Lysophosphatidic acid induces neointima formation through PPARgamma activation

Neointimal lesions are characterized by accumulation of cells within the arterial wall and are a prelude to atherosclerotic disease. Here we report that a brief exposure to either alkyl ether analogs of the growth factor–like phospholipid lysophosphatidic acid (LPA), products generated during the oxidative modification of low density lipoprotein, or to unsaturated acyl forms of LPA induce progressive formation of neointima in vivo in a rat carotid artery model. This effect is completely inhibited by the peroxisome proliferator-activated receptor (PPAR)γ antagonist GW9662 and mimicked by PPARγ agonists Rosiglitazone and 1-O-hexadecyl-2-azeleoyl-phosphatidylcholine. In contrast, stearoyl-oxovaleryl phosphatidylcholine, a PPARα agonist and polypeptide epidermal growth factor, platelet-derived growth factor, and vascular endothelial growth factor failed to elicit neointima. The structure-activity relationship for neointima induction by LPA analogs in vivo is identical to that of PPARγ activation in vitro and disparate from that of LPA G protein–coupled receptor activation. Neointima-inducing LPA analogs up-regulated the CD36 scavenger receptor in vitro and in vivo and elicited dedifferentiation of cultured vascular smooth muscle cells that was prevented by GW9662. These results suggest that selected LPA analogs are important novel endogenous PPARγ ligands capable of mediating vascular remodeling and that activation of the nuclear transcription factor PPARγ is both necessary and sufficient for neointima formation by components of oxidized low density lipoprotein.

Advanced management of venous malformation with ethanol sclerotherapy: mid-term results

PURPOSE

This paper is an update of previously published data on the basis of a retrospective review of midterm results of ethanol sclerotherapy on 87 patients (January 1995 to December 2000) for assessment of its efficacy as an improved treatment method for venous malformation (VM). According to this assessment, VMs were defined with a new classification and studied with advanced diagnostic technology and an advanced care system.

METHODS

The average follow-up period was 24 months after completion of a multisession treatment (mean, 8.2 months). Classification of VM was based on a modification of the Hamburg classification. Advanced diagnostic technology, mostly noninvasive, was used on 226 of 520 patients with congenital vascular malformation registered at the Congenital Vascular Malformation Clinic at the Samsung Medical Center. Of the 226 patients with VM, 87 with infiltrating extratruncular lesions had a total of 399 sessions of sclerotherapy. Follow-up assessment with periodic clinical examinations by the multidisciplinary team was supplemented with body blood pool scans, duplex scans, and magnetic resonance imaging, according to protocol, once the multisession therapy was completed. Angiographic assessment was seldom included. The endpoint of this phase II study was 24 months.

RESULTS

Of 399 sessions, initial success was seen in 379 sessions (95.0%) and failure was seen in 20 sessions (5%). This was mostly caused by forced abandonment from technical difficulty in delivering ethanol safely to the lesion (eg, direct drainage of VM into normal deep vein system). Later results after completion of the multisession therapy with a minimum follow-up of 24 months on 71 VMs have shown no evidence of recurrence. Eighty-seven patients have shown the same results without recurrence on an average of 18.2 months of follow-up. Fifty-one minor to major complications, mostly skin damage, developed after 47 sessions among the 379 sessions (12.4% in 24/87 patients; 27.9%). However, complications resolved spontaneously or were managed successfully, except for one permanent facial nerve palsy and one peroneal nerve palsy.

CONCLUSION

Absolute ethanol sclerotherapy can deliver excellent results as an independent therapy to the infiltrating type of extratruncular form of VM, which was once taboo because of prohibitively high morbidity. Absolute ethanol may be accepted as an effective treatment method because no recurrence has been observed in the relatively long-term observation period and the morbidity has been acceptable. However, it should be reserved only for individuals and centers with expertise. The morbidity involved should be clearly understood and accepted by the patient or family, and the risk of acute and chronic complications, both major or minor, should be explained to the patient. Long-term assessment of the complication's sequelae is warranted.

Differential diagnosis of cervical lymphadenopathy: usefulness of color Doppler sonography

OBJECTIVE

The purpose of this study was to evaluate the usefulness of color Doppler sonography in differentiating benign from malignant cervical lymphadenopathy.

MATERIALS AND METHODS

We used color Doppler sonography to evaluate 117 lymph nodes in 105 patients. The patients were pathologically and clinically confirmed to have benign reactive lymphadenitis (n = 28), tuberculosis (n = 17), lymphoma (n = 14), and metastasis (n = 46). The patterns of hilar vascularity, central nodal vascularity, and peripheral vascularity were assessed. The highest resistive index and pulsatility index in 116 lymph nodes were measured from spectral waveforms. Histologic findings of nodal vessels were analyzed in 14 nodes and compared with findings on color Doppler sonograms.

RESULTS

Thirty-two (94%) of 34 nodes with benign reactive disease showed normal patterns of nodal vascularity; central hilar vascularity, radial symmetric central vascularity, and no peripheral vascularity. At least one of six abnormal patterns of vascularity (eccentric or absent hilar vascularity; deformed radial, aberrant multifocal, or absent central vascularity; and peripheral vascularity) was observed in 98% (65/66) of nodes with malignant disease and in all tuberculous nodes. We established cutoff values of 0.8 for the resistive index and 1.5 for the pulsatility index that were 100% specific for malignancy. However, sensitivities for these cutoff values were 47% and 55%, respectively. Also, histologic examinations showed that most flow signals in nodes with malignant disease represented arterioles or veins in the septa between tumor nests or near the capsule.

CONCLUSION

Unlike nodes with benign reactive disease, 98% of nodes with malignant disease and 100% of tuberculous nodes showed abnormal patterns of nodal vascularity. Also, high values for the resistive and pulsatility indexes were highly specific for malignant lymphadenopathy. Color Doppler sonography combined with analysis of spectral waveforms was useful in differentiating benign from malignant cervical lymphadenopathy.

CREB-binding protein and histone deacetylase regulate the transcriptional activity of Kaposi's sarcoma-associated herpesvirus open reading frame 50

Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) open reading frame 50 (ORF50) encodes a viral transcriptional activator, which binds to the KSHV promoter and stimulates the transcription of viral early and late genes, thus activating the lytic cycle of KSHV. We report here that KSHV ORF50 binds to the cellular proteins CREB-binding protein (CBP) and histone deacetylase (HDAC) and these binding events modulate ORF50-activated viral transcription. Binding of ORF50 to CBP and HDAC activates and represses, respectively, ORF50-mediated viral transcription. KSHV ORF50 was shown to bind to the C/H3 domain and the C-terminal transcriptional activation domain of CBP, while CBP bound to the amino-terminal basic domain and the carboxyl-terminal transactivation domain of ORF50. The LXXLL motif within the transcriptional activation domain of ORF50 is reminiscent of the CBP-binding sequence found in nuclear receptor proteins. The adenovirus E1A protein, which also binds to the C/H3 domain of CBP, repressed the transcriptional activation activity of ORF50. The cellular protein c-Jun, which binds to the kinase-induced activation domain of ORF50, stimulated ORF50-mediated viral transcription. The HDAC1-interacting domain of ORF50 was shown to be a central proline-rich sequence. Our data provide a framework for delineating the regulatory mechanisms used by KSHV to modulate its transcription and replication through interaction with both histone acetyltransferases and HDACs.

Carba analogs of cyclic phosphatidic acid are selective inhibitors of autotaxin and cancer cell invasion and metastasis

Autotaxin (ATX, nucleotide pyrophosphate/phosphodiesterase-2) is an autocrine motility factor initially characterized from A2058 melanoma cell-conditioned medium. ATX is known to contribute to cancer cell survival, growth, and invasion. Recently ATX was shown to be responsible for the lysophospholipase D activity that generates lysophosphatidic acid (LPA). Production of LPA is sufficient to explain the effects of ATX on tumor cells. Cyclic phosphatidic acid (cPA) is a naturally occurring analog of LPA in which the sn-2 hydroxy group forms a 5-membered ring with the sn-3 phosphate. Cellular responses to cPA generally oppose those of LPA despite activation of apparently overlapping receptor populations, suggesting that cPA also activates cellular targets distinct from LPA receptors. cPA has previously been shown to inhibit tumor cell invasion in vitro and cancer cell metastasis in vivo. However, the mechanism governing this effect remains unresolved. Here we show that 3-carba analogs of cPA lack significant agonist activity at LPA receptors yet are potent inhibitors of ATX activity, LPA production, and A2058 melanoma cell invasion in vitro and B16F10 melanoma cell metastasis in vivo.

New experiences with absolute ethanol sclerotherapy in the management of a complex form of congenital venous malformation

BACKGROUND

Complex forms of congenital venous malformation have defied proper classification and confounded therapy. Through a newly designed multidisciplinary approach, these venous defects were properly diagnosed and classified according to the Hamburg classification. Absolute ethanol was adopted as a new scleroagent for this complex form of venous defects to improve overall treatment results with acceptable morbidity and recurrence rates.

PATIENTS AND METHODS

Among 318 patients aged 2 months to 60 years (130 men: mean age, 24.6 years; 188 women: mean age, 24.5 years), 143 patients were confirmed as having venous defects predominantly (45%). We conducted diagnostic evaluation with magnetic resonance imaging, whole body blood pool scan, duplex scans, transarterial microalbumin lung scans, air plethysmography, bone x-ray film, and angiography. Thirty of 143 patients were indicated for the absolute ethanol sclerotherapy for the complex form of venous defects, and they completed 98 sessions of multistage therapy with direct puncture technique. Follow-up assessment (minimum, 6 months; average, 10.2 months) was made as early results after completion of therapy.

RESULTS

The immediate success rate at the completion of treatment through 98 sessions on 30 patients was 92% (90/98). The reason for the failure of 8% (8/98 sessions) was mainly due to the lesion's inaccessibility to the nidus to deliver the alcohol safely. On follow-up assessment available on 28 of 30 patients, overall improvement of the lesions with good to fair response on clinical assessment was obtained in 27 (96%) of 28 patients. Similar good to fair responses were obtained on whole body blood pool scan assessment (14 [93%] of 15 patients) and also on magnetic resonance imaging assessment (12 [93%] of 13 patients). Various major to minor acute complications developed during the procedure in eight (26.7%) of 30 patients through 16 (16.3%) of 98 sessions of the therapy: ischemic bullae, tissue fibrosis, deep venous thrombosis, pulmonary embolism, peripheral nerve palsy, and temporary pulmonary hypertension. All 24 incidences of complication were successfully managed with full recovery except one case of permanent peroneal nerve palsy that was present during 18 months of follow-up. No single recurrence has been detected to date.

CONCLUSION

Absolute ethanol sclerotherapy alone can deliver excellent results in complex forms of venous malformations with considerable but acceptable morbidity and may be able to reduce the morbidity involved with the conventional surgical therapy alone on complex forms of venous malformation. No recurrence or deterioration of the therapy results was observed during the follow-up period (average, 10.2 months) after the completion of multistaged therapy.

The 4,5-double bond of ceramide regulates its dipole potential, elastic properties, and packing behavior

The biological activities of ceramides show a large variation with small changes in molecular structure. To help understand how the structure regulates the activity of this important lipid second messenger, we investigated the interfacial features of a series of synthetic ceramide analogs in monomolecular films at the argon-buffer interface. To minimize differences arising from the N-acyl moiety, each analog had either a N-hexadecanoyl or a N-cis-4-hexadecenoyl moiety amide linked to the nitrogen of the sphingosine backbone. We found that the trans 4,5-unsaturation in the sphingosine backbone promoted closer packing and lower compressibilities of ceramide analogs in interfaces relative to comparable saturated species. Moreover, structures with this feature exhibited dipole potentials as much as 150-250 mV higher than comparable compounds lacking 4,5-unsaturation. The results support the hypothesis by M.C. Yappert and co-workers that trans unsaturation in the vicinity of C4 of the sphingoid backbone augments intramolecular hydration/hydrogen bonding in the polar region. This intramolecular hydration may allow the close packing of the ceramide molecules and engender their high dipole potentials. These properties of ceramides and their analogs may be important determinants of biological function.

Esophagorespiratory fistula associated with esophageal cancer: treatment with a Gianturco stent tube

A self-expanding silicone-covered tube constructed of Gianturco stents was used for palliative treatment of esophagorespiratory fistula related to esophageal carcinoma in eight patients. All eight were unable to swallow food or water before treatment. The tubes were inserted under fluoroscopic guidance, without technical failure or complication. Clinical improvement was determined by grading food intake capacity on a five-point scale: none, liquid, soft food, most food, or all food. After the procedure, all fistulas were occluded. Four patients could swallow most foods, two could swallow soft food, one could swallow all foods, and one (who died of preexisting pneumonia 10 days after the procedure) could manage only liquids. Three patients were surviving without symptoms of aspiration for 4-24 weeks. Four patients died 6-16 weeks after placement of the stent tubes. Insertion of a silicone-covered stent tube was an effective palliative treatment for esophagorespiratory fistulas caused by esophageal cancer.

A stereocontrolled, efficient synthetic route to bioactive sphingolipids: synthesis of phytosphingosine and phytoceramides from unsaturated ester precursors via cyclic sulfate intermediates

An efficient and highly enantioselective method for the preparation of D-ribo- and L-lyxo-phytosphingosines (1a,b, respectively) and phytoceramides (2a,b) has been developed. The key steps in the syntheses are as follows: (i) osmium-catalyzed asymmetric dihydroxylation of 4-O-protected (E)-alpha,beta-unsaturated ester 5 (generated by dihydroxylation of 1-hexadecene, followed by oxidation to the aldehyde and Horner-Wadsworth-Emmons olefination), (ii) conversion to cyclic sulfate intermediate 7, and (iii) regioselective alpha-azidation of 7. Reduction of 4-O-protected 2-azido ester 8 via alpha-azidolactone 9 afforded phytosphingosine 1a. Staudinger reduction of the azido group of 8, followed by in situ N-acylation in aqueous media and reduction of the ester functionality with NaBH(4)/LiBr, provided phytoceramide 2a. By using a similar approach, phytosphingosine 1b was synthesized. D-erythro-4, 5-Dihydrosphingosine 1c and D-erythro-4,5-dihydroceramide 2c were synthesized in high yield from 1-hexadecanol via cyclic sulfate intermediate 15. The desired configurations at C-2, C-3, and C-4 of the sphingoid chain can be accessed readily by the route described here.

Current Concepts in Lymphatic Malformation

A lymphatic malformation (LM) is the most common form of congenital vascular malformation (CVM). The new Hamburg classification of CVM distinguishes the truncular (T) form from the extratruncular (ET) form of LMs. Both are consequences of a developmental arrest at the different stages of lymphangiogenesis as a result of defective genes. The purpose of this review was to evaluate the current management results of both forms of LMs. A retrospective review of the clinical data of 315 patients with a diagnosis of LMs treated between September 1994 and December 2001 was performed. Lymphoscintigraphy was the most frequent diagnostic test. The patients with the ET form were treated with sclerotherapy with OK-432 and/or ethanol. Combinations of CDP (complex decongestive physiotherapy) and/or compressotherapy were used to treat all the T-form patients. In addition, surgery, either reconstructive or ablative, was offered to patients with the T form who failed to respond to the proper CDP. A multidisciplinary team performed the management of LM, and the results were evaluated every 6 months.

Among 797 patients with CVM, 315 were confirmed to have LMs, either as the T form (226) or the ET form (89). Another 66 LMs were diagnosed with hemolymphatic malformations (HLM). Most of the ET forms (89/315) were the cystic type (70/89), while the T forms included aplasia and/or an obstruction (204/226). The ET form was most frequent in the head, neck, and thorax (69/89). The T form was located most frequently to the extremities (202/226), mostly to the lower limb (180/202). Two hundred and twenty-six T forms belonged to the various clinical stages: stages I-32, II-104, III-48, IV-18, and an unclear stage-24. The ET form was treated with sclerotherapy using OK-432 (108/120) and absolute ethanol (12/120). Among the 11 patients with the multiple ET form, 7 patients underwent perioperative sclerotherapy with OK-432 and a subsequent surgical excision. The clinical response of the T form at the extremity to CDP was excellent to good in a majority of clinical stages I to II (121/136) but decreased to a good to fair degree in stages III to IV (31/66). The additional surgical therapy, either reconstructive (10/19) or ablative (9/19), provided limited success in improving CDP efficacy, owing mainly to poor compliance. The long-term outcome of the initial success through self-motivated home-maintenance care during the follow-up period of up to 48 months was totally dependent on patient compliance. OK-432 sclerotherapy to 51 ET forms has shown excellent results on 88.9% of the cystic type (40/45) and 50% (3/6) of the cavernous type (minimum follow-up for 24 months). Seventeen ET forms in 7 patients were treated with a preoperative OK-432 sclerotherapy and a subsequent surgical excision, which provided good to excellent results in 14 for a minimum of 24 months.

Primary lymphedema, which is the T form of LMs, can be managed safely by a combination of CDP with compressotherapy. Patients with good compliance can benefit from additional surgical therapy, either reconstructive or ablative. The ET form, particularly the cystic type, can be treated with various scleroagents that are preferably less toxic as the primary therapy. A surgical excision with or without perioperative sclerotherapy provides good results for patients with the localized cavernous type of the ET form. A multidisciplinary team approach is essential for the proper care of LM.

The sphingolipid degradation product trans-2-hexadecenal induces cytoskeletal reorganization and apoptosis in a JNK-dependent manner

The bioactive signaling molecule D-erythro-sphingosine-1-phosphate (S1P) is irreversibly degraded by the enzyme S1P lyase (SPL). The reaction of SPL with C18-S1P generates ethanolamine phosphate and a long-chain fatty aldehyde, trans-2-hexadecenal. Modulation of SPL expression in cells and organisms produces significant phenotypes, most of which have been attributed to corresponding changes in S1P-dependent signaling. However, the physiological functions of SPL products are not well understood. In the present study, we explored the biological activities of trans-2-hexadecenal in human and murine cells. We demonstrate that trans-2-hexadecenal causes cytoskeletal reorganization leading to cell rounding, detachment and eventual cell death by apoptosis in multiple cell types, including HEK293T, NIH3T3 and HeLa cells. Trans-2-hexadecenal stimulated a signaling pathway involving MLK3 and the respective phosphorylation of MKK4/7 and JNK, whereas ERK, AKT and p38 were unaffected. Trans-2-hexadecenal-induced apoptosis was accompanied by activation of downstream targets of JNK including c-Jun phosphorylation, cytochrome c release, Bax activation, Bid cleavage and increased translocation of Bim into mitochondria. The antioxidant N-acetylcysteine prevented JNK activation by trans-2-hexadecenal. Further, inhibition of JNK abrogated the cytoskeletal changes and apoptosis caused by trans-2-hexadecenal, whereas Rac1 and RhoA were not involved. In conclusion, our studies provide a new paradigm of sphingolipid signaling by demonstrating for the first time that S1P metabolism generates a bioactive product that induces cellular effects through oxidant stress-dependent MAP kinase cell signaling.

Novel anti-apoptotic mechanism of A20 through targeting ASK1 to suppress TNF-induced JNK activation

The zinc-finger protein A20 has crucial physiological functions as a dual inhibitor of nuclear factor-κB (NF-κB) activation and apoptosis in tumor necrosis factor (TNF) receptor 1 signaling pathway. Although the molecular basis for the anti-NF-κB function of A20 has been well elucidated, the anti-apoptotic function of A20 is largely unknown. Here, we report a novel mechanism underlying the anti-apoptotic function of A20: A20 blocks TNF-induced apoptosis through suppression of c-jun N-terminal kinase (JNK) by targeting apoptosis signal-regulating kinase1 (ASK1). First, the ectopic expression of A20 drastically inhibits TNF-induced JNK activation and apoptosis in multiple cell types including those deficient of NF-κB activation. Unexpectedly, the blunting effect of A20 on TNF-induced JNK activation is not mediated by affecting the TNFR1 signaling complex formation. Instead, A20 interacts with ASK1, an important MAPKK kinase in the JNK signaling cascade. More importantly, overexpression of wild-type A20, but not of mutant A20 (ZnF4; C624A, C627A), promotes degradation of the ASK1 through the ubiquitin-proteasome system. Taken together, the results from this study reveal a novel anti-apoptotic mechanism of A20 in TNF signaling pathway: A20 binds to ASK1 and mediates ASK1 degradation, leading to suppression of JNK activation and eventually blockage of apoptosis.

Salivary gland tumors: evaluation with two-phase helical CT

PURPOSE

To evaluate two-phase helical computed tomography (CT) in the characterization of salivary gland tumors.

MATERIALS AND METHODS

Sixty-four patients with major salivary gland tumors underwent two-phase helical CT. The histopathologic diagnosis was obtained by means of surgical resection or biopsy in all patients. After the injection of 90 mL of contrast material at a rate of 3 mL/sec, helical CT scans were obtained at early and delayed phases with scanning delays of 30 and 120 seconds, respectively. The attenuation change and enhancement patterns in the tumors were assessed. The attenuation change in the tumor also was assessed quantitatively as the ratio of the CT number (in Hounsfield units) at delayed phase scanning to that at early phase scanning.

RESULTS

There were 35 pleomorphic adenomas, nine Warthin tumors, and 20 malignant tumors. Two-phase helical CT showed increase in attenuation in 30 (86%) pleomorphic adenomas, decrease in eight (89%) Warthin tumors, and increase in 11 (55%) and no change in eight (40%) malignant tumors at delayed phase scanning. A multinodular enhancement pattern was found in only 12 (34%) pleomorphic adenomas. The ratio of CT numbers was significantly different between Warthin tumors and pleomorphic adenomas and between Warthin tumors and malignant tumors.

CONCLUSION

The analysis of enhancement patterns by using two-phase helical CT will be helpful in the differential diagnosis of salivary gland tumors.

Prevalence and risk factors of silent cerebral infarction in apparently normal adults

Cerebrovascular disease is a major cause of death and disability in adults. Silent cerebral infarction (SCI) portends more severe cerebral infarctions or may lead to insidious progressive brain damage resulting in vascular dementia. This study was designed to evaluate the prevalence and risk factors of SCI in an apparently normal adult population. Nine hundred ninety-four consecutive symptom-free adults (mean age 49.0+/-7.7; men:women 830:164) who underwent brain magnetic resonance imaging at the Center for Health Promotion at Samsung Medical Center were assessed. All were neurologically normal in history and physical examination. A total of 121 SCI lesions was observed in 58 subjects. The lesion prevalence adjusted for patient age was 5.1%. There was no gender difference in prevalence. Ninety-nine lesions were <1 cm in diameter, 15 were between 1 and 2 cm, 3 were between 2 and 3 cm, and 4 were >3 cm in diameter. The most frequent site of the SCI lesion was basal ganglia, after which the periventricular white matter, cerebral cortex, and thalamus were the most frequent sites. Old age, hypertension, a history of coronary artery disease, evidence of cardiomegaly in chest radiographs, and high fasting glucose/hemoglobin A1c levels were associated with SCI on univariate analysis. Multivariate analysis demonstrated old age and hypertension to be independent risk factors for SCI, and mild alcohol consumption was revealed as an independent protective factor against SCI.

White-matter change in mesial temporal sclerosis: correlation of MRI with PET, pathology, and clinical features

PURPOSE

To assess the magnetic resonance imaging (MRI), positron emission tomography (PET), pathology, and clinical findings of patients with the MRI feature of white-matter change (WMC) in the anterior temporal lobe.

METHODS

Fifty-six patients with pathologically proven mesial temporal sclerosis were included in this study. MRI and 18F-2-deoxyglucose-(FDG) PET images were obtained before surgery in all patients. The patients were divided into two groups according to the presence of WMC on their MRI. WMC consists of an indistinct gray-white matter demarcation and an increased signal intensity of the anterior temporal lobe on T2-weighted images. The two groups were then compared in terms of MRI, PET, pathology, and clinical features.

RESULTS

The MRI feature of WMC was observed in 18 (32%) of the 56 patients. PET images of those patients revealed more severe hypometabolism of the ipsilateral temporal lobes (p< 0.05). In terms of histologic findings, larger numbers of heterotopic neurons were observed in the anterior temporal lobe white matter of these patients who also shared the following clinical features: earlier seizure onset, frequent history of febrile convulsions, and favorable surgical outcomes.

CONCLUSIONS

The MRI feature of WMC is an additive sign for correct seizure lateralization and may be related to a favorable surgical outcome in patients with temporal lobe epilepsy.

Solitary fibrous tumor of the orbit: CT and MR imaging findings

BACKGROUND AND PURPOSE

Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm originating from mesenchymal fibroblast-like cells. The purpose of this study was to describe the CT and MR imaging features of SFTs in the orbit.

MATERIALS AND METHODS

We retrospectively reviewed CT and MR images in 6 patients (2 men and 4 women), aged 18 to 51 years, with SFT proved on histologic examination located in and around the orbit. All patients underwent CT (including dual-phase CT in 3), and MR imaging was obtained in 3. We evaluated the imaging findings with emphasis on the location, size, margin, internal architecture, and pattern of enhancement of the lesion.

RESULTS

All 6 lesions were found as a solitary, well-defined mass, ranging in size from 18 to 30 mm (mean, 24 mm). Three were located in the postseptal orbit, 2 in the lacrimal sac, and 1 on the lower eyelid. Compared with the cerebral cortex, all 3 lesions examined by MR imaging showed homogeneous isointense signal intensity on T1-weighted images and heterogeneous mixed isointense and hyperintense signal intensity on T2-weighted images. On visual inspection, all 6 lesions showed marked homogeneous (n = 4) or heterogeneous (n = 2) enhancement on postcontrast CT and MR images. In 3 patients examined with dual-phase CT, all lesions demonstrated rapid enhancement with early washout of contrast material.

CONCLUSION

SFT might be included in the differential diagnosis of soft tissue masses in the orbit, if one sees a markedly enhancing mass showing the similar characteristics to those of the internal carotid artery on postcontrast CT or MR images.

Intracranial solitary fibrous tumors: imaging findings in 6 consecutive patients

BACKGROUND AND PURPOSE

Intracranial solitary fibrous tumors (ISFTs) are rare mesenchymal neoplasms originating in the meninges. The aim of this study was to describe the CT, MR imaging, and angiographic features of the solitary fibrous tumor and to identify imaging characteristics.

MATERIALS AND METHODS

We retrospectively reviewed CT, MR, and angiographic findings in 6 cases of ISFT. We evaluated the size, shape, and location of the tumor; the internal content and margin of the lesion; the pattern of enhancement; and the change of the adjacent structures. Density on noncontrast CT scans, signal intensity on MR images, and angiographic features were also documented.

RESULTS

Each lesion appeared as a discrete extra-axial mass (size, 3-7 cm; mean, 5 cm). Five lesions were entirely solid, and 1 had peritumoral cyst. All 5 of the noncontrast CT scans showed hyperattenuated masses, and the tumors exhibited marked heterogeneous enhancement. No lesion contained calcification, and 2 cases showed bone invasions. On the MR images, 4 lesions showed mixed signal intensity on T2-weighted imaging. All of the lesions revealed marked heterogeneous enhancement. All of the tumors had thickening of the meninges adjacent to the tumor. Angiography showed delayed tumor blushing in all, and 3 of them had dysplastic dilation of the tumor vessels.

CONCLUSION

Although there are no pathognomonic imaging findings, some imaging features, such as the "black-and-white mixed" pattern on T2-weighted images and marked heterogeneous enhancement, might be helpful in the diagnosis of intracranial solitary fibrous tumor.

Chemopreventive sphingadienes downregulate Wnt signaling via a PP2A/Akt/GSK3β pathway in colon cancer

Sphingadienes (SDs) derived from soy and other natural sphingolipids are cytotoxic to colon cancer cells via an Akt-dependent mechanism and reduce adenoma formation in Apc(Min/+) mice. Wnt signaling is fundamental to colon carcinogenesis and is the basis for spontaneous tumorigenesis in Apc(Min/+) mice and patients with familial adenomatous polyposis. In the present study, we investigated the impact of SDs on Wnt signaling. Oral SD administration reduced levels of active β-catenin and Wnt targets c-Myc and cyclin D1 in Apc(Min/+) mouse intestinal tissues. Colon cancer cells treated with SDs exhibited reduced Wnt transcriptional activity, as well as reduced nuclear β-catenin localization and subsequent reduction in active-β-catenin levels. Further, we observed a decrease in phosphorylated (inactive) GSK3β in SD-treated mice and colon cancer cells. Expression of constitutively active myristoylated-Akt or inactivation of GSK3β using LiCl attenuated SD-mediated inhibition of Wnt transcriptional activity and active-β-catenin levels. SDs exhibited additive effects with inhibitors of the phosphatidylinositol-3-kinase/Akt/mTOR pathway to induce cytotoxicity. Further, a combination regime of SDs and low-dose rapamycin decreased visible polyps in Apc(Min/+) mice and reduced the levels of Wnt target gene expression and mTOR target activation. SD-mediated inhibition of Akt and Wnt pathways and cytotoxicity in colon cancer cells was dependent upon the activity of protein phosphatase 2A, as shown by reversal of these effects by pretreatment with okadaic acid or calyculin A. Our cumulative findings indicate that SDs inhibit Wnt signaling through a protein phosphatase 2A/Akt/GSK3β-dependent mechanism that may contribute to their chemopreventive effects in intestinal tumorigenesis.

Focal cortical dysplasia: comparison of MRI and FDG-PET

PURPOSE

The purpose of this work was to compare the use of MRI and [18F]fluorodeoxyglucose (FDG) positron emission tomography (PET) in the diagnosis of focal cortical dysplasia (FCD).

METHOD

Nineteen patients with surgically proven FCD were analyzed retrospectively. MRI was performed in all patients, and FDG-PET was performed in 17 patients. We compared the MR and FDG-PET findings of FCD according to the histologic findings that were classified into three grades.

RESULTS

Four cases were classified as Grade I, 4 cases as Grade II, and 11 cases as Grade III FCD. The lesions were detected on MRI in 9 (82%) of the 11 patients with Grade III FCD and in only 1 (13%) of the 8 patients with Grade I and II FCD. Cortical hypometabolism of the lesion was revealed on FDG-PET in 6 (86%) of the 7 patients with Grade I and II FCD and in 9 (90%) of the 10 patients with Grade III FCD. The extent of the cortical abnormality was larger on FDG-PET than on MRI in 11 (65%) of the 17 patients.

CONCLUSION

FDG-PET is more useful in delineating the cortical abnormality in patients with mild degrees of FCD. The extent of the lesion was larger or similar on FDG-PET compared with that of the MRI.

Triphasic perfusion computed tomography in acute middle cerebral artery stroke: a correlation with angiographic findings

OBJECTIVE

To evaluate the usefulness of triphasic perfusion computed tomography (TPCT) in diagnosing middle cerebral artery (MCA) occlusion and in assessing the perfusion deficit and collateral circulation in patients with acute ischemic stroke.

BACKGROUND

Conventional angiography is the criterion standard for the diagnosis of MCA occlusion and for the assessment of perfusion deficit and collateral blood supply. The risk of hemorrhagic transformation after recanalization of occluded arteries by thrombolytic therapy is considered high when pretherapeutic residual flow is markedly reduced.

PATIENTS AND METHODS

In 8 patients within 3 hours of onset of acute MCA stroke, precontrast computed tomographic scans were taken, and then TPCT was performed after power-injector controlled intravenous administration of contrast media. Sequential images of early, middle, and late phases were obtained. The whole procedure took 5 minutes. Perfusion deficit on TPCT was graded as "severe" or "moderate," depending on the state of collateral flow. Digital subtraction angiography (DSA) was performed in all patients within 6 hours of acute stroke. Direct intra-arterial urokinase infusion was begun immediately after the angiographic superselection of the MCA occlusion site in 6 of the 8 patients within 7 hours of onset (range, 4.3-6.2 hours).

RESULTS

The DSA findings showed occlusion of the MCA stem (n = 1) and at the bifurcation (n = 4). The sites of proximal MCA occlusion could be identified on the early and middle images of TPCT in all 5 patients. On DSA findings, all 8 patients had a zone of perfusion deficit with markedly slow leptomeningeal collaterals and a zone of perfusion deficit with no collaterals. The zone of severe perfusion deficit on TPCT corresponded to the zone of perfusion deficit with no or few collaterals on angiography, and the zone of moderate perfusion deficit on TPCT corresponded to that of perfusion deficit with markedly slow leptomeningeal collaterals. Early parenchymal hypoattenuation on precontrast computed tomography was confined to the zone of severe perfusion deficit on TPCT. The initial National Institutes of Health Stroke Scale score correlated better with the total extent of severe perfusion deficit and moderate perfusion deficit on TPCT than that of severe perfusion deficit alone. After direct intra-arterial thrombolysis within 7 hours of onset, symptomatic hemorrhagic transformation did not develop in 4 patients with small severe perfusion deficit (33% or less of the presumed MCA territory). However, the remaining 2 patients with large severe perfusion deficit (more than 50% of the presumed MCA territory) deteriorated to death with hemorrhagic transformation.

CONCLUSIONS

Triphasic perfusion computed tomography is useful for diagnosing proximal MCA occlusion and assessing perfusion deficit and collateral circulation as reliably as DSA. The zone of severe perfusion deficit on TPCT may be presumed to be the ischemic core, and that of moderate perfusion deficit, the penumbra zone. Triphasic perfusion computed tomography may be used as a rapid and noninvasive tool to make thrombolysis safer.

Novel sphingosine-containing analogues selectively inhibit sphingosine kinase (SK) isozymes, induce SK1 proteasomal degradation and reduce DNA synthesis in human pulmonary arterial smooth muscle cells

Sphingosine 1-phosphate (S1P) is involved in hyper-proliferative diseases such as cancer and pulmonary arterial hypertension. We have synthesized inhibitors that are selective for the two isoforms of sphingosine kinase (SK1 and SK2) that catalyze the synthesis of S1P. A thiourea adduct of sphinganine (F02) is selective for SK2 whereas the 1-deoxysphinganines 55-21 and 77-7 are selective for SK1. (2S,3R)-1-Deoxysphinganine (55-21) induced the proteasomal degradation of SK1 in human pulmonary arterial smooth muscle cells and inhibited DNA synthesis, while the more potent SK1 inhibitors PF-543 and VPC96091 failed to inhibit DNA synthesis. These findings indicate that moderate potency inhibitors such as 55-21 are likely to have utility in unraveling the functions of SK1 in inflammatory and hyperproliferative disorders.

Unsuspected multiple sclerosis in patients with psychiatric disorders: a magnetic resonance imaging study

Over a 6-year period, 2,783 subjects, consecutively referred from the inpatient unit of a private psychiatric hospital, were evaluated with brain MRI. Twenty-three patients (0.83%) had brain white matter hyperintensities (WMH) that were highly suggestive of multiple sclerosis (MS). The subjects with WMH consistent with MS were most commonly diagnosed with affective illness. They had a significantly longer length of hospital stay during the index admission, a greater number of past psychiatric admissions, a greater prevalence of brain atrophy, and a history of more frequent neurological symptoms and signs than those without these findings.