A multicenter randomized controlled trial to evaluate the efficacy and safety of nelfinavir in patients with mild COVID-19

Nelfinavir, an orally administered inhibitor of human immunodeficiency virus protease, inhibits the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro. We conducted a randomized controlled trial to evaluate the clinical efficacy and safety of nelfinavir in patients with SARS-CoV-2 infection. We included unvaccinated asymptomatic or mildly symptomatic adult patients who tested positive for SARS-CoV-2 infection within 3 days before enrollment. The patients were randomly assigned (1:1) to receive oral nelfinavir (750 mg; thrice daily for 14 days) combined with standard-of-care or standard-of-care alone. The primary endpoint was the time to viral clearance, confirmed using quantitative reverse-transcription PCR by assessors blinded to the assigned treatment. A total of 123 patients (63 in the nelfinavir group and 60 in the control group) were included. The median time to viral clearance was 8.0 (95% confidence interval [CI], 7.0 to 12.0) days in the nelfinavir group and 8.0 (95% CI, 7.0 to 10.0) days in the control group, with no significant difference between the treatment groups (hazard ratio, 0.815; 95% CI, 0.563 to 1.182; P = 0.1870). Adverse events were reported in 47 (74.6%) and 20 (33.3%) patients in the nelfinavir and control groups, respectively. The most common adverse event in the nelfinavir group was diarrhea (49.2%). Nelfinavir did not reduce the time to viral clearance in this setting. Our findings indicate that nelfinavir should not be recommended in asymptomatic or mildly symptomatic patients infected with SARS-CoV-2. The study is registered with the Japan Registry of Clinical Trials (jRCT2071200023). IMPORTANCE The anti-HIV drug nelfinavir suppresses the replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in vitro. However, its efficacy in patients with COVID-19 has not been studied. We conducted a multicenter, randomized controlled trial to evaluate the efficacy and safety of orally administered nelfinavir in patients with asymptomatic or mildly symptomatic COVID-19. Compared to standard-of-care alone, nelfinavir (750 mg, thrice daily) did not reduce the time to viral clearance, viral load, or the time to resolution of symptoms. More patients had adverse events in the nelfinavir group than in the control group (74.6% [47/63 patients] versus 33.3% [20/60 patients]). Our clinical study provides evidence that nelfinavir, despite its antiviral effects on SARS-CoV-2 in vitro, should not be recommended for the treatment of patients with COVID-19 having no or mild symptoms

Effects of downhill running incorporated into long-term endurance training on skeletal muscle fiber-type switching and fatigue resistance

The effects of the intermittent incorporation of high-intensity downhill running sessions into long-term endurance training were assessed by examination of the plantaris muscle of rats. First, the intrinsic effects of a single session were evaluated in otherwise sedentary rats. The experimental group showed histological injuries in 2-3 days after the session. In addition, compared with the sedentary control, the experimental group showed a sevenfold increase in the fraction of type IIc fibers, and deceases of 74 and 88% in tetanic force evoked indirectly and directly, respectively, by electric stimulation. The injured muscle fibers showed regeneration within 21 days as evidenced by centrally located nuclei. Next, the effects of intermittently incorporated downhill-running sessions into a 9-week endurance training regimen were tested using two experimental groups: Training and Training + Downhill. On the first day of the 1st, 3rd, 5th, and 7th weeks of the training period, the rats in the Training + Downhill group experienced downhill-running sessions. After the endurance training period, the plantaris muscle of the two experimental groups demonstrated higher fatigue resistance with an increase in the type IIa fiber fraction, at an expense of the type IIb fiber fraction. Compared with the Training group, the Training + Downhill group had a higher type IIa fiber fraction, with clusters of 70-100 type IIa fibers. These results indicate that intermittent high-intensity sessions promote the fiber type transition induced by daily endurance training. However, the potentially adverse effect of fiber type cluster formation suggests that there is an optimum intensity and frequency of the high-intensity exercise sessions for better enhancing the effects of long-term endurance training

Activating Efficiency of Ca 2؉ and Cross-Bridges As Measured by Phosphate Analog Release

ABSTRACT To assess the activating efficiency of Ca 2ϩ and cross-bridges, the release rates of phosphate analogs from skinned fibers were estimated from the recovery of contractility and that of stiffness. Estimations were performed based on the assumptions that contractility was indicative of the population of analog-free myosin heads and that stiffness reflected the population of formed cross-bridges. Aluminofluoride (AlFx) and orthovanadate (Vi) were used as phosphate analogs with mechanically skinned fibers from rabbit psoas muscle. The use of the analogs enabled the functional assessment of activation level in the total absence of ATP. Fibers loaded with the analogs gradually recovered contractility and stiffness in normal plain rigor solution. The addition of Ca 2ϩ to the plain rigor solution significantly accelerated their recovery, whereas ADP had no appreciable effect. ATP plus Ca 2ϩ (contracting condition) accelerated the recovery by several tens of times. These results indicate that the cross-bridges formed during contraction have prominent activating efficiency, which is indispensable to attain full activation. A comparison between the activating efficiency evaluated from stiffness and that from contractility suggested that Ca 2ϩ is more potent in accelerating the binding of actin to analog-bound myosin heads whereas crossbridges mainly accelerate the subsequent analog-releasing step

X-ray Diffraction Analysis to Explore Molecular Traces of Eccentric Contraction on Rat Skeletal Muscle Parallelly Evaluated with Signal Protein Phosphorylation Levels

We performed X-ray diffraction analyses on rat plantaris muscle to determine if there are strain-specific structural changes at the molecular level after eccentric contraction (ECC). ECC was elicited in situ by supramaximal electrical stimulation through the tibial nerve. One hour after a series of ECC sessions, the structural changes that remained in the sarcomere were evaluated using X-ray diffraction. Proteins involved in cell signaling pathways in the muscle were also examined. ECC elicited by 100, 75, and 50 Hz stimulation respectively developed peak tension of 1.34, 1.12 and 0.79 times the isometric maximal tetanus tension. The series of ECC sessions phosphorylated the forkhead box O proteins (FoxO) in a tension-time integral-dependent manner, as well as phosphorylated the mitogen-activated protein kinases (MAPK) and a protein in the mammalian target of rapamycin (mTOR) pathway in a maximal tension dependent manner. Compared to isometric contractions, ECC was more efficient in phosphorylating the signaling proteins. X-ray diffraction revealed that the myofilament lattice was preserved even after intense ECC stimulation at 100 Hz. Additionally, ECC −1, and of myosin reflection at 1/14.4 nm−1. These two reflections demonstrated no appreciable decrease with triple repetitions of the standard series of ECC sessions at 50 Hz, suggesting that the intensity decrease depended on the instantaneous maximal tension development rather than the total load of contraction, and was more likely linked with the phosphorylation of MAPK and mTOR signaling proteins

Skinning Effects on Skeletal Muscle Myowater Probed by T(2) Relaxation of (1)H-NMR

To find the cause of the skinning-induced fragility of frog skeletal muscle, the transverse relaxation process of (1)H-NMR signals from skinned muscle was observed. A set of four characteristic exponentials well described the process. Aside from the extremely slow exponential component (time constant T(2) > 0.4 s) representing surplus solution, the process was generally slower than that in living muscle. It had larger amplitudes of slow (T(2) ≈ 0.15 s) and intermediate (0.03 < T(2) < 0.06 s) exponentials and had smaller amplitude and faster T(2) in the rapid one (T(2) < 0.03 s), suggesting that skinned muscle is more sol-like than intact myoplasm. To resolve their causes, we traced the exponentials following a stepwise treatment of living whole muscle to an isolated skinned fiber. Osmotic expansion of living muscle comparable to skinned muscle increased the intermediate exponential and decreased the rapid one without affecting T(2). Subsequent chemical skinning markedly increased the slow exponential, decreased the rapid one, and slowed the intermediate one. The fiber isolation had no appreciable effect. Because l-carnosine at physiological concentration could not recover the skinning-induced difference, the difference would reflect the dilution and efflux of larger macromolecules, which stabilize myoplasm as a gel