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Article ; Online: The 2012 Garrod lecture: discovery of antibacterial drugs in the 21st century.

Chopra, Ian

The Journal of antimicrobial chemotherapy

2012 Volume 68, Issue 3, Page(s) 496–505

Abstract: The discovery and development of antibacterial drugs in the twentieth century were major scientific and medical achievements that have had profound benefits for human society. However, in the twenty-first century the widespread global occurrence of ... ...

Abstract	The discovery and development of antibacterial drugs in the twentieth century were major scientific and medical achievements that have had profound benefits for human society. However, in the twenty-first century the widespread global occurrence of bacteria resistant to the antibiotics and synthetic drugs discovered in the previous century threatens to reverse our ability to treat infectious diseases. Although some new drugs are in development they do not adequately cover growing medical needs. Furthermore, these drugs are mostly derivatives of older classes already in use and therefore prone to existing bacterial resistance mechanisms. Thus, new drug classes are urgently needed. Despite investment in antibacterial drug discovery, no new drug class has been discovered in the past 20 years. In this review, based upon my career as a research scientist in the field of antibacterial drug discovery, I consider some of the technical reasons for the recent failure and look to the future developments that may help to reverse the poor current success rate. Diversification of screening libraries to include new natural products will be important as well as ensuring that the promising drug hits arising from structure-based drug design can achieve effective concentrations at their target sites within the bacterial cell.
MeSH term(s)	Anti-Bacterial Agents/isolation & purification ; Anti-Bacterial Agents/pharmacology ; Drug Discovery/methods ; Drug Discovery/organization & administration ; Drug Discovery/trends ; Drug Resistance, Bacterial ; Humans
Chemical Substances	Anti-Bacterial Agents
Language	English
Publishing date	2012-11-06
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Review
ZDB-ID	191709-2
ISSN	1460-2091 ; 0305-7453
ISSN (online)	1460-2091
ISSN	0305-7453
DOI	10.1093/jac/dks436
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Zs.MO 124: Show issues

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Book ; Online: 28 GHz Phased Array-Based Self-Interference Measurements for Millimeter Wave Full-Duplex

Chopra, Aditya / Roberts, Ian P. / Novlan, Thomas / Andrews, Jeffrey G.

2022

Abstract: We present measurements of the 28 GHz self-interference channel for full-duplex sectorized multi-panel millimeter wave (mmWave) systems, such as integrated access and backhaul. We measure the isolation between the input of a transmitting phased array ... ...

Abstract	We present measurements of the 28 GHz self-interference channel for full-duplex sectorized multi-panel millimeter wave (mmWave) systems, such as integrated access and backhaul. We measure the isolation between the input of a transmitting phased array panel and the output of a co-located receiving phased array panel, each of which is electronically steered across a number of directions in azimuth and elevation. In total, nearly 6.5 million measurements were taken in an anechoic chamber to densely inspect the directional nature of the coupling between 256-element phased arrays. We observe that highly directional mmWave beams do not necessarily offer widespread high isolation between transmitting and receiving arrays. Rather, our measurements indicate that steering the transmitter or receiver away from the other tends to offer higher isolation but even slight steering changes can lead to drastic variations in isolation. These measurements can be useful references when developing mmWave full-duplex solutions and can motivate a variety of future topics including beam/user selection and beamforming codebook design.
Keywords	Electrical Engineering and Systems Science - Signal Processing
Subject code	535
Publishing date	2022-03-05
Publishing country	us
Document type	Book ; Online
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Article ; Online: Giant cell tumour of soft tissue-a rare presentation of a common pathology.

Chopra, Annu / Kinsella, Matthew / Edwards, Sara / Smith, Ian / Robinson, Philip

BJR case reports

2020 Volume 6, Issue 3, Page(s) 20200012

Abstract: We present the case of a giant cell tumour of soft tissue (GCT-ST) presenting as a slow-growing paraspinal mass. Imaging investigations revealed a well-circumscribed subcutaneous lesion containing fluid-fluid levels and an internal solid nodule. The ... ...

Abstract	We present the case of a giant cell tumour of soft tissue (GCT-ST) presenting as a slow-growing paraspinal mass. Imaging investigations revealed a well-circumscribed subcutaneous lesion containing fluid-fluid levels and an internal solid nodule. The imaging findings resulted in only a tentative differential which included haematoma or complex epidermoid cyst but failed to provide a definitive diagnosis. The patient underwent an image-guided biopsy from which a histopathological diagnosis of a GCT-ST was made. GCT-ST is a primary soft tissue neoplasm that is clinically and histologically similar to giant cell tumour of bone. Given its rare occurrence, there is very little published literature on the characteristic imaging findings of GCT-ST to help with its diagnosis which is usually only made histologically. The aim of this case report is to highlight our specific imaging findings and add to the limited pre-existing imaging data on GCT-ST.
Language	English
Publishing date	2020-05-27
Publishing country	England
Document type	Case Reports
ISSN	2055-7159
ISSN (online)	2055-7159
DOI	10.1259/bjrcr.20200012
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Article ; Online: A critical evaluation of the approaches to targeted protein degradation for drug discovery.

Chopra, Rajesh / Sadok, Amine / Collins, Ian

Drug discovery today. Technologies

2019 Volume 31, Page(s) 5–13

Abstract: There is a great deal of excitement around the concept of targeting proteins for degradation as an alternative to conventional inhibitory small molecules and antibodies. Protein degradation can be undertaken by bifunctional molecules that bind the target ...

Abstract	There is a great deal of excitement around the concept of targeting proteins for degradation as an alternative to conventional inhibitory small molecules and antibodies. Protein degradation can be undertaken by bifunctional molecules that bind the target for ubiquitin mediated degradation by complexing them with Cereblon (CRBN), von Hippel-Lindau or other E-3 ligases. Alternatively, E-3 ligase receptors such as CRBN or DCAF15 can also be used as a 'template' to bind IMiD or sulphonamide like compounds to degrade multiple context specific proteins by the selected E-3 ligases. The 'template approach' results in the degradation of neo-substrates, some of which would be difficult to drug using conventional approaches. The chemical properties necessary for drug discovery, the rules by which neo-substrates are selected by E-3 ligase receptors and defining the optimal components of the ubiquitin proteasome for protein degradation are still to be fully elucidate. Theis review will aim to critically evaluate the different approaches and principles emerging for targted protein degradation.
MeSH term(s)	Adaptor Proteins, Signal Transducing ; Animals ; Carrier Proteins/metabolism ; Drug Discovery ; Humans ; Molecular Targeted Therapy ; Peptide Hydrolases/metabolism ; Proteolysis ; Ubiquitin-Protein Ligases/metabolism
Chemical Substances	Adaptor Proteins, Signal Transducing ; CRBN protein, human ; Carrier Proteins ; Ubiquitin-Protein Ligases (EC 2.3.2.27) ; Peptide Hydrolases (EC 3.4.-)
Language	English
Publishing date	2019-03-06
Publishing country	England
Document type	Journal Article ; Review
ISSN	1740-6749
ISSN (online)	1740-6749
DOI	10.1016/j.ddtec.2019.02.002
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Article ; Conference proceedings: Translational medicine for antibacterial drug development - A Marcus Evans conference: overcoming the challenge of proof of concept.

Chopra, Ian

IDrugs : the investigational drugs journal

2008 Volume 11, Issue 4, Page(s) 236–238

MeSH term(s)	Animals ; Anti-Bacterial Agents/pharmacokinetics ; Anti-Bacterial Agents/therapeutic use ; Bacteria/drug effects ; Bacteria/enzymology ; Bacterial Infections/drug therapy ; Bacterial Infections/microbiology ; Disease Models, Animal ; Drug Evaluation, Preclinical ; Enzyme Inhibitors/pharmacology ; Enzyme Inhibitors/therapeutic use ; Gram-Negative Bacterial Infections/drug therapy ; Gram-Negative Bacterial Infections/microbiology ; Humans ; Methionine-tRNA Ligase/antagonists & inhibitors ; Research Design ; Software
Chemical Substances	Anti-Bacterial Agents ; Enzyme Inhibitors ; Methionine-tRNA Ligase (EC 6.1.1.10)
Language	English
Publishing date	2008-04
Publishing country	England
Document type	Congresses
ZDB-ID	2086568-5
ISSN	2040-3410 ; 1369-7056
ISSN (online)	2040-3410
ISSN	1369-7056
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Zs.A 6320: Show issues

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Article ; Online: High-resolution HLA genotyping in inclusion body myositis refines 8.1 ancestral haplotype association to DRB1*03:01:01 and highlights pathogenic role of arginine-74 of DRβ1 chain.

Slater, Nataliya / Sooda, Anuradha / McLeish, Emily / Beer, Kelly / Brusch, Anna / Shakya, Rakesh / Bundell, Christine / James, Ian / Chopra, Abha / Mastaglia, Frank L / Needham, Merrilee / Coudert, Jerome D

Journal of autoimmunity

2023 Volume 142, Page(s) 103150

Abstract: Objectives: Inclusion body myositis (IBM) is a progressive inflammatory-degenerative muscle disease of older individuals, with some patients producing anti-cytosolic 5'-nucleotidase 1A (NT5C1A, aka cN1A) antibodies. Human Leukocyte Antigens (HLA) is the ...

Abstract	Objectives: Inclusion body myositis (IBM) is a progressive inflammatory-degenerative muscle disease of older individuals, with some patients producing anti-cytosolic 5'-nucleotidase 1A (NT5C1A, aka cN1A) antibodies. Human Leukocyte Antigens (HLA) is the highest genetic risk factor for developing IBM. In this study, we aimed to further define the contribution of HLA alleles to IBM and the production of anti-cN1A antibodies. Methods: We HLA haplotyped a Western Australian cohort of 113 Caucasian IBM patients and 112 ethnically matched controls using Illumina next-generation sequencing. Allele frequency analysis and amino acid alignments were performed using the Genentech/MiDAS bioinformatics package. Allele frequencies were compared using Fisher's exact test. Age at onset analysis was performed using the ggstatsplot package. All analysis was carried out in RStudio version 1.4.1717. Results: Our findings validated the independent association of HLA-DRB103:01:01 with IBM and attributed the risk to an arginine residue in position 74 within the DRβ1 protein. Conversely, DRB401:01:01 and DQA101:02:01 were found to have protective effects; the carriers of DRB103:01:01 that did not possess these alleles had a fourteenfold increased risk of developing IBM over the general Caucasian population. Furthermore, patients with the abovementioned genotype developed symptoms on average five years earlier than patients without. We did not find any HLA associations with anti-cN1A antibody production. Conclusions: High-resolution HLA sequencing more precisely characterised the alleles associated with IBM and defined a haplotype linked to earlier disease onset. Identification of the critical amino acid residue by advanced biostatistical analysis of immunogenetics data offers mechanistic insights and future directions into uncovering IBM aetiopathogenesis.
MeSH term(s)	Humans ; Myositis, Inclusion Body/genetics ; Genotype ; Haplotypes ; Arginine ; Australia ; Myositis ; HLA Antigens ; HLA-DRB1 Chains/genetics ; Alleles
Chemical Substances	Arginine (94ZLA3W45F) ; HLA Antigens ; HLA-DRB1 Chains
Language	English
Publishing date	2023-12-02
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	639452-8
ISSN	1095-9157 ; 0896-8411
ISSN (online)	1095-9157
ISSN	0896-8411
DOI	10.1016/j.jaut.2023.103150
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Zs.A 2368: Show issues

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Article: The increasing use of silver-based products as antimicrobial agents: a useful development or a cause for concern?

Chopra, Ian

The Journal of antimicrobial chemotherapy

2007 Volume 59, Issue 4, Page(s) 587–590

Abstract: Silver first gained regulatory approval for use as an antimicrobial agent in the early 20th century, but its usage diminished with the introduction of antibiotics in the 1940s. Recently, however, topical silver has gained popularity once again, ... ...

Abstract	Silver first gained regulatory approval for use as an antimicrobial agent in the early 20th century, but its usage diminished with the introduction of antibiotics in the 1940s. Recently, however, topical silver has gained popularity once again, principally in the management of open wounds. This has been largely due to the spread of methicillin-resistant Staphylococcus aureus and the resultant reduction in first-line antibiotic prescribing. The increase in the use of topical silver has raised issues concerning silver resistance, together with questions about the standardization of antimicrobial testing methods for silver. Issues related to silver product testing include a failure to establish standard procedures for determining MIC values, an absence of recognized breakpoints, a lack of conformity in the way different products release silver and variations in the effects of microbiological media on silver release and the measurement of inhibitory activity. The clinical incidence of silver resistance remains low, and emergence of resistance can be minimized if the level of silver ions released from products is high and the bactericidal activity rapid.
MeSH term(s)	Anti-Infective Agents/chemistry ; Anti-Infective Agents/pharmacology ; Bacteria/drug effects ; Drug Resistance, Microbial ; Humans ; Infection/drug therapy ; Infection/microbiology ; Microbial Sensitivity Tests ; Silver Compounds/chemistry ; Silver Compounds/pharmacology
Chemical Substances	Anti-Infective Agents ; Silver Compounds
Language	English
Publishing date	2007-04
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Review
ZDB-ID	191709-2
ISSN	1460-2091 ; 0305-7453
ISSN (online)	1460-2091
ISSN	0305-7453
DOI	10.1093/jac/dkm006
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Zs.A 1197: Show issues			Location: Je nach Verfügbarkeit (siehe Angabe bei Bestand) bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular Jg. 1995 - 2021: Lesesall (1.OG) ab Jg. 2022: Lesesaal (EG)
Zs.MO 124: Show issues

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Article: Bacterial RNA polymerase: a promising target for the discovery of new antimicrobial agents.

Chopra, Ian

Current opinion in investigational drugs (London, England : 2000)

2007 Volume 8, Issue 8, Page(s) 600–607

Abstract: Prokaryotic DNA-dependent RNA polymerase (RNAP) is a multi-subunit enzyme responsible for transcription in bacteria. It is an important target for antibacterial chemotherapy because it is essential for bacterial growth and survival, and possesses ... ...

Abstract	Prokaryotic DNA-dependent RNA polymerase (RNAP) is a multi-subunit enzyme responsible for transcription in bacteria. It is an important target for antibacterial chemotherapy because it is essential for bacterial growth and survival, and possesses features that distinguish it from mammalian counterparts. The rifamycins are currently the only class of RNAP inhibitors that have been approved for clinical use, and consequently bacterial RNAP remains relatively underexploited as an antibacterial drug target. However, improved understanding of the molecular basis of rifamycin action, revealed by X-ray crystallographic studies, has resulted in the development of new rifamycins, such as the benzoxazinorifamycins, with improved properties. Structural studies on other RNAP inhibitors have also been described, and a number of older inhibitors now await detailed investigation to provide molecular explanations for their modes of action. New approaches have also resulted in the discovery of inhibitors of RNAP assembly. This review discusses various RNAP inhibitors in the context of their modes of action and potential development for therapeutic application. Opportunities for the discovery of new inhibitors are also discussed.
MeSH term(s)	Anti-Bacterial Agents/chemistry ; Anti-Bacterial Agents/pharmacology ; Bacterial Proteins/antagonists & inhibitors ; Bacterial Proteins/chemistry ; Bacterial Proteins/metabolism ; DNA-Directed RNA Polymerases/antagonists & inhibitors ; DNA-Directed RNA Polymerases/chemistry ; DNA-Directed RNA Polymerases/metabolism ; Drug Delivery Systems ; Drug Resistance, Bacterial ; Humans ; Molecular Structure ; Peptides/chemistry ; Peptides/pharmacology ; Rifamycins/chemistry ; Rifamycins/pharmacology ; Transcription, Genetic
Chemical Substances	Anti-Bacterial Agents ; Bacterial Proteins ; Peptides ; Rifamycins ; DNA-Directed RNA Polymerases (EC 2.7.7.6)
Language	English
Publishing date	2007-08-01
Publishing country	England
Document type	Journal Article ; Review
ZDB-ID	2027913-9
ISSN	2040-3429 ; 1472-4472 ; 0967-8298
ISSN (online)	2040-3429
ISSN	1472-4472 ; 0967-8298
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Zs.A 5305: Show issues

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Book ; Online: Spatial and Statistical Modeling of Multi-Panel Millimeter Wave Self-Interference

Roberts, Ian P. / Chopra, Aditya / Novlan, Thomas / Vishwanath, Sriram / Andrews, Jeffrey G.

2022

Abstract: Characterizing self-interference is essential to the design and evaluation of in-band full-duplex communication systems. Until now, little has been understood about this coupling in full-duplex systems operating at millimeter wave (mmWave) frequencies, ... ...

Abstract	Characterizing self-interference is essential to the design and evaluation of in-band full-duplex communication systems. Until now, little has been understood about this coupling in full-duplex systems operating at millimeter wave (mmWave) frequencies, and it has been shown that the highly-idealized models proposed for such do not align with practice. This work presents the first spatial and statistical model of mmWave self-interference backed by measurements, enabling engineers to draw realizations that exhibit the large-scale and small-scale spatial characteristics observed in our nearly 6.5 million measurements taken at 28 GHz. Core to our model is its use of system and model parameters having real-world meaning, which facilitates its extension to systems beyond our own phased array platform through proper parameterization. We demonstrate this by collecting nearly 13 million additional measurements to show that our model can generalize to two other system configurations. We assess our model by comparing it against actual measurements to confirm its ability to align spatially and in distribution with real-world self-interference. In addition, using both measurements and our model of self-interference, we evaluate an existing beamforming-based full-duplex mmWave solution to illustrate that our model can be reliably used to design new solutions and validate the performance improvements they may offer.
Keywords	Electrical Engineering and Systems Science - Signal Processing
Subject code	006
Publishing date	2022-10-14
Publishing country	us
Document type	Book ; Online
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Book ; Online: Beamformed Self-Interference Measurements at 28 GHz

Roberts, Ian P. / Chopra, Aditya / Novlan, Thomas / Vishwanath, Sriram / Andrews, Jeffrey G.

Spatial Insights and Angular Spread

2022

Abstract: We present measurements and analysis of self-interference in multi-panel millimeter wave (mmWave) full-duplex communication systems at 28 GHz. In an anechoic chamber, we measure the self-interference power between the input of a transmitting phased array ...

Abstract	We present measurements and analysis of self-interference in multi-panel millimeter wave (mmWave) full-duplex communication systems at 28 GHz. In an anechoic chamber, we measure the self-interference power between the input of a transmitting phased array and the output of a colocated receiving phased array, each of which is electronically steered across a number of directions in azimuth and elevation. These self-interference power measurements shed light on the potential for a full-duplex communication system to successfully receive a desired signal while transmitting in-band. Our nearly 6.5 million measurements illustrate that more self-interference tends to be coupled when the transmitting and receiving phased arrays steer their beams toward one another but that slight shifts in steering direction (on the order of one degree) can lead to significant fluctuations in self-interference power. We analyze these measurements to characterize the spatial variability of self-interference to better quantify and statistically model this sensitivity. Our analyses and statistical results can be useful references when developing and evaluating mmWave full-duplex systems and motivate a variety of future topics including beam selection, beamforming codebook design, and self-interference channel modeling.
Keywords	Electrical Engineering and Systems Science - Signal Processing
Subject code	003
Publishing date	2022-06-15
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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