Imaging features of hepatic angiomyolipomas.

We review the imaging appearances of hepatic angiomyolipomas in patients with and without tuberous sclerosis. Sporadic hepatic angiomyolipomas have a varied appearance because of the inconstant proportion of fat, making confident imaging diagnosis difficult and necessitating biopsy in many cases. In patients with tuberous sclerosis, hepatic angiomyolipomas have a more consistent imaging appearance and, together with other features of the syndrome, can be more easily diagnosed. Preoperative diagnosis helps obviate unnecessary surgery.

Calcification in breast lesions: pathologists' perspective.

Evaluation of calcification in breast lesions is a major assessment criterion for breast mammography. The morphology and distribution of the calcification are related to the histology of the lesions. Radiologically, calcifications can be divided into: benign; intermediate concern; and higher probability of malignancy according to the morphology. Different pathological entities may give rise to different calcifications. Fibrocystic changes may give rise to milk of calcium or teacup type calcification, or small calcifications occurring in a cluster. Fibroadenoma may be associated with large popcorn like calcifications, and sclerosing adenosis may have fine, punctate or granular calcifications. Fat necrosis may give rise to egg shell calcification. Precursor malignant lesions give rise to benign to indeterminate type calcifications, and may occasionally be associated with malignant type calcifications. For malignant lesions, ductal carcinoma in situ and invasive duct carcinoma may be associated with large irregular, rod or V shaped, pleomorphic or branching type calcifications that follow the distribution of the duct. Furthermore, analysis of the characteristics of the calcifications may help to predict the tumour size and grade, and presence of invasion.

Effects of fibrinolytic inhibitors on chondrogenesis of bone-marrow derived mesenchymal stem cells in fibrin gels.

The objective of this study was to examine the effect of two fibrinolytic inhibitors, aprotinin and aminohexanoic acid, on chondrogenesis of rabbit bone marrow mesenchymal stem cells (BM-MSCs). Rabbit BM-MSCs were obtained from the tibias and femurs of New Zealand White rabbits. Cell-fibrin constructs were made by mixing a cell-fibrinogen (10(7) cells/ml; 40 mg/ml fibrinogen) solution with a thrombin (5 IU/ml) solution and then divided into four groups: aprotinin control, aprotinin + transforming growth factor beta (TGF-beta), aminohexanoic acid control, and aminohexanoic acid + TGF-beta. Each of these groups was further treated with three different concentrations of inhibitors and the TGF-beta groups were treated with 10 ng/ml of TGF-beta1. The chondrogenic gene expressions, DNA content, and glycosaminoglycan content of samples were analyzed after 14 days of culture. The aprotinin groups exhibited significantly higher levels of aggrecan gene expression and glycosaminoglycan content than the aminohexanoic acid groups. However, inhibitor neither influenced gene expression of type II collagen nor proliferation (i.e., DNA content) of BM-MSCs. These findings suggest that fibrinolytic inhibitors used to control degradation of fibrin clot may influence TGF-beta-induced chondrogenesis of BM-MSCs.

New insight into deformation-dependent hydraulic permeability of gels and cartilage, and dynamic behavior of agarose gels in confined compression.

Equilibrium, creep, and dynamic behaviors of agarose gels (2.0-14.8%) in confined compression were investigated in this study. The hydraulic permeabilities of gels were determined by curve-fitting creep data to the biphasic model (J. Biomech. Eng. 102 (1980) 73) and found to be similar in value to those published in the literature (AIChE J. 42 (1996) 1220). A new relationship between intrinsic permeability and volume fraction of water was found for agarose gel, capable of predicting deformation-dependent permeabilities of bovine articular cartilage and 2% agarose gel published in literature. This relationship is accurate for gels and cartilage over a wide range of permeabilities (four orders of magnitude variation). The dynamic stiffness of the gels increases with gel concentration and loading frequency (0.01-1.0Hz). The increase in dynamic stiffness with loading frequency is less pronounced for gels with higher concentrations. The results of this study provide a new insight into deformation-dependent permeability behavior of agarose gel and cartilage, and are important for understanding biological responses of cells to interstitial fluid flow in gel or in cartilage under dynamic mechanical loading.

Hamartoma of the breast: a clinicopathological review.

AIMS: To review 25 cases of breast hamartoma and discuss the pathological criteria, and the usefulness of imaging modalities, fine needle aspiration cytology (FNAC), and needle core biopsy in the diagnosis. METHODS: The hamartomas were assessed for interlobular fibrotic stroma, stromal adipose tissue content, pseudo-angiomatous stromal hyperplasia, and epithelial changes (hyperplasia, adenosis or apocrine metaplasia, and cyst formation). All imagings, previous FNACs, and biopsies were also reviewed. RESULTS: Imaging (mammography, ultrasound, and magnetic resonance imaging) was performed in 18 cases, and mostly showed encapsulated masses with a heterogeneous appearance. Microscopically, all hamartomas demonstrated good demarcation with fibrous tissue condensation. Adipose tissue was noted in all cases (5-90%; mean, 31%), and interlobular fibrosis in 21 cases. Benign epithelial hyperplasia occurred in 10 cases, and pseudo-angiomatous stromal hyperplasia or cystic ducts in eight cases each. Apocrine metaplasia, calcification, stromal giant cells, and adenosis occurred in four cases or less. Two cases showed coexisting ductal carcinoma in situ limited to within the hamartoma. Needle core biopsies (four cases) and FNAC (14 cases) were largely insufficient, inconclusive, or non-specific. CONCLUSIONS: Hamartomas do not possess specific diagnostic histological features. The role of FNAC and needle core biopsy in making the diagnosis is limited, and requires clinical and radiological correlation to avoid underdiagnosis.

Ductal carcinoma in situ arising in mammary hamartoma.

Hamartoma of the breast is an uncommon lesion. Although it can possess characteristic radiological features, the pathological appearance is not distinctive. Hamartoma is generally considered benign, but four cases have been reported with ductal and lobular carcinoma arising in hamartomas. This report describes further cases of hamartoma from which ductal carcinoma in situ arose, with one showing early invasion. In both cases, the tumours were within the hamartomas and were adequately excised during lumpectomies of the hamartomas, and the patients were well afterwards. This report emphasises the importance of adequate sampling of mammary hamartoma.

Peroxisome proliferator-activated receptor gamma activators inhibit MMP-1 production in human synovial fibroblasts likely by reducing the binding of the activator protein 1.

OBJECTIVE: To investigate the expression and activity of PPARgamma in human synovial fibroblasts and the effects of PPARgamma agonists on the expression of MMP-1. The molecular mechanisms by which PPARgamma agonists modulate MMP-1 expression were also examined. METHODS: PPARgamma expression and activity were measured using reverse-transcription polymerase chain reaction (RT-PCR) and transient transfection assays. Human synovial fibroblasts were cultured with IL-1beta in the absence or presence of PPARgamma activators, and the expression and production of MMP-1 were evaluated by Northern blot and ELISA, respectively. The effect of 15d-PGJ(2) on MMP-1 promoter activation was analysed in transient transfection experiments, while electrophoretic mobility shift assays were performed to study the binding activity of the transcription factor AP-1. RESULTS: PPARgamma was expressed and transcriptionally functional in human synovial fibroblasts. PPARgamma activators (15d-PGJ(2) and BRL 49653) inhibited IL-1beta-induced MMP-1 synthesis in a dose-dependent manner. Similarly, both activators inhibited IL-1-induced MMP-1 mRNA expression. Activation of the human MMP-1 promoter was also attenuated by 15d-PGJ(2), indicating that the inhibitory effect of 15d-PGJ(2) occurs at the transcriptional level. Interestingly, 15d-PGJ(2) reduced both basal and IL-1beta-induced AP-1 binding activity. CONCLUSIONS: These data indicate that PPARgamma agonists inhibit MMP-1 gene expression by transcriptional mechanisms, and suggest that they may be useful in reducing joint tissue destruction.

Induction of matrix metalloproteinase-8 in human fibroblasts by basic calcium phosphate and calcium pyrophosphate dihydrate crystals: effect of phosphocitrate.

Although matrix metalloproteinase-8 (MMP-8) was regarded as the exclusive product of the neutrophils, recent studies have shown that it is also expressed in articular chondrocytes, rheumatoid synovial fibroblasts and endothelial cells. Our aim was to determine the expression of MMP-8 in human fibroblasts (HF) by reverse transcription/polymerase chain reaction (RT/PCR). Northern and Western blotting methods and MMP-8 activity assay. We have shown the expression of MMP-8 in HF and its dose-dependent upregulation by basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPPD) crystals which are markers of severe joint degeneration in osteoarthritis. These effects require new protein synthesis and are reversed by phosphocitrate (PC). The results also show that this fibroblast MMP-8 is distinct from the neutrophil MMP-8 and from the fibroblast MMP-1. These results indicate that MMP-8 may play a significant role in the pathogenic effects of the crystals in osteoarthritis.

Epithelioid haemangioendothelioma of the brain: a case report.

We report a rare epithelioid haemangioendothelioma in the frontal lobe. The CT and MRI findings are characteristic and correspond to histological features intermediate between those a cavernous haemangioma and an aggressive vascular tumour.

Altered mechanics and histomorphometry of canine tibial cartilage following joint immobilization.

Joint immobilization is associated with altered cartilage biosynthesis and catabolism that may affect cartilage mechanics and joint function. In this study, the mechanical behavior of articular cartilage was studied in an experimental model of joint immobilization, in which the canine knee was cast-immobilized at 90 degrees of flexion for 4 weeks. Articular cartilage from the medial tibial plateau was tested in compression and in shear. Biochemical assays for water and glycosaminoglycan content and histomorphometric grading were performed on site-matched samples. Significant decreases in the equilibrium and dynamic shear moduli, but not compressive moduli, were observed in cartilage after 4 weeks of joint immobilization as compared to cartilage from a separate control population. Importantly, there was also evidence of a decrease in the compressive and shear moduli of tibial cartilage from the contralateral knee joints compared to control joints that were not immobilized. No significant effect of immobilization on the biochemical parameters or histomorphometric scores was detected, expect for a significant loss of proteoglycan staining following immobilization. These findings for changes in the tibial cartilage following cast immobilization are consistent with a mild form of cartilage degeneration.

Basic calcium phosphate crystals up-regulate metalloproteinases but down-regulate tissue inhibitor of metalloproteinase-1 and -2 in human fibroblasts.

OBJECTIVE: To examine the effect of basic calcium phosphate (BCP) crystals on expression of tissue inhibitors of metalloproteinases (TIMP)-1 and -2 in human fibroblasts. METHOD: Using a semi-quantitative reverse transcription-polymerase chain reaction method and phosphocitrate (PC), a specific inhibitor of the biological effects of BCP crystals, we examined the effects of BCP on the steady state transcript levels of metalloproteinase (MMP)-1, -3, -9 and -13 and TIMP-1 and -2 in human fibroblasts. DNA primers against elongation factor were used as internal controls. RNAs isolated from human fibroblasts treated with BCP crystals (50 microg/ml) in the presence or absence of PC (10(-3) M) were used as templates, and RNA from untreated control cultures and cultures treated with Interleukin-1-beta (IL-1beta) were used as negative and positive controls, respectively. RESULTS: We observed increases in MMP-1, -3, -9 and -13 transcripts by BCP crystals. BCP crystal down-regulated TIMP-1 and -2 over untreated controls. Western blot analysis confirmed that BCP crystals down-regulate the synthesis of TIMP-1 and -2. While IL-1beta up-regulated MMP-1, -3, -9 and -13, it had no significant effect on expression of either TIMP. In all cases, PC specifically reversed the differential regulation of MMPs and TIMPs by BCP crystals but had no effect on IL-1beta induction of MMP expression. CONCLUSION: The ability of BCP to induce the synthesis of degradative MMPs while down-regulating the synthesis of the naturally occurring counterpart TIMPs may explain the changes consistent with a role of BCP crystal in the pathogenesis of degenerative changes in osteoarthritis. The ability of PC to reverse both degradative effects of BCP crystal suggests that PC can be a potential therapeutic agent for BCP crystal deposition diseases.

Human breast lesions: characterization with contrast-enhanced in vivo proton MR spectroscopy--initial results.

PURPOSE: To assess the clinical usefulness of localized proton (hydrogen 1) magnetic resonance (MR) spectroscopy in the characterization of contrast material-enhanced breast lesions on the basis of choline detection. MATERIALS AND METHODS: Examinations were performed at 1.5 T with use of a standard breast coil. Contrast-enhanced MR imaging was performed in 30 consecutive patients (mean age, 50 years; age range, 20--80 years) who had nonspecific lesions (>1.5 cm in diameter) on sonograms or mammograms. Single-voxel (1)H MR spectroscopy was performed in the enhancing lesions by using a point-resolved spectroscopic sequence with echo times of 38, 135, and 270 msec. MR spectroscopic and histopathologic findings were determined in blinded fashion and compared. RESULTS: Twenty-four patients had carcinoma of the breast (tumor size, 2.0--11.2 cm; mean, 4.7 cm), and six had benign lesions (lesion size, 1.8--3.8 cm; mean, 2.7 cm). Choline was detected in 22 patients with carcinoma. Choline was not detected in five patients with benign lesions and in two patients with carcinoma. The preliminary results indicate that this technique had a sensitivity of 92%, specificity of 83%, and accuracy of 90%. CONCLUSION: Choline can be reliably detected in less than 45 minutes in large contrast-enhanced breast lesions by using a multiecho point-resolved spectroscopic protocol. The presence of water-soluble choline metabolites obtainable with (1)H MR spectroscopy could complement MR imaging findings to improve specificity and to reduce the number of unnecessary biopsies.

Basic calcium phosphate crystals activate human osteoarthritic synovial fibroblasts and induce matrix metalloproteinase-13 (collagenase-3) in adult porcine articular chondrocytes.

OBJECTIVE: To determine the ability of basic calcium phosphate (BCP) crystals to induce (a) mitogenesis, matrix metalloproteinase (MMP)-1, and MMP-13 in human osteoarthritic synovial fibroblasts (HOAS) and (b) MMP-13 in cultured porcine articular chondrocytes. METHODS: Mitogenesis of HOAS was measured by [3H]thymidine incorporation assay and counts of cells in monolayer culture. MMP messenger RNA (mRNA) accumulation was determined either by northern blot analysis or reverse transcriptase-polymerase chain reaction (RT-PCR) of RNA from chondrocytes or HOAS treated with BCP crystals. MMP-13 secretion was identified by immunoprecipitation and MMP-1 secretion by western blot of conditioned media. RESULTS: BCP crystals caused a 4.5-fold increase in [3H]thymidine incorporation by HOAS within 20 hours compared with untreated control cultures (p< or =0.05). BCP crystals induced MMP-13 mRNA accumulation and MMP-13 protein secretion by articular chondrocytes. In contrast, in HOAS, MMP-13 mRNA induced by BCP crystals was detectable only by RT-PCR, and MMP-13 protein was undetectable. BCP crystals induced MMP-1 mRNA accumulation and MMP-1 protein secretion by HOAS. MMP-1 expression was further augmented when HOAS were co-incubated with either BCP and tumour necrosis factor alpha (TNFalpha; threefold) or BCP and interleukin 1alpha (IL1alpha; twofold). CONCLUSION: These data confirm the ability of BCP crystals to activate HOAS, leading to the induction of mitogenesis and MMP-1 production. MMP-13 production in response to BCP crystals is substantially more detectable in porcine articular chondrocytes than in HOAS. These data support the active role of BCP crystals in osteoarthritis and suggest that BCP crystals act synergistically with IL1alpha and TNFalpha to promote MMP production and subsequent joint degeneration.

Phosphocitrate as a potential therapeutic strategy for crystal deposition disease.

The deposition of basic calcium phosphate and calcium pyrophosphate dihydrate crystals in articular tissues is probably an under-recognized event. Clinical observations indicate that exaggerated and uniquely distributed cartilage degeneration is associated with these deposits. Measurements of putative markers of cartilage breakdown suggest that these crystals magnify the degenerative process. In vitro studies reveal two potential mechanisms by which crystals cause degeneration. These involve the stimulation of mitogenesis in synovial fibroblasts and the secretion of metalloproteinases by cells that phagocytose these crystals. Approaches that may ameliorate the degenerative process may ensue from new information about how crystals form and how they exert their biologic effects.

Calcium crystal effects on the cells of the joint: implications for pathogenesis of disease.

In the past three years, there has been considerable progress in delineating the mechanism of calcium-containing crystal-induced cell activation: (1) the identification of Ca2+ influx and p42/44 mitogen-activated protein kinase activation as the signal transduction pathways; (2) induction of nuclear transcription factors of cyclic adenosine monophosphate (cAMP) response element binding protein, activator protein-1, and nuclear factor kappaB; (3) the differential role of crystal endocytosis and dissolution in crystal-induced metalloproteinase synthesis and mitogenesis; (4) crystal upregulation of matrix metalloproteinases, including MMP-13 but downregulation of tissue inhibitor of metalloproteinase-1 and -2, thus magnifying the degenerative effect of crystals. Phosphocitrate, a specific inhibitor of biologic effect of calcium crystals, reverses the degenerative effects of crystals.

Wild type and mutant p53 differentially regulate the gene expression of human collagenase-3 (hMMP-13).

Matrix metalloproteinases (MMPs) are a family of secreted or transmembrane proteins that can degrade all the proteins of the extracellular matrix and have been implicated in many abnormal physiological conditions including arthritis and cancer metastasis. Recently we have shown for the first time that the human MMP-1 gene is a p53 target gene subject to repression by wild type p53 (Sun, Y., Sun, Y. I., Wenger, L., Rutter, J. L., Brinckerhoff, C. E., and Cheung, H. S. (1999) J. Biol. Chem. 274, 11535-11540). Here, we report that cotransfection of fibroblast-like synoviocytes with p53 expression and hMMP13CAT reporter plasmids revealed that (i) hMMP13, another member of the human MMP family, was down-regulated by wild type p53, whereas all six of the p53 mutants tested lost the wild type p53 repressor activity in fibroblast-like synoviocytes; (ii) this repression of hMMP-13 gene expression by wild type p53 could be reversed by overexpression of p53 mutants p53-143A, p53-248W, p53-273H, and p53-281G; (iii) the dominant effect of p53 mutants over wild type p53 appears to be a promoter- and mutant-specific effect. An intriguing finding was that p53 mutant p53-281G could conversely stimulate the promoter activity of hMMP13 up to 2-4-fold and that it was dominant over wild type p53. Northern analysis confirmed these findings. Although the significance of these findings is currently unknown, they suggest that in addition to the effect of cytokines activation, the gene expression of hMMP13 could be dysregulated during the disease progression of rheumatoid arthritis (or cancer) associated with p53 inactivation. Since hMMP13 is 5-10 times as active as hMMP1 in its ability to digest type II collagen, the dysregulation or up-modulation of MMP13 gene expression due to the inactivation of p53 may contribute to the joint degeneration in rheumatoid arthritis.

Cellular responses to whitlockite.

Whitlockite crystals have been observed in both degenerating and normal articular cartilages. To determine their potential for inducing cartilage degeneration, we studied their ability to induce mitogenesis and synthesis and secretion of metalloproteases in vitro. Whitlockite crystals were found to stimulate cell proliferation and to stimulate synthesis and secretion of stromelysin and collagenase. However, they were less stimulatory than crystals that contained calcium (Ca) and phosphate without magnesium substitution for Ca. Whitlockite crystals elicit biologic cellular responses that suggest potential pathogenicity in arthritis, but are less potent than Ca phosphate crystals without magnesium.

Phosphocitrate blocks nitric oxide-induced calcification of cartilage and chondrocyte-derived apoptotic bodies.

OBJECTIVE: To examine whether phosphocitrate (PC) will block nitric oxide-induced calcification of cartilage or chondrocyte-derived apoptotic bodies. DESIGN: Articular cartilage vesicles (ACV) or apoptotic bodies (AB) were isolated from untreated or 1mM sodium nitroprusside (SNP) treated porcine cartilage slices. Mineralization of ACV, AB, control untreated and SNP-treated cartilage were done in the presence or absence of PC (1mM)+/-ATP (1mM). RESULTS: PC [1mM] blocked both the ATP-dependent and -independent mineralization in ACV and AB, untreated and SNP treated cartilage. Moreover, PC had no effect on NTPPPH activity in either ACV or AB fraction in the presence or absence of ATP suggesting that PC did not block the mineralization through the inhibition of NTPPPH activity. CONCLUSIONS: PC inhibits nitric oxide-induced calcification of cartilage and cartilage-derived apoptotic bodies.