A cross-sectional, multicenter survey of the prevalence and risk factors for Long COVID.

Long-term sequelae of the coronavirus disease (COVID-19) constitute Long COVID. Although Long COVID has been reported globally, its risk factors and effects on quality of life (QOL) remain unclear. We conducted a cross-sectional study using questionnaires and electronic medical records of COVID-19 patients who were diagnosed or hospitalized at five facilities in Japan. Responses were obtained from 285 out of 1,150 patients. More than half of the participants reported Long COVID symptoms of varying severity 1 year after COVID-19. Common sequelae included fatigue, dyspnea, alopecia, concentration problems, memory problems, sleeplessness, and joint pain, which often significantly reduced their QOL. COVID-19 severity was strongly associated with sputum production, chest pain, dyspnea, sore throat, and diarrhea, but not with fatigue, dysgeusia, anosmia, alopecia, and sleeplessness. Fatigue, dysgeusia, anosmia, alopecia, and sleeplessness affected the QOL among participants with asymptomatic or mild COVID-19 during the acute phase. Moreover, these sequelae persisted for prolonged periods.

Functional changes in cytotoxic CD8+ T-cell cross-reactivity against the SARS-CoV-2 Omicron variant after mRNA vaccination.

Understanding the T-cell responses involved in inhibiting COVID-19 severity is crucial for developing new therapeutic and vaccine strategies. Here, we characterized SARS-CoV-2 spike-specific CD8+ T cells in vaccinees longitudinally. The BNT162b2 mRNA vaccine can induce spike-specific CD8+ T cells cross-reacting to BA.1, whereas the T-cell receptor (TCR) repertoire usages decreased with time. Furthermore the mRNA vaccine induced spike-specific CD8+ T cells subpopulation expressing Granzyme A (GZMA), Granzyme B (GZMB) and Perforin simultaneously in healthy donors at 4 weeks after the second vaccination. The induced subpopulation was not maintained at 12 weeks after the second vaccination. Incorporating factors that efficiently induce CD8+ T cells with highly cytotoxic activity could improve future vaccine efficacy against such variants.

Aerobic metabolism on muscle contraction in porcine gastric smooth muscle.

Exposure to chronic hypoxic conditions causes various gastric diseases, including gastric ulcers. It has been suggested that gastric smooth muscle contraction is associated with aerobic metabolism. However, there are no reports on the association between gastric smooth muscle contraction and aerobic metabolism, and we have investigated this association in the present study. High K+- and carbachol (CCh)-induced muscle contractions involved increasing O2 consumption. Aeration with N2 (hypoxia) and NaCN significantly decreased high K+- and CCh-induced muscle contraction and O2 consumption. In addition, hypoxia and NaCN significantly decreased creatine phosphate (PCr) contents in the presence of high K+. Moreover, decrease in CCh-induced contraction and O2 consumption was greater than that of high K+. Our results suggest that hypoxia and NaCN inhibit high K+- and CCh-induced contractions in gastric fundus smooth muscles by decreasing O2 consumption and intracellular PCr content. However, the inhibition of CCh-induced muscle contraction was greater than that of high K+-induced muscle contraction.

Imidazole-induced contractions in bovine tracheal smooth muscle are not dependent on the cAMP pathway.

The mechanism of imidazole-induced contraction on the bovine tracheal smooth muscle was investigated. Imidazole induced muscle contraction in a concentration-dependent manner on bovine, porcine and guinea-pig tracheas, but not in rat or mouse. In bovine tracheas, imidazole was cumulatively applied and induced muscle tension and increasesd intracellular Ca2+ level in a concentration -dependent manner. Imidazole, even at 300 µM, the concentration at which maximum contractile response occurs, did not significantly increase in cAMP content relative to control. Atropine inhibited imidazole-induced contraction at a concentration- dependent manner and pretreatment of hemicholinium-3 almost abolished imidazole-induced contraction. Conversely, pretreatment of tripelennamine, indomethacin or tetrodotoxin did not affect imidazole-induced contraction. Acetylcholine or eserine induced contraction in bovine, porcine, guinea pig, rat and mice trachea in a concentration-dependent manner. However, there was little difference in the rank order of maximum contraction of these agents. Imidazole-induced contraction was greater in bovine trachea compared to the other species tested. Further, cAMP did not appear to play a role in imidazole-induced contraction, suggesting other mechanisms, such as the release of endogenous acetylcholine.

Phloridzin inhibits high K+-induced contraction via the inhibition of sodium: glucose cotransporter 1 in rat ileum.

Recent studies have shown that phloridzin, an inhibitor of sodium-glucose cotransporter (SGLT), strongly decreases high K+-induced contraction in phasic muscle, such as tenia coli, but slightly affects tonic muscle, such as trachea . In this study, we examined the inhibitory mechanism of phloridzin on high K+-induced muscle contraction in rat ileum, a phasic muscle. Phloridzin inhibited the high K+-induced contraction in the ileum and the aorta, and the relaxing effect of phloridzin at 1 mM in the ileum was approximately five-fold more potent than that in the aorta. The expression of SGLT1 mRNA in the ileum was higher than that of the aorta. Phloridzin significantly inhibited NADH/NAD ratio and phosphocreatine (PCr) content in the ileum; however, application of pyruvate recovered the inhibition of contraction and PCr content, but had no effect on ratio of NADH/NAD. High K+ increased 2-(N (7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino)-2-deoxyglucose (2-NBDG) uptake in ileal smooth muscle cells, and phloridzin inhibited the increase in a concentration-dependent manner. These results suggest that phloridzin inhibits high K+-induced contraction because of the inhibition of energy metabolism via the inhibition of SGLT1.

Aerobic metabolism on muscle contraction in porcine iris sphincter.

Eyes are supplied O2 through the cornea and vessels of the retina and iris, which are tissues characterized by aerobic metabolism. Meanwhile, there are no reports on the association between iris sphincter contraction and aerobic metabolism. In this paper, we studied the aforementioned association. Eyes from adult pigs of either sex were obtained from a local abattoir. A muscle strip was connected to a transducer to isometrically record the tension. O2 consumption was measured using a Clark-type polarograph connected to a biological oxygen monitor. Creatine phosphate (PCr) and adenosine triphosphate (ATP) contents were measured in the muscle strips by high-performance liquid chromatography (HPLC). Iris sphincter muscles were measured in resting, contractile or hypoxic phases. Contraction was induced by hyperosmotic 65 mM KCl (H-65K+) or carbachol (CCh), and hypoxia was induced by aeration with N2 instead of O2 or by addition of sodium cyanide (NaCN). H-65K+- and CCh-induced muscle contraction, involved increasing O2 consumption. Hypoxia and NaCN significantly decreased H-65K+- and CCh-induced muscle contraction and/or O2 consumption and PCr contents. Our results suggest that the contractile behavior in porcine iris sphincter highly depends on mitogen oxidative metabolism.

Effects of hypoxia and glucose-removal condition on muscle contraction of the smooth muscles of porcine urinary bladder.

To elucidate the dependence of aerobic energy metabolism and utilization of glucose in contraction of urinary bladder smooth muscle, we investigated the changes in the reduced pyridine nucleotide (PNred) fluorescence, representing glycolysis activity, and determined the phosphocreatine (PCr) and ATP contents of the porcine urinary bladder during contractions induced by high K(+) or carbachol (CCh) and with and without hypoxia (achieved by bubbling N2 instead of O2) or in a glucose-free condition. Hyperosmotic addition of 65 mM KCl (H-65K(+)) and 1 µM CCh induced a phasic contraction followed by a tonic contraction. A glucose-free physiological salt solution (PSS) did not change the subsequent contractile responses to H-65K(+) and CCh. However, hypoxia significantly attenuated H-65K(+)- and CCh-induced contraction. H-65K(+) and CCh induced a sustained increase in PNred fluorescence, representing glycolysis activity. Hypoxia enhanced H-65K(+)- and CCh-induced increases in PNred fluorescence, whereas glucose-free PSS decreased these increases, significantly. In the presence of H-65K(+), hypoxia decreased the PCr and ATP contents; however, the glucose-free PSS did not change the PCr contents. In conclusion, we demonstrated that high K(+)- and CCh-induced contractions depend on aerobic metabolism and that an endogenous substrate may be utilized to maintain muscle contraction in a glucose-free PSS in the porcine urinary bladder.

Effects of papaverine on carbachol- and high K+ -induced contraction in the bovine abomasum.

The effects of papaverine on carbachol (CCh) -and high K(+)- induced contraction in the bovine abomasum were investigated. Papaverine inhibited CCh (1 µM) -and KCl (65 mM) -induced contractions in a concentration-dependent manner. Forskolin or sodium nitroprusside inhibited CCh-induced contractions in a concentration-dependent manner in association with increases in the cAMP or cGMP contents, whereas papaverine increased cGMP contents only at 30 µM. Changes in the extracellular Ca(2+) from 1.5 mM to 7.5 mM reduced verapamil-induced relaxation in high K(+)-depolarized muscles, but papaverine-induced relaxation did not change. Furthermore, papaverine (30 µM) and NaCN (300 µM) decreased the creatine phosphate contents. These results suggest that the relaxing effects of papaverine on the bovine abomasum are mainly due to the inhibition of aerobic energy metabolism.