Potential Anti-Mpox Virus Activity of Atovaquone, Mefloquine, and Molnupiravir, and Their Potential Use as Treatments

BACKGROUND

Mpox virus (MPXV) is a zoonotic orthopoxvirus and caused an outbreak in 2022. Although tecovirimat and brincidofovir are approved as anti-smallpox drugs, their effects in mpox patients have not been well documented. In this study, by a drug repurposing approach, we identified potential drug candidates for treating mpox and predicted their clinical impacts by mathematical modeling.

METHODS

We screened 132 approved drugs using an MPXV infection cell system. We quantified antiviral activities of potential drug candidates by measuring intracellular viral DNA and analyzed the modes of action by time-of-addition assay and electron microscopic analysis. We further predicted the efficacy of drugs under clinical concentrations by mathematical simulation and examined combination treatment.

RESULTS

Atovaquone, mefloquine, and molnupiravir exhibited anti-MPXV activity, with 50% inhibitory concentrations of 0.51-5.2 μM, which was more potent than cidofovir. Whereas mefloquine was suggested to inhibit viral entry, atovaquone and molnupiravir targeted postentry processes. Atovaquone was suggested to exert its activity through inhibiting dihydroorotate dehydrogenase. Combining atovaquone with tecovirimat enhanced the anti-MPXV effect of tecovirimat. Quantitative mathematical simulations predicted that atovaquone can promote viral clearance in patients by 7 days at clinically relevant drug concentrations.

CONCLUSIONS

These data suggest that atovaquone would be a potential candidate for treating mpox.

Identification of IMP Dehydrogenase as a Potential Target for Anti-Mpox Virus Agents

Mpox virus (formerly monkeypox virus [MPXV]) is a neglected zoonotic pathogen that caused a worldwide outbreak in May 2022. Given the lack of an established therapy, the development of an anti-MPXV strategy is of vital importance. To identify drug targets for the development of anti-MPXV agents, we screened a chemical library using an MPXV infection cell assay and found that gemcitabine, trifluridine, and mycophenolic acid (MPA) inhibited MPXV propagation. These compounds showed broad-spectrum anti-orthopoxvirus activities and presented lower 90% inhibitory concentrations (0.026 to 0.89 μM) than brincidofovir, an approved anti-smallpox agent. These three compounds have been suggested to target the postentry step to reduce the intracellular production of virions. Knockdown of IMP dehydrogenase (IMPDH), the rate-limiting enzyme of guanosine biosynthesis and a target of MPA, dramatically reduced MPXV DNA production. Moreover, supplementation with guanosine recovered the anti-MPXV effect of MPA, suggesting that IMPDH and its guanosine biosynthetic pathway regulate MPXV replication. By targeting IMPDH, we identified a series of compounds with stronger anti-MPXV activity than MPA. This evidence shows that IMPDH is a potential target for the development of anti-MPXV agents. IMPORTANCE Mpox is a zoonotic disease caused by infection with the mpox virus, and a worldwide outbreak occurred in May 2022. The smallpox vaccine has recently been approved for clinical use against mpox in the United States. Although brincidofovir and tecovirimat are drugs approved for the treatment of smallpox by the U.S. Food and Drug Administration, their efficacy against mpox has not been established. Moreover, these drugs may present negative side effects. Therefore, new anti-mpox virus agents are needed. This study revealed that gemcitabine, trifluridine, and mycophenolic acid inhibited mpox virus propagation and exhibited broad-spectrum anti-orthopoxvirus activities. We also suggested IMP dehydrogenase as a potential target for the development of anti-mpox virus agents. By targeting this molecule, we identified a series of compounds with stronger anti-mpox virus activity than mycophenolic acid.

An ACAT inhibitor suppresses SARS-CoV-2 replication and boosts antiviral T cell activity

The severity of disease following infection with SARS-CoV-2 is determined by viral replication kinetics and host immunity, with early T cell responses and/or suppression of viraemia driving a favourable outcome. Recent studies uncovered a role for cholesterol metabolism in the SARS-CoV-2 life cycle and in T cell function. Here we show that blockade of the enzyme Acyl-CoA:cholesterol acyltransferase (ACAT) with Avasimibe inhibits SARS-CoV-2 pseudoparticle infection and disrupts the association of ACE2 and GM1 lipid rafts on the cell membrane, perturbing viral attachment. Imaging SARS-CoV-2 RNAs at the single cell level using a viral replicon model identifies the capacity of Avasimibe to limit the establishment of replication complexes required for RNA replication. Genetic studies to transiently silence or overexpress ACAT isoforms confirmed a role for ACAT in SARS-CoV-2 infection. Furthermore, Avasimibe boosts the expansion of functional SARS-CoV-2-specific T cells from the blood of patients sampled during the acute phase of infection. Thus, re-purposing of ACAT inhibitors provides a compelling therapeutic strategy for the treatment of COVID-19 to achieve both antiviral and immunomodulatory effects. Trial registration: NCT04318314.

Mefloquine, a Potent Anti-severe Acute Respiratory Syndrome-Related Coronavirus 2 (SARS-CoV-2) Drug as an Entry Inhibitor in vitro

Coronavirus disease 2019 (COVID-19) has caused serious public health, social, and economic damage worldwide and effective drugs that prevent or cure COVID-19 are urgently needed. Approved drugs including Hydroxychloroquine, Remdesivir or Interferon were reported to inhibit the infection or propagation of severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), however, their clinical efficacies have not yet been well demonstrated. To identify drugs with higher antiviral potency, we screened approved anti-parasitic/anti-protozoal drugs and identified an anti-malarial drug, Mefloquine, which showed the highest anti-SARS-CoV-2 activity among the tested compounds. Mefloquine showed higher anti-SARS-CoV-2 activity than Hydroxychloroquine in VeroE6/TMPRSS2 and Calu-3 cells, with IC₅₀ = 1.28 μM, IC₉₀ = 2.31 μM, and IC₉₉ = 4.39 μM in VeroE6/TMPRSS2 cells. Mefloquine inhibited viral entry after viral attachment to the target cell. Combined treatment with Mefloquine and Nelfinavir, a replication inhibitor, showed synergistic antiviral activity. Our mathematical modeling based on the drug concentration in the lung predicted that Mefloquine administration at a standard treatment dosage could decline viral dynamics in patients, reduce cumulative viral load to 7% and shorten the time until virus elimination by 6.1 days. These data cumulatively underscore Mefloquine as an anti-SARS-CoV-2 entry inhibitor.

Potential anti-COVID-19 agents, cepharanthine and nelfinavir, and their usage for combination treatment

Antiviral treatments targeting the coronavirus disease 2019 are urgently required. We screened a panel of already approved drugs in a cell culture model of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and identified two new agents having higher antiviral potentials than the drug candidates such as remdesivir and chroloquine in VeroE6/TMPRSS2 cells: the anti-inflammatory drug cepharanthine and human immunodeficiency virus protease inhibitor nelfinavir. Cepharanthine inhibited SARS-CoV-2 entry through the blocking of viral binding to target cells, while nelfinavir suppressed viral replication partly by protease inhibition. Consistent with their different modes of action, synergistic effect of this combined treatment to limit SARS-CoV-2 proliferation was highlighted. Mathematical modeling in vitro antiviral activity coupled with the calculated total drug concentrations in the lung predicts that nelfinavir will shorten the period until viral clearance by 4.9 days and the combining cepharanthine/nelfinavir enhanced their predicted efficacy. These results warrant further evaluation of the potential anti-SARS-CoV-2 activity of cepharanthine and nelfinavir.

Potential anti-COVID-19 agents, cepharanthine and nelfinavir, and their usage for combination treatment

Antiviral treatments targeting the coronavirus disease 2019 are urgently required. We screened a panel of already approved drugs in a cell culture model of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and identified two new agents having higher antiviral potentials than the drug candidates such as remdesivir and chroloquine in VeroE6/TMPRSS2 cells: the anti-inflammatory drug cepharanthine and human immunodeficiency virus protease inhibitor nelfinavir. Cepharanthine inhibited SARS-CoV-2 entry through the blocking of viral binding to target cells, while nelfinavir suppressed viral replication partly by protease inhibition. Consistent with their different modes of action, synergistic effect of this combined treatment to limit SARS-CoV-2 proliferation was highlighted. Mathematical modeling in vitro antiviral activity coupled with the calculated total drug concentrations in the lung predicts that nelfinavir will shorten the period until viral clearance by 4.9 days and the combining cepharanthine/nelfinavir enhanced their predicted efficacy. These results warrant further evaluation of the potential anti-SARS-CoV-2 activity of cepharanthine and nelfinavir.

Does high-resolution MR imaging have better accuracy than standard MR imaging for evaluation of the triangular fibrocartilage complex?

We compared the findings of high-resolution MR imaging and standard MR imaging in the detection of tears of the triangular fibrocartilage in 33 patients with chronic wrist pain on the ulnar side. With arthroscopy as the standard of reference, sensitivity was 100%, specificity 53%, and accuracy 79% with the high-resolution MR imaging, against 83%, 67%, and 76% with the standard MR imaging. High-resolution MR imaging showed a higher sensitivity, but a decreased specificity in the assessment of the triangular fibrocartilage. The results showed that diagnosis of tears in the triangular fibrocartilage by MR imaging, even high-resolution MR imaging, is unsatisfactory, although further technological advances may well improve the accuracy.

Late treatment of unreduced perilunate dislocations

Twenty-eight patients with perilunate dislocations that had been untreated for a minimum of 6 weeks after injury were assessed at a mean of 6.8 years after subsequent treatment. Treatment consisted of open reduction with or without internal fixation of the scaphoid in six patients, proximal row carpectomy in 16, total excision of the lunate in four, and carpal tunnel release and partial excision of the lunate in two. Open reduction yielded satisfactory results in cases of less than 2 months standing. We believe that proximal row carpectomy should be considered in the treatment of chronic perilunate dislocations in patients who are seen later than 2 months after injury, if the cartilage of the proximal pole of the capitate is well preserved. The results of lunate excision were less favourable.

Ulnar styloid malunion with dislocation of the distal radioulnar joint

Four patients with dorsal dislocation of the distal radioulnar joint and ulnar styloid malunion had corrective osteotomy of the ulnar styloid. Dislocation of the distal radioulnar joint was reduced in three of four patients. Subluxation persisted in the remaining patient. Wrist function improved in all patients. These results support the contention that a displaced ulnar styloid fracture with distal radioulnar joint dislocation should be reduced and internally fixed. Corrective osteotomy is recommended for malunion of the ulnar styloid associated with dislocation of the distal radioulnar joint.

Corrective ulnar osteotomy for malunited anterior Monteggia lesions in children. 12 patients followed for 1-12 years

We reviewed 12 children, mean 5 (1-12) years, after corrective osteotomy of the ulna, combined with open reduction of the radial head for malunited anterior Monteggia lesions (Bado type I). A simple corrective osteotomy was used in the first 6 patients (group A) and a posterior angular osteotomy was used in the second group of 6 patients (group B). All osteotomies healed uneventfully, but 3 patients had a persistent dislocation of the radial head. Children who had been treated with an angular osteotomy had the best clinical outcome).

Herbert screw fixation for scaphoid nonunions. An analysis of factors influencing outcome

A retrospective review of 160 cases of scaphoid nonunion treated by internal fixation using a Herbert screw with bone grafting was conducted at an average followup of 24 months. Definite radiographic union was achieved in 90% of cases. Based on Cooney's clinical scoring system, 80 cases had an excellent result, 37 had a good result, 33 had a fair result, and 10 had a poor result. Failure of union was related to the existence of avascular changes of the proximal fragment, instability of the fracture fragment, the prolonged delay in surgery, and the location of the fracture site. In the united scaphoids, the lengthy period of postoperative immobilization, the existence of osteoarthritis, and the prolonged delay in surgery were significant factors in the patient's functional outcome. Overall, the results do not support the view that a residual flexion deformity of the scaphoid is less likely to yield a satisfactory outcome, although it seems worthwhile to correct excessive angulation at the time of repair to promote an anatomic union, thereby preventing early arthritis. A bone graft with internal fixation using a Herbert screw and a shorter period of immobilization may give a satisfactory functional result when the nonunion is treated before the onset of arthritic changes in the wrist.

HERBERT SCREW FIXATION BY LIMITED ACCESS FOR ACUTE FRACTURES OF THE SCAPHOID

We describe a semi-closed method of Herbert screw fixation for acute fractures of the scaphoid. All 40 patients treated achieved solid union with satisfactory wrist function. This technique gave a significantly shorter time to union and allowed an earlier return to manual labour compared with conservative treatment. There were no complications.

Semi-closed insertion requires considerable skill, but produces consistently satisfactory results after minimal exposure of the scaphoid.

Herbert screw fixation by limited access for acute fractures of the scaphoid

We describe a semi-closed method of Herbert screw fixation for acute fractures of the scaphoid. All 40 patients treated achieved solid union with satisfactory wrist function. This technique gave a significantly shorter time to union and allowed an earlier return to manual labour compared with conservative treatment. There were no complications. Semi-closed insertion requires considerable skill, but produces consistently satisfactory results after minimal exposure of the scaphoid.

Ununited proximal pole scaphoid fractures. Treatment with a Herbert screw in 16 cases followed for 0.5-8 years

We treated 16 cases of delayed union and nonunion of proximal one-third scaphoid fractures with cancellous bone grafting and retrograde insertion of a Herbert screw through a dorsal approach. Definite radiographic union was obtained in 13 of 16 patients after a median of 2 (0.5-8) years of follow-up. Using Cooney's clinical scoring system, 5 cases were excellent, 5 good, 5 fair and 1 poor. The treatment of ununited proximal pole scaphoid fractures with retrograde insertion of the Herbert screw offers the advantages of a short period of immobilization and a good function.

Ulnar impaction syndrome: MR imaging findings

PURPOSE

To evaluate magnetic resonance (MR) imaging findings in ulnar impaction syndrome and changes after ulnar recession arthroplasty.

MATERIALS AND METHODS

MR imaging and arthroscopy were performed in 30 wrists in 27 patients (aged 15-62 years) in whom ulnar impaction syndrome was diagnosed on the basis of physical examinations. MR imaging was performed in 11 wrists before and after surgery. T1- and T2-weighted spin-echo images were obtained. Signal intensities in the lunate, triquetrum, and ulnar head were evaluated.

RESULTS

There was focal abnormal signal intensity of the ulnar aspect of the lunate in 87% of wrists, of the radial aspects of the triquetrum in 43%, and of the radial aspects of the ulnar head in 10% before surgery. The signal intensity of the abnormalities was decreased on T1-weighted and decreased or increased on T2-weighted images. After surgery, the signal intensity of the lunate shifted from low through slightly low to normal on T1-weighted and from low through high to normal on T2-weighted images.

CONCLUSION

Most ulnar impaction syndrome cases have characteristic focal signal intensity changes in the ulnar part of the lunate. The signal intensity often returns to normal after ulnar recession arthroplasty.

Constrictive paralysis of the posterior interosseous nerve without external compression

Four cases of constrictive neuropathy of the posterior interosseous nerve (PIN) in the absence of external compression are reported. All patients presented with a history of severe elbow pain with no apparent cause, followed by paralysis of the PIN. There were one or two well-localized constrictions on the PIN proximal to the arcade of Frohse where no obvious external compressive structure was observed. After epineurotomy with or without neurorrhaphy, three patients had a complete return of motor function within 1 year. The remaining patient required tendon transfer after resection of the abnormal segment of nerve.

Angiotensin II-dependent down-regulation of vascular natriuretic peptide type C receptor gene expression in hypertensive rats

Biological actions of natriuretic peptide (NP) are determined by the condition of the receptor as well as that of the hormone. Although we previously demonstrated in hypertensive rats the up-regulation of NP-A receptor that mediates various biological actions of NPs, the pathophysiologic significance of NP-C receptor, another subtype thought to be related to clearance of NPs and possibly to biological actions, remains unknown. In the present study, we determined NP-C receptor messenger RNA (mRNA) level in the aortic tissue of stroke-prone spontaneously hypertensive rats (SHR-SP/Izm) and in cultured aortic smooth muscle cells by ribonuclease protection assay. The aortic NP-C receptor mRNA level in SHR-SP/Izm was significantly lower than that in the control WKY/Izm. Oral administration of an angiotensin (Ang) II receptor (AT1) antagonist, TCV-116, but not a calcium channel blocker, manidipine, reversed the down-regulated NP-C receptor mRNA in SHR-SP/Izm to the level in WKY/Izm, whereas the latter was more potent in decreasing the blood pressure. In cultured aortic smooth muscle cells, the NP-C receptor was the predominant subtype. Ang II decreased the NP-C receptor mRNA level in a dose-dependent manner, but this effect was reversed by an AT1 antagonist, CV-11974. Neither the NP-A nor NP-B receptor mRNA level was altered by Ang II. These findings indicate that vascular NP-C receptor is down- regulated via Ang-II-mediated mechanism in SHR-SP/Izm. The phenomenon, together with the up-regulation of the NP-A receptor, may play an important role in counteracting hypertension by enhancing the action of NPs.

Angiotensin converting enzyme inhibitor normalizes vascular natriuretic peptide type A receptor gene expression via bradykinin-dependent mechanism in hypertensive rats

We previously demonstrated that angiotensin converting enzyme (ACE) inhibitor normalizes the up-regulated gene expression of vascular natriuretic peptide type A (NP-A) receptor in hypertensive rats. To elucidate the mechanism, we examined the effect of angiotensin II receptor (AT1) antagonist (TCV-116) and bradykinin receptor (B2) antagonist (Hoe 140) on the NP-A receptor mRNA level in the aorta of genetically hypertensive rats (SHR-SP/Izm) using ribonuclease protection assay. The effect of ACE inhibitor on the NP-A receptor mRNA level was completely abolished by a concomitant administration of Hoe 140, while TCV-116 did not show any significant effect on the NP-A receptor mRNA level. These results suggest that bradykinin plays an important role in the regulation of the vascular NP-A receptor gene expression.

C-type natriuretic peptide as a possible local modulator of aldosterone secretion in bovine adrenal zona glomerulosa

Although atrial and brain natriuretic peptides are well known to be involved in the regulation of cardiovascular and endocrine functions as circulating hormones, the roles of the C-type natriuretic peptide (CNP) remain unknown. We examined the effects of CNP on the secretion of aldosterone and cyclic nucleotides from bovine adrenal zona glomerulosa cells in culture. CNP produced a dose-dependent increase in the basal secretion of cGMP, with an EC50 of 3.8 x 10(-10)M. CNP significantly inhibited the ACTH-induced increase in aldosterone and cAMP in a dose-related manner, with an IC50 of 3.6 x 10(-10)M. Although ACTH itself did not increase cGMP secretion, the addition of CNP elicited a significant increase in cGMP secretion. The effects of CNP on the basal secretion of cGMP and the ACTH-induced secretion of aldosterone were significantly reversed by a nonpeptide natriuretic peptide receptor antagonist, HS-142-1. CNP immunoreactivity was localized in the zona glomerulosa by immunohistochemical staining. In addition, expression of CNP messenger RNA and natriuretic peptide B receptor messenger RNA was demonstrated by RT-PCR in the zona glomerulosa tissue and cells in culture. These findings suggest that CNP is a local factor regulating ACTH-induced aldosterone secretion through a guanylyl cyclase-cGMP pathway.

Differential gene expression of vascular natriuretic peptide receptor subtype in artery and vein

Although the vasorelaxation by natriuretic peptide (NP) is much less potent in the vein than in the artery, mechanism underlying the phenomenon remains unknown. Since NP receptor consists of three subtypes with different functions, we determined the mRNA level of each NP receptor subtype in the artery and vein by ribonuclease protection assay. In the aorta, NP-A receptor related to the biological action of NP was the predominant form. By contrast, NP-C receptor related mainly to the clearance of NP was the predominant form in the inferior vena cava: NP-C mRNA level was about two fold higher than in the aorta, while both NP-A and NP-B receptor mRNA levels were about half of that in the aorta. These results provide the molecular basis for the different biological response to NP in the artery and vein. Differential gene expression of NP receptor subtype could be an important determinant of the biological actions of NP.

[Electronmicroscopic study on tongue squamous cell carcinoma--radiotherapy cases]

We examined the ultrastructures of the tongue squamous cell carcinomas which received radiotherapy and compared the metastatic cases with the non-metastatic cases. The results were as follows: 1. The non-metastatic cases were clinically T1N0 or T2N0 and histologically Grade I or II of the WHO classification. Electronmicroscopic observation of these cases revealed that numerous microvilli and a small number of desmosomes were found and the cell attachment seemed to be weak. These findings were different from those of the non-metastatic cases which received surgery. 2. In the metastatic cases of which the primary lesions were controlled, microvilli were not developed and a number of desmosomes were shown as compared with those in the non-metastatic cases. However, cell atypia and dispersion of the nuclear chromatin were clearly recognized.

[A study of relationship between proliferative activity and expressed transferrin receptor content in cancer cells]

Transferrin receptor (TfR) is expressed in the proliferating cells. The author performed an immunohistochemical investigation with TfR and an analysis of TfR protein and mRNA in several cell-lines and examined the relationship between the TfR content and the proliferative activity of the tumor cells. Immunohistochemical examination revealed a strong reaction of the TfR was found in the cell membrane of the epithelial malignant tumors and the non-epithelial malignant tumors showed diffuse staining in the cytoplasm. TfR was almost regulated by the cellular density in the culture dishes. A confluent phase growth led to a low level of TfR. And among the several cell-lines, a higher level of TfR was seen in the cell of the short-doubling time than that of the long-doubling time. In vivo, similarly the rapid growth tumor indicated a high level of TfR rather than the slow growth one. Thus, the level of TfR indicates the degree of the proliferative activity of the tumor cells, so the examination of TfR content is helpful for the determination of the degree of malignancy in each tumor case.

Aetiology of maxillofacial fracture

The aetiological factors associated with maxillofacial fractures, and the trends in these factors over a 13 year period are reported. The First Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Tokyo Medical and Dental University, managed 695 patients with maxillofacial fractures between 1977 and 1989. The male to female ratio was 3.2:1 and the majority of patients were aged between 10 and 30 years old. Road traffic accidents and accidental falls were the main causes of fractures throughout the 13 year study period. Mandibular fractures occurred in 477 patients (68.6%). A high percentage of patients were treated by closed reduction and maxillo-mandibular fixation, or occlusal splinting.

Continuous non-diluted serum sample measurement with an ISFET glucose sensor

An ion-sensitive field-effect transistor (ISFET) glucose sensor with a new membrane structure is fabricated and its characteristics are evaluated in continuous measurement of non-diluted serum glucose. This sensor chip is composed of two ISFETs and a gold electrode. An albumin-glutaraldehyde crosslinked membrane, patterned on one of the ISFET gates and the gold electrode, contacts an enzyme membrane deposited on the other gate in edge to edge. Making an electrical connection between the gold electrode and two ISFETs, this membrane enables stable sensor responses to be made. This sensor is mounted on a flow cell into which serum samples and air are alternately fed. The sensor output shows a good linear relationship, up to 300 mg dl-1 glucose, and correlates well with a conventional glucose analyzer. This sensor shows promise as a key device in the development of portable glucose monitors.