysis of stresses during three quasi-static walking phases: heel-strike, mid-stance and push-off. It is found that in all the walking phases the maximum values of principal stresses occur in the dorsal anterior region of the talus, whereas the highest stress occurs in the push-off phase. The model is used for the simulation of muscle paralysis and its effect on the distribution of principal stresses. Subsequently, the model is used to analyse stresses in the deformed feet of three leprosy patients with complete paralysis of certain muscles. The results demonstrate that both the shape of the foot and the type of muscle paralysis contribute to the development of high stresses in different regions of the foot. These high stresses in regions with reduced mechanical strength could be one of the important factors in the process of tarsal disintegration in leprosy.
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Affiliation(s)
- K M Patil
- Department of Applied Mechanics, Indian Institute of Technology, Madras
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Abstract
Four-bar linkage mechanisms produced by many designers of knee joints for trans-femoral prostheses can provide knee rotation to permit walking only. In Afro-Asian countries people are accustomed to a squatting posture in their daily activities. A six-bar linkage knee-ankle mechanism trans-femoral prosthesis is described which was developed and fitted to an amputee. The motion patterns of the ankle, knee and thigh during walking and squatting (obtained using a flickering light emitting diode system) for the above prosthesis is compared with motion patterns obtained for normal subjects. The closeness between both the patterns establishes the suitability of the new modular trans-femoral prosthesis for producing near normal patterns of motion during walking and squatting. The additional facility of cross-legged sitting provided in the prosthesis makes it functionally suitable for Afro-Asian amputees.
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Affiliation(s)
- J K Chakraborty
- Department of Applied Mechanics, Bengal Engineering College, Howrah, India
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Abstract
The four-bar linkage mechanism used by many designers for the knee joint of an above-knee prosthesis can provide knee rotation suitable for walking only. In Afro-Asian countries people are habituated to the squatting posture in their daily activities. A six-bar linkage knee-ankle mechanism above-knee prosthesis with a pneumatic swing phase control is developed and its analysis shows its suitability for producing a motion closely resembling that of a normal subject during walking and squatting.
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Affiliation(s)
- K M Patil
- Department of Applied Mechanics, Indian Institute of Technology, Madras
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Abstract
A new image-processing system, using a video digitiser with an IBM-compatible PC/AT, is developed for acquisition and processing of low-contrast, low-intensity barographic images of both feet for assessment of pressure distribution during standing and walking. Data displays, in the form of centres of pressures, isopressures contours, perspective views of pressures, grey scale image and walking pressure patterns, combined image of walking pressures, paths of centres of pressures and pressure variations with time, are developed. These have provided very useful and early information regarding the internal structural changes in the bones of the foot and sites at risk of ulcer development in leprosy subjects and enable suitable corrective orthopaedic procedures to be adopted.
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Affiliation(s)
- K M Patil
- Department of Applied Mechanics, Indian Institute of Technology, Madras
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Patil KM, Babu TS, Oommen PK, Srinivasan H. Foot pressure measurement in leprosy and footwear design. Indian J Lepr 1986; 58:357-66. [PMID: 3794406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Leprosy patients deprived of sensory feedback allow excessive pressures to be applied to feet, thereby cause foot ulcers. Quantitative knowledge of the pressure distribution under leprotic feet is helpful to prevent further damage to foot by designing suitable footwear. This paper describes barographic technique for measurement of pressures under the leprotic feet and the design of special footwear for prevention of foot ulcers.
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Radhakrishnan S, Ghista DN, Jayaraman G, Patil KM. Analysis for the in vivo determination of the non-linear elastic parameters of an artery. BIOMED ENG-BIOMED TE 1981; 26:147-50. [PMID: 7295854 DOI: 10.1515/bmte.1981.26.6.147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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Ghista DN, Patil KM, Gould P, Woo KB. Computerized left ventricular mechanics and control system analyses models relevant for cardiac diagnosis. Comput Biol Med 1973; 3:27-46. [PMID: 4269290 DOI: 10.1016/0010-4825(73)90017-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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