Time to redefine hyperuricemia? The serum uric acid cut-off level for precipitation might be lower: a pilot study

BACKGROUND

Hyperuricemia is classically defined as serum uric acid (SUA) value higher than 6.8 mg∕dL; between hyperuricemic patients, only 15-20% will develop gout. Our first goal was to find if there is a specificity of the "snowstorm" feature on ultrasound (US) for hyperuricemia. Moreover, we aimed to determine if there is a level of SUA from which the urates tend to appear in the synovial fluid, without generating a typical clinical gouty flare.

PATIENTS, MATERIALS AND METHODS

We conducted a cross-sectional, transverse study, including 108 consecutive patients that displayed a set of clinical and imaging features, such as swollen knee and US proof for knee joint effusion.

RESULTS

Performing binary logistic regression, the relation between the explanatory variable (hyperechogenic spots) and the response variable (SUA) was demonstrated to be a significant one (p=0.005). The value of 0.397 for the statistical phi coefficient suggests a medium intensity association between the diagnosis of gout or asymptomatic hyperuricemia and whether the patients have hyperechogenic spots or not. We found the cut-off value for SUA equal to 4.815 mg∕dL, regardless of gender, from which, the urate starts to precipitate. Values for men tend to be higher in comparison to the ones found for women (4.95 mg∕dL vs. 3.9 mg∕dL).

CONCLUSIONS

The "snowstorm" aspect of the fluid might be the result of an increased level of SUA and more than this, the cut-off level for SUA to precipitate might be lower than the fore used values.

A stochastic model for water-vegetation systems and the effect of decreasing precipitation on semi-arid environments

Current climate change trends are affecting the magnitude and recurrence of extreme weather events. In particular, several semi-arid regions around the planet are confronting more intense and prolonged lack of precipitation, slowly transforming part of these regions into deserts in some cases. Although it is documented that a decreasing tendency in precipitation might induce earlier disappearance of vegetation, quantifying the relationship between decrease of precipitation and vegetation endurance remains a challenging task due to the inherent complexities involved in distinct scenarios. In this paper we present a model for precipitation-vegetation dynamics in semi-arid landscapes that can be used to explore numerically the impact of decreasing precipitation trends on appearance of desertification events. The model, a stochastic differential equation approximation derived from a Markov jump process, is used to generate extensive simulations that suggest a relationship between precipitation reduction and the desertification process, which might take several years in some instances.

[Research on quality regionalization of cultivated Pseudostellaria heterophylla based on climate factors]

Maxent model was applied in the study to filtering the climate factors layer by layer. Polysaccharides and pseudostellarin B the two internal quality evaluation index were combined to analyse the interlinkages between climate factors and chemical constituents in order to search for the critical climate factors of Pseudostellaria heterophylla. Then based on the key climate factors to explicit the quality spatial distribution of P. heterophylla. The results showed that polysaccharides and climatic factors had no significant correlation, suggesting that the indicator was not climate-driven metabolites. Pseudostellarin B could construct regression model with the precipitation. And quality regionalization results showed that pseudostellarin B content presented firstly increased and then decreased trend from southeast to northwest, which was the consistent change with precipitation. It clearly proposed that precipitation was the key climate factor, which affected the accumulation of cyclopeptide compound for Pseudostellariae Radix.