Aim: To investigate the mechanisms underlying the vasorelaxant effect of formononetin, an O-methylated isoflavone, in isolated arteries, and its antihypertensive activity in vivo. Methods: Arterial rings of superior mesenteric arteries, renal arteries, cerebral basilar arteries, coronary arteries and abdominal aortas were prepared from SD rats. Isometric tension of the arterial rings was recorded using a myograph system. Arterial pressure was measured using tail-cuff method in spontaneously hypertensive rats. Results: Formononetin (1–300 μmol/L) elicited relaxation in arteries of the five regions that were pre-contracted by KCl (60 mmol/L), U46619 (1 μmol/L) or phenylephrine (10 μmol/L). The formononetin-induced relaxation was reduced by removal of endothelium or by pretreatment with L-NAME (100 μmol/L). Under conditions of endothelium denudation, formononetin (10, 30, and 100 μmol/L) inhibited the contraction induced by KCl and that induced by CaCl₂ in Ca²⁺-free depolarized medium. In the absence of extracellular Ca²⁺, formononetin (10, 30, and 100 μmol/L) depressed the constriction caused by phenylephrine (10 μmol/L), but did not inhibit the tonic contraction in response to the addition of CaCl₂ (2 mmol/L). The contraction caused by caffeine (30 mmol/L) was not inhibited by formononetin (100 μmol/L). Formononetin (10 and 100 μmol/L) reduced the change rate of Ca²⁺-fluorescence intensity in response to KCl (50 mmol/L). In spontaneously hypertensive rats, formononetin (5, 10, and 20 mg/kg) slowly lowered the systolic, diastolic and mean arterial pressure. Conclusion: Formononetin causes vasodilatation via two pathways: (1) endothelium-independent pathway, probably due to inhibition of voltage-dependent Ca²⁺ channels and intracellular Ca²⁺ release; and (2) endothelium-dependent pathway by releasing NO. Both the pathways may contribute to its antihypertensive effect.

The severe adverse reaction to vitamin K₁ injection is always remarkable and is thought to result from anaphylaxis. Paradoxically, however, some patients administered vitamin K₁ injection for the first time have adverse reactions. Using beagle dogs, the present study tested the hypothesis that the response to vitamin K₁ is an anaphylactoid reaction. The results showed that serious anaphylaxis-like symptoms appeared in beagle dogs after the administration of vitamin K₁ injection for the first time. The plasma histamine concentration increased, and blood pressure decreased sharply. After sensitization, dogs were challenged with vitamin K₁ injection and displayed the same degree of symptoms as prior to sensitization. However, when the vitamin K₁ injection-sensitized dogs were challenged with a vitamin K₁-fat emulsion without solubilizers such asTween-80, the abnormal reactions did not occur. Furthermore, there was no significant change in the plasma immunoglobulin E concentration after vitamin K₁ challenge. Following treatment with vitamin K₁ injection, the release of histamine and β-hexosaminidase by rat basophilic leukemia-2H3 cells as well as the rate of apoptosis increased. The Tween-80 group displayed results similar to those observed following vitamin K₁ injection in vivo. However, the dogs in the vitamin K₁-fat emulsion group did not display any abnormal behavior or significant change in plasma histamine. Additionally, degranulation and apoptosis did not occur in rat basophilic leukemia-2H3 cells. Our results indicate that the adverse reaction induced by vitamin K₁ injection is an anaphylactoid reaction, not anaphylaxis. Vitamin K₁ injection induces the release of inflammatory factors via a non-IgE-mediated immune pathway, for which the trigger may be the solubilizer.

The outbreak of coronavirus disease 2019 (COVID-19) in China has been basically controlled. However, the global epidemic of COVID-19 is worsening. We established a method to estimate the instant case fatality rate (CFR) and cure rate of COVID-19 in China. A total of 82 735 confirmed cases released officially by the Chinese authorities from December 8, 2019 to April 18, 2020 were collected. The estimated diagnosis dates of deaths and cured cases were calculated based on the median cure time or median death time of individual cases. Following this, the instant CFR was calculated according to the number of deaths and cured cases on the same estimated diagnosis date. In China, the instant CFR of COVID-19 was 3.8-14.6% from January 1 to January 17; it then declined gradually and stabilized at 5.7% in April. The average CFR in China was 6.1±2.9%, while the CFR was 1.0±0.4% in China except Hubei Province. The cure rate of COVID-19 was 93.9±2.9% in China, and stabilized at 94.3%, while it was 99.0±0.4% in China except Hubei Province. The instant CFR of COVID-19 in China overall was much higher than that in China except Hubei Province. The CFR of COVID-19 in China was underestimated.

Background: Cigarette smoking is a strong risk factor for vascular disease and known to cause dysfunction of the endothelium. However, the molecular mechanisms involved are still not fully understood. Methods: In order to reveal the direct effects of lipid-soluble smoke particles on the endothelium, ring segments isolated from rat mesenteric arteries and human middle cerebral arteries (MCA) obtained at autopsy were incubated for 6 to 48 hrs in the presence of dimethylsulphoxide (DMSO)-soluble particles from cigarette smoke (DSP), i.e. lipid-soluble smoke particles. The endothelial microstructure was examined by transmission electron microscopy. The endothelial function was evaluated by acetylcholine (ACh)-induced endothelium-dependent vasodilatation, using a sensitive myograph. Results: After DSP treatment, the arterial endothelium was swollen and loosing its attachment. In functional tests, the total ACh-induced dilatation, the nitric oxide (NO)-mediated and the endothelium-derived hyperpolarization factor (EDHF)-mediated dilatations were significantly decreased by DSP in a time- and concentration-dependent manner (p < 0.05). Nicotine, an important compound in cigarette smoke had, in an equivalent concentration as in DSP, no such effects (p > 0.05). Similar results were obtained in the human MCA. Conclusion: Thus, we demonstrate that the lipid-soluble smoke particles, but not nicotine, caused damage to arterial endothelium and reduced the endothelium-dependent dilatation in man and rat.