Efficient production of recombinant SARS-CoV-2 spike protein using the baculovirus-silkworm system.

In the case of a new viral disease outbreak, an immediate development of virus detection kits and vaccines is required. For COVID-19, we established a rapid production procedure for SARS-CoV-2 spike protein (S protein) by using the baculovirus-silkworm expression system. The baculovirus vector-derived S proteins were successfully secreted to silkworm serum, whereas those formed insoluble structure in the larval fat body and the pupal cells. The ectodomain of S protein with the native sequence was cleaved by the host furin-protease, resulting in less recombinant protein production. The S protein modified in furin protease-target site was efficiently secreted to silkworm serum and was purified as oligomers, which showed immunoreactivity for anti-SARS-CoV-2 S2 antibody. By using the direct transfection of recombinant bacmid to silkworms, we achieved the efficient production of SARS-CoV-2 S protein as fetal bovine serum (FBS)-free system. The resultant purified S protein would be useful tools for the development of immunodetection kits, antigen for immunization for immunoglobulin production, and vaccines.

Effects of Magnesium Oxide on the Serum Duloxetine Concentration and Antidepressant-Like Effects of Duloxetine in Rats.

Duloxetine is a serotonin/noradrenaline reuptake inhibitor that is used as an antidepressant. However, it is known to cause constipation as a side effect. Magnesium compounds, such as magnesium oxide and magnesium hydroxide aqueous solution, are often combined with duloxetine to ameliorate the constipation caused by duloxetine. However, there is concern that these magnesium compounds might alter the effects of duloxetine via physicochemical interactions. In this study, we attempted to clarify the interactions that take place between duloxetine and magnesium oxide using in vivo and in vitro experiments. We evaluated the influence of magnesium oxide on in vitro duloxetine concentrations using HPLC. In addition, we examined the in vivo antidepressant-like effects and serum concentrations of duloxetine in rats. In the in vitro experiment, the duloxetine concentration was significantly decreased by co-treatment with magnesium oxide. In the in vivo experiment, the antidepressant-like effects of duloxetine were not affected by the combined oral administration of magnesium oxide and a duloxetine formulation although the serum duloxetine level was significantly decreased. However, the antidepressant-like effects of a duloxetine reagent were significantly attenuated by the co-administration of magnesium oxide. These results suggest that duloxetine and magnesium oxide directly interact and that such interactions affect the absorption and antidepressant-like effects of duloxetine.

Neural-network Kohn-Sham exchange-correlation potential and its out-of-training transferability.

We incorporate in the Kohn-Sham self-consistent equation a trained neural-network projection from the charge density distribution to the Hartree-exchange-correlation potential n → VHxc for a possible numerical approach to the exact Kohn-Sham scheme. The potential trained through a newly developed scheme enables us to evaluate the total energy without explicitly treating the formula of the exchange-correlation energy. With a case study of a simple model, we show that the well-trained neural-network VHxc achieves accuracy for the charge density and total energy out of the model parameter range used for the training, indicating that the property of the elusive ideal functional form of VHxc can approximately be encapsulated by the machine-learning construction. We also exemplify a factor that crucially limits the transferability-the boundary in the model parameter space where the number of the one-particle bound states changes-and see that this is cured by setting the training parameter range across that boundary. The training scheme and insights from the model study apply to more general systems, opening a novel path to numerically efficient Kohn-Sham potential.

Rupture of the right upper pulmonary vein and left atrium caused by blunt chest trauma.

A 49-year-old man was transferred to our hospital by ambulance due to blunt chest trauma sustained in a car accident. Echocardiography and enhanced computed tomography showed hemopericardium without other vital organ damage. Emergent surgery was performed under strong suspicion of traumatic cardiac rupture. Careful inspection showed a rupture of the right upper pulmonary vein at the junction of the left atrium, a laceration of the inferior vena cava, and a left-side pericardium rupture, and they were repaired with running 4-0 polypropylene suture. Postoperative hemodynamics were stable. The patient was discharged ambulatory on postoperative day 15.

[Mitral regurgitation and atrial septum aneurysm complicated with osteogenesis imperfecta; report of a case].

A 43-year-old female with a history of osteogenesis imperfecta was admitted to our hospital for congestive heart failure due to mitral valve regurgitation. The patient had suffered from bone fractures 5 times, dislocation of elbow and fingers 3 times since childhood, and subarachnoid hemorrhage 2 years before. She and her son have blue scleras. She was diagnosed with osteogenesis imperfecta type IA clinically. Echocardiography revealed severe mitral regurgitation and aneurysmal formation in the interatrial septum bulging to the right atrium. Mitral valve replacement and repair of the atrial septum were performed without any blood transfusion, but with rib fractures. Echocardiography showed no peri-valvular regurgitation at 1 year after the valve replacement. Cardiovascular disease is rarely associated with osteogenesis imperfecta, but its surgical mortality rate is high due to coagulation abnormality and fragile tissue. To reduce postoperative complications, precise classification of the disease and careful handling of the tissues during operation will be needed.

Increased cholesterol biosynthesis and hypercholesterolemia in mice overexpressing squalene synthase in the liver.

Squalene synthase (SS) is the first committed enzyme for cholesterol biosynthesis, located at a branch point in the mevalonate pathway. To examine the role of SS in the overall cholesterol metabolism, we transiently overexpressed mouse SS in the livers of mice using adenovirus-mediated gene transfer. Overexpression of SS increased de novo cholesterol biosynthesis with increased 3-hydroxy-3-methyglutaryl-CoA (HMG-CoA) reductase activity, in spite of the downregulation of its own mRNA expression. Furthermore, overexpression of SS increased plasma concentrations of LDL, irrespective of the presence of functional LDL receptor (LDLR). Thus, the hypercholesterolemia is primarily caused by increased hepatic production of cholesterol-rich VLDL, as demonstrated by the increases in plasma cholesterol levels after intravenous injection of Triton WR1339. mRNA expression of LDLR was decreased, suggesting that defective LDL clearance contributed to the development of hypercholesterolemia. Curiously, the liver was enlarged, with a larger number of Ki-67-positive cells. These results demonstrate that transient upregulation of SS stimulates cholesterol biosynthesis as well as lipoprotein production, providing the first in vivo evidence that SS plays a regulatory role in cholesterol metabolism through modulation of HMG-CoA reductase activity and cholesterol biosynthesis.