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The aim of this study was to validate the preventive effects of koumine (KM), a monoterpene indole alkaloid, on gouty arthritis (GA) and to explore its possible mechanisms. C57BL/6 mice were intraperitoneally administered KM (0.8, 2.4 or 7.2 mg/kg), colchicine (3.0 mg/kg) or sterile saline. One hour later, a monosodium urate (MSU) suspension was injected into the right hind paws of the mice to establish an acute gout model. Inflammation symptoms were evaluated at 0, 3, 6, 12 and 24 h, and the mechanical withdrawal threshold was evaluated at 0, 6 and 24 h. After 24 h, the mice were euthanized, and the joint tissue, kidney and blood were collected for subsequent experiments. Histological examination and antioxidant enzyme, kidney index and serum uric acid (UA) measurements were taken. The expression levels of the signalling pathway components were determined. KM effectively alleviated the symptoms of redness, swelling and pain; counteracted inflammatory cell infiltration; and increased antioxidant enzyme levels, reduced kidney index and serum UA levels through regulating UA excretion in MSU‐induced mice. The expression of toll‐like receptor 4 (TLR4)/nuclear factor kappa‐B (NF‐κB)/nucleotide‐binding oligomerization domain, leucine‐rich repeat and pyrin domain‐containing 3 (NLRP3) signalling pathway proteins and mRNA were reduced in the KM group. These results suggest that KM may be effective in alleviating GA through the TLR4/NF‐κB/NLRP3 pathway. [ABSTRACT FROM AUTHOR]

In this study, idealized cloud-resolving simulations are performed for horizontally uniform and steady southwesterly flow at fixed direction/speed combinations to investigate rainfall characteristics and the role of the complex topography in Taiwan during the Mei-yu season, without the influence of a front or other disturbances. Eight directions (180° to 285°, every 15°) and eight speeds (5 to 22.5 m s-1, every 2.5 m s-1) are considered, and near-surface relative humidity (RH) is also altered (from 55-100 %) in a subset of these tests to further investigate the effects of moisture content, yielding a total 109 experiments each having a integration length of 50 h. Three rainfall regimes that correspond to different ranges of the wet Froude number (Frw) are identified from the idealized simulations (with a grid size of 2 km). The low-Frw regime (Frw ≤ ~0.3) where the island circulation from thermodynamic effects during daytime is the main cause of rainfall in local afternoon. The lower the wind speed (and Frw), the more widespread and amount of rainfall. On the other hand, the high-Frw regime (Frw ≥ ~0.4) occurs when the flow at least 12.5 m s-1 impinges on Taiwan terrain at a large angle to favor the flow-over scenario. Thus, topographic rainfall production becomes dominant through mechanical uplift of unstable air. In this scenario, the faster and wetter the flow, the heavier the rainfall on the windward slopes, with the most favorable direction from 240°-255°. Between the two regimes above, a third and mixed regime also exists. The idealized results are discussed for their applicability to the real atmosphere. [ABSTRACT FROM AUTHOR]