LOS ALAMOS, N.M., Aug. 15, 2023 — A potentially game-changing theoretical approach to quantum computing hardware avoids much of the problematic complexity found in current quantum computers. The strategy implements an algorithm in natural quantum interactions to process a variety of real-world problems faster than classical computers or conventional gate-based quantum computers can.
“Our finding eliminates many challenging requirements for quantum hardware,” said Nikolai Sinitsyn, a theoretical physicist at Los Alamos National Laboratory. He is coauthor of a paper on the approach in the journal Physical Review A. “Natural systems, such as the electronic spins of defects in diamond, have precisely the type of interactions needed for our computation process.”
Sinitsyn said the team hopes to collaborate with experimental physicists also at Los Alamos to demonstrate their approach using ultracold atoms. Modern technologies in ultracold atoms are sufficiently advanced to demonstrate such computations with about 40 to 60 qubits, he said, which is enough to solve many problems not currently accessible by classical, or binary, computation. A qubit is the basic unit of quantum information, analogous to a bit in familiar classical computing.
Longer-lived qubits
Instead of setting up a complex system of logic gates among a number of qubits that must all share quantum entanglement, the new strategy uses a simple magnetic field to rotate the qubits, such as the spins of electrons, in a natural system. The precise evolution of the spin states is all that is needed to implement the algorithm. Sinitsyn said the approach could be used to solve many practical problems proposed for quantum computers.
Quantum computing remains a nascent field handicapped by the difficulty of connecting qubits in long strings of logic gates and maintaining the quantum entanglement required for computation. Entanglement breaks down in a process known as decoherence, as the entangled qubits begin to interact with the world outside the quantum system of the computer, introducing errors. That happens quickly, limiting the computation time. True error correction has not yet been implemented on quantum hardware.
The new approach relies on natural rather than induced entanglement, so it requires fewer connections among qubits. That reduces the impact of decoherence. Thus, the qubits live for a relatively a long time, Sinitsyn said.
The Los Alamos team’s theoretical paper showed how the approach could solve a number-partitioning problem using Grover’s algorithm faster than existing quantum computers. As one of the best-known quantum algorithms, it allows unstructured searches of large data sets that gobble up conventional computing resources. For instance, Sinitsyn said, Grover’s algorithm can be used to divvy up the runtime for tasks equally between two computers, so they finish at the same time, along with other practical jobs. The algorithm is well-suited to idealized, error-corrected quantum computers, although it is difficult to implement on today’s error-prone machines.
Protected against errors
Quantum computers are built to perform computations much faster than any classical device can do, but they have been extremely hard to realize so far, Sinitsyn said. A conventional quantum computer implements quantum circuits — sequences of elementary operations with different pairs of qubits.
The Los Alamos theorists proposed an intriguing alternative.
“We noticed that for many famous computational problems it is sufficient to have a quantum system with elementary interactions, in which only a single quantum spin — realizable with two qubits — interacts with the rest of the computational qubits,” Sinitsyn said. “Then a single magnetic pulse that acts only on the central spin implements the most complex part of the quantum Grover’s algorithm.” Called the Grover’s oracle, this quantum operation points to the desired solution.
“No direct interactions between the computational qubits and no time-dependent interactions with the central spin are needed in the process,” he said. Once the static couplings between the central spin and qubits are set, the entire computation consists only of applying simple time-dependent external field pulses that rotate the spins, he said.
Importantly, the team proved that such operations can be made fast. The team also discovered that their approach is topologically protected. That is, it is robust against many errors in the precision of the control fields and other physical parameters even without quantum error correction.
The paper: “Topologically protected Grover’s oracle for the partition problem.” Physical Review A. https://journals.aps.org/pra/abstract/10.1103/PhysRevA.108.022412
The funding: Department of Energy Office of Science, Office of Advanced Scientific Computing Research and the Laboratory Directed Research and Development program at Los Alamos National Laboratory.
-30-
LA-UR-23-29314
Journal
Physical Review A
Method of Research
Computational simulation/modeling
Subject of Research
Not applicable
Article Title
Topologically protected Grover's oracle for the partition problem
Article Publication Date
14-Aug-2023
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.
It's a difficult, impressive feat on its own to help children work through speech problems. It's even more inspiring when you take into account the bridge of language itself.
That's a path just crossed by UNM Speech & Hearing Sciences Assistant Professor Carlos Irizarry-Pérez, in his newly published research, titled "A Complexity Approach to Promoting Within- and Cross-Language Generalization in Bilingual Children With Phonological Delays."
The work is published in the journal Language, Speech, and Hearing Services in Schools.
"Generalization is taking a skill that you've learned in one particular context and being able to use it in another context. Best practice is to approach generalization from the most complex aspects of speech with the belief that the simpler pieces fall in place," Irizarry-Pérez said.
This was part of a massive undertaking. Phonological delays, the inability to fully and correctly form the sound system of a language, is a predictable and therefore treatable speech disorder. Irizarry-Pérez found a new way to do so.
"Speech sound disorders, which can look a lot of different ways, but in really simple terms, are difficulty with producing sounds accurately," he said. "With bilingual children, there's more than one language, so it's harder, and there just hasn't been a lot done in that area for bilingual children."
Whether it's missing a certain sound, or replacing one sound with another, the causeless condition is a difficult one when working with bilingual children. It's even more challenging, given the lack of bilingual speech therapists working—a startlingly low 8%.
"We don't have a lot of bilingual therapists. So how do we address this need for children that are bilingual and have these disorders? We kind of have to be creative in how we do that," Irizarry-Pérez said.
"Try to be the most efficient about things; that's the strategy I at least recommend that clinicians take. You can always find the pieces within languages that are complex. Then find the pieces that overlap with English. That is really the novel piece we were testing and that I think is applicable to most bilingual children and their clinicians."
Irizarry-Pérez's unique approach focused on choosing complex sounds, consonant clusters, similar to both languages and integrating those sounds into children's sound systems for them to generalize.
"If we also choose sounds that are harder for the child, they will have the least amount of information, so we'll get even more generalization within the child's sound system. This is really important for children that have difficulty organizing sounds in their sound system," he said.
Once that sound gets acquired in one language, then the concept of generalization should get the child to acquire similar sounds in the other language.
"When we choose sounds as intervention targets, they're the same or very similar, at least across the child's languages, so those skills generalize," Irizarry-Pérez said. "If we can get a child to be accurate with those sounds, either of the languages will typically generalize into the other with intervention."
It's different from many other processes, which escalate from simple, single sounds to piecing harder sounds together one by one.
"We took shared sounds, complex clusters that were shared across Spanish and English, and provided intervention in just Spanish. We looked for the generalization of the skills to be able to produce that cluster in both languages," Irizarry-Pérez said.
For a year, a handful of 4 to 7-year-olds practiced weekly in one-hour sessions. They were guided tirelessly by Clinical Instructor Andrea Martinez-Fischer and their dedicated graduate students.
"It was really interesting to watch the students grow from being brand new clinicians to being able to independently scaffold and support their clients," she said. "It is difficult to find speech therapy done in Spanish, so this work with bilingual graduate clinicians is so important not only for them and their training but also for putting out research that informs our bilingual practice as a whole."
Not only did the children themselves come out of this process with notable speech improvement, but parents earned new tools with immense gratitude.
"They all expressed gratitude and happiness just for the fact that we were considering both of the child's languages and their experiences," Irizarry-Pérez said. "These children come home in most cases to bilingual or Spanish-only environments, and the parents and children need to communicate and understand each other as well."
The marked success is just one piece of the puzzle involving phonological delays, but Irizarry-Pérez and Martinez-Fischer believe speech therapists across the country can learn something from this.
"In a minority-majority state like NM, services delivered in a child's native/home language should be accessible and is best practice," Martinez-Fischer said. "The research completed, and training of our graduate students assists in making the services provided to our Spanish-speaking population evidence-based and appropriate for the people we serve. "
It could even help fill the current gap of bilingual speech therapists. On top of training UNM graduate students early on, if this research gains steam, it could inspire positive interventions for speech therapists hesitant to take the extra step.
"Any time I think that a therapist has a bilingual child on their caseload that has difficulty with phonology, speech sounds, and falls within that kind of age range and characteristics, the approach we were testing does work. That is to choose sounds first that are shared and that are complex," Irizarry-Pérez said.
This theory is something he hopes to eventually apply to additional language pairs beyond Spanish and English.
"We know that these language systems are connected through interdependence. There are aspects as well that are shared across languages. It's just a matter of whether those complex sounds and the sounds that are shared overlap enough to take this approach," Irizarry-Pérez said.
More information: Carlos D. Irizarry-Pérez et al, A Complexity Approach to Promoting Within- and Cross-Language Generalization in Bilingual Children With Phonological Delays, Language, Speech, and Hearing Services in Schools (2023). DOI: 10.1044/2023_LSHSS-22-00128
Citation: Research team describes novel approach to bilingual speech therapy (2023, August 17) retrieved 23 August 2023 from https://phys.org/news/2023-08-team-approach-bilingual-speech-therapy.html
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Retrospective analyses of epidemiologic data have repeatedly shown that COVID-19 mortality is higher in males compared to females. However, the underlying factors mediating sex-specific disease outcome were largely unknown.
In a new study published in Cell Reports Medicine, an interdisciplinary research team analyzed genetic data obtained from 2,866 COVID-19 patients and identified a mutation in the CYP19A1 gene that is associated with an increased risk for hospitalization in male patients. CYP19A1 plays a key role in testosterone metabolism. Lung samples analyzed from deceased COVID-19 patients also showed increased expression of the CYP19A1 gene in male patients compared to female patients. These findings suggest that this gene is involved in sex-differences observed in COVID-19 outcomes.
"This collaborative work stresses the importance of host genetics in understanding molecular mechanisms of severity and treatment of viral disorders," says Professor Alessandra Renieri of the University of Siena who provided the genetic data of the large COVID-19 cohort.
Preclinical studies in animal models confirmed these findings. Treatment of SARS-CoV-2-infected animals with the aromatase inhibitor letrozole improved long-term lung function and restored hormonal balance, particularly in male animals. This suggests that aromatase inhibitors may provide a promising therapeutic strategy for the treatment of male COVID-19 patients.
Professor Gülşah Gabriel confirms the importance of international and interdisciplinary collaboration and highlights, "Our collaborative findings may form a basis for individualized therapeutic strategies against COVID-19."
More information: Stephanie Stanelle-Bertram et al, CYP19A1 mediates severe SARS-CoV-2 disease outcome in males, Cell Reports Medicine (2023). DOI: 10.1016/j.xcrm.2023.101152
Provided by Leibniz-Institut für Virologie (LIV)
Citation: Novel therapeutic approach against severe COVID-19 in males (2023, August 14) retrieved 23 August 2023 from https://medicalxpress.com/news/2023-08-therapeutic-approach-severe-covid-males.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
A Dutch-German research team has used a unique method to detect silver shortages in the PV industry. By mapping the silver supply chain from 1995 to 2021, they have identified distinct supply patterns and associated risks.
Researchers at Germany's Fraunhofer Institute for Solar Energy (Fraunhofer ISE) and the Institute of Environmental Sciences (CML) in the Netherlands have conducted risk-based due diligence on the silver supply for the PV industry, in order to identify possible shortages in the future.
“Considering the current typical lead times of the mining industry and the constraints such as permitting and environmental, social, and governance (ESG) issues linked to mine expansion, it is clear that material bottlenecks of unknown duration are in the cards,” researcher Estelle Gervais told pv magazine. “Supply disruptions can therefore be expected for silver, as they can be expected for numerous other materials required in energy technologies, including copper.”
She said that the silver industry has historically been resilient to these challenges because of strategic stocks and recycling, which have played key roles during periods of undersupply over the last 50 years. Silver reserves have also not significantly decreased relative to production over time, which suggests that exhausted reserves have been replenished through mine expansion.
“This is at least a cautiously optimistic sign for the medium to long-term,” said Gervais. “Estimates of future supply are linked to high uncertainty. We could, however, identify concrete risks related to market concentration and ESG issues in silver supply chains, which could translate into supply constraints in the short term. This is especially true for PV markets like the EU and the USA, which are increasingly working towards supply security and sustainability.”
Gervais and her colleagues mapped the solar supply chain of silver from 1995 to 2021 and identified a series of supply patterns and risks. They also analyzed the impact of alternative supply routes and the reshoring PV manufacturing to Europe.
The research group said that most ESG risks from silver paste fabrication are in China, due to its market dominance. The researchers said Mexico and China account for most ESG risks in mining and refining. They also noted the need to prioritize due diligence and traceability with local players, as ESG risk monitoring becomes the norm.
“Reducing silver consumption in PV is crucial, both to alleviate the silver price pain point and reduce the environmental and social impacts along the supply chain,” Gervais said, in reference to the ability of PV producers to reduce silver content in solar cell production – a process referred to as thrifting. “Silver prices are however both a problem and part of the solution. They will play a role in bringing supply and demand into balance, and provide an incentive for PV recycling.”
Gervais said that prolongated periods of silver undersupply could be a clear deterrent for the PV industry and would intensify the focus on substitutes.
“Copper prices make it a great alternative to silver in PV and there have been considerable technological advances in this area,” Gervais added. “Copper contact paste development for screen printing is advancing and industrial manufacturing solutions for copper plating are available. It should nevertheless be underlined that switching from silver to copper will not automatically ensure PV manufacturers have a ‘sustainable' product. Not all copper is created equal: only a careful examination of the underlying copper supply chains and a diversified supply would support that.”
Gervais and her team presented their findings in “Risk-based due diligence in supply chains: The case of silver for photovoltaics,” which was recently published in Resources, Conservation and Recycling.
This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com.
Summary: Researchers are launching a pioneering study using low-intensity focused ultrasound to address cocaine addiction by targeting the insula region of the brain. This noninvasive technique aims to reprogram brain cells to diminish cocaine cravings.
If successful, this approach could revolutionize addiction treatment. The initiative springs from increasing cocaine use and related deaths in Virginia and a lack of FDA-approved treatments for the addiction.
Key Facts:
- The study will use focused ultrasound to target the insula, a part of the brain associated with various addictions.
- There are currently no FDA-approved medications specifically to help people quit cocaine.
- UVA’s investigation on focused ultrasound has previously led to FDA approval for treatments related to Parkinson’s symptoms and essential tremor.
Source: University of Virginia
Pioneering researchers at UVA Health are testing whether focused sound waves can help people overcome cocaine addiction, a growing problem across the nation.
The scientists have launched a clinical trial, believed to be the first of its kind in the world, to test whether low-intensity focused ultrasound can help reprogram brain cells to reduce the desire for cocaine.
The noninvasive approach focuses sound waves on a portion of the brain called the insula, thought to play a critical role in multiple forms of addiction. If the trial is successful, it could pave the way for an important new tool to treat addiction in general.
“This trial will inform us if focused ultrasound could change the way some patients feel about cocaine,” said principal investigator Nassima Ait-Daoud Tiouririne, MD, the director of UVA’s Center for Leading Edge Addiction Research (CLEAR). “What if we could reverse brain changes caused by drug use? This would change the way we treat addiction as a whole.”
Cocaine Addiction: A Growing Problem
Cocaine use has been increasing steadily in Virginia for a decade, the researchers note. Overdose deaths jumped by a third from 2019 to 2020 alone. Those troubling trends have the UVA scientists eager to find innovative ways to reduce people’s cravings for the highly addictive drug. There are currently no medications approved by the federal Food and Drug Administration that can help people quit.
In their new trial, the UVA researchers will use focused sound waves to gently massage cells within the insula. The scientists will then see if the approach causes chemical changes in the brain that reduce cocaine cravings. (Prior studies have already shown that the insula plays an important role in both cocaine cravings and relapse; further, the researchers note, humans who suffered injuries to the insula were able to quit smoking easily, without suffering cravings or relapse.)
If the approach proves safe and effective, patients might one day soon go for a simple outpatient visit and leave with less desire to use cocaine.
“If successful, we become one step closer to developing new, safer ways to treat addiction,” said Ait-Daoud Tiouririne, of UVA’s Department of Psychiatry and Neurobehavioral Sciences. “Addiction is brain disorder. Treatment should include noninvasive neuromodulation of the brain circuits that cause the addiction in the first place.”
UVA’s trial is recruiting people ages 18 or older who have been diagnosed with cocaine-use disorder and who are not trying to provide up using cocaine.
For more information about the trial, visit https://med.virginia.edu/uva-clear/lifu-cocaine-use-disorder/.
The trial has received $5 million in support from the National Institutes of Health’s National Institute on Drug Abuse, grant 1UG3DA054789-01A1.
Focused Ultrasound at UVA
The cocaine trial joins an expansive portfolio of research underway at the University of Virginia School of Medicine to explore the vast potential of focused ultrasound to treat serious diseases ranging from cancer to Alzheimer’s.
UVA has long been a world leader in pioneering applications of focused ultrasound that will benefit patients. Prior research led by UVA’s Jeff Elias, MD, and colleagues, for example, paved the way for the FDA to approve high-intensity focused ultrasound to treat both Parkinson’s symptoms and essential tremor, a common movement disorder.
The success of its focused ultrasound efforts prompted UVA Health last year to launch the world’s first center devoted specifically to combining focused ultrasound with immunotherapy to Improve cancer care. The researchers hope that the combination will open new fronts in the war against many different forms of cancer, from breast cancer to brain tumors.
UVA’s game-changing research with focused ultrasound recently spurred CNN’s Sanjay Gupta, MD, to put together an in-depth story on one patient’s experience that was broadcast around the world.
Author: Josh Barney
Source: University of Virginia
Contact: Josh Barney – University of Virginia
Image: The image is credited to Neuroscience News
A team led by researchers from Mass Eye and Ear, a member of Mass General Brigham, reports the results of a phase I trial of a revolutionary stem cell treatment called cultivated autologous limbal epithelial cell transplantation (CALEC), which was found to be safe and well-tolerated over the short term in four patients with significant chemical burns in one eye. According to the study published August 18 in Science Advances, the patients who were followed for 12 months experienced restored cornea surfaces -- two were able to undergo a corneal transplant and two reported significant improvements in vision without additional treatment.
While the phase I study was designed to determine preliminary safety and feasibility before advancing to a second phase of the trial, the researchers consider the early findings promising.
"Our early results suggest that CALEC might offer hope to patients who had been left with untreatable vision loss and pain associated with major cornea injuries," said principal investigator and lead study author Ula Jurkunas, MD, associate director of the Cornea Service at Mass Eye and Ear and an associate professor of ophthalmology at Harvard Medical School. "Cornea certified have been hindered by a lack of treatment options with a high safety profile to help our patients with chemical burns and injuries that render them unable to get an artificial cornea transplant. We are hopeful with further study, CALEC can one day fill this crucially needed treatment gap."
In CALEC, stem cells from a patient's healthy eye are removed via a small biopsy and then expanded and grown on a graft via an innovative manufacturing process at the Connell and O'Reilly Families Cell Manipulation Core Facility at Dana-Farber Cancer Institute. After two to three weeks, the CALEC graft is sent back to Mass Eye and Ear and transplanted into the eye with corneal damage.
The CALEC project is a collaboration between Jurkunas and colleagues in the Cornea Service at Mass Eye and Ear, researchers at Dana-Farber Cancer Institute, led by Jerome Ritz, MD, Boston Children's Hospital, led by Myriam Armant, PhD, and the JAEB Center for Health Research. The clinical trial represents the first human study of a stem cell therapy to be funded by the National Eye Institute (NEI), a part of the National Institutes of Health (NIH).
Expanding one's own stem cells to address limitations in existing treatments
People who experience chemical burns and other eye injuries may develop limbal stem cell deficiency, an irreversible loss of cells on the tissue surrounding the cornea. These patients experience permanent vision loss, pain and discomfort in the affected eye. Without limbal cells and a healthy eye surface, patients are unable to undergo artificial cornea transplants, the current standard of vision rehabilitation.
Existing treatment strategies have limitations and associated risks the CALEC procedure aims to address through its unique approach of using a small amount of a patient's own stem cells that can then be grown and expanded to create a sheet of cells that serves as a surface for normal tissue to grow back.
According to the authors, despite landmark studies describing an autologous stem cell approach over the past 25 years and similar methods being utilized in Europe, no U.S. research team had successfully developed a manufacturing process and quality control tests that met U.S. Food and Drug Administration (FDA) requirements or showed any clinical benefit.
"It was challenging to develop a process for creating limbal stem cell grafts that would meet the FDA's strict regulatory requirements for tissue engineering," said Ritz, executive director of the Connell and O'Reilly Families Cell Manipulation Core Facility at Dana-Farber and professor of medicine at Harvard Medical School. "Having developed and implemented this process, it was very gratifying to see encouraging clinical outcomes in the first cohort of patients enrolled on this clinical trial."
Studies like this show the promise of cell therapy for treating incurable conditions. Mass General Brigham's Gene and Cell Therapy Institute is helping to translate scientific discoveries made by researchers into first-in-human clinical trials and, ultimately, life-changing treatments for patients. The Institute's multidisciplinary approach sets it apart from others in the space, helping researchers to rapidly advance new therapies and pushing the technological and clinical boundaries of this new frontier.
Case studies hold early promise as clinical trial advances
In the phase I study, five patients with chemical burns to one eye were enrolled and biopsied. Four received CALEC; a series of quality control tests determined the cells in the fifth patient were unable to adequately expand. The CALEC patients were tracked for 12 months.
The first patient treated, a 46-year-old male, experienced a resolution of his eye surface defect, which primed him to undergo an artificial cornea transplant for vision rehabilitation. The second, a 31-year-old male, experienced a complete resolution of symptoms with vision improving from 20/40 to 20/30. The third, a 36-year-old male, had his corneal defect resolved and his vision improved from hand motion -- only being able to see broad movements like waving -- to 20/30 vision. The fourth, a 52-year-old male, initially did not have a successful biopsy that resulted in a viable stem cell graft. After re-attempting CALEC three years later, he underwent a successful transplant and his vision improved from hand motion to being able to count fingers. He then received an artificial cornea.
The researchers are finalizing the next phase of the clinical trial in 15 CALEC patients they are tracking for 18 months to better determine the procedure's overall efficacy. Their hope is that CALEC can one day become a treatment option for patients who previously had to endure long-term deficits when existing treatment options were not an option given the severity of their injuries.
This study was funded by NEI/NIH grants UG1EY026508 [Massachusetts Eye and Ear], UG1EY027726 [Cell Manipulation Core Facility at Dana-Farber Cancer Institute], UG1EY027725 [Coordinating Center at the Jaeb Center for Health Research]. Pre-trial work (Boston Children's Hospital) was also funded by PACT, an initiative of the of the NIH's National Heart, Lung, and Blood Institute.
In addition to Drs. Jurkunas, Ritz, and Armant, additional investigators include Jia Yin, MD, PhD,MPH, Reza Dana, MD, Lynette Johns, OD, Sanming Li, PhD, Ahmad Kheirkhah, MD, Kishore Katikireddy, PhD, Alex Gauthier, PhD, Stephan Ong Tone, MD, PhD and Stacey Ellender, PhD of Mass Eye and Ear, Hélène Negre, PharmD, PhD, Kit L. Shaw, PhD, Diego E. Hernandez Rodriguez, PhD, Heather Daley, BS, of Dana-Farber Cancer Institute, and Allison Ayala, MS, Maureen Maguire, PhD and Lassana Samarakoon, MPH, of Jaeb Center for Health Research.
The CALEC procedure is patent pending. Jurkunas and Dana also disclose equity in Ocucell, a company interested in developing cell-based therapies for the eye.
Image source: The Motley Fool.
Ocugen (OCGN 17.66%)
Q2 2023 Earnings Call
Aug 22, 2023, 8:30 a.m. ET
Contents:
- Prepared Remarks
- Questions and Answers
- Call Participants
Prepared Remarks:
Operator
Good morning and welcome to Ocugen s second-quarter 2023 financial results and business update. Please note that this call is being recorded at this time. All participants' lines are in listen-only mode. Following the speakers' commentary, there will be a question-and-answer session.
I will now turn the call over to Tiffany Hamilton, Ocugen's head of corporate communications. You may begin.
Tiffany Hamilton -- Head of Corporate Communications
Thank you, operator. Joining me today are Ocugen's Chairman, CEO, and Co-Founder Dr. Shankar Musunuri, who will provide a business and financial update; and Dr. Arun Upadhyay, our financial scientific officer, head of research development and medical, who is also on the call to answer questions during the Q&A.
Yesterday afternoon, we issued a press release detailing business and operational highlights for the second quarter of 2023. We encourage listeners to review the press release, which is available on our website at ocugen.com. This call is being recorded and a replay with the accompanying slide presentation will be available on the Investors section of the Ocugen website for approximately 45 days. This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, which are subject to risks and uncertainties. We may, in some cases, use terms such as predicts, believes, potential, proposed, continue, estimates, anticipates, expects, plans, intends, may, could, might, will, should, or other words that convey uncertainty of future events or outcomes to identify these forward-looking statements. Such statements include but are not limited to statements regarding our clinical development activities and related anticipated timelines. Such statements are subject to numerous important risk factors, and uncertainties, and may cause genuine events or results to differ materially from our current expectations.
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These and other risks and uncertainties are more fully described in our periodic filings with the Securities and Exchange Commission, the SEC, including the risk factors described in the section entitled Risk Factors and the quarterly and annual reports that we filed with the SEC. Any forward-looking statements that we make in this presentation speak only as of the date of this presentation. Except as required by law, we assume no obligation to update forward-looking statements contained in this presentation whether as a result of new information, future events, or otherwise after the date of this presentation. Finally, Ocugen's quarterly report on Form 10-Q covering the second quarter of 2023 has been filed.
I will now turn the call to Dr. Musunuri.
Shankar Musunuri -- Co-Founder, Chairman, and Chief Executive Officer
Thank you, Tiffany. Good morning and thank you all for joining us today. The second quarter of 2023 marked a period of continued progress toward our regulatory and clinical milestones, which we are delight -- dedicated to advancing through the end of the year. With the strategic focus on our novel modifier gene therapy and biologic-based ophthalmic programs, we expect to begin dosing patients across these platforms by the end of this year. We're on track to initiate the OCU400 phase 3 adult trial near the end of 2023, early 2024, subject to outcome of the ongoing phase 1/2 trial and discussions with FDA on proposed phase 3 trial plan.
We also anticipate a clinical study results update for OCU400 this quarter. Investigational new drug applications were cleared by FDA for OCU410 and OCU410ST for geographic atrophy and Stargardt disease, respectively. We plan to initiate phase 1/2 trials by the end of 2023. We are also planning to initiate the phase 3 clinical trial for our regenerative cell therapy product candidate, NeoCart, in the second half of 2024. This would mean Ocugen would have late-stage programs in gene and cell therapies in 2024.
In an effort to conserve our working capital and advance our patient-centric agenda to develop a novel inhaled mucosal vaccine platform, we have submitted multiple proposals to obtain non-dilutive government funding and are having discussions with pertinent agencies to secure their support for our OCU500 vaccine series. Our first-in-class modifier gene therapy to treat multiple inherited retinal diseases remains unmatched industrywide. This unique gene-agnostic approach has the potential to address retinal diseases caused by mutations in multiple genes with one product. Our goal is to build on the innovation of gene therapy and expand its potential to treat a wider population of patients suffering from a host of rare retinal diseases that single gene replacement therapies are unable to address.
In the second quarter, we were honored to present in detail the mechanism of action and scientific basis for our modified gene therapy platform to preeminent researchers and medical professionals in attendance at the Association for Research in Vision and Ophthalmology and BIO International conferences. As we advance our clinical agenda, we will continue to identify and secure opportunities to educate stakeholders on the differentiation and potential benefits of this innovation -- innovative approach to gene therapy. In April, we announced encouraging and compelling positive preliminary safety and efficacy results from our OCU400 phase 1/2 multicenter, open-label, dose-ranging clinical trial in patients afflicted with RP. We believe the preliminary findings from the study support the potential for our modifier gene therapy to be a viable alternative to traditional treatments to the increasing population of patients suffering from these diseases. Enrollment is ongoing for all defined subjects in the study, adults with LCA and children between ages of six to 17.
Pending positive feedback from the FDA, we aim to initiate our phase 3 adult clinical trial in the end of this year or early 2024. We continue to execute our comprehensive strategy to develop OCU400 and bring it to market by 2026 with the goal of providing desperately needed treatment options for the estimated 125,000 patients estimated in the U.S. alone that suffer from RP and LCA. In parallel, we'll continue progressing or other modified gene therapy programs to address additional ophthalmic conditions. We believe that upon successful realization of these goals, Ocugen will have built a vast commercial footprint that may hold significant upside for our shareholders and, most importantly, meet a critical medical need for patients.
Dry age-related macular degeneration is one of the most prevalent neurodegenerative eye diseases affecting approximately 10 million people in the U.S. and nearly 266 million people worldwide. Dry AMD results in irreversible loss of sight among elderly populations, leading to a lack of functional independence that severely impacts quality of life. A variety of biotechnology companies, small and large, are working to develop therapies for Dry AMD. However, we believe our OCU410 candidate can offer a less burdensome option for our patients.
With OCU410, we are again investigating the potential for our novel modifier gene therapy to provide a one-time treatment option that targets all four hallmark conditions of Dry AMD, including lipid metabolism, inflammation, oxidative stress, and complement activation. The current standard of care only targets the complement factor requires multiple injections per year and has reported side effects. We're excited to initiate the phase 1/2 clinical trial this year because of the significant global unmet medical need. Moving on to OCU410ST. We're extremely pleased to receive orphan drug designation from the FDA to address ABCA4-associated retinal diseases such as Stargardt disease, RP19, and cone-rod dystrophy for which there are currently no treatment options.
OCU410ST is a novel modified gene therapy that leverages nuclear hormone receptors to modulate cell activity and utilizes an AAV delivery platform for retinal delivery of the RAR-related orphan receptor A. Nuclear hormone receptors are master gene regulators that help maintain homeostasis by regulating diverse physiological functions such as photoreceptor development and maintenance, metabolism, phototransduction, inflammation, and cell survival networks. We believe that by harnessing the power of nuclear hormone receptors, we can develop one-time treatments that can modulate cell activity disrupted by disease-causing gene mutations. Now, turning to our efforts to develop a series of next-generation inhalation vaccines for which the company intends to submit an IND application in 2024 pending government funding.
In multiple preclinical trials, mucosal vaccines have demonstrated vaccine-induced high neutralization titer and effector responses. Inhaled mucosal vaccines represent a distinct product candidate profile that could help remedy major global health challenges and maximize our opportunity to serve a broader cross-section of patients through a less invasive delivery mechanism with the potential for superior durability when compared with the current intramuscular administration. Clinical studies using a similar vector of inhaled administration have shown mucosal antibodies, systemic and antibodies, and durable immune response up to one year, with one-fifth of the dose compared to traditional intramuscular vaccines. Greater ease of administration presents the potential for improved vaccination compliance and wider adoption, particularly among traditionally underserved populations and throughout the developing world. Current COVID-19 vaccines are limited by a lack of durability and marginal ability to prevent transmission.
As part of our commitment to address barriers to widespread vaccination to protect against COVID-19, we are developing this inhaled vaccine platform that includes OCU500, a bivalent COVID-19 vaccine; OCU510, a seasonal quadrivalent flu inhaled vaccine; and OCU520, a combination of quadrivalent seasonal flu and bivalent COVID-19 inhaled vaccine. The OCU500 vaccine series is based on a novel ChAd platform designed to reduce transmission and protect against new variants with potential durability up to one year. To optimize resources across our diverse and critically needed development programs and maintain shareholder value, our team has been engaging with public health officials and federal government agencies to pursue non-dilutive funding to support the development of our OCU500 vaccine series. We maintain an ongoing dialogue with respective agencies and anticipate receiving further information on the status of our funding request later this year. Earlier this year, the FDA notified us that they were putting a hold on our OCU200 program and requested additional information related to chemistry, manufacturing, and controls. We are working with the FDA to release the hold and expect the phase 1 trial to be initiated in Q4 2023. We believe OCU200 works with a distinct mechanism of action compared to existing therapies for the treatment of diabetic macular edema and targets multiple causative pathways such as angiogenesis, oxidation, and inflammation as potential to offer better treatment to all patients. NeoCart is our phase 3-ready regenerative cell therapy technology that combines novel advancements in bioengineering and cell processing to enhance the autologous cartilage repair process.
Manufacturing facility construction for NeoCart is on target to be completed by the end of 2023 as planned. The company plans to initiate the phase 3 trial in subjects with articular cartilage defect in the second half of 2024. We are highly dedicated to completing our stated objectives with the strategies we believe will enable Ocugen to reach total value-enhancing milestones and are planning to file BLAs across all first-in-class platform technologies, gene therapies, cell therapies, and vaccines in the next three to five years. I will now provide an overview of the key financial results for second quarter 2023. Our research and development expenses for the quarter ended June 30, 2023 were 14.2 million, compared to 9 million for the second quarter of 2022.
This included a nonrecurring noncash expense of 4.4 million as a result of the impairment of the short-term asset for the advanced payment for the supply of Covaxin, as well as the associated loss on the disposal of related fixed assets. General administrative expenses for the quarter ended June 30, 2023 were 9.6 million, compared to 10.6 million for the second quarter of 2022. Net loss was approximately 22.9 million, or 0 point -- $0.10 -- $0.10 net loss per share for the quarter ended June 30, 2023, compared to a net loss of approximately 19.5 million or $0.09 net loss per share for the second quarter of 2022. Our cash, cash equivalents, and investments totaled 70.6 million as of June 30, 2023, compared to 90.9 million as of December 31, 2022. In May, we closed a public offering of 30 million shares of common stock for gross proceeds of 16.5 million.
Net proceeds from the offering are being used for general corporate purposes, capital expenditures, working capital, general and administrative expenses, and R&D. We're continuously exploring opportunities to increase our working capital and will be focused on seeking out corporate partnerships for gene therapies and non-dilutive funding for vaccines. That concludes my update for the quarter. Tiffany, back to you.
Tiffany Hamilton -- Head of Corporate Communications
Thank you, Shankar. We will now open the call for questions. Operator?
Questions & Answers:
Operator
The floor is now open for your questions. [Operator instructions] We'll now take a moment to compile our roster. Our first question comes from the line of Jennifer Kim from Cantor Fitzgerald. Please go ahead.
Jen Kim -- Cantor Fitzgerald -- Analyst
Hi, good morning. Thank you for taking my questions. I have two. The first is as you're thinking about cash burn going forward and you're seeking non-dilutive funding opportunities.
Excluding the one-time impairment expense -- expense, is this quarter a good basis as we think about quarterly burn? And then, my second question is on the OCU400 program. Can you remind us what you're looking for in that updated data this quarter as sort of the go/no-go for the phase 3 adult trial? Thanks.
Shankar Musunuri -- Co-Founder, Chairman, and Chief Executive Officer
Yeah, Jennifer, good morning. Let me address the first question, then Arun is going to take the second one. Yes, there is a one-time impairment charge. There's also a noncash stock comp charge of 2.6 million.
And if you add those two, the cash comes out to be 15.9 million total for quarter. So, that would be a good guidance for you for the future. I'll let Arun address the other question on OCU400 program.
Arun Upadhyay -- Chief Scientific Officer
Thank you, Shankar. Thanks, Jennifer. So, yeah, you are right, I think our -- this quarter update on OCU400 clinical phase1/2 data will guide us about our phase 3 study. Yeah, that's the data will be used as a basis for our decision for phase 3.
Jen Kim -- Cantor Fitzgerald -- Analyst
OK, and can you remind us what you're looking for in that data?
Arun Upadhyay -- Chief Scientific Officer
So, primarily, we are looking at the -- the functional improvement in the patients treated with OCU400. And the focus is going to be the RP patient.
Jen Kim -- Cantor Fitzgerald -- Analyst
OK. And then, in your discussions with the FDA later on for the phase 3 trial, is that going to focus on RP patients, or are you also considering the inclusion of LCA patients? Thank you.
Arun Upadhyay -- Chief Scientific Officer
So, to begin with, we'll start with the RP patient. And as we collect the data for LCA patients, then -- then later, we include LCA. But to begin with, we are planning to go with adult RP patient.
Jen Kim -- Cantor Fitzgerald -- Analyst
All right. Thanks for taking my questions. Bye.
Arun Upadhyay -- Chief Scientific Officer
Thank you.
Operator
Our next question comes from the line of William Ramakanth from H.C. Wainwright. Please go ahead.
Unknown speaker
Thank you. This is RK from H.C. Wainwright. So, a couple of quick -- quick questions on the 400 program and then maybe one on the NeoCart.
On the 400, so in terms of your discussions with the FDA, is that being planned once you see the data on the phase 1/2, or you have already initiated, you know, some initial conversations and started putting together a phase 3 plan?
Arun Upadhyay -- Chief Scientific Officer
Thanks, RK. So, we have not initiated our discussion with FDA yet. So, once we -- we, you know, complete the data analysis, only then we are going to reach out to FDA. But that is planned for this quarter, you know, related to data update and followed by reaching out to FDA.
Unknown speaker
Thank you for that. And then, on the 410 program, you know, in terms of now that you've already been cleared by the FDA, what else needs to get done before you can initiate the phase 1/2 studies?
Arun Upadhyay -- Chief Scientific Officer
Just we need to get the site ready and, you know, initiate the patient screening. And so -- so, that's why I think we are planning like, you know, to lodge -- lodge, you know, first subject in this study both, you know, GA as well as Stargardt this year. So, it is more like Getting ready with, you know, with the clinical, you know, sites.
Unknown speaker
Got it. Got it. Then on the -- on the NeoCart program, if -- just trying to understand if the facility does -- gets completed by the end of '23, you know, what else needs to get done, you know, in terms of commissioning the plant and getting the clinical material ready to start your program on the -- on the phase 3 study by second half? You know, is it just that, or is it, you know, you still have to design the protocol? I'm just trying to understand what all because we've been talking about this program for almost a year and a half now.
Shankar Musunuri -- Co-Founder, Chairman, and Chief Executive Officer
Yeah, no, so, RK, the facility construction will be completed -- it's a GMP facility -- by the end of this year. It's on target. And then, as you know, as a GMP facility, it takes a few months for getting the qualification done, and then they'll be ready to produce NeoCart in that facility. In the interim, obviously, the team is going to prepare, you know, CMC and clinical sections.
And they'll continue to, you know, update those so that they're ready for submission next year before they start the clinical trial. And we do have RMAT designation, right, I just wanted to remind, Regenerative Medicine Advanced Therapy designation with FDA. So, when we have any questions in the interim, we can always reach out to them and get clarifications.
Unknown speaker
Perfect. Thanks. Thanks for taking the questions.
Operator
Our next question comes from the line of Robert LeBoyer from Noble Capital Markets. Please go ahead.
Robert LeBoyer -- Noble Capital Markets -- Analyst
Good morning, everyone. My question has to do with the upcoming data presentation. And I was wondering if you could disclose whether the data to be presented will update the previous data on all patients or whether it will just be in new patients that haven't been reported. And wondering if there are any endpoints that you could share with us at this point.
Arun Upadhyay -- Chief Scientific Officer
Thank you. So, yeah, definitely, we'll be providing detailed, you know, update when we kind, of you know, present this data to the market. But to address your first part of the question whether it is going to include the percent we presented in our previous, you know disclosure, yes. So, we will include those subjects as well as some new subjects which has, you know, completed additional follow-up visits.
So, it will be a combination of both, yeah.
Robert LeBoyer -- Noble Capital Markets -- Analyst
OK. Great. And you had mentioned corporate partnerships for the gene therapy. Can you discuss any type of arrangements whether they're going to be research and development, or just marketing, or any objectives to the business development activities?
Shankar Musunuri -- Co-Founder, Chairman, and Chief Executive Officer
I mean, Robert, this is a -- yeah, it's a loaded question. Obviously, we'll be open to -- when you seek partnerships at this stage as a biotech, you know, big pharma established with a infrastructure and everything else, obviously, your first target is going to be commercial. This has, as you know, complex sciences involved in these clinical trials. Obviously, when you're going into phase 3, once we have the data out, we'll obviously work very hard with any potential partners. And obviously, as you know, if they are interested in commercial development, they would be interested in phase 3 program too.
So, I think we'll keep our options open whatever can maximize our value for Ocugen as well as, you know, make sure we have ability to provide market access to patients who desperately need this product.
Robert LeBoyer -- Noble Capital Markets -- Analyst
OK, great. Thank you very much.
Operator
Our final question comes from the line of Daniil Gataulin from Chardan. Please go ahead.
Daniil Gataulin -- Chardan Capital Markets -- Analyst
Hey, good morning, guys. Thank you for taking that question. Got a couple. One for -- for OCU410 program.
Just wanted to ask, strategically, how do you see it positioned, long-term view, as a stand-alone approach or in combination with anything else and the patient population that you'll be targeting? And the second question is for the inhaled vaccine series. You know, can you comment on your interactions to date regarding the funding and, particularly, if you can comment on the interest in this program given that there are several other approved options? Thank you.
Arun Upadhyay -- Chief Scientific Officer
Thank you. So, I'll take the first question. So, yeah, we are thinking of, you know, taking it just stand-alone product. And to begin with, definitely, we'll be targeting the advanced form of AMD, that is geographic atrophy.
But subsequently, you know, based on the outcome, it -- it may be further developed for, you know, early and intermediate stage depending on the clinical benefit coming from the GA trial. And regarding, like, how we -- how we see this product, you know, against other what we see in the market, so as you all know that AMD is a multifactorial disease. And so, far we have been, you know, seeing in this space that most of the companies are focused on targeting only one pathway. And by, like, very nature of this disease, you know, being multifactorial in nature, there are various causes which lead to this disease. So, our product has potential to target all those -- those pathways which are linked to the AMD pathogenesis. So, we believe that this could be a differentiated product and -- and has potential to -- to offer a better, you know, clinical benefit compared to what -- what we have right now.
Shankar Musunuri -- Co-Founder, Chairman, and Chief Executive Officer
And, Daniil, good morning. The second question related to government funding, again, we have been working with, you know, various agencies and will provide an update. Obviously, the current products, as you know, the vaccines we have, especially for COVID, they lack a couple of things. One, they're struggling to control the transmission. There's a lot of data available so -- right now.
And also, they lack durability. So, what would be ideal option going into the future? I think there is definitely a need for mucosal vaccines. The scientific community agrees on that. And also, that will provide systemic as well as mucosal immunity.
So, you can actually potentially prevent at the target of viral entry into mucosal system. The second thing is durability. I mean, we believe, and the scientific community believes, that COVID vaccinations, in order to gain the compliance with public, you cannot keep on vaccinating every three months. That's why, you know, people get vaccine fatigue. So, you need to move into like annual vaccinations such as flu so compliance rate will go up.
So, that's the intent. I think as, you know, we stated, there are ex-U.S. trials with inhalation vaccine using a similar technology showed durability up to one year. That's really important.
So, there are two things: controlling transmission and durability are very important for next-gen vaccines. And we believe our platform-technology inhalation vaccines for COVID and flu, they can provide that.
Daniil Gataulin -- Chardan Capital Markets -- Analyst
Thank you so much.
Operator
This concludes the Q&A portion. I will now turn the call back over to chairman and CEO, Dr. Shankar Musunuri.
Shankar Musunuri -- Co-Founder, Chairman, and Chief Executive Officer
Thank you, operator. In closing, I'd like to recognize the entire team for their resilient efforts to advance our patient-centric mission. To our shareholders and partners, thank you for your ongoing trust and support. We're already well into the second half of 2023 and are steadfast in our commitment to transparency, informed decision-making based on sound scientific principles, and a tireless work ethic dedicated to excellence in all phases of research, development, and clinical testing. We remain confident that we will be able to fulfill our mission of developing novel therapies with innovative discovery to bring to market effective treatments for patients suffering from a range of conditions that currently lack treatment options.
We look forward to sharing more details on our progress in the coming months.
Tiffany Hamilton -- Head of Corporate Communications
Thanks, everyone. Have a great day.
Duration: 0 minutes
Call participants:
Tiffany Hamilton -- Head of Corporate Communications
Shankar Musunuri -- Co-Founder, Chairman, and Chief Executive Officer
Jen Kim -- Cantor Fitzgerald -- Analyst
Arun Upadhyay -- Chief Scientific Officer
Unknown speaker
Robert LeBoyer -- Noble Capital Markets -- Analyst
Daniil Gataulin -- Chardan Capital Markets -- Analyst
In a recent study published in the PNAS Journal, researchers used a multidisciplinary approach to investigate a nonstructural protein essential in SARS-CoV-2 replication.
They characterized the protein and discovered how it contributes to RNA replication. They also discovered the inhibitory effects of the stable nitroxide TEMPOL against the protein, paving the road for a new class of anti-viral drugs against the disease.
Study: An iron–sulfur cluster in the zinc-binding domain of the SARS-CoV-2 helicase modulates its RNA-binding and -unwinding activities. Image Credit: MiniStocker/Shutterstock.com
SARS-CoV-2 replication and RdRp
The severe acute respiratory syndrome coronavirus 2 (SARS‑CoV‑2) is a strain of coronavirus (SARSr‑CoV) that caused the coronavirus disease 2019 (COVID-19) pandemic.
It is a positive-sense single-stranded RNA virus (+ssRNA) from the same family as the SARS virus (SARS‑CoV‑1) and Hepatitis C. These viruses lack DNA, with their RNA serving as messenger RNA and template genome.
In SARS‑CoV‑2, the RNA genome is 30 kb in size and comprises structural- (sp) and nonstructural proteins (nsp), which perform both viral transcription and replication.
Previous studies have identified 16 nsp, three of which collectively make up the RNA-dependent RNA polymerase (RdRp) – nsp12 (catalytic subunit), nsp7, and nsp8 (auxiliary factors). While a growing body of literature characterizing the structure and function of these three for their potential in anti-viral drug therapy exists, the remaining 13 nsp have been largely ignored.
Recent research has begun exploring the functional properties of helicases (enzymes mainly responsible for DNA or RNA unwinding) belonging to the helicase superfamily 1B (SF1B).
One of these, nsp13, is interesting in that its independent helicase activity is poor and inefficient, but when paired with the RdRp complex, shows a significant augmentation in its RNA unwinding action, thereby playing a vital role in the replication of SARS‑CoV‑2. Research has additionally suggested nsp13 as essential in 5' mRNA cap formation.
The 5' mRNA cap is critical in protecting the RNA from environmental RNA exonucleases (enzymes that damage RNA) and promoting viral translation by the infected hosts' ribosomes.
Electron microscopy and X-ray crystallography of the nsp13 structure have shown it to be one of the most structurally conserved parts of the SARSr‑CoV genome. Genetic analyses have confirmed this by elucidating that nsp13s in SARS‑CoV‑2 and SARS‑CoV‑1 differ by a conservative change in only one amino acid (V570I).
One of the main difficulties in developing vaccines and anti-viral drugs against COVID-19 is its high mutation rate. Vaccines and medications developed against one strain usually show poor efficiency against a different strain.
Focusing efforts on genomic regions that remain largely conserved across strains has the potential for developing drugs effective against a broad range of strains. Research thus suggests that compounds effective at inhibiting the action of SARS-CoV-2 nsp13 would have similar effects on SARS-CoV-1 and future SARS‑CoV variants.
About the study
In the present study, researchers added to their previous work on nsp characterization and functional evaluation. They investigated nsp13 using a multidisciplinary approach incorporating inductively coupled plasma mass spectrometry (ICP-MS), UV-visible absorption, electron paramagnetic resonance (EPR), and Mössbauer spectroscopies to characterize the structure.
These spectrometric techniques were conducted on recombinant strains of SARS‑CoV‑2 expressed in Expi293F mammalian cells (a human in vitro cell line). Strains were designed to overexpress nsp13, and site-directed mutagenesis was used to create multiple Expi293F clones will point mutations in the nsp13 region.
This was done so that downstream comparisons between wild-type (WT) and clone nsp13 inhibitions could be made. Proteins were extracted, isolated, and purified using subcellular fractionation and immunoprecipitation (IP).
Researchers began characterization by using mass spectrometry to evaluate the chemical peptide composition of nsp13 and quantify its expression amount by different Expi293F clones.
ICP-MS was then employed to evaluate the proteins' total zinc and iron content. Ferrozine-based colorimetric assays were used to quantify the amount of Fe2+ and Fe3+ in each nsp13 sample.
UV-vis absorption spectroscopy was used to quantify the densities of Expi293F transfected colonies. Amino acid analysis (AAA) was used to quantify the nsp13 protein contents of the colonies. EPR and Mössbauer spectroscopies were used to investigate the type and stoichiometry of iron-sulfur cluster(s) in nsp13.
Researchers finally used helicase unwinding activity assays to evaluate the efficiency of SARS‑CoV‑2 unwinding by WT and mutant nsp13.
Since their results indicated that the iron content of nsp13 played a vital role in its helicase property, metal-free (apo-) nsp13 was obtained by treating the purified protein with ethylenediaminetetraacetic acid (EDTA) and passing the mixture through a trial cleanup gravity column.
Zinc was reconstituted into the protein at values matching those from ICP-MS analyses to reduce the confounding effects of zinc ion removal.
Study findings
In their previous work on nsp12 (the main catalytic subunit of RdRp), the present research group identified two cubane [Fe4S4] iron-sulfur (Fe-S) clusters in the protein. It established the critical role that Fe-S clusters play in CoV replication and the interaction of nsp12 with nsp13.
In the present work, proteomic analysis from mass spectrometry data identified a leucine-tyrosine-lysine (LYK) motif in nsp13, which was indicated to function as the binding site for nsp12 Fe-S clusters.
This suggests the mechanism behind Fe-S transfer from nsp12 to nsp13. WT nsp13 was seen to have zinc and iron ions. Nsp13 variants lacking the LYK motif were observed to retain zinc but lose iron ions, implying replacement by alanines (α-amino acids with the chemical formula C3H7NO2).
(UV-vis) absorption spectroscopy suggested that purified nsp13 expressed in Expi293F cells harbored Fe–S clusters. Mössbauer spectrum analysis was used to determine the type and stoichiometry of nsp13 and its components. The role of the Fe–S cluster in nsp13 was revealed by comparing variants with and without the cluster and those with and without zinc ions.
"Loss of the Fe–S cluster in nsp13C50S-C55S impaired the unwinding activity of the helicase, likely as a result of diminished binding of the variant to the substrate, whereas the absence of the zinc ions from either of the two metal-binding sites in the nsp13C5S-C8S, nsp13C26S-C29S, nsp13C16S-C19S, and nsp13H33S-H39S variants did not affect the unwinding activity."
Of the three US Food and Drug Administration (FDA) drugs used as anti-viral to SARS-CoV-2 replication, at least one has been ineffective against novel drug-resistant strains. This is due to its mechanism of action targeting the RdRp, a rapidly evolving part of the SARS-CoV-2 genome.
This necessitates the development of anti-virals that target conserved RNA segments, one of which is TEMPOL. TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl) is a stable nitroxyl antioxidant.
This research identified TEMPOL effectively inhibiting SARS-CoV-2 replication by targeting the RdRp and nsp13.
"We propose that TEMPOL could be regarded as an anti-viral that works through a different mechanism than other anti-virals; its likely low toxicity could make it attractive for use as an oral postexposure preventative treatment against SARS-CoV-2."
Conclusion
In the present study, researchers investigated the structure and function of nsp13, a nonstructural protein present in coronavirus strains. They utilized multiple spectrometric techniques to elucidate its structure and stoichiometry.
These analyses revealed that the nsp13 plays a vital yet underestimated role in SARSr‑CoV replication by remarkably increasing its RNA unwinding ability on accepting Fe-S from nsp12, the catalytic subunit of the RdRp complex.
Nsp13 is one of the most conserved regions of the SARSr‑CoV genome. This research identified and recommended TEMPOL, a stable nitroxyl antioxidant that inhibits the nsp13, as an effective broad-spectrum anti-viral, with its low toxicity to humans making it an attractive candidate in the oral postexposure intervention against SARS-CoV-2.
Journal reference:
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Maio, N., Raza, M. K., Li, Y., Zhang, D., Bollinger, J. M., Krebs, C., & Rouault, T. A. (2023). An iron–sulfur cluster in the zinc-binding domain of the SARS-CoV-2 helicase modulates its RNA-binding and -unwinding activities. Proceedings of the National Academy of Sciences., doi: 10.1073/pnas.2303860120. https://www.pnas.org/doi/10.1073/pnas.2303860120
