Additional Rounds Research Articles

GIGYF2 and 4EHP Inhibit Translation Initiation of Defective Messenger RNAs to Assist Ribosome-Associated Quality Control

Ribosome-associated quality control (RQC) pathways protect cells from toxicity caused by incomplete protein products resulting from translation of damaged or problematic mRNAs. Extensive work in yeast has identified highly conserved mechanisms that lead to degradation of faulty mRNA and partially synthesized polypeptides. Here we used CRISPR-Cas9-based screening to search for additional RQC strategies in mammals. We found that failed translation leads to specific inhibition of translation initiation on that message. This negative feedback loop is mediated by two translation inhibitors, GIGYF2 and 4EHP. Model substrates and growth-based assays established that inhibition of additional rounds of translation acts in concert with known RQC pathways to prevent buildup of toxic proteins. Inability to block translation of faulty mRNAs and subsequent accumulation of partially synthesized polypeptides could explain the neurodevelopmental and neuropsychiatric disorders observed in mice and humans with compromised GIGYF2 function.

Parity reduces mammary repopulating activity but does not affect mammary stem cells defined as CD24 + CD29/CD49fhi in mice.

Breast cancer (BCa) mortality is decreasing with early detection and improvement in therapies. The incidence of BCa, however, continues to increase, particularly estrogen-receptor-positive (ER +) subtypes. One of the greatest modifiers of ER + BCa risk is childbearing (parity), with BCa risk halved in young multiparous mothers. Despite convincing epidemiological data, the biology that underpins this protection remains unclear. Parity-induced protection has been postulated to be due to a decrease in mammary stem cells (MaSCs); however, reports to date have provided conflicting data. We have completed rigorous functional testing of repopulating activity in parous mice using unfractionated and MaSC (CD24midCD49fhi)-enriched populations. We also developed a novel serial transplant method to enable us to assess self-renewal of MaSC following pregnancy. Lastly, as each pregnancy confers additional BCa protection, we subjected mice to multiple rounds of pregnancy to assess whether additional pregnancies impact MaSC activity. Here, we report that while repopulating activity in the mammary gland is reduced by parity in the unfractionated gland, it is not due to a loss in the classically defined MaSC (CD24+CD49fhi) numbers or function. Self-renewal was unaffected by parity and additional rounds of pregnancy also did not lead to a decrease in MaSC activity. Our data show instead that parity impacts on the stem-like activity of cells outside the MaSC population.

Daudi cell stroma: An alternative to dithiothreitol to resolve daratumumab interference in pretransfusion testing.

The Daudi B-cell line was found to express high levels of CD38 and was sonicated in a sonication buffer to achieve complete cell lysis. The resulting stroma preparation was centrifuged at 20 000g for 20 minutes and then mixed with 250 μL of DARA-plasma and incubated for 10 minutes at 37°C. The stroma-DARA-plasma mixture was centrifuged again, and the supernatant was collected and subjected to four additional rounds of adsorption with fresh stroma. DARA-depleted plasma was tested by gel indirect antiglobulin test (IAT). CD38 expression on Daudi cells was confirmed by flow cytometry. Gel IAT analysis showed that the incubation of plasma from DARA-treated patients with Daudi cells stroma resulted in a significant depletion of DARA but allowing detection of other alloantibodies of interest such as anti-K, anti-Yta , and anti-Gya . Daudi cell stroma is inexpensive, easy to prepare in large batches, and can be used as an off-the-shelf reagent. Incubation of plasma from DARA-treated patients with Daudi cell stroma can efficiently overcome DARA interference in serologic testing without affecting DTT- or trypsin-sensitive antigens.

A Downscaled Faster-RCNN Framework for Signal Detection and Time-Frequency Localization in Wideband RF Systems

We propose a wideband spectrum sensing technique to detect and localize wireless radio frequency (RF) signals of interest in time and frequency when uninteresting signals cause RF interference (RFI). Specifically, we adopt and downscale the existing Faster-RCNN (FRCNN) framework to achieve better signal detection and localization than the state-of-the-art. For experimental evaluation, we present a data generation framework for Wi-Fi as the signals of interest and the Bluetooth and microwave oven signals as the RFI. Experiments reveal that (i) the downscaled FRCNN model can achieve up to a mean average precision (mAP) of 0.8, significantly outperforming the state-of-the-art, (ii) feature extraction with the VGG-13 architecture gives the best mAP with pretrained weights and configured as trainable, (iii) for signal detection in real RF traces, when compared to training purely with synthetic RF data, a better mAP can be achieved by training with a mixture of synthetic and real RF traces or by fine tuning the synthetically-trained weights with an additional round of training on a small amount of real RF traces, and (iv) the mAP performance decreases as the signal to noise ratio (SNR) is lowered.

Security definitions, entropy measures and constructions for implicitly detecting data corruption

We discuss security definitions, entropy measures and cryptographic constructions associated with the recently proposed implicit data integrity methodology. Such methodology is applied in order to detect data corruption without producing, storing or verifying mathematical summaries of the content such as Message Authentication Codes (MACs) or checksums. The main idea is that, whereas typical user data demonstrate patterns such as repeated bytes or words, decrypted data resulting from corrupted ciphertexts no longer demonstrate such patterns. Thus, by checking the entropy of decrypted ciphertexts, corruption can be possibly detected.The paper expands on earlier contributions, arguing for the need of a new notion of security based on the assumption that it is computationally difficult for an adversary to corrupt some ciphertext so that the resulting plaintext demonstrates specific patterns. A second contribution of the paper is a proposal for a new entropy measure that is applicable to short messages. The entropy measure we propose is called “pattern entropy index” and can be efficiently computed for messages that can be as small as 64 bytes. Third, we extend the security analysis of the known cryptographic construction called IVP (Integrity Via Preprocessing). We show that IVP supports implicit data integrity and is secure in input perturbing and oracle replacing adversary models. The cryptographic strength of IVP is 32.169 bits, which is sufficient for defending against online data corruption and content replay attacks. Computationally, IVP is much lighter than other authenticated encryption approaches requiring only two additional encryption rounds in the critical path of a 128-bit block cipher such as AES.

Policy and Pandemic: The Changing Practice of Nephrology During the Coronavirus Disease-2019 Outbreak.

The coronavirus (coronavirus disease-2019) pandemic has changed care delivery for patients with end-stage kidney disease. We explore the US healthcare system as it pertains to dialysis care, including existing policies, modifications implemented in response to the coronavirus disease-2019 crisis, and possible next steps for policy makers and nephrologists. This includes policies related to resource management, use of telemedicine, prioritization of dialysis access procedures, expansion of home dialysis modalities, administrative duties, and quality assessment. The government has already established policies that have instated some flexibilities to help providers focus their response to the crisis. However, future policy during and after the coronavirus disease-2019 pandemic can bolster our ability to optimize care for patients with end-stage kidney disease. Key themes in this perspective are the importance of policy flexibility, clear strategies for emergency preparedness, and robust health systems that maximize accessibility and patient autonomy.

Biding time versus timely retreat: Asymmetric dependence, issue salience, and conflict duration

Trade-conflict studies focus on whether and how economic interdependence suppresses interstate conflict initiation. Meanwhile, formal theories of war show that conflict initiation is inherently tied to its termination. In this article, I seek to bridge the two literature by utilizing a war of attrition model to formalize the relationship between economic dependence and conflict duration. I theorize that the strategic calculation ultimately comes down to a trade-off between biding one’s time and retreating in a timely manner. In the context of economic attrition, states weigh the relative costs of suffering an additional round of economic disruption against the potential benefits of winning the disputed good. As such, economic dependence can have both coercive and informational effects and these effects are contingent upon issue salience. When the issue salience is low, the coercive effect dominates; states are more likely to quit conflicts as they suffer proportionally larger economic costs. When the issue salience is high enough, the informational effect can kick in; states are less likely to quit conflicts with increasing economic costs. I test these implications on the International Crisis Behavior (ICB) and the Militarized Interstate Dispute (MID) data, finding strong support for the informational effect and suggestive evidence for the coercive one.

Efficient determination of equivalence for encrypted data

Secure computation of equivalence has fundamental application in many different areas, including healthcare. We study this problem in the context of matching an individual's identity to link medical records across systems under the socialist millionaires’ problem: Two millionaires wish to determine if their fortunes are equal without disclosing their net worth (Boudot, et al. 2001). In Theorem 2, we show that when a "greater than" algorithm is carried out on a totally ordered set it is easy to achieve secure matching without additional rounds of communication. We present this efficient solution to assess equivalence using a set intersection algorithm designed for “greater than” computation and demonstrate its effectiveness on equivalence of arbitrary data values, as well as demonstrate how it meets regulatory criteria for risk of disclosure.

Improving design choices in Delphi studies in medicine: the case of an exemplary physician multi-round panel study with 100% response

BackgroundA proper application of the Delphi technique is essential for obtaining valid research results. Medical researchers regularly use Delphi studies, but reports often lack detailed information on methodology and controlled feedback: in the medical literature, papers focusing on Delphi methodology issues are rare. Since the introduction of electronic surveys, details on response times remain scarce. We aim to bridge a number of gaps by providing a real world example covering methodological choices and response times in detail.MethodsThe objective of our e(lectronic)-Delphi study was to determine minimum standards for emergency departments (EDs) in the Netherlands. We opted for a two-part design with explicit decision rules. Part 1 focused on gathering and defining items; Part 2 addressed the main research question using an online survey tool. A two-person consensus rule was applied throughout: even after consensus on specific items was reached, panellists could reopen the discussion as long as at least two panellists argued similarly. Per round, the number of reminders sent and individual response times were noted. We also recorded the methodological considerations and evaluations made by the research team prior to as well as during the study.ResultsThe study was performed in eight rounds and an additional confirmation round. Response rates were 100% in all rounds, resulting in 100% consensus in Part 1 and 96% consensus in Part 2. Our decision rules proved to be stable and easily applicable. Items with negative advice required more rounds before consensus was reached. Response delays were mostly due to late starts, but once panellists started, they nearly always finished the questionnaire on the same day. Reminders often yielded rapid responses. Intra-individual differences in response time were large, but quick responders remained quick.ConclusionsWe advise those considering Delphi study to follow the CREDES guideline, consider a two-part design, invest in personal commitment of the panellists, set clear decision rules, use a consistent lay-out and send out your reminders early. Adopting this overall approach may assist researchers in future Delphi studies and may help to improve the quality of Delphi designs in terms of improved rigor and higher response rates.

Managing patients with rheumatic diseases during the COVID-19 pandemic: The French Society of Rheumatology answers to most frequently asked questions up to May 2020.

BackgroundRheumatologists must contend with COVID-19 pandemic in the management of their patients and many questions have been raised on the use of both anti-inflammatory drugs and disease-modifying anti-rheumatic drugs (DMARD). The French Society of Rheumatology (SFR) selected the most critical ones to the daily practice of a rheumatologist and a group of 10 experts from SFR and Club Rheumatism and Inflammation (CRI) boards proposed responses based on the current knowledge of May 2020.MethodsFollowing the availability of the first 18 questions and statements, 1400 individuals consulted the frequently asked questions between the March 31, 2020 and April 12, 2020. As a result, 16 additional questions were forwarded to the SFR, and answered by the board. An additional round of review by email and video conference was organized, which included updates of the previous statements. The scientific relevance of 5 of the questions led to their inclusion in this document. Each response received a final assessment on a scale of 0–10 with 0 meaning no agreement whatsoever and 10 being in complete agreement. The mean values of these votes for each question are presented as the levels of agreement (LoA) at the end of each response. This document was last updated on April 17, 2020.ResultsBased on current scientific literature already published, in most circumstances, there is no contraindication to the initiation or continuation of anti-inflammatory drugs as well as DMARDs. If signs suggestive of infection (coronavirus or other) occur, treatments should be discontinued and resumed, if necessary, after 2 weeks without any symptoms. Only, some signals suggest that people taking an immunosuppressive dose of corticosteroid therapy are at greater risk of developing severe COVID-19. Intra-articular injections of glucocorticoids are allowed when there is no reasonable therapeutic alternative, and providing that precautions to protect the patient and the practitioner from viral contamination are adopted, included appropriate information to the patient.conclusionsCurrently available data on managing patients with rheumatic diseases during the COVID-19 pandemic are reassuring and support continuing or initiating symptomatic as well as specific treatments of these diseases, the main target of their management remaining their appropriate control, even during this pandemic.

CHOROIDAL GRANULOMAS VISUALIZED BY SWEPT-SOURCE OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY.

To assess the visualization of choroidal granulomas with swept-source optical coherence tomography angiography (OCTA). Consecutive patients with granulomatous choroiditis due to tuberculosis, sarcoidosis, or Vogt-Koyanagi-Harada disease underwent baseline OCTA images using a 12 × 12-mm field of view, and the choroidal slabs were analyzed by two independent examiners who counted the oval areas of flow void. Simultaneously, indocyanine green angiography (ICGA) and enhanced-depth imaging OCT were performed to mark visible choroidal changes corresponding to granulomatous lesions. The lesion areas on OCTA and ICGA were assessed using the in-built caliper tool. Three hundred and one round-shaped areas of flow void on OCTA, 209 hypofluorescent round lesions on ICGA, and 42 hyporeflective choroidal lesions on enhanced-depth imaging OCT were identified in 23 eyes from 14 patients. Of the 209 ICGA granulomas, 197 (94.3%) had a corresponding round area of flow void on OCTA that was interpreted as a granuloma. One hundred and four additional round flow voids were identified on OCTA that did not correspond to any hypofluorescent lesion on ICGA. The mean area of the 197 granulomas detected with both imaging modalities was significantly larger on ICGA (mean 0.33 mm2) than that on OCTA (mean 0.28 mm2). Optical coherence tomography angiography seems to be an optimal imaging method for the visualization of choroidal granulomas.

Abstract 272: Sensitivity of Conventional Monitoring Strategies to Diagnose Patients With Pause Arrhythmias Relative to Insertable Cardiac Monitors

Background: Diagnosing cardiac pauses that could produce syncopal episodes is clinically important to guide appropriate therapy. However, the infrequent nature of these episodes can make their detection a challenge with conventional monitoring (CM) strategies with short-term ECG monitors. We simulated several CM strategies and analyzed the sensitivity to diagnose patients with pause arrhythmias compared to continuous monitoring with an insertable cardiac monitor (ICM). Methods: CM was simulated from syncope patients’ ICM data by assuming the 1st detected true pause episode (≥5s) was symptomatic and prompted further evaluation. Based on published literature, 32% of patients were assumed to be admitted for 3 days of inpatient monitoring followed by CM of varying durations (24 or 48 hrs, and 14, 30 or 60 days) beginning at random within the next week; the other 68% were assumed to be discharged home, with CM of varying durations beginning at random within the next week. Subsequent true pause episodes in patients remaining undiagnosed with CM triggered additional rounds of CM, with simulations repeated 1,000 times. Longer pause definitions of ≥6-8s were also evaluated. ECG diagnosis was considered successful if a pause episode occurred simultaneous to CM. Results: A total of 105 true pause episodes from 44 patients (mean±SD age 66±17, 48% male) were detected by ICM, during 505±333 days of continuous follow-up. Patients experienced an average of 2.4±2.7 pause episodes ≥5s during follow-up. Relative to ICM-diagnosed patients, the mean sensitivity of CM to capture an ECG diagnosis for these pause episodes during follow-up ranged from 13.8% (on average, 6.1 of 44 patients) with 24-hr holter to 30.2% with two 30-day monitors (13.3 of 44 patients) (Figure). Sensitivity further decreased for pause durations of ≥6-8s, due to the less frequent occurrence of these episodes and consequently lower likelihood of capture with CM. Average days of follow-up without a diagnosis was 109 days with ICM versus a range of 384-452 days with CM modalities. Conclusion: Of syncope patients diagnosed with pause arrhythmias via ICM, the vast majority would go undiagnosed via CM strategies and therefore may not be optimally managed for syncope prevention. The cost-effectiveness of these strategies requires further study.

Calnexin cycle - structural features of the ER chaperone system.

The endoplasmic reticulum (ER) is the major folding compartment for secreted and membrane proteins and is the site of a specific chaperone system, the calnexin cycle, for folding N‐glycosylated proteins. Recent structures of components of the calnexin cycle have deepened our understanding of quality control mechanisms and protein folding pathways in the ER. In the calnexin cycle, proteins carrying monoglucosylated glycans bind to the lectin chaperones calnexin and calreticulin, which recruit a variety of function‐specific chaperones to mediate protein disulfide formation, proline isomerization, and general protein folding. Upon trimming by glucosidase II, the glycan without an inner glucose residue is no longer able to bind to the lectin chaperones. For proteins that have not yet folded properly, the enzyme UDP‐glucose:glycoprotein glucosyltransferase (UGGT) acts as a checkpoint by adding a glucose back to the N‐glycan. This allows the misfolded proteins to re‐associate with calnexin and calreticulin for additional rounds of chaperone‐mediated refolding and prevents them from exiting the ERs. Here, we review progress in structural studies of the calnexin cycle, which reveal common features of how lectin chaperones recruit function‐specific chaperones and how UGGT recognizes misfolded proteins.

Fuzzy-logic threat classification for multi-level selective encryption over real-time video streams

This paper proposes a Fuzzy-logic Threat Classification (FTC) model as the basis of a method to auto-detect three different confidentiality levels for videos streamed from heterogeneous, mobile devices via web edge servers, possibly part of a Content Distribution Network (CDN). The FTC consists of three parallel Fuzzy Inference Systems (FIS) corresponding to device, network, and type of video application, for the real-time, intelligent selection of an appropriate confidentiality level for a specific end-user. After selection of the level, an encryption module implements the corresponding form of encryption. In tests to demonstrate the concept, there were three increasing confidentiality levels, namely (1) low-level with no encryption, (2) Medium level with an in-house cipher [variant of eXclusive OR (XOR)], named P-XOR (XOR with additional rounds of permutation) applied to Selective Encryption (SE) and (3) high level with the Advanced Encryption Standard again for SE of compressed video syntax components. Results were obtained by considering realistic specifications of multiple digital devices, networks, and differing real-time streaming applications. Visual analysis of encrypted test video clips established that the FTC outputs an appropriate privacy level by reason of the implemented FISs. Absolute encryption times across the privacy levels were distinguished by their real-time response level, which is proportionate to the required degree of confidentiality.

Coupling arginine with DNA replication and chemoresistance

How cells adapt DNA replication to meet amino acid demands is an active area of interest across biology. Among a broad range of functions, the extracellular arginine is needed for the availability of newly synthesized histones to promote DNA replication fork progression. We show herein that transient deprivation of extracellular arginine, but not glutamine or leucine, causes a reversible S‐phase arrest. This unexpected dynamic S‐phase arrest feature is independent of mTORC1 signaling inhibition, insufficient metabolites, endogenous de novo arginine biosynthesis, and general amino acid control pathway. Moreover, knockdown of arginyl‐tRNA‐transferase recapitulated the loss of histone H4 lysine 5 and 12 acetylation marks and the reduction of replication fork speed without inhibition of origin firing. Importantly, single round of arginine depletion and addition did not induce ATR/Chk1 activation and DNA double‐stand breaks associated γH2AX. The halt of arginine‐dependent histone H4 synthesis is therefore emerging as a “brake” for DNA replication bypassing checkpoint control. However, repeated arginine fluctuation promote the emergence of nuclear p53‐binding protein 1 bodies in the subsequent G1‐phase, creating vulnerabilities of DNA replications and can be exploited by cancer cells that promote DNA repair and resistance to genotoxic agents. Thus, intratumoral variation in the arginine microenvironment synchronizes DNA replication with therapeutic responses.

Mechanistic basis for microhomology identification and genome scarring by polymerase theta

DNA polymerase theta mediates an end joining pathway (TMEJ) that repairs chromosome breaks. It requires resection of broken ends to generate long, 3' single-stranded DNA tails, annealing of complementary sequence segments (microhomologies) in these tails, followed by microhomology-primed synthesis sufficient to resolve broken ends. The means by which microhomologies are identified is thus a critical step in this pathway, but is not understood. Here we show microhomologies are identified by a scanning mechanism initiated from the 3' terminus and favoring bidirectional progression into flanking DNA, typically to a maximum of 15 nucleotides into each flank. Polymerase theta is frequently insufficiently processive to complete repair of breaks in microhomology-poor, AT-rich regions. Aborted synthesis leads to one or more additional rounds of microhomology search, annealing, and synthesis; this promotes complete repair in part because earlier rounds of synthesis generate microhomologies de novo that are sufficiently long that synthesis is more processive. Aborted rounds of synthesis are evident in characteristic genomic scars as insertions of 3 to 30 bp of sequence that is identical to flanking DNA ("templated" insertions). Templated insertions are present at higher levels in breast cancer genomes from patients with germline BRCA1/2 mutations, consistent with an addiction to TMEJ in these cancers. Our work thus describes the mechanism for microhomology identification and shows how it both mitigates limitations implicit in the microhomology requirement and generates distinctive genomic scars associated with pathogenic genome instability.

Has the Polyploid Wave Ebbed?

There was a wave of whole genome duplications (WGD) during and subsequent to the K-Pg interface, which was followed by an increase in the proportion of species that were polyploid. I consider why this wave of polyploid speciation has continued to rise through the divergent evolution of polyploid lineages, and through rounds of homoploid and heteroploid chromosomal change. I also consider why the polyploid speciation wave is likely to rise in the next millennium. I propose that the speed of polyploid genesis through ploidal increase and through diversification among polyploids likely will be greater than the speed of diploid speciation. The increase in polyploid diversity is expected to lag well behind episodes of WGD, owing to the very long period required for species diversification either by lineage splitting or additional rounds of polyploidy, in addition to the long period of genomic adjustment to higher ploidal levels in neopolyploids.

Prevalence of Listeria spp. in produce handling and processing facilities in the Pacific Northwest

Listeria monocytogenes is a significant concern for the produce industry; however, there is limited information to support the practical decision-making to mitigate this risk. This study investigated the prevalence of Listeria spp. and L. monocytogenes in seven produce handling and processing (PHP) facilities in the Pacific Northwest. PHP facilities were defined as facilities that receive raw agricultural commodities and further handle, pack, wash, or process prior to distribution into the retail sector. Environmental swabs (n = 50/facility) were collected in high-risk areas (e.g., near raw product entry points) from seven PHP facilities over two visits. Listeria spp. were isolated using modified ISO 11290-1 method and speciated with Microgen® Listeria-ID. Listeria spp., including L. monocytogenes, were found in 5/7 PHP. Prevalence of Listeria spp. ranged from 2% to 26% in these five facilities. Drains, entry areas, and portable equipment consistently tested positive for Listeria spp. during active production. Two additional sampling rounds (n = 50/round) were conducted in the highest prevalence facility (Facility #1). Overall, Listeria spp. were detected in 44/150 (29.3%) swabs collected from Facility #1. This study demonstrated the high prevalence of Listeria spp. near raw product entry points across PHP facilities.

Minimization of Network Induced Jitter Impact on FPGA-Based Control Systems for Power Electronics through Forward Error Correction

In modular distributed architectures, the adoption of a communication method that is at the same time robust and has a low and predictable latency is of utmost importance in order to support the required system dynamics. The aim of this paper is to evaluate the consequences of the random jitter on machine drives distributed control, caused by the messages’ re-transmission in case of an error in the received data. To achieve this goal, two different Forward Error Correction (FEC) techniques are introduced in the chosen protocol, so that the recipient of the message can correct random errors without the need of any additional round trip delays needed to request and obtain a re-transmission. Experimentally validated simulations are used to evaluate the impact of random network derived jitter on a real world closed loop control system for distributed power electronic converters.

Elongation factor-Tu can repetitively engage aminoacyl-tRNA within the ribosome during the proofreading stage of tRNA selection

The substrate for ribosomes actively engaged in protein synthesis is a ternary complex of elongation factor Tu (EF-Tu), aminoacyl-tRNA (aa-tRNA), and GTP. EF-Tu plays a critical role in mRNA decoding by increasing the rate and fidelity of aa-tRNA selection at each mRNA codon. Here, using three-color single-molecule fluorescence resonance energy transfer imaging and molecular dynamics simulations, we examine the timing and role of conformational events that mediate the release of aa-tRNA from EF-Tu and EF-Tu from the ribosome after GTP hydrolysis. Our investigations reveal that conformational changes in EF-Tu coordinate the rate-limiting passage of aa-tRNA through the accommodation corridor en route to the peptidyl transferase center of the large ribosomal subunit. Experiments using distinct inhibitors of the accommodation process further show that aa-tRNA must at least partially transit the accommodation corridor for EF-Tu⋅GDP to release. aa-tRNAs failing to undergo peptide bond formation at the end of accommodation corridor passage after EF-Tu release can be reengaged by EF-Tu⋅GTP from solution, coupled to GTP hydrolysis. These observations suggest that additional rounds of ternary complex formation can occur on the ribosome during proofreading, particularly when peptide bond formation is slow, which may serve to increase both the rate and fidelity of protein synthesis at the expense of GTP hydrolysis.