Species segregation in one-dimensional granular-system simulations.

We present one-dimensional molecular dynamics simulations of a two-species, initially uniform, freely evolving granular system. Colliding particles swap their relative position with a 50% probability allowing for the initial spatial ordering of the particles to evolve in time and frictional forces to operate. Unlike one-dimensional systems of identical particles, two-species one-dimensional systems of quasi-elastic particles are ergodic and the particles' velocity distributions tend to evolve towards Maxwell-Boltzmann distributions. Under such conditions, standard fluid equations with merely an additional sink term in the energy equation, reflecting the non-elasticity of the interparticle collisions, provide an excellent means to investigate the system's evolution. According to the predictions of fluid theory we find that the clustering instability is dominated by a non-propagating mode at a wavelength of the order 10 pi L/N epsilon , where N is the total number of particles, L the spatial extent of the system and epsilon the inelasticity coefficient. The typical fluid velocities at the time of inelastic collapse are seen to be supersonic, unless N epsilon

Angiotensin-converting enzyme inhibition modulates high-glucose-induced extracellular matrix changes in mouse glomerular epithelial cells.

BACKGROUND/AIM: Extracellular matrix alterations are involved in the pathogenesis of diabetic nephropathy. We evaluated the effects of high glucose concentrations and inhibition of angiotensin-converting enzyme on the laminin and fibronectin production by glomerular epithelial cells. METHODS: Glomerular epithelial cells were cultured in 5 and 30 mmol/l glucose, with and without enalaprilat (0.3 mmol/l). Laminin and fibronectin were measured (35S-methionine, immunoprecipitation), and their mRNA expression was evaluated (RT-PCR). RESULTS: The laminin concentration was higher in the cells than in the medium, where an increase of its content was observed under high-glucose conditions (p < 0.01). Fibronectin, found only in the medium, was not modified by the high glucose concentration. Following enalaprilat administration, the laminin concentration was decreased under high-glucose conditions, both in the cell and in the medium (p < 0.001), whereas the fibronectin concentration was increased under high-glucose conditions (p < 0.001). The mRNA expression of laminin and fibronectin under high-glucose conditions only slightly increased. Enalaprilat decreased the fibronectin mRNA synthesis dramatically (>50%, p < 0.0001) under high-glucose conditions. CONCLUSIONS: Enalaprilat normalizes the abnormal, high-glucose-induced concentration of laminin, while it decreases the fibronectin synthesis. The improvement of the renal function in diabetic patients treated with angiotensin-converting enzyme inhibitors may, in part, be due to a modulator effect on extracellular matrix content and composition.

Immunocytochemical expression of Ki67 and laminin in Hurthle cell adenomas and carcinomas.

BACKGROUND: Hurthle cell neoplasms may occur as a benign adenoma or carcinoma; the latter displays comparatively aggressive clinical behaviour. Fine-needle aspiration cytology (FNAC) represents a reliable tool for screening Hurthle cell lesions before surgery. Nevertheless, the cytological interpretation of these lesions is not always unequivocal. We analyzed cell growth and cellular adhesiveness by means of two different antibodies, Mib1 (Ki67) and laminin. AIM: The aim of the study was to analyze Ki67 and laminin immunocytochemical expression on FNAC to evaluate their usefulness in the preoperative differential diagnosis of Hurthle cell neoplasms. RESULTS: A higher expression of Ki67 has been recorded in malignant lesions as compared to benign ones (8% to 20% vs 1% to 5% nuclear staining, respectively; p < 0.001). An increased reactivity of anti-laminin antibody was recorded in the cytoplasm of cells from all malignant lesions. In Hurthle cell adenomas this adhesion molecule showed an intensity ranging from low to moderate. Moreover, a few benign lesions showing a moderate proliferative activity were associated with evident laminin expression. CONCLUSION: These findings support the hypothesis that benign Hurthle cell lesions with a high cellular proliferation associated with an increased laminin expression could define a subset of lesions prone to malignant transformation. Conversely, since all cases with low expression of both laminin and Ki67 always correspond to adenomas, we suggest that the different expression of these two antibodies on FNAC can provide a further tool for the preoperative identification of lesions at low risk of malignancy, thus avoiding unnecessary surgery.

Thyroiditis and oncocytic carcinoma: incidental association? A case report.

BACKGROUND: Several studies have reported an association between Hashimoto's disease and thyroid carcinoma although the cause/effect relationship is still controversial. CASE REPORT: In this paper we report the case of a 38-year-old female who first presented with a clinical history of Hashimoto's thyroiditis. Ultrasound examination showed a diffuse thyroid irregularity more pronounced in the right lobe. FNAC (Fine Needle Aspiration Cytology) was performed in this area, and the cytological diagnosis was "Hashimoto's thyroiditis". The patient underwent clinical follow-up. Two years later, an ultrasound examination showed a nodular lump in the area previously aspirated. A new FNAC evidenced a Hurthle cell neoplasia. Therefore, the patient underwent surgery. The histological diagnosis was "Hurthle cell carcinoma". CONCLUSION: In the present case, the clinical and ultrasound history suggest the development of a malignant lesion strictly related to thyroiditis, as previously reported by other studies on papillary carcinoma. A cause-effect relationship between chronic lymphocytic thyroiditis and oncocytic neoplasia is still a matter of controversy. Therefore, patients suffering from chronic thyroiditis require a careful follow-up and, in case of nodules development, FNAC is recommended.

[Recurrent brown tumors as initial manifestation of primary hyperparathyroidism. An unusual presentation]. / Tumori bruni recidivanti come prima manifestazione di iperparatiroidismo primitivo. Un esordio insolito.

Primary hyperparathyroidism is a rather frequent pathology characterised by hypersecretion of parathormone (PTH) which is caused by adenomas in 85% of all cases. At clinical onset, the most common symptoms are hypercalcemia-related (pain due to kidney stones, polyuria, gastrointestinal and neurological disorders) while rarer symptoms are due to brown tumors, expansive lesions often found in fibro-cystic osteitis. A case in which the patient showed recurrent mandibular brown tumors as initial clinical symptoms of primary hyperparathyroidism is described. This patient was examined for hypercalcemia, and a tumor mass at the left inferior mandibular branch was found. The patient had undergone surgical removal of a tumor in the left mandibular some years before, which was diagnosed as osteoclastoma. Primary hyperparathyroidism was diagnosed during recovery, and surgical removal of the parathyroid adenoma and mandibular tumor was performed. A histological diagnosis of large cell brown tumor was made. A microscopic observation of brown tumors which are made up of large multinuclear osteoclastic cells can often be confused with other large cell tumors during diagnosis. It is therefore necessary to exclude the presence of hyperparathyroidism with ionised calcium and, in cases of high values, intact PTH (iPTH), before performing a histological diagnosis of a large cell bone tumor. Throughout the course of primary hyperparathyroidism, brown tumors might appear in the absence of other specific symptoms and localize at the level of a single bone segment.

High glucose modifies heparansulphate synthesis by mouse glomerular epithelial cells.

BACKGROUND: Alterations in proteoglycan metabolism are involved in the pathogenesis of diabetic nephropathy. The aim of this study is to evaluate the effects of high glucose on proteoglycan production and to find a reliable in vitro model for the study of diabetic nephropathy. METHODS: A clone of mouse glomerular epithelial cells was cultured in media containing elevated (30 mmol) and physiological (5 mmol) glucose, or iso-osmolar (30 mmol) mannitol concentrations. We evaluated the synthesis of 35SO4-labeled molecules and the amount of proteoglycans by Sepharose CL6B and DEAE-Sephacel chromatographies. RESULTS: A clear decrease (56%) in total cell-layer proteoglycan synthesis was induced by 30 mmol glucose, in comparison with normal glucose. A reduction of 25% in medium associated proteoglycan synthesis was observed in high glucose cultured cells. After Sepharose CL6B, in cells cultured in high glucose, cell layer heparansulphate proteoglycan-I (Kav 6B 0. 04) synthesis was reduced by about 81%, heparansulphate proteoglycan-II (Kav 6B 0.21) by about 87% and heparansulphate glycosaminoglycan (Kav 0.4-0.8) by about 91%, respectively. In mannitol-incubated cells the reductions observed were less evident and not significantly different from those in normal glucose. CONCLUSIONS: These results indicate that (1) glomerular epithelial cells play a central role in proteoglycan synthesis, (2) high glucose modifies the amount and influences the different species production of these macromolecules, while osmotic forces seem to be only partially involved in these effects, and (3) this cellular clone of glomerular epithelial cells can represent a reliable in vitro model for the study of the mechanisms involved in diabetic nephropathy.