Different Degrees Of Calcification Research Articles

A comparative approach tothe microstructure in the carpus and tarsus in anurans.

Despite the significant literature about morphological features of limb skeletons involved in tetrapod limb evolution, some questions about carpal and tarsal elements remain. In anurans, the ecomorphological and biomechanical approaches studied long hind limbs (to jump) and forelimbs (to land) and emphasized the role of the long bones in locomotion but disregarded what happens with the nodular elements of the carpus and tarsus. Here, we present a comparative study of nodular elements of the carpus and tarsus in anurans based on whole-mount specimens stained with Alcian Blue (cartilage) and Alizarin Red S (bone and calcified cartilage). The sample comprises 113 species belonging to 33 anuran families and postmetamorphic series in selected species. Further, we analyze the histology of the carpus and tarsus in individuals of nine species. In most anurans, the carpal and tarsal elements are cartilaginous in adult stages. The cartilaginous matrix may present different degrees of calcification. Few taxa present truly ossified carpals and tarsals with marrow cavity, blood cells, and hematopoietic cells. Interpretation of the interspecific variation in the carpus and tarsus skeletons on the most recent anuran phylogeny suggests that the delayed ossification of carpals and tarsals has evolved in derived lineages (e.g. Pelobatoidea and Neobatrachia).

Optimization of polymer coating thickness and strut width in drug Eluting stents using Magnetic field

The transport of drug/magnetic particle (MP) conjugates in the presence of a Magnetic Field (MF) in Drug Eluting Stents (DESs) is modeled numerically using the Finite Volume Method (FVM). The effects of physiological conditions corresponding to different degrees of calcification, drug particles sizes and hematocrit level, were analyzed by investigating the roles of the tissue permeability, its anisotropy and the plasma viscosity. It was found that both in the absence and presence of the MF, as the tissue permeability decreases or the plasma viscosity increases, the free-phase drug and Extracellular Matrix (ECM)-bound phase contents increase. Stronger tissue anisotropy leads to a decrease of the free-phase drug content and an increase of the ECM-bound phase content. Within the explored ranges, the Specific Receptor (SR)-bound phase of the drug was found to be insensitive to the tissue permeability and plasma viscosity, and to be larger in anisotropic tissues. The activation of the MF leads systematically to larger free-phase drug contents, with the increases most prominent at smaller tissue permeability, anisotropy and plasma viscosity. On the other hand, the effects on the ECM-bound phase content are found to be stronger at larger permeability, smaller plasma viscosity and lower tissue anisotropy. For an isotropic tissue, the MF induces a decrease of the ECM-bound phase content at early times, followed by an increase at later times. For the considered ranges of permeability and viscosity, the MF does not seem to have any noticeable effects on the SR-bound phase. However, this phase of the drug tends to increase with the activation of the MF in isotropic tissues and is unchanged in anisotropic ones. These reported effects of the MF hold promise for alleviating two factors contributing to In-Stent Restenosis, namely the polymer coating width and thickness. The study reveals that a narrower or thinner polymer layer, in combination with the MF, can mimic the drug release dynamics of a wider or thicker polymer layer in the absence of the MF. The corresponding width and thickness of the magnetized stents, that we referred to as the equivalent polymer width (EPW) and equivalent polymer thickness (EPT) were determined and their dependence on the tissue permeability, isotropy and the plasma viscosity, was investigated. The study shows that it is possible to achieve the same drug delivery with polymer coating of half the width or half the thickness of the non-magnetized stent when an electric intensity of 3A is used.

Accurate low-energy pulse system for intravascular lithotripsy

In response to biomedical imperatives, a novel approach is presented for the endovascular management of atherosclerosis. This approach is grounded in the electrohydraulic effect of a precisely controlled low-energy pulse discharge system, coupled with sequential control within the incomplete discharge electrode, to generate shockwaves aimed at softening blood vessels and rupturing calcified plaques. Theoretical analysis encompassed circuit design, control timing, and operational processes, while experimental investigations demonstrated precise control of non-oscillation and incomplete discharge by adjusting key parameters. Utilizing a 3 kV DC high-voltage power supply, a 220 nF capacitor, and two sets of 3.3 Ω resistors in parallel, with pin–plate electrodes as the load for discharge in normal saline, resulted in a 1 kV reduction in voltage across the capacitor and a peak current of 170 A. Energy release occurred through non-oscillatory and incomplete discharge, effectively generating shockwaves with peak pressures of 5–10 MPa at distances of 1–2 mm from the discharge center to treat calcified lesions. Compared with the existing intravascular lithotripsy devices, the shockwave system realizes accurate control of discharge energy by adjusting the turn-off time of incomplete discharge so as to realize accurate control of shockwave energy. Doctors can choose different intensities of shockwaves according to different degrees of calcification in the treatment process so as to minimize the discomfort caused by shockwaves and improve safety. Valuable insights are provided for intravascular lithotripsy devices in engineering.

Efficacy and Safety of Covered Stents Versus Bare-Metal Stents for Aortoiliac Occlusive Disease: A Systematic Review and Meta-Analysis.

This study aimed to assess the efficacy and safety outcome of covered stents (CSs), as compared with bare-metal stents (BMSs), for the treatment of patients with aortoiliac occlusive disease (AIOD). A systematic literature search was conducted in PubMed, Embase, and Cochrane Library up to August 2023 to identify all studies comparing efficacy and safety outcomes of CSs versus BMSs for treating AIOD. Our outcome was primary patency, secondary patency, technical success, ankle-brachial index (ABI) variation, target lesion revascularization (TLR), limb salvage, complications, and long-term survival. Dichotomous outcomes were pooled as relative risks (RR) or hazard ratio with the 95% confidence interval (CI). Continuous outcomes were pooled as weighted mean differences and 95% CI. Model selection was based on the heterogeneity of the included studies. There were 10 studies (2 randomized controlled trials, 8 retrospective cohort studies), comprising 1676 sample size. Compared with BMSs, CSs use was associated with better primary patency of patients with a Trans-Atlantic Inter-Society Consensus II (TASC) D lesion (RR, 1.15, 95% CI, 1.04 to 1.27, p=0.007), TLR (RR, 0.39, 95% CI, 0.27 to 0.56, p<0.001), technical success (RR, 1.01, 95% CI, 1.00 to 1.02, p=0.010), and long-term survival (RR, 1.06, 95% CI, 1.01 to 1.11, p=0.020). There is no difference between CSs and BMSs regarding primary patency of all patients, secondary patency, variation in ABI, limb salvage, and complications. Compared with BMSs, CSs used in AIOD was associated with more favorable primary patency in patients with TASC D lesions, TLR, technical success rates, and patient long-term survival. These results provide evidence of the advantages of using CSs for AIOD treatment. Future studies focusing on long-term variations in ABI, primary patency of different degrees of calcification, vascular segments, and TASC classification are warranted. Although several studies evaluated the clinical efficacy of CS in the context of AIOD treatment, the significance and consistency of these findings were not determined to date. We found that CS was used in AIOD associated with better technical success rate, long-term patient survival, lower target lesion revascularization, and higher primary patency of patients with a Trans-Atlantic Inter-Society Consensus II D lesion when compared with BMSs. Our study provides evidence supporting the superiority of CSs over BMSs in the treatment of AIOD, and furnishing clinicians with guidance for treatment decisions.

Subtraction Improves the Accuracy of Coronary CT Angiography in Patients with Severe Calcifications in Identifying Moderate and Severe Stenosis: A Multicenter Study

To investigate the diagnostic accuracy of subtraction coronary computed tomographic angiography (CCTAsub) in identifying ≥ 50% and ≥ 70% coronary stenosis in patients with different degrees of calcification. In this study, 180 patients with coronary calcified plaques who underwent both coronary CT angiography and invasive coronary angiography (ICA) were prospectively enrolled at five centers. Patients were divided into three groups according to the Agatston score: group A (low to moderate, < 400), group B (high, 400-999), and group C (very high, ≥ 1000). Diagnostic accuracies estimated by area under the receiver operating characteristic curve (AUC) were compared between conventional CCTA (CCTAcon) and CCTAsub, with ICA as a reference standard. There were 86 patients in group A, 44 in group B, and 50 in group C. In identifying ≥ 70% coronary stenosis, subtraction improved the diagnostic accuracies on a per-segment basis in group B (AUC: 0.80 vs 0.92, p=0.001) and group C (AUC: 0.75 vs 0.84, p=0.001) after subtraction. When identifying ≥ 50% coronary stenosis, the per-segment AUC of CCTAsub in group B and C were significantly higher than that in CCTAcon (group B: 0.81 vs 0.92, p < 0.001; group C: 0.77 vs 0.88, p < 0.001). However, no improvement was observed in group A. Subtraction achieved better diagnostic accuracy in patients with Agatston score ≥ 400, both in identifying ≥ 50% and ≥ 70% coronary stenosis, which was instructive for the application of subtraction in clinical practice.

Distinct ex vivo biomarker profiles of calcified and non-calcified acetabular labrum tissues in primary hip OA

Purpose: Hip OA has a prevalence of 7.4% in individuals older than 60 years and involves structural degeneration of several joint compartments, including femoral head cartilage, periarticular ligaments and the acetabular labrum. The latter is a ring-form fibrocartilage tissue that plays a fundamental role in hip joint stability and articular cartilage homeostasis. Degeneration of the labrum involves chondrocyte apoptosis, macrophage infiltration and calcification and is thought to promote progression of primary hip OA. Moreover, labrum is a vascularized and innervated tissue and therefore strongly implied in hip OA pain. While several histological studies have documented morpological tissue changes, biochemical changes have not been extensively reported. In this study, we characterized biomarker secretion of explanted human labrum tissues under basal and inflammatory conditions. Methods: Intact labrum specimens were obtained from patients undergoing total hip arthroplasty (n=11, mean age 65.5, 3 women) and dissected in equal-sized samples (200-400 mg wet weight). Labrum tissues were subjected to explant culture for one week in the presence or absence of an inflammatory stimulus (1 ug/mL LPS). To evaluate the role of TGF-beta signaling in labrum tissue metabolism, samples were treated with 10 uM SB-505124 (TGF-beta type I receptor inhibitor) in the presence or absence of LPS. Secretion of Aggrecan (ACAN), Cartilage Oligomeric Matrix Protein (COMP), MMP13, Pro-Collagen-Ia and IL-6 was assessed by ELISA. Tissue proteoglycans and calcification were evaluated by whole mount Alcian blue/Alizarin red staining followed by ethyl cinnamate-based optical clearing and fluorescence microscopy. Results: Whole mount staining for proteoglycans and calcium revealed different degrees of calcification of labrum tissues (Figure). Five samples contained numerous calcified nodules and one sample was completely ossified. Non-calcified specimens displayed strong proteoglycan tissue staining interspersed with fibrous tissue. Labrum tissues secreted low levels of IL-6 and ACAN (5-50 ng/gr tissue), moderate levels of MMP13 and COMP (100-300 ng/gr tissue) and high levels of Pro-Collagen-Ia (∼900 ng/gr tissue). Subgroup analysis revealed significantly higher Pro-Collagen-Ia (1170+230 vs. 596+305) and MMP13 (157+22 vs. 60+15) secretion by calcified labrum specimens. Inflammatory stimulation led to a ∼10-fold upregulation of IL-6 and ∼2-fold dowregulation of Pro-Collagen-Ia secretion, in both non-calcified and calcified specimens. Neither basal expression, nor effects of LPS stimulation were mediated through TGF-beta signaling. Conclusions: Biomarker profiling of degenerative acetabular labrum tissues revealed distinct secretion patterns in non-decalcified and calcified specimens, displaying elevated Pro-Collagen-Ia and MMP13 secretion by the latter. In contrast to articular cartilage, regulation of IL-6 and Pro-Collagen-Ia was not TGF-beta, but rather TLR4-dependent and calcification appeared IL-6-independent. Whether labrum fibrochondrytes or infiltrated macrophages are crucially involved in these effects remains to be elucidated. Due to its close proximity to articular cartilage, secreted mediators from degenerated labrum might contribute to or even accelerate the development of hip OA.

RETRACTED: Neuroimaging diagnosis of intraventricular Central neurocytoma

To study the CT and MRI imaging manifestations of central and intraventricular central neurocytoma in the ventricle. In this paper, 39 patients with central nervous cell tumour treated in our hospital from August 2015 to June 2018 were selected. All patients were performed plain CT scans using GE Highspeed CT; GE signa Twin speed 1.5 T superconducting magnet Resonance scanners were used to perform MRI plain scans on all patients. Observe the specific location, size, and morphology of tumours in the supra- and sub-ventricular ventricles of 39 central nervous cell tumour patients, and compare the performance of CT examination with the performance of MRI examination. Of the 39 patients with central neurocytoma, 13 were in the right lateral ventricle, 9 were in the left lateral ventricle, 11 patients had tumours in both lateral ventricles, and 6 patients had bilateral ventricles and bilateral ventricles. There were tumours in the third ventricle; 39 patients had an average tumour size of 52 mm; 36 patients had irregular lobes, and 3 patients had blurred tumour boundaries; some tumours had different degrees of calcification. The location and characteristics of the imaging manifestations of central nervous cell tumours are typical. Both CT scans and MRI scans can effectively detect central neuroblastomas, and MRI imaging examinations can effectively improve the diagnosis accuracy of tumour is better than that of CT.

Effect of Cyclic Stretch on Vascular Endothelial Cells and Abdominal Aortic Aneurysm (AAA): Role in the Inflammatory Response.

Abdominal aortic aneurysm (AAA) is a focal dilatation of the aorta, caused by both genetic and environmental factors. Although vascular endothelium plays a key role in AAA progression, the biological mechanisms underlying the mechanical stress involvement are only partially understood. In this study, we developed an in vitro model to characterize the role of mechanical stress as a potential trigger of endothelial deregulation in terms of inflammatory response bridging between endothelial cells (ECs), inflammatory cells, and matrix remodeling. In AAA patients, data revealed different degrees of calcification, inversely correlated with wall stretching and also with inflammation and extracellular matrix degradation. In order to study the role of mechanical stimulation, endothelial cell line (EA.hy926) has been cultured in healthy (10% strain) and pathological (5% strain) dynamic conditions using a bioreactor. In presence of tumor necrosis factor alpha (TNF-α), high levels of matrix metalloproteinase-9 (MMP-9) expression and inflammation are obtained, while mechanical stimulation significantly counteracts the TNF-α effects. Moreover, physiological deformation also plays a significant role in the control of the oxidative stress. Overall our findings indicate that, due to wall calcification, in AAA there is a significant change in terms of decreased wall stretching.

Dynamics of transparent exopolymer particle production and aggregation during viral infection of the coccolithophore, Emiliania huxleyi.

Emiliania huxleyi produces calcium carbonate (CaCO3 ) coccoliths and transparent exopolymer particles (TEP), sticky, acidic carbohydrates that facilitate aggregation. E. huxleyi's extensive oceanic blooms are often terminated by coccolithoviruses (EhVs) with the transport of cellular debris and associated particulate organic carbon (POC) to depth being facilitated by TEP-bound 'marine snow' aggregates. The dynamics of TEP production and particle aggregation in response to EhV infection are poorly understood. Using flow cytometry, spectrophotometry and FlowCam visualization of alcian blue (AB)-stained aggregates, we assessed TEP production and the size spectrum of aggregates for E. huxleyi possessing different degrees of calcification and cellular CaCO3 :POC mass ratios, when challenged with two EhVs (EhV207 and EhV99B1). FlowCam imaging also qualitatively assessed the relative amount of AB-stainable TEP (i.e., blue:red ratio of each particle). We show significant increases in TEP during early phase EhV207-infection (∼ 24 h) of calcifying strains and a shift towards large aggregates following EhV99B1-infection. We also observed the formation of large aggregates with low blue:red ratios, suggesting that other exopolymer substances contribute towards aggregation. Our findings show the potential for virus infection and the associated response of their hosts to impact carbon flux dynamics and provide incentive to explore these dynamics in natural populations.

Comparison of Acute Expansion of Bioresorbable Vascular Scaffolds Versus Metallic Drug-Eluting Stents in Different Degrees of Calcification: An Optical Coherence Tomography Study. DOI: 10.1002/ccd.26676.

Comparison of Acute Expansion of Bioresorbable Vascular Scaffolds Versus Metallic Drug-Eluting Stents in Different Degrees of Calcification: An Optical Coherence Tomography Study. DOI: 10.1002/ccd.26676.

Serum Soluble Klotho Level Is Associated with Abdominal Aortic Calcification in Patients on Maintenance Hemodialysis

Background: Klotho is a single transmembrane protein originally identified as an ‘aging suppressor'. Emerging evidence reveals that soluble Klotho (sKl) in the circulation plays important roles in anti-aging, anti-oxidation, anti-apoptosis and Wnt signaling. However, the role of serum sKl in the vascular calcification in hemodialysis patients is not clear. The aim of this study was to determine the associations of sKl with abdominal aortic calcification in patients on maintenance hemodialysis (MHD). Methods: 129 MHD patients were enrolled prospectively. Serum sKl level was detected by ELISA. Abdominal aortic calcification was measured by abdomen lateral plain radiograph, and the abdominal aorta calcification (AAC) score was calculated. The sKl levels were observed in patients with different degrees of calcification. Logistic regression analysis was used to determine the risk factor of abdominal aortic calcification in MHD patients. The diagnostic value of sKl for abdominal aortic calcification was assessed using receiver operator characteristic (ROC). Results: Abdominal aortic calcification was seen in 87 of 129 patients. The median AAC score was 4.0 (0.00, 11.00) and the median sKl level was 616.29 (378.19, 821.61) pg/ml. Serum sKl levels were inversely associated with AAC. When evaluated as AAC categories (<5, 5-15, >15) with ordinal logistic regression, each SD higher sKl was associated with 37.1% lower odds of AAC severity (proportional odds ratio: 0.629; 95% confidence interval: 0.413-0.959, p = 0.031) in models adjusted for demographic data, lifestyle factors, traditional CVD risk factors and uremic risk factors. Multivariate logistic regression analysis showed that serum sKl levels and smoking were independent risk factors for severe AAC. The area under the receiver-operating characteristic curve (AUC) of serum sKl for severe abdominal aortic calcification was 0.746 (0.612-0.880, p = 0.001), sensitivity was 0.885, and specificity was 0.562 for a cutoff value of 265.39 pg/ml. Conclusions: Lower serum sKl levels are independently associated with severe AAC. Serum sKl might have a diagnostic value for the severe AAC in MHD patients.

Through IVUS study of characterised the relationship as stable angina (SA) and unstable angina (UA) patients

PurposeAs medical technology advances, the understanding of coronary heart disease from the previous clinical diagnosis, diagnostic ECG, ECG to diagnosis, then diagnostic coronary angiography (coronary angiography CAG), and then by...

Comparison of Chest Dual-Energy Subtraction Digital Tomosynthesis and Conventional Digital Tomosynthesis for the Detection of Simulated Pulmonary Nodules with Calcifications: Phantom Study

To compare the effectiveness of chest dual-energy subtraction digital tomosynthesis (DES-DT) with that of conventional digital tomosynthesis for the detection of calcifications superimposed over simulated pulmonary nodules. A DES-DT system with pulsed X-rays and rapid kV switching was used to examine calcifications in simulated pulmonary nodules. Low-voltage, high-voltage, and soft-tissue or bone-subtracted tomograms of the desired layer thicknesses were reconstructed from the image data acquired during a single tomographic scan, bone-subtracted images, and a scan angle of 40°. Our analysis took into account the signal-to-noise ratio (SNR) of the different degrees of calcification in the simulated pulmonary nodules. For DES-DT, the SNR for the simulated pulmonary nodules increased about 63%. Based on the results of receiver operating characteristic performance analysis, the detection ability of our DES-DT was significantly better than that of conventional digital tomosynthesis (P < 0.03). The study results confirmed with a further study to assess influence of reconstruction and filtering for detection of simulated nodules. DES-DT provided greater sensitivity than conventional digital tomosynthesis.

Degenerative processes in bioprosthetic mitral valves in juvenile pigs

BackgroundGlutaraldehyde-treated bioprosthetic heart valves are commonly used for replacement of diseased heart valves. However, calcification and wear limit their durability, and the development of new and improved bioprosthetic valve designs is needed and must be evaluated in a reliable animal model. We studied glutaraldehyde-treated valves 6 months after implantation to evaluate bioprosthetic valve complications in the mitral position in juvenile pigs.MaterialsThe study material comprised eight, 5-month old, 60-kg pigs. All pigs received a size 27, glutaraldehyde-treated, stented, Carpentier-Edwards S.A.V. mitral valve prosthesis. After six months, echocardiography was performed, and the valves explanted for gross examination, high resolution X-ray, and histological evaluation.ResultsFive pigs survived the follow-up period. Preexplant echocardiography revealed a median peak and mean velocity of 1.61 m/s (range: 1.17-2.00) and 1.20 (SD = ±0.25), respectively, and a median peak and mean pressure difference of 10.42 mmHg (range: 5.83-16.55) and 6.51 mmHg (SD = ±2.57), respectively. Gross examination showed minor thrombotic depositions at two commissures in two valves and at all three commissures in three valves. High resolution X-ray imaging revealed different degrees of calcification in all explanted valves, primarily in the commissural and belly areas. In all valves, histological evaluation demonstrated various degrees of fibrous sheath formation, limited immunological infiltration, and no overgrowth of host endothelium.ConclusionsBioprosthetic glutaraldehyde-treated mitral valves can be implanted into the mitral position in pigs and function after 6 months. Echocardiographic data, calcification, and histological examinations were comparable to results obtained in sheep models and human demonstrating the suitability of the porcine model.

Effect of varying calcium concentrations and light intensities on calcification and photosynthesis in Emiliania huxleyi

Various protective and metabolic functions for coccolithophore calcification have been proposed such as providing a means to supply CO2 for photosynthesis. It has also been speculated that calcification helps to dissipate excess energy under high irradiance, thereby circumventing photoinhibition. To address these questions, cells of a calcifying strain of Emiliania huxleyi were grown at three irradiances (30, 300, and 800 µmol photons m−2 s−1) in combination with four calcium (Ca) concentrations (0.1, 1, 2.5, and 10 mmol L−1) leading to different degrees of calcification in the same strain. Growth rates (µ), particulate organic carbon (POC), and inorganic carbon (PIC) production as well as carbon isotope fractionation (p) were determined. Photosynthetic O2 evolution and CO2 and HCO3− uptake rates were measured by membrane inlet mass spectrometry (MIMS). The application of this multimethod approach provides new information on the role of calcification in E. huxleyi. Noncalcifying cells showed POC production rates as high as calcifying ones. No differences in p were observed under different Ca concentrations. MIMS measurements indicate that noncalcifying cells can photosynthesize as efficiently as, or even more efficiently than, calcifying ones and that both use HCO3− as the main carbon source. The ratio of photosynthetic HCO3− uptake relative to net fixation did not differ among cells acclimated to 10 mmol L−1 or to 0.1 mmol L−1 Ca. These results indicate that (1) calcification is not involved in photosynthetic carbon acquisition, and (2) calcification does not provide a means of energy dissipation under high irradiances.

Large chondroma of the dural convexity in a patient with Noonan's syndrome. Case report and review of the literature

Intracranial chondromas are extremely rare intracranial tumours that usually arise from the skull base synchondrosis. Exceptionally, they may grow from cartilage rests within the dura mater of the convexity or the falx. They may be part of Ollier's multiple enchondromatosis or Maffuci's syndrome. We describe the case of a young male diagnosed of Noonan's syndrome that underwent resection of a large intracranial chondroma arising from the dural convexity. To our best knowledge this is the first report of such association. An 18-year-old male presented with a single generalized seizure. The patient was previously diagnosed of Noonan's syndrome on the basis of his special phenotype (Turner-like), low stature, cardiac malformation, retarded sexual and bone development and normal karyotype. He harboured mild psychomotor retardation. Physical and neurological examinations were unremarkable. Brain Magnetic Resonance image showed a large well-circumscribed intracranial mass in the dural convexity of the left frontal-parietal lobes, with heterogeneous contrast enhancement and no peritumoural oedema. The patient was initiated on valproic acid and underwent craniotomy and complete excision of the tumour. The tumour was firm, white-greyish, avascular and could be finely dissected away from the cortex. Postoperative seizures required additional anticonvulsant therapy. He was discharged uneventfully. The pathological study revealed a mature chondroma. Subsequent brain MRI studies have shown no evidence of recurrence after 33 months of follow up. Chondromas comprise less than 0.3% of intracranial tumours. Only twenty-five cases of intracranial dural convexity chondromas are reported in the literature. Several hystopathogenetic theories have been proposed: metaplasia of meningeal fibroblasts and perivascular meningeal tissue, traumatic or inflammatory cartilaginous activation of fibroblasts and growth of aberrant embryonal cartilaginous rests in the dura mater. Chondromas present clinical features similar to meningiomas. CT scan imaging shows a mass of variable density due to different degrees of calcification with minimum to moderate contrast enhancement. MRI studies show a well-circumscribed lesion without surrounding tissue oedema, that exhibit heterogeneous signal with intermediate to low intensity on T1-weighted images and mixed intensity on T2-weighted images with minimum enhancement. Angiogram is clue to differentiate from meningiomas since chondromas are completely avascular. Complete tumour resection including its dural attachment is the treatment of choice. Long-term prognosis is favourable. Radiation therapy is currently not recommended for residual tumours or inoperable patients due to risk of malignization. Noonan's syndrome (also known as pseudo-Turner syndrome) is a complex familial genetic disorder with a phenotype that resembles that of Turner's syndrome but exhibits no chromosomal defect. No predisposition of Noonan's syndrome for tumoural development is reported in the literature. Association of a dural convexity chondroma with Noonan's syndrome is unique as far as the literature is concerned.

Reproducibility of two coronary calcium quantification algorithms in patients with different degrees of calcification.

To evaluate the reproducibility of coronary calcium quantification algorithms by electron beam CT (EBT) in patients with different amounts of calcified plaque using the conventional (Agatston) score and an area score and to demonstrate a potential application of these results for evaluation of follow-up scans. In 50 consecutive patients. the conventional calcium score (CCS = Agatston score) and the area score (AS) were summed for each artery and patient. Data were analyzed in four groups according to degrees of calcification: 0 (absent-minimal): CCS 0-9, I (mild): CCS 10-99, II (moderate): CCS 100-399, III (severe): CCS > or = 400. We determined and compared the reproducibility for each algorithm within and among groups. Median percent reproducibility improved with increasing amounts of calcified plaque for the CCS and the AS (p = 0.002 and p = 0.004, respectively). We demonstrate how these reproducibility values can be used to evaluate long-term follow-up studies. The reduction of median reproducibility per patient using the AS vs. the CCS was 32% (13 vs. 19%, respectively). On a vessel-by-vessel basis, the reduction of median reproducibility was 7% (24.3 vs. 22.6%, CCS vs. AS, p < 0.02), which was attributable to a 45% reduction in reproducibility in arteries with mild scores (46.1 vs. 25.5%, CCS vs. AS, p < 0.005). The AS has an improved reproducibility compared with the CCS, especially in patients with small amounts of coronary calcifications which may prove clinically useful. Different reproducibility values in different degrees of calcification can be used for an individual assessment of changes in amounts of coronary calcification.

Atherosclerotic carotid arteries--calcification and radio-morphological findings.

Are there any predictable factors influencing the process of calcification in carotid arteries? The carotid arteries and especially the carotid bifurcation are one of the predisposed regions of atherosclerotic disease. Whether topography of the carotid sinus, flow patterns or different patient characteristics (e.g., diabetes mellitus, age, sex) are a factor determining calcification of atherosclerotic lesions is still hardly understood. Morphological and morphometrical analysis including radiographic classification of different degrees of calcification on postmortal carotid arteries (90 men and 19 women) and 306 surgical samples after intramural desobliterations of carotid arteries (202 patients with diabetes, 104 patients without diabetes). Most common localization of radiographically identified calcified deposits are the carotid bulb (76%) especially on the lateral wall opposite the flow divider and the internal carotid artery (55%) especially the proximal 1 cm section. No difference in degree of calcification was found when comparing patients with and without diabetes (intermediate calcification in 59% of patients with diabetes and 50% without diabetes). More female patients with diabetes show calcification when compared to the group of patients without diabetes. Females produce calcification in atherosclerotic carotid lesions at an older age compared to male patients. Calcification is a frequent finding in advanced atherosclerotic carotid lesions. There is no difference in regard to degree, pattern of calcification or age distribution when comparing patients with and without diabetes mellitus. Atherosclerotic lesions more frequently found in female patients with diabetes may be due to less vasoprotection by estrogens.

The role of magnesium on the structure of biological apatites.

X-ray diffraction, infrared absorption spectroscopy, and chemical investigation have been carried out on deproteinated samples of turkey leg tendon at different degrees of calcification. The inorganic phase consists of poorly crystalline B carbonated apatite. On increasing calcification, the apatite crystal size, as well as its thermal stability, increase while the relative magnesium content is reduced. On the other hand, synchrotron X-ray diffraction data clearly indicate that apatite lattice parameters do not change as the crystals get larger. At the last stage of calcification the crystal size, chemical composition, and thermal conversion of the apatite crystallites approximate those of bone samples, which have been examined for comparison. The results provide a quantitative relationship between relative magnesium content and extent of apatite conversion into B-tricalcium phosphate by heat treatment. Furthermore, they suggest that the smaller crystallites laid down inside the gap region of the collagen fibrils are richer in magnesium than the longer ones that fill the space between collagen fibrils.

Hydroxyapatite crystals orientation during a pathological calcification of human tendons

The structural relationship between collagen fibers and apatite deposits in mineralized tissues has been widely investigated by electron microscopy and X-ray diffraction techniques [1]. For these studies oriented samples, such as osteons and turkey leg tendon at different degrees of calcification, have been particularly useful [2–4]. However many features of the problem are still obscure. The availability of oriented samples containing collagen fibers at low degrees of calcification is an essential condition to obtain information about the sites of the initial deposition of the apatite crystals in the collagen fibers structure using diffraction techniques. Tendon affected by diffuse idiopatic skeletal hyperostosis, which is a disease characterized by calcification and ossification of tendons and ligaments [5], is a suitable tissue because calcium hydroxyapatite is laid down within the tissue to different degrees along its length and to different degrees with the development of the disease. We have examined fragments of human tendons which showed radiographic evidence of this pathological calcification at the sites of attachment to olecranon by small and high angle X-ray diffraction techniques in order to investigate the inorganic deposits and their interaction with collagen fibers. X-ray diffractometric analysis carried out on powdered mineralized samples permitted the recognition of the mineral deposit present in the tissue as hydroxyapatite. This inorganic phase exhibits a good degree of crystallinity and cell parameters a = 9.40(1) Å, c = 6.89(1) Å very close to those of bone apatite. High angle X-ray diffraction analysis carried out by means of a flat camera on fragments dissected from several zones of the tendons revealed a different orientation of the apatite crystals as a function of the degree of calcification of the tissue. The apatite crystals appear to be preferentially oriented with their c-axis parallel to the tendon axis in the zones at a low degree of calcification. This orientation reduces progressively as the degree of calcification increases and no preferential orientation can be observed in the fully calcified zones. The X-ray reflections characteristic of collagen molecular structure appear superimposed on those of the inorganic phase and show that collagen fibers orientation is always coincident with that of the c-axis of the hydroxyapatite crystals. The small angle X-ray diffraction pattern recorded on fragments at a low degree of calcification shows the characteristic reflections of collagen fibrillar structure which appear oriented parallel to the tendon axis. No diffraction reflection due to collagen can be observed in the small angle X-ray diffraction pattern obtained from fully calcified fragments. These results show a clear relationship between apatite crystals deposition and collagen fibers distribution and orientation. In fact at a low degree of calcification apatite are aligned parallel to the collagen fibers of the tendon whereas at a high degree of calcification no orientation of collagen fibers as well as of apatite crystals could be revealed. This agrees with the morphological observations which show that at a high degree of calcification the collagen fibers lose their characteristic orientation parallel to the tendon axis and assume an isotropic distribution in a structure closely resembling that characteristic of cancellous bone. Furthermore it must be noted that the collagen molecular packing does not seem to be affected by the mineralization process, at least during the initial stage of the deposition.