Prognostic Implication of Exfoliative Airway Pathology in Cancer-Free Coal Workers' Pneumoconiosis.

BACKGROUND: The purpose of this study is to see if exfoliative pulmonary airway pathology in cancer-free coal workers' pneumoconiosis (CWP) can be used as a biomarker for predicting pulmonary morbidity. METHODS: We investigated persistent metaplastic changes in bronchoscopic washing cytology and differential cell counts in bronchoalveolar lavages (BAL) in 97 miners with CWP and 80 miners without CWP as the control. Clinicopathological parameters were examined including pulmonary function tests and the presence of progressive massive fibrosis. RESULTS: When compared to the control group, severe alveolitis, severe goblet cell hyperplasia (GCH), severe hyperplastic epithelial change, and severe squamous metaplasia were the distinguishing biomarkers in CWP. Multivariate analysis revealed that severe alveolitis and severe GCH, along with miner duration and current smoker, were independent predictors of pulmonary mortality. The survival analysis revealed a significantly different survival rate between the three groups: no evidence of severe alveolitis and severe GCH, presence of severe alveolitis or severe GCH but not both, and both severe alveolitis and severe GCH. CONCLUSIONS: The severities of alveolitis and goblet cell hyperplasia in the bronchoscopic study are independent prognostic factors for CWP. A pathologic grading system based on these two parameters could be used in the stratification and clinical management of CWP patients.

Ethyl Carbamate Formation from Cyanate in Model System of Ethanol-Water Media Using Response Surface Methodology.

Ethyl carbamate (EC) has been identified as a possible human carcinogen belonging to Group 2A. EC is naturally formed during the fermentation and storage of alcoholic drinks and fermented foods. When ingested in large amounts, EC can cause various health problems, such as gastroenteric hemorrhage, vomiting, and cancer. In this study, optimization of EC formation from cyanate was examined using response surface methodology (RSM), a central composite design that includes variables such as alcohol concentration (10, 15, 20, 25, and 30%), pH (2.5, 3.0, 3.5, 4.0, and 4.5), storage temperature (5, 10, 15, 20, and 25°C), and storage duration (2, 4, 6, 8, and 10 days). EC content was determined using gas chromatography with flame ionization detection and the results were optimized using RSM. EC formation from cyanate degradation was found to increase with storage duration and temperature, acidity, and alcohol concentration. Cy-anate degradation was associated with the formation of EC. Approximately 83.1±0.1% of cyanate was degraded to 538±9 µM of EC. However, not all of the cyanate reacted with ethanol during fermentation to form EC. This study aimed to develop the ideal conditions for EC analysis to reduce EC production in alcoholic drinks and fermented foods.

Idiopathic pleuroparenchymal fibroelastosis presenting in recurrent pneumothorax: a case report.

Idiopathic pleuroparenchymal fibroelastosis (PPFE) is a rare, recently classified entity that consists of pleural and subjacent parenchymal fibrosis predominantly in the upper lungs. In an official American Thoracic Society/European Respiratory Society statement in 2013, this disease is introduced as a group of rare idiopathic interstitial pneumonias. We describe a case of a 76-year-old woman with cough and recurrent pneumothorax. She was admitted to our hospital with severe cough at first. High resolution computed tomography (HRCT) disclosed multifocal subpleural consolidations with reticular opacities in both lungs, primarily in the upper lobes, suggesting interstitial pneumonia. Rheumatoid lung was diagnosed initially through an elevated rheumatoid factor, HRCT and surgical biopsy at the right lower lobe. However, one month later, pneumothorax recurred. Surgical biopsy was performed at the right upper lobe at this time. The specimens revealed typical subpleural fibroelastosis. We report this as a first case of idiopathic PPFE in Korea after reviewing the symptoms, imaging and pathologic findings.

CT evaluation of airway foreign bodies in children: emphasis on the delayed diagnosis and differentiation from airway mucus plugs.

PURPOSE: To review clinical and CT findings of airway foreign bodies (FBs) among children, with an emphasis on delayed diagnosis and differentiation from mucus plugs (MPs). METHODS: The CT findings and medical records of 27 patients (M:F = 17:10; mean age, 18.2 months) confirmed for FB (n = 20) and MP (n = 7) were reviewed. These findings were correlated with the bronchoscopic results and clinical outcomes. RESULTS: CT revealed air-trapping (70 %), atelectasis (35 %), pneumonia (25 %), and pneumomediastinum (5 %). Three patients with FB in the carina did not show air-trapping. The densities of the FBs ranged from 17 to 123 Hounsfield units (HU) (n = 17). Eight out of 20 patients (33 %) had a delayed diagnosis of FB. The CT of eight patients revealed air-trapping (n = 2), air-trapping with pneumonia or atelectasis (n = 3), and atelectasis only (n = 1). The airway MPs had a low density (0-5 HU) and were associated with atelectasis (29 %), atelectasis with pneumonia (43 %), and pneumonia (14 %). CONCLUSION: Air-trapping of the ipsilateral lung may not be a reliable finding among patients with an FB located in the carina and with a small-calibered FB. The absence of air-trapping, the difference in the HU, and the shape of the endobronchial lesion are helpful findings in the differential diagnosis of an MP.

Usefulness of albuminuria as predictor for coronary artery stenosis, regardless of estimated glomerular filtration rate, in patients with type 2 diabetes mellitus.

The aim of the present study was to evaluate the independent predictors of coronary artery stenosis in patients with type 2 diabetes mellitus (DM) and subclinical atherosclerosis. A total of 232 patients with type 2 DM and subclinical atherosclerosis underwent multislice computed tomography coronary angiography. Subclinical atherosclerosis was determined by the carotid intima-media thickness (IMT) or carotid plaque. Multislice computed tomography coronary angiography revealed significant coronary stenosis (>50% in diameter) in 71 subjects (31%). The subjects who had significant coronary stenosis were much older and had had a longer duration of DM. In particular, the log-transformed albumin/creatinine ratio (ACR) was greater in the subjects with significant coronary stenosis compared to the subjects without significant coronary stenosis. The age- and gender-adjusted odds ratio for significant coronary stenosis increased in proportion to albuminuria with a given estimated glomerular filtration rate. The ACR as a continuous variable (odds ratio 4.167, 95% confidence interval 1.497 to 11.599) or categorical variable (ACR >30 µg/mg, odds ratio 4.619, 95% confidence interval 1.562 to 13.659) was associated with an increased risk of significant coronary stenosis, independent of conventional cardiovascular risk factors. In receiver operating characteristic analysis, the ACR had an additive effect with carotid IMT for predicting significant coronary stenosis (area under the curve 0.625 with carotid IMT; area under the curve 0.710 with carotid IMT plus ACR, p = 0.0144). In conclusion, the presence of albuminuria is an independent predictor for significant coronary stenosis in patients with type 2 DM and subclinical atherosclerosis.

Swine-origin influenza A viral (H1N1) infection in children: chest computed tomography findings.

PURPOSE: The aim of this study was to review the chest computed tomography (CT) findings in children with swine-origin influenza (H1N1) virus (S-OIV) infection. MATERIALS AND METHODS: The radiologists retrospectively reviewed chest CT findings in 12 children with S-OIV infection and recorded the following findings: ground-glass opacities (GGO), consolidation, nodules, reticular opacities, peribronchial cuffing, and air trapping; distribution; affected lobes. The presence of pleural effusions, pneumomediastinum, pulmonary interstitial emphysema (PIE), and lymphadenopathy was also recorded. RESULTS: Chest CT revealed GGO (67%), consolidation (67%), nodules (25%), peribronchial cuffing (42%), and air trapping (33%). The distribution of the lesions was random (75%), peribronchial (17%), or subpleural (8%). The lobes affected were the lower (92%), upper (58%), and middle (17%) lobes. There were associated pleural effusions (42%), PIE (42%), pneumomediastinum (33%), and lymphadenopathy (75%). Among five patients with air-leak complications, three had a history of allergies and three required the intensive care unit. CONCLUSION: Chest CT findings in children with S-OIV infection were peribronchial thickening and a mixture of airspace consolidation and GGO with random distribution and lower lobe predominance. Pleural effusion, lymphadenopathy, PIE, and pneumomediastinum may be associated findings.

Computed tomographic analysis of the esophagus, left atrium, and pulmonary veins: implications for catheter ablation of atrial fibrillation.

PURPOSE: The aim of this study was to investigate the anatomic relationship around the left atrium (LA) and to provide clinical information to help avoid the risk of an atrio-esophageal fistula during atrial fibrillation (AF) ablation. METHODS: The multidetector spiral computed tomography images of 77 male patients (mean age, 54 ± 9 years) with drug-refractory AF and 37 male control subjects (mean age, 50 ± 11 years) were analyzed. We measured the following variables: (1) distance between the ostia of the pulmonary veins (PVs) and the ipsilateral esophageal border, (2) presence of a pericardial fat pad around each PV, and (3) contact width/length and presence of a fat pad between the LA and the esophagus. RESULTS: The distance between the esophagus and the ostia of right superior PV, right inferior PV (RIPV), left superior PV, and left inferior PV (LIPV) was 27.2 ± 9.4 mm, 22.9 ± 10.3 mm, 2.7 ± 9.4 mm, and 7.1 ± 8.8 mm, respectively. A fat pad between the esophagus and the superior PV was present in more than 90% of the subjects in both groups. However, the fat pad around inferior PV was present less frequently in the patients than in the control group (p = 0.011, RIPV; p < 0.001, LIPV). The average length of the LA-esophagus contact in the patients and the control group subjects was 26.2 ± 10.4 and 18.5 ± 5.1 mm, respectively (p < 0.001). CONCLUSION: Caution should be exercised when ablating the LIPV because the esophagus is located in close proximity to the left-sided PV and most of the inferior PVs in patients with AF are not covered with fat pads.

The potential role of dynamic MRI in assessing the effectiveness of high-intensity focused ultrasound ablation of breast cancer.

PURPOSE: To retrospectively evaluate magnetic resonance imaging (MRI) features of breast cancer after high-intensity focused ultrasound (HIFU) ablation. MATERIALS AND METHODS: Six patients with invasive ductal carcinomas underwent HIFU ablation. In all patients, dynamic MRI was performed prior to and two weeks after HIFU. Serial follow-up studies were performed. Changes in signal intensity and size of the index tumour in addition to peripheral enhancement patterns were evaluated. Histopathological results were compared with MRI findings. RESULTS: All patients had a single index tumour with a mean size 25.6 mm (range 12 to 37 mm) at the ablation time. In three of six patients, thin rim enhancement around the ablation zone was seen on the subtraction image after first ablation, which showed no change on follow-up MRI. Complete ablation was confirmed by the histopathology (biopsy in two and surgery in one). In the remaining three patients, nodular or irregular thick enhancement was shown on the subtraction image and viable tumour was confirmed by surgery and biopsy in two patients. CONCLUSION: The MR characteristics of successfully ablated breast cancers included central dark signal intensities with thin rim enhancement on subtraction images. Nodular or irregular thick enhancements should raise concern of partial ablation. We propose MRI plays a critical role in assessing the effectiveness of HIFU treatment.

A case of chloroquine-induced cardiomyopathy that presented as sick sinus syndrome.

A 52-year-old woman with rheumatoid arthritis who had been treated with prednisone and hydroxychloroquine for >12 years presented with chest discomfort and a seizure. She was diagnosed with restrictive cardiomyopathy combined with sick sinus syndrome. A myocardial muscle biopsy was performed to identify the underlying cardiomyopathy, which showed marked muscle fiber hypertrophy, fiber dropout, slightly increased interstitial fibrous connective tissue, and extensive cytoplasmic vacuolization of the myocytes under light microscopy. Electron microscopy of the myocytes demonstrated dense, myeloid, and curvilinear bodies. The diagnosis of hydroxychloroquine-induced cardiomyopathy was made based on the clinical, hemodynamic, and pathologic findings. This is the first case report describing chloroquine-induced cardiomyopathy involving the heart conduction system.

Typical and atypical manifestations of intrathoracic sarcoidosis.

Sarcoidosis is a systemic disorder of unknown cause that is characterized by the presence of noncaseating granulomas. The radiological findings associated with sarcoidosis have been well described. The findings include symmetric, bilateral hilar and paratracheal lymphadenopathy, with or without concomitant parenchymal abnormalities (multiple small nodules in a peribronchovascular distribution along with irregular thickening of the interstitium). However, in 25% to 30% of cases, the radiological findings are atypical and unfamiliar to most radiologists, which cause difficulty for making a correct diagnosis. Many atypical forms of intrathoracic sarcoidosis have been described sporadically. We have collected cases with unusual radiological findings associated with pulmonary sarcoidosis (unilateral or asymmetric lymphadenopathy, necrosis or cavitation, large opacity, ground glass opacity, an airway abnormality and pleural involvement) and describe the typical forms of the disorder as well. The understanding of a wide range of the radiological manifestations of sarcoidosis will be very helpful for making a proper diagnosis.

Wuweizisu C from Schisandra chinensis decreases membrane potential in C6 glioma cells.

AIM: To study the effects of dibenzocyclooctadiene lignans isolated from Schisandra chinensis, such as wuweizisu C, gomisin N, gomisin A, and schisandrin, on the membrane potential in C6 glioma cells. METHODS: The membrane potential was estimated by measuring the fluorescence change in DiBAC-loaded glioma cells. RESULTS: Wuweizisu C decreased the membrane potential in a concentration-dependent manner. Gomisin N and gomisin A, however, showed differential modulation and no change was induced by schisandrin or dimethyl- 4,4'-dimethoxy-5,6,5',6'-dimethylene dioxybiphenyl-2,2'-dicarboxylate, a synthetic drug derived from dibenzocyclooctadiene lignans. We found no involvement of G(i/o ) proteins, phospholipase C, and extracellular Na(+) on the wuweizisu C-induced decrease of the membrane potential. Wuweizisu C by itself did not change the intracellular Ca(2+)[Ca(2+)](i) concentration, but decreased the ATP-induced Ca(2+) increase in C6 glioma cells. The 4 lignans at all concentrations used in this study did not induce any effect on cell viability. Furthermore, we found a similar decrease of the membrane potential by wuweizisu C in PC12 neuronal cells. CONCLUSION: Our results suggest that the decrease in the membrane potential and the modulation of [Ca(2+)](i) concentration by wuweizisu C could be important action mechanisms of wuweizisu C.

N,N-Dimethyl-D-erythro-sphingosine inhibits store-operated Ca2+ entry in U937 monocytes.

Calcium is a ubiquitous second messenger that controls a broad range of cellular functions, and store-operated calcium entry (SOCE) is the primary mechanism of regulated Ca(2+) entry in non-excitable immunocytes. In this study, we found that N,N-dimethyl-D-erythro-sphingosine (DMS) inhibited SOCE. In U937 cells, treatment with DMS for 2 h inhibited thapsigargin-induced SOCE by about 70%. DMS inhibited SOCE in a concentration-dependent manner when it was added to the cells after SOCE reached a plateau. DMS-induced SOCE inhibition was also confirmed by the Mn(2+)-quenching method, which monitors only Ca(2+) influx. Because sphingosine kinase inhibitors or protein kinase C (PKC) inhibitors could not mimic the SOCE inhibition, sphingosine kinase and PKC could be excluded as targets of DMS-induced inhibition of SOCE. Furthermore, disruption of lipid rafts with methyl-beta-cyclodextrin and bacterial sphingomyelinase did not influence DMS-induced inhibition of SOCE. DMS-induced inhibition of SOCE in U937 human monocytes is a unique observation and could serve as a basis to study modulation of intracellular Ca(2+) concentration by sphingolipids, although the precise mechanism should be elucidated in the future.

Dioleoyl phosphatidic acid induces morphological changes through an endogenous LPA receptor in C6 glioma cells.

Previously, we suggested that dioleoyl phosphatidic acid (PA) and lysophosphatidic acid (LPA) increased [Ca(2+)](i) through endogenous LPA receptors coupled to pertussis toxin-sensitive G proteins in rat C6 glioma cells. In the present report, we investigated morphological changes and cytotoxicity induced by PA and LPA in C6 glioma cells. Isoproterenol treatment led to changes in the cell morphology of rat C6 glioma cells, which were reverted by the addition of PA and LPA. PA-and LPA-induced morphological reversions were inhibited by treatment with Ki16425, an LPA(1)/LPA(3) receptor antagonist. VPC32183, another LPA(1)/LPA(3) receptor antagonist with a different structure, only inhibited PA-induced morphological reversion but not LPA-induced reversion. However, the reversions were not inhibited by treatment with pertussis toxin, a specific inhibitor of G(i/o) proteins. In addition, cytotoxicity was only induced by LPA but not by PA in C6 glioma cells. Our results suggest that PA may act as a partial agonist at endogenous LPA receptors, which are sensitive to Ki16425 and coupled to PTX-insensitive G proteins, to evoke morphological changes in C6 glioma cells.

Differential signaling of sphingosine derivatives in U937 human monocytes depends on the degree of N-methylation.

Previously, we studied N,N-dimethyl-D-erythro-sphingosine (DMS)-induced cell death and signaling in U937 human monocytes; we found that DMS-induced sphingosine kinase- and PKC-independent apoptosis. In the present study, we studied apoptotic responses by three N-methyl derivatives of sphingosine: N-monomethyl-D-erythro-sphingosine (MMS), N,N,N-trimethyl-D-erythro-sphingosine (TMS), and D-erythro-sphingosine (SPH). The potency order in the apoptotic response was DMS>or=MMS>TMS>SPH. We compared cellular responses to the derivatives in terms of activities of MAPK signaling molecules, mitochondrial membrane potential (DeltaPsi(m)), and reactive oxygen species (ROS) generation. Our results suggest that the degree of N-methylation affects the apoptosis-inducing capacity and other related responses including MAPK modulation, DeltaPsi(m), and ROS generation. Dimethylation and monomethylation on the C2 amine of sphingosine enhance the apoptotic response; however, trimethylation induces differential modulation of signaling molecules and less cytotoxicity. Our investigation will be useful for understanding the actions of sphingolipids in apoptosis and for developing chemotherapeutics based on DMS structure.

Lysophosphatidylserine induces calcium signaling through Ki16425/VPC32183-sensitive GPCR in bone marrow-derived mast cells and in C6 glioma and colon cancer cells.

Lysophosphatidylserine (LPS) can be generated following phosphatidylserine-specific phospholipase A2 activation. The effects of LPS on cellular activities and the identities of its target molecules, however, have not been fully elucidated. In this study, we observed that LPS stimulated intracellular calcium increased in mouse bone marrow-derived mast cells (BMMC), and rat C6 glioma and human HCT116 colon cancer cells and compared the LPS-induced Ca2+ increases with the response by lysophosphatidic acid (LPA), a structurally related bioactive lysolipid. In order to test involvement of signaling molecules in the LPS-induced Ca2+ signaling, we used pertussis toxin (PTX), U73122, and 2-APB, which are specific inhibitors for G proteins, phospholipase C (PLC), and IP3 receptors, respectively. The increases due to LPS and LPA were inhibited by PTX, U-73122 and 2-APB, suggesting that both lipids stimulate calcium signaling via G proteins (Gi/o types), PLC activation, and subsequent IP3 production, although the sensitivity to pharmacological inhibitors varied from complete inhibition to partial inhibition depending on cell type and lysolipid. Furthermore, we observed that Ki16425 completely inhibited an LPS-induced Ca2+ response in three cell types, but that the effect of VPC32183 varied from complete inhibition in BMMC and C6 glioma cells to partial inhibition in HCT116 cells. Therefore, we conclude that LPS increases [Ca2+]i through Ki16425/VPC32183-sensitive G protein-coupled receptors (GPCR), G protein, PLC, and IP3 in mouse BMMC, rat C6, and human HCT116 cells.

Characterization of N,N,-dimethyl-D-erythro-sphingosine-induced apoptosis and signaling in U937 cells: independence of sphingosine kinase inhibition.

In the present study, we studied N,N-dimethyl-D-erythro-sphingosine (DMS)-induced cell death and its signaling mechanism in U937 human monocytes. We found that DMS induced cell death in a concentration-dependent manner, while sphingosine 1-phosphate did not. DMS also induced DNA fragmentation, nuclear disruption, and cytochrome c release from mitochondria in a concentration- and time-dependent manner, implying apoptotic cell death. DMS was found to increase mitochondrial membrane potential (MMP) immediately after addition of DMS and to decrease MMP at 2h after addition. However, sphingosine kinase inhibitors and PKC inhibitors did not induce cell death in U937 cells, a result that appears to exclude sphingosine kinase and PKC as target molecules of DMS in the cell death induction process. Furthermore, DMS modulated the activity of several signaling molecules. DMS induced activation of JNK and p38 MAP kinase, while it decreased the activity of ERK and Akt kinase. However, decrease of MMP, inhibition of JNK, p38 MAP kinase, ERK, or Akt with specific inhibitors could not mimic the DMS-induced cell death, implying multiple concerted processes are involved in DMS-induced cell death. In summary, DMS induced apoptotic cell death via modulation of MMP, JNK, p38 MAP kinase, ERK, and Akt kinase, but not through inhibition of sphingosine kinase or PKC in U937 cells.

N, N-dimethyl-D-erythro-sphingosine increases intracellular Ca2+ concentration via Na+-Ca2+-exchanger in HCT116 human colon cancer cells.

N,N-dimethyl-D-erythro-sphingosine (DMS), an N-methyl derivative of sphingosine, is an inhibitor of protein kinase C (PKC) and sphingosine kinase (SK). In previous reports, DMS-induced intracellular Ca2+ increase concentration ([Ca2+]i) was studied in T lymphocytes, monocytes, astrocytes and neuronal cells. In the present study, we studied DMS-induced increase of [Ca2+]i in HCT116 human colon cancer cells. We found that the DMS-induced increase of [Ca2+]i in colon cancer cells is composed of Ca2+ release from intracellular Ca2+ stores and subsequent Ca2+ influx. The Ca2+ release is not related to modulation of inositol 1,4,5-trisphosphate (IP3) receptor or ryanodine receptor. On the other hand, the Ca2+ influx is mediated largely through Ca2+ channels sensitive to verapamil, nifedipine, Ga3+, and La3+. Furthermore, we found that the response is inhibited by bepridil and Ni2+, specific inhibitors of Na+-Ca2+-exchanger, suggesting involvement of Na+-Ca2+ exchanger in the DMS-induced [Ca2+]i increase in colon cancer cells. This inhibition was also observed in U937 monocytes, but not in 1321N1 astrocytes.

Effect of direct albumin binding to sphingosylphosphorylcholine in Jurkat T cells.

We investigated the effects of serum on lysophospholipid-induced cytotoxicity in Jurkat T cells. We found that sphingosylphosphorylcholine (SPC, also known as lysosphingomyelin) induced cytotoxicity and that albumin in serum could protect cells by binding directly to SPC. Furthermore, we also found that SPC induced ROS generation, increased [Ca(2+)](i), and decreased MMP. However, those effects were only observed at concentrations higher than 10 microM and were only induced in albumin-free media. Therefore, SPC may be trapped by albumin in plasma and unable to exert its effects under normal conditions, although at high concentrations, SPC could induce several responses such as ROS generation, increased [Ca(2+)](i), and decreased MMP in Jurkat T cells.

Lysophosphatidylserine increases membrane potentials in rat C6 glioma cells.

Previously, we reported on the distinct effects of bioactive lysophospholipids, including lysophosphatidic acid (LPA), lysophosphatidylcholine (LPC), and sphingosylphosphorylcholine (SPC), on membrane potentials in rat C6 glioma cells. In the present report we have tested lysophosphatidylserine (LPS), another bioactive lysophospholipid, on membrane potentials in the same cell line. Membrane potentials were estimated by measuring the fluorescence changes of DiBAC-loaded glioma cells. LPS largely increased membrane potentials in a concentration-dependent manner. The LPS-induced membrane potential increases were not affected by treatment with pertussis toxin, implying no involvement of Gi/o proteins. In contrast to other lysophospholipids, the LPS-induced membrane potential increase was not diminished by a Na(+)-free media but was enhanced by suramin. Furthermore, this change was blunted by EIPA, an inhibitor of Na(+)/H(+) exchanger, but not by SITS, a specific inhibitor of bicarbonate transporter. Our observations suggest that LPS acts on membrane potentials in a unique manner in the C6 glioma cells, although the precise action mechanism requires additional investigation.

Sphingosine 1-phosphate (S1P) induces shape change in rat C6 glioma cells through the S1P2 receptor: development of an agonist for S1P receptors.

Treatment with isoprenaline led to a change in the cell morphology of rat C6 glioma cells. This morphological change was reverted by the addition of sphingosine 1-phosphate (S1P). Using this morphological change as a response marker we determined that DS-SG-44 ((2S,3R)-2-amino-3-hydroxy-4-(4-octylphenyl)butyl phosphoric acid) was an agonist of S1P receptors. The DS-SG-44-induced morphological reversion was not observed with such structurally related molecules as DS-SG-45 ((2S,3R)-2-amino-3-hydroxy-4-(3-octylphenyl)butyl phosphoric acid) and DS-SG-12 ((2S,3R)-2-amino-4-(4-octylphenyl)butane-1,3-diol). The S1P- and DS-SG-44-induced shape changes were neither reproduced with the S1P1/S1P3 receptor agonist VPC24191 nor inhibited by the S1P1/S1P3 receptor antagonist, VPC23019. Transfection with small interfering RNA (siRNA) for the S1P2 receptor greatly inhibited the DS-SG-44-induced shape change, and in part an S1P-induced response. In the presence of VPC23019, siRNA transfection for the S1P2 receptor almost completely blocked the S1P- and DS-SG-44-induced shape changes. Our results suggested that DS-SG-44, a newly-synthesized S1P analogue, acted as an S1P receptor agonist and that the S1P-induced shape change in rat C6 glioma cells was mediated mainly through the S1P2 receptor, and cooperatively through the S1P1/S1P3 receptors.