The current study aimed to investigate the association of calcium pyrophosphate (CPP) and basic calcium phosphate (BCP) crystals in synovial fluid (SF) of patients with osteoarthritis (OA) with disease severity, clinical symptoms, and synovial inflammation. One-hundred-and-ten patients with knee OA completed the Western Ontario and McMaster Universities Arthritis Index (WOMAC) self-assessment questionnaire, the Lequesne algofunctional index survey, and the visual analogic scale forms; they also underwent power Doppler ultrasonography (PDUS) to assess synovial inflammation. Scanning electron microscopy (SEM) was used to detect SF crystals. SEM analyses uncovered CPP crystals in 26 patients (23.6%), BCP crystals in 24 patients (21.8%), and both types of crystals in 7 patients (6.3%). Categorizing patients according to SF crystal type, a strong association between BCP crystal presence, and higher WOMAC and Lequesne index scores has been uncovered. Classifying our patients according the severity Kellgre-Lawrence score, we found that the prevalence of CPP alone (27.8%) or in combination with BCP (11.1%) was higher in the late stage group with respect to the early one (CPP 21.6% and CPP + BCP 4.1%, respectively). The prevalence of BCP crystals alone was, instead, higher in the early (23%) with respect to the late group (19.4%). No association between the presence of crystals and the radiographic scores has been observed. Considering the growing evidence supporting a role of low-grade inflammation in OA pathogenesis, the results of this study suggest a role for calcium crystals in the development of the disease.

In 2020 North Italy suffered the SARS-CoV-2-related pandemic with a high number of deaths and hospitalization. The effect of atmospheric parameters on the amount of hospital admissions (temperature, solar radiation, particulate matter, relative humidity and wind speed) is studied through about 8 months (May–December). Two periods are considered depending on different conditions: a) low incidence of COVID-19 and very few regulations concerning personal mobility and protection (“free/summer period”); b) increasing incidence of disease, social restrictions and use of personal protections (“confined/autumn period”). The “hospitalized people in medical area wards/100000 residents” was used as a reliable measure of COVID-19 spreading and load on the sanitary system. We developed a chemometric approach (multiple linear regression analysis) using the daily incidence of hospitalizations as a function of the single independent variables and of their products (interactions). Eight administrative domains were considered (altogether 26 million inhabitants) to account for relatively homogeneous territorial and social conditions. The obtained models very significantly match the daily variation of hospitalizations, during the two periods. Under the confined/autumn period, the effect of non-pharmacologic measures (social distances, personal protection, etc.) possibly attenuates the virus diffusion despite environmental factors. On the contrary, in the free/summer conditions the effects of atmospheric parameters are very significant through all the areas. Particulate matter matches the growth of hospitalizations in areas with low chronic particulate pollution. Fewer hospitalizations strongly correspond to higher temperature and solar radiation. Relative humidity plays the same role, but with a lesser extent. The interaction between solar radiation and high temperature is also highly significant and represents surprising evidence. The solar radiation alone and combined with high temperature exert an anti-SARS-CoV-2 effect, via both the direct inactivation of virions and the stimulation of vitamin D synthesis, improving immune system function.

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Background Osteoarthritis (OA) is the most common joint disease and the knee is frequently involved. OA is characterized by a progressive loss of articular cartilage, osteophyte formation, thickening of the subchondral bone, but as well as some signs of intraarticular inflammation with synovitis. Multiple factors such as mechanical factors, genetics and aging are involved in the pathogenesis of OA. However there is still some debate about the role of inflammation in pathogenetic mechanisms of OA (1). Only a few studies have recently recognized the potential role of calcium crystals (CC) in synovial inflammation and in OA progression (2-4). The most common CC in OA are calcium pyrophosphate dihydrate (CPP) and basic calcium phosphate (BCP), including hydroxyapatite, octacalcium and tricalcium phosphate. Several studies demonstrated that CC occur in up to 60% of SF in OA patients. Although it is difficult to identify CC in SF of OA, the relationship between pathogenetic mechanisms or disease progression and the presence of CC is very interesting. Recognition of CPP, which range in length from 2-20 μm, is a relatively simple procedure. Nevertheless they are not always released in a uniform manner and it is not simple to detect them even when the most sensitive methods are been used in. Due to their sub-microscopic size BCP (70-250 Å) detection is particularly difficult. Objectives The aim of the study was to identify CC in SF of OA patients through compensated polarized light microscopy (CPML) and alizarin red S staining (AS), and by ultrasensitive analysis with scanning electronic microscopy (SEM), to detect whatever concordance exists between them. Methods We analyzed the SF74 patients with knee osteothritis (KOA) (48 F, mean age 64.85±9.33, range 50-89 yrs) by CPML, AS and by SEM. The concordance between CPML and SEM was evaluated by Cohen’s kappa coefficient Results CPP crystals were found in 28.4% by CPML and in 32.4% by SEM. BCP crystals were suspected in 32.4% of the samples that were positive according to AS, while they we found by SEM in 10.8% of SF. By according to kappa coefficient, the concordance between CPML and SEM was 0.78% for CPP and 0.69% for BCP. CPP and BCP were simultaneously positive in 26% of the samples by SEM. Conclusions CPML and AS are tecniques routinely used to detect CC in SF of OA patients. However use of a highly sensitive method such as SEM, ensures accurate detection of CC and this could help to clarify the its potential role in pathogenetic mechanisms and in progression of OA. References AK Rosenthal. Crystls, inflammation, and osteothritis 2011;Curr Opin Rheumatol 23:170-3 S Nalbant, JAM Martinez, T Kitumnuaypong, G Clayburnet, M Sieck and HR Jr. Synovial fluid features and their relations to osteothritis severity: new findings from sequential atudies. Osteoarthritis and Cartilage 2003;11:54-4 GM McCarthy, HS Cheung. Point: Hydroxyapatite crystal deposition is intimately involved in the pathogenesis and progression of human osteoarthritis. Curr Rheumatol Rep. 2009;11:141-7. ...