Scanning electron microscopic observations of calcium pyrophosphate crystals of joint tissues and synovial fluid (author's transl)]

The deposition and ultrastructure of calcium pyrophosphate (CPPD) crystals in joint tissues of pseudogout patients and cadavers were studied. Nine calcified menisci, 2 articular cartilages and 6 samples of synovial fluid were examined by scanning electron microscopy (SEM). Some of them were examined by analytical electron microscopy (EMMA). In the samples of menisci and cartilages, the findings were compared with those in the soft X-ray examinations and polarized light microscopy. The results are summarized as follows: 1) SEM observation of the cut surfaces of calcified menisci and cartilages showed a three-dimensional ultrastructure for the CPPD crystals. The crystals in the synovial fluid taken from pseudogout knees were also clearly demonstrated by this method. The EMMA analysis provided the possibility to examine the structure and content of the crystals simultaneously. 2) Crystal deposition in the meniscus varied with the depth of the tissues; it was diffuse in the collagen framework of the superficial layer, but showed accumulation in the deep layer where a clear line of demarcation between the collagen framework and crystals was seen. 3) The crystals in the meniscus were rod, granular or rectangular in shape, and 0.2-6.5 micro by 0.2-3.5 micro in size. Crystals from the articular cartilage were granular or rod-like in shape, and 0.2-3.5 micro by 0.2-1.0 micro in size. Most of the crystals found in the synovial fluid were rod-shaped. 4) X-ray microanalysis of the meniscus crystals by EMMA showed the same pattern of PK alpha, CaK alpha, and CaK beta content as that of CPPD crystals commercially available. The P/Ca ratio was about 0.7. 5) SEM and EMMA examination can be very useful for accurate identification of the form and content of the tiny crystals in joint tissues and synovial fluid. This can also be useful in proving a diagnosis of crystal-induced synovitis.     

Monosodium urate and calcium pyrophosphate dihydrate (CPPD) crystals, inflammation, and cellular signaling

Monosodium urate (MSU) and calcium pyrophosphate dihydrate (CPPD) crystals are responsible for acute synovial inflammation but also contribute to cartilage degradation and bone lesions within the joint. They activate multiple signal transduction pathways leading to cell activation and recruitment. Some signalling pathways are activated by both types of crystals, and other pathways may only be activated by one type depending on cell type, namely neutrophils, monocytes, macrophages, synovial fibroblasts, endothelial cells and chondrocytes. Cascades of activated proteins involve cytoplasmic membrane related proteins (FAK complex, Src family tyrosine kinases), but also MAPK and NF-kB pathways, leading to NO, prostanoid and cytokine production, and protease activation. This review will also focus on potential therapeutic targets related to cellular signalling in MSU and CPPD crystal-induced inflammation.     

双能量能谱CT检测男性痛风患者足踝关节尿酸盐结晶沉积特点分析

目的采用双能量能谱CT分析男性痛风患者足踝关节周围尿酸盐(MSU)沉积特点,评价MSU沉积与痛风性关节炎急性发作的相关解剖学和形态学特征。方法对27例近期足踝部位痛风急性发作的男性痛风患者行双足踝关节双能量能谱扫描,采用χ~2检验分析MSU沉积的形态学特征及解剖学部位与相应区急性关节炎发作的关系。结果 27例患者均检测到MSU,分布于266处沉积区,最常出现MSU沉积的部位依次为软组织(66/266,24.81%)、第一跖趾关节(45/266,16.92%)、皮下(41/266,15.41%)、肌腱(27/266,10.15%)、距骨(26/266,9.77%)、胫骨下端(26/266,9.77%)、腓骨下端(18/266,6.77%)、跟骨(12/266,4.51%)、第一趾中远端(5/266,1.88%)。足关节中第一跖趾关节(χ~2=5.05,P0.05)有MSU沉积、呈点状分布(χ~2=8.02,P0.01)更易引起相应部位的急性关节炎发作。对于踝关节,无论MSU沉积的部位及形态均易引起相应部位关节炎的急性发作。足踝关节中多个MSU沉积亦易引起相应部位痛风性关节炎的急性发作。结论双能量能谱CT可清晰显示MSU的沉积,MSU在足踝关节周围最易沉积于软组织及第一跖趾关节。MSU在足踝关节的沉积部位、形态及数目等对痛风性关节炎的急性发作有影响。     

Reaction of MDCK cells to crystals of monosodium urate monohydrate and uric acid

Madin-Darby canine kidney (MDCK) cells exhibit many of the characteristics of cells of the cortical collecting tubule. Since hypotheses concerning the development of gouty and uric acid nephropathy involve a reaction between such cells and crystals, either of monosodium urate monohydrate (MSUM) or uric acid, the reaction between MDCK cells in culture and the above crystals was studied, both morphologically and functionally. In monolayer cultures, reaction sites developed within four hours of exposure to urate crystals. These increased in number for up to 72 hours and subsided gradually after removal of the crystals. At these reaction sites, crystals were observed to have passed beneath the cell surface and could be demonstrated both within intra-cellular lysosomes as well as within the inter-cellular spaces. When the MDCK cells were maintained as single cells in suspension, phagocytosis of crystals by the majority of the cells could be observed, but the response was much more rapid than in monolayers. During the cell/crystal reaction, significant amounts of lysosomal enzymes and prostaglandin E2 were released and, to a less significant degree, cytosolic enzymes, presumably due to cell lysis. This enzyme release did not occur in MDCK cells grown in protein-free medium, and protein coating of the crystals was necessary for reactivity with cells. In this regard, coating with IgG or lysozyme was more effective than albumin. The reaction with uric acid crystals revealed a reactivity which was lesser in degree but qualitatively similar to that of urate crystals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Deposition of calcium pyrophosphate dihydrate crystals in the hand

A rare case with deposition of calcium pyrophosphate dihydrate crystals around the proximal portion of the first and second metacarpal bones is reported. The second metacarpal had a cystic lesion, and the cortex of the first metacarpal had irregular osteolytic change. There were degenerative changes in the first carpometacarpal joint, trapeziotrapezoid articulation, and second carpometacarpal joint. The patient had recurrent acute inflammatory attacks at the affected site. Initially the patient was thought to have tumoral calcinosis, or a calcifying soft-tissue tumor, with the possibility of a malignant tumor because of angiographic evidence of tumor stain and hypervascularity. Surgical biopsy with partial curettage of the calcified mass resulted in early recurrence of deposition of the crystals. Total excision would seem to be necessary to avoid recurrence.     

Electrophoretic separation of the synovial fluid proteins in patients with temporomandibular joint disorders.

OBJECTIVE: The present study was performed to characterize the patterns of protein expression in the synovial fluid (SF) of patients with temporomandibular joint disorders (TMD) by electrophoretic fractionation. STUDY DESIGN: Samples of the SF of 26 consecutive patients consisting of 16 with closed locking (CL group) and 10 with osteoarthritis (OA group), as well as 7 asymptomatic control subjects (AS group), were analyzed in the present study. SF samples were obtained from the upper compartment of the temporomandibular joint (TMJ) and equal quantities of SF protein were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). RESULTS: The mean total protein concentrations in the SF from both of the TMD groups were higher than that in the AS group (1353 microg/mL in the CL group and 2485 microg/mL in the OA group vs 615 microg/mL in the AS group; P < .01). Moreover, the mean total SF protein concentration was higher in the OA group than in the CL group (P < .01). There was a correlation between the total protein concentration in the SF from both patient groups and the degree of expanded joint effusion (P = .003, r = 0.685). Approximately 22 different protein bands with molecular weights ranging from 14 to 700 kd were clearly discernible on electrophoresis. The relative amounts of specific proteins in the SF of the TMD group were also different from those in the AS group (P < .05). The major difference in total protein concentration appeared to be due to the increased abundance of relatively high molecular weight proteins (>140 kd) in the TMD patients as compared to the AS group. CONCLUSIONS: The SF of patients with TMD showed significant quantitative differences in total protein abundance as compared to healthy subjects. Moreover, this protein abundance was correlated strongly with the degree of expanded joint effusion. The major difference in total protein concentration appeared to be due to the increased abundance of relatively high molecular weight polypeptides in the TMD patients as compared to the healthy control subjects. These observations of changes in the pattern of protein expression may help in understanding the etiological factors involved in the pathophysiology of TMD.     

The effect of crystalline monosodium urate on the crystallisation of calcium oxalate in whole human urine

Summary (1) Samples of undiluted urine from normal men were preincubated with crystalline monosodium urate and their metastable limits and responses to a standard oxalate challenge were compared with results obtained from control samples preincubated without urate. (2) Preincubation with urate had no significant effect on the metastable limits of the urines, the morphology, size, or growth rates of calcium oxalate crystals precipitated from the urines, or on the total amount of calcium oxalate deposited in a given time. (3) It was concluded that particulate monosodium urate is unlikely to influence calcium oxalate stone formation by binding to and attenuating the potency of urinary inhibitors.     

Urinary excretion of urate in patients with calcium oxalate stone disease

Summary The diurnal variation in excretion and concentration of urinary urate was studied in 31 patients with calcium oxalate stone disease. Urate excretion was highest during the day-time, decreased in the evening and was low during the night. Meal-related peaks were observed. The concentration of urate reached the highest levels during the morning hours and, attributable to a low pH in morning urine, most samples were at this time super-saturated with respect to uric acid. In addition, many urines appeared to be at high risk of exceeding the uric acid formation product. Concerning the ion-activity product of sodium urate, supersaturated samples were frequently found, but the risk of exceeding the formation product for sodium urate at a normal urate excretion was apparently low.     

Lipid peroxidation and antioxidant enzymes in synovial fluid of patients with primary and secondary osteoarthritis of the knee joint

OBJECTIVE: Osteoarthritis of the knee (KOA) is a common, age-related, joint disorder associated with loss of articular cartilage, osteophyte formation, sub-chodral bone change and synovitis. Recent studies have shown that reactive oxygen species (ROS) may participate in the initiation and progression of KOA. This study examines potential changes in the activities of antioxidant enzymes (superoxide dismutase, both isoenzymes zinc-copper superoxide dismutase and manganese superoxide dismutase) and glutathione transformation enzymes (glutathione peroxidase, glutathione reductase and glutathione-S-transferase) in synovial fluid of KOA patients, and estimates their relationship to the degree of lipid peroxidation in synovial fluid evaluated by malondialdehyde concentration, synovial fluid viscosity, type and duration of KOA. DESIGN: Synovial fluid samples obtained by transdermal arthrocentesis from 41 patients with KOA (23 had primary KOA and 18 had secondary KOA) and 22 control subjects were analyzed. Activities of antioxidant enzymes were analysed with the use of kinetic method, MDA concentration was measured fluorometrically by the Ohkawa method, and synovial fluid viscosity was measured using a cone-late viscometer Brookfield DV-II+ and a test by Ropes. RESULTS: Patients with KOA had significantly increased activities of all enzymes when compared to the control subjects for both KOA subgroups. The synovial fluid viscosity was significantly decreased and the synovial fluid test by Ropes was abnormal in KOA patients, mainly in the secondary KOA subgroup. The activities of all antioxidant enzymes were significantly negatively correlated with synovial fluid viscosity and duration of KOA. CONCLUSIONS: Patients with KOA display abnormal antioxidant status of synovial fluid with increased activities of antioxidant enzymes and decreased synovial fluid viscosity. Furthermore, synovial fluid viscosity, and activity of GR can be used to distinguish the primary from the secondary type of KOA.     

Exfoliative cytology interpretation of synovial fluid in joint disease.

Criteria for the specific diagnoses of the several arthritides, on the basis of exfoliative cytology examination of fluids aspirated from diseased joints, were derived from examinations of 126 specimens of synovial fluid. They were screened cytologically and wholly on the basis of the cytological findings were classified into seven groups: rheumatoid arthritis, osteoarthritis, traumatic arthritis, gouty arthritis, Reiter's syndrome, pigmented villonodualr synovitis, and septic arthritis. The cytological features of each group appeared relatively constant and reproducible. Subsequent comparison of the clinical and cytological diagnoses showed excellent correlation.     

Simultaneous occurrence of calcium pyrophosphate dihydrate and basic calcium phosphate (hydroxyapatite) crystals in a knee

An 82-year-old man developed periarticular roentgenographic calcifications of the knee joint. Fragments of meniscus and peritendinous tissue were collected during total knee arthroplasty. Crystals were released from tissues by collagenase digestion. Calcium pyrophosphate dihydrate crystals were identified in the meniscus, and basic calcium phosphate crystals were identified in the peritendinous tissue. Methods of crystal identification included compensated polarized light microscopy, scanning electron microscopy with X-ray energy dispersive analysis, and X-ray diffraction.     

Effects of sodium urate and uric acid crystals on the crystallization of calcium oxalate

Summary Crystallization of calcium oxalate in the presence of uric acid and sodium urate crystals was analyzed in a metastable crystallization system containing calcium chloride and sodium oxalate (A), in urine highly supersaturated with respect to calcium oxalate (B), and in urine with a high level of metastable supersaturations (C). In system A uric acid crystals in concentrations up to 11.4 mMol/l did not affect calcium oxalate crystallization, neither did sodium urate during the first 6 h in concentrations below 5 mMol/l. In system B neither uric acid nor sodium urate crystals affected calcium oxalate crystallization. However, an increased rate of crystallization was observed with both uric acid and sodium urate in system C, but the effect was less pronounced than with calcium oxalate seed. Urine pre-treated with sodium urate and subsequently analyzed in system A in a concentration of 2%, gave a slightly lower inhibition of calcium oxalate crystal growth. Concerning the crystal size distribution in the same system, larger crystals were observed in several urines pre-treated with uric acid and sodium urate.