Effects of Uric Acid on the NO Production of HUVECs and its Restoration by Urate Lowering Agents.

BACKGROUND: Although urate impaired the endothelial function, its underlying mechanism remains unknown. We hypothesized that urate impaired nitric oxide (NO) production in human umbilical vein endothelial cells (HUVECs) via activation of uric acid transporters (UATs). PURPOSE AND METHOD: In the present study, we studied effects of urate on NO production and eNOS protein expression in HUVEC cells in the presence and absence of urate lowering agents using molecular biological and biochemical assays. RESULTS: HUVECs expressed the 4 kinds of UATs, URATv1, ABCG2, MRP4 and MCT9. Exposure to urate at 7 mg/dl for 24 h significantly reduced production of NO. Pretreatment with benzbromarone, losartan or irbesartan normalized NO production. The same exposure resulted in dephosphorylation of endothelial NO synthase (eNOS) in HUVECs. Again pretreatment with benzbromarone, losartan or irbesartan abolished this effect. CONCLUSION: Urate reduced NO production by impaired phosphorylation of eNOS in HUVEC via activation of UATs, which could be normalized by urate lowering agents.

Carvedilol Suppresses Apoptosis and Ion Channel Remodelling of HL-1 Cardiac Myocytes Expressing E334K cMyBPC.

BACKGROUND: Besides its antiarrhythmic action, carvedilol has an activity to suppress cardiac tissue damage. However, it is unknown whether it has any effect on cellular apoptosis and ion channel remodelling. PURPOSE: To know whether carvedilol has any effect on apoptosis and ion channel remodeling of HL-1 cells expressing E334K MyBPC, and comparing it with bisoprolol. METHOD: We examined effects of carvedilol and bisoprolol on the levels of pro- and anti-apoptotic proteins and ion channels as well as apoptosis of HL-1 cells transfected with E334K MyBPC using Western blot and flow cytometry. RESULTS: Carvedilol decreased the protein levels of p53, Bax and cytochrome c and increased that of Bcl-2 in HL-1 cells expressing E334K MyBPC. Bisoprolol failed to affect the protein levels. Both carvedilol and bisoprolol increased the protein levels of Cav1.2 but not that of Nav1.5. Carvedilol was stronger than bisoprolol at decreasing the number of annexin-V positive cells in HL-1 cells expressing E334K MyBPC. CONCLUSION: Carvedilol suppressed apoptosis of HL-1 cells expressing E334K MyBPC through modification of pro- and anti-apoptotic proteins, whose was associated with an increase of Cav 1.2 protein expression.

Simultaneous treatment with azelnidipine and olmesartan inhibits apoptosis of Hl-1 cardiac myocytes expressing E334k cMyBPC.

BACKGROUND: Apoptosis appears to play an important role in the pathogenesis of hypertrophic cardiomyopathy (HCM). We have previously reported 3 HCM patients carrying the E334K MYBPC3, and that heterologous expression of E334K cMyBPC in cultured cells induced apoptosis. The purpose of this study was to identify pharmacological agents that would inhibit apoptosis in HL-1 cardiomyocytes expressing E334K cMyBPC. METHODS AND RESULTS: E334K cMyBPC expression in cells increased levels of pro-apoptosis (p53, Bax and cytochrome c) and decreased levels of anti-apoptosis (Bcl-2 and Bcl-XL). While the beta blocker carvedilol (1 µM) normalized the level of p53 and Bcl-2 and the calcium channel blocker (CCB) bepridil (0.5 µM) normalized that of Bcl-2, both the CCB azelnidipine (1 µM) and the angiotensin receptor blocker (ARB) olmesartan (10 µM) normalized those of p53, Bax, cytochrome c, and Bcl-XL. Among those proteins, cytochrome c was the one which showed the highest degree of change. Both azelnidipine (0.1 µM) and olmesartan (1 µM) reduced the level of cytochrome c by 40.2 ± 4.3% and 31.3 ± 5.1%, respectively. The CCB amlodipine and the ARB valsartan reduced it only by 19.1 ± 2.1% and 20.1 ± 5.2%, respectively. Flow cytometric analysis and annexin V staining showed that treatment of cells with azelnidipine (0.1 µM) plus olmesartan (0.3 µM) or that with amlodipine (0.1 µM) plus valsartan (0.3 µM) reduced the number of apoptotic cells by 35.8 ± 10.5% and 18.4 ± 3.2%, respectively. CONCLUSION: Azelnidipine plus olmesartan or amlodipine plus valsartan inhibited apoptosis of HL-1 cells expressing E334K cMyBPC, and the former combination was more effective than the latter.

Tuning glycosidase inhibition through aglycone interactions: pharmacological chaperones for Fabry disease and GM1 gangliosidosis.

Competitive inhibitors of either α-galactosidase (α-Gal) or ß-galactosidase (ß-Gal) with high affinity and selectivity have been accessed by exploiting aglycone interactions with conformationally locked sp(2)-iminosugars. Selected compounds were profiled as potent pharmacological chaperones for mutant lysosomal α- and ß-Gal associated with Fabry disease and GM(1) gangliosidosis.

The pro-apoptotic BH3-only protein Bim regulates cell cycle progression of hematopoietic progenitors during megakaryopoiesis.

SUMMARY BACKGROUND: The pro-apoptotic BH3-only protein Bim is recognized as a pivotal regulator of apoptosis induced by the depletion of cytokines. In the present study, we examined the role of Bim in megakaryopoiesis. METHODS: Megakaryocyte (MK) progenitors obtained from bim knockout (KO) mice were analyzed in vitro for liability to apoptosis after the depletion of cytokines, ability to differentiate into MKs and proliferation/cell cycle progression in response to thrombopoietin (TPO). The production of platelets in vitro was evaluated by assaying the formation of proplatelets in MKs. Megakaryopoiesis in vivo was observed in a mouse model of thrombocytopenia induced by injecting fluorouracil (5-FU). RESULTS: Bim-deficient CD34-/c-kit+/Sca-1+/Lineage- stem cells and MKs were highly resistant to apoptosis induced by cytokine depletion, suggesting that Bim is involved in the apoptotic process in both stem cells and MKs. As bim KO mice exhibited splenomegaly and thrombocytopenia, splenectomized mice were used for experiments in vivo. Platelet recovery after 5-FU-induced thrombocytopenia was significantly delayed in bim KO mice. Corresponding with this, numbers of MKs in the recovery phase bone marrow were significantly reduced in bim KO mice. Culture of c-kit+/Lineage- progenitors with TPO revealed that Bim-deficient cells poorly proliferate and differentiate into CD41+ cells in comparison with wild-type (WT) cells. However, once differentiated into MKs, these cells matured normally. Furthermore, cell cycle analyses demonstrated that transition from the G1 to the S phase was delayed in Bim-deficient stem cells. CONCLUSIONS: In the present study, we demonstrated that Bim plays a pivotal role in the regulation of cell cycle progression in hepatopoietic progenitors during megakaryopiesis.

Caspase activation is involved in early megakaryocyte differentiation but not in platelet production from megakaryocytes.

To elucidate whether caspase activation is involved in megakaryopoiesis, we characterized megakaryocytes (MKs) in vav-bcl-2 transgenic (Tg) mice, in which Bcl-2 is overexpressed in hematopoietic cells. To exclude the effect of splenomegaly in Tg mice on megakaryopoiesis, splenectomy was performed. After splenectomy, basal platelet counts in peripheral blood were not significantly different between Tg and wild-type (WT) mice. However, when experimental thrombocytopenia was induced by injecting 5-fluorouracil into splenectomized mice, overshoot of platelet counts during the recovery phase was hardly observed in Tg mice. Analyses of MK ploidy during the recovery phase showed that MKs less than 16 N ploidy were significantly decreased in Tg mice, suggesting that MK supply from progenitors is impaired. Supporting this, differentiation of CD34-/c-kit+/Sca-1+/Lineage- stem cells into MKs was significantly hampered in Tg mice, whereas megakaryocyte-erythroid progenitors (MEPs) normally differentiated into MKs. It suggests that differentiation into MKs is impaired in Tg mice before the stage of MEP. Furthermore, MK colony formation in WT cells was dose-dependently inhibited in the presence of a caspase inhibitor. Contrary, Bcl-2-overexpressing MKs showed normal ability for in vitro platelet production. We thus believe that caspase activation is involved in the differentiation of progenitors into megakaryocytic lineage but not in platelet production.

Genetic instability in lung cancer: concurrent analysis of chromosomal, mini- and microsatellite instability and loss of heterozygosity.

To investigate what kind of genetic instability plays important roles in lung carcinogenesis, we analyzed micro- and minisatellite instability, loss of heterozygosity (LOH) and chromosome instability in 55 cases of lung cancer, including, 10 squamous cell, 5 large cell, and 3 small cell carcinomas, and 37 adenocarcinomas. Analysis of minisatellite instability, the mechanism of which is different from microsatellite instability, has not been reported previously. Minisatellite instability was detected in only one case (1/55, 1.8%), and the frequency of microsatellite instability was low, being found only in three cases (3/55, 5.5%). In contrast, LOH, for at least in one locus, was observed in 27 cases (49.1%). In adenocarcinomas, the frequency of LOH was higher in poorly differentiated compared to more differentiated carcinomas. For chromosome instability, a similar correlation between differentiation grade and instability was observed in adenocarcinomas. And instability was more common in large cell and small cell carcinomas than in adenocarcinomas. Our analysis showed that chromosome instability and LOH, rather than mini- and microsatellite instability, play significant roles in the development of lung cancer.

Microvascular growth of 7,12-dimethylbenz(alpha)anthracene-induced adenocarcinomas in rats: histology and scanning electron microscopy of resin casts.

Vascular changes at various stages of growth of 7,12-dimethylbenz(alpha)anthracene (DMBA)-induced mammary adenocarcinomas in 22 female Sprague-Dawley rats were investigated using histology, immunohistochemistry and scanning electron microscopy (SEM) of corrosion casts. In the early stage of tumour growth, capillaries within the neoplasms were thin, with 8-10 microm diameter, and characterized by rows of vascular sprouts representing extensive neovascularization and formation of a high-density capillary plexus. In the intermediate stage of tumour growth, the growing tumour was multi-nodular and tumour cells were arranged in a tubulopapillary pattern. Capillaries formed spheroid vascular capsules and were characterized by dilation, to a diameter of 10-80 mum, and blind ends. In the late stage of tumour growth, a remarkable reduction in the number of vascular endothelial growth factor-positive cells and Ki-67-stained nuclei was demonstrated. The tunica media of nutritive arteries displayed a tendency to atrophy. Many arteriovenous anastomoses between the major arteries and the veins were found in regions just before their entry into the tumour. The central regions of the tumour were degenerative and necrotic, and vasculature was confined to surface regions of the tumour, forming a basket-like configuration around the avascular central regions. Resin leakages representing haemorrhage or oedema and distortions such as flattening, break-off and strangulations of capillaries were frequently observed, all of which are known as late tumour signs. We concluded that these microvascular alterations might change the homogeneity of tumour perfusion and contribute to necrosis in central portions of the tumour.

Penetration to the aortic wall by a metallic airway stent. A successfully treated case with left pneumonectomy and aortic repair.

Metallic airway stents were used widely at the beginning of airway stent use, but an accumulation of cases has revealed complications due to their use. A patient who received a Gianturco Z stent for bronchial tuberculosis suffered massive haemoptysis due to stent migration into the aortic wall. Left pneumonectomy with aortic repair was successfully performed. We suggest that metallic stents should not be used for benign airway palliation, as they may later cause life-threatening complications.

Open radiofrequency ablation for the management of intractable epilepsy associated with sessile hypothalamic hamartoma.

Sessile hypothalamic hamartoma (HH) often causes intractable epilepsy, which is difficult to control even by microsurgical resection and gamma knife surgery (GKS), especially when the hamartoma is intrahypothalamic, large, or irregularly shaped. We successfully applied radiofrequency ablation (RFA) to reduce its epileptogenicity and to disconnect seizure propagation. The patient was a 26-year-old man who presented with refractory epilepsy and severe mental retardation from age 6 months. He had undergone three surgeries yielding partial resection and conventional irradiation treatments. The residual HH was thin and shaped like a bent plate, attached widely to the floor of the third ventricle. He underwent open RFA via the transcallosal sub-choroidal approach under strict image guidance, which resulted in immediate and remarkable seizure remission without complications. This suggests that open RFA is a minimally invasive technique for an irregularly shaped HH that is difficult to treat by other modalities.

[Primary lung cancer; assessment of the disclosed 5-year survival rate by the Internet website].

The disclosed 5-year survival rate for lung cancer in the Internet website represents a various difference by each institution. The better inferiority of the survival has been listed in a table to compare with other institutions and has been reported in magazines and media with a lack of an enough inspection, i.e., with a sufficient considering of a risk adjustment such as patient's background, operative policy, postoperative adjuvant therapy, and statistical background. We report our outcome of the surgical treatment for primary lung cancer. Of 875 patients treated for lung cancer in our department for 23 years between January 1980 and December 2002, 115 patients containing of 42 cases in 1997 and of 48 ones in 1992 and of 25 ones in 1987 were selected and the accumulated survival analysis was treated by Kaplan-Meier method. Eighty males and 35 females were between 15 and 80-year-old (average 63.2 +/- 11.4). The pathological classification was adenocarcinoma (n=69), squamous cell carcinoma (n=32), and others (n=14). The operative procedures were pneumonectomy (n=14), bilobectomy (n=12), lobectomy (n=85), and wedge resection (n=4). The survival time was from 29 days to 182 months (median survival time was 1471+/- 1180 days, the averaged time was 49 months). The 5-year survival rate was 41.4 +/- 9.1% (n=25) in 1987, 35.6 +/- 6.2% (n=48) in 1992, and 56.0 +/- 7.0% (n=42) in 1987, respectively (log-rank test, p = 0.2555). The 10-year survival rate was 24.1 +/- 7.9% in 1987 and 8.5 +/- 3.6% in 1992, respectively. The 5-year survival rate was as follows: IA 81.0 +/- 8.6% (n=20), IB 73.7 +/- 10.1% (n=19), IIA 57.1 +/- 18.7% (n=7), IIB 55.6 +/- 16.6% (n=9), IIIA 28.6 +/- 7.6% (n=35), IIIB 15.4 +/- 10.0% (n=13), IV 16.7 +/- 10.8% (n=12), respectively. The 5-year survival rate was as follows: male 42.8 +/- 5.3% (n=80), female 63.2 +/- 7.3% (n=35), respectively (p = 0.0147). In regard to the histological classification, the 5-year survival rate was as follows: adenocarcinoma 47.2 +/- 5.9% (n=69), squamous cell carcinoma 50.8 +/- 8.9% (n=32), respectively (p = 0.9012). As a rule of the disclosure on the internet website, we report our survival data by accompanying with minimum parameters such as, patient's background, pathological types, gender, pathological stages, and mean survival rate with standard error. When we compare the 5-year survival rate with other institutes, in considering of a risk adjustment, we would carefully have to estimate the determined survival rate with a standard error.

[Clinical assessment of the thoracic surgical diseases associated with von Recklinghausen's disease].

Type I neurofibromatosis (NF-I), also referred to as von Recklinghausen's disease, is an autosomal dominant disease characterized by neurofibromas and abnormal cutaneous pigmentation (café-au-lait spot). We studied retrospectively the 8 cases operated in our hospital between January 1979 to December 2002, which were complicated with von Recklinghausen's disease and a thoracic surgical disease. The patients were 6 males and 2 females and the age from 16 to 70 (the averaged age was 36 +/- 22). The thoracic diseases were consist of mediastinal tumors (n = 7) and esophageal cancer (n = 1). The operative procedures were tumorectomy (n = 6), subtotal esophagectomy (n = 1), and pericardial cystectomy (n = 1). The mediastinal tumors were neurofibroma (n = 3), malignant schawannoma (n = 1), ganglioneurinoma (n = 2), and pericardial cyst (n = 1). Malignant neoplasms were recognized in 2 cases (25%). The postoperative survival was 10 months for malignant schwannoma, and 8 months for esophageal cancer, and the others were alive. For 1 case of neurofibromas, there was observed to be the reoperated one after the postoperative recurrence. von Recklinghausen's disease are apt to be complicated with thoracic surgical neoplasms, it should be required a careful and systemic exploration especially for malignant neoplasms.

[Bilateral lower lobectomies for pulmonary mucormycosis].

Mucormycosis is an extremely rare case of pulmonary mycosis, its prognosis is very poor, and known as an opportunistic infection among immunocompromised hosts accompanied with other primary chronic disease. We report here a case of bilateral lower lobectomies carried out by two-stage operation for pulmonary mucormycosis combined with diabetes mellitus (type I) and severe resistance to an antimycobiotics under biblicographical considerations. A 36-year-old female was diagnosed as a diabetes mellitus (type I), and has been administrated with an insulin injection in 1989 at the age of 22-year-old. The patient was suffered a dry cough in June and the bilateral abnormal shadows were pointed out by the chest X-ray film in November, 2002. By transbronchial lung biopsy, Mucor fungus was confirmed in grannulomatous lung specimen. Intravenous injection of amphotericin B could not be continued due to the unavoidable side-effects from this agent. As the lung mass shadow was enlarged increasing and strongly suggested an abscess, formation in its focus, and then the left lower lobectomy was performed as the first step of surgical treatment and the right lower lobectomy was done on the postoperative forty-fourth day as the second step. The postoperative prognosis was considerably uneventful. After bilateral lower lobectomies, the patient could try a walk and go upstairs with a moderate dyspnea. A possible surgical resection should be conducted for the pulmonary mucormycosis, when the medicinal therapy showed an uneffectiveness and/or an infectious lesion was shown as restricted lesion.

[Thymothymectomy for the thymoma with pure red cell aplasia; report of a case].

UNLABELLED: We report a case of thymothymectomy for the thymoma with pure red cell aplasia (PRCA). A 31-year-old male with a general fatigue had a severe anemia (hemoglobin 3.1 g/dl) since November 1997. By the bone marrow examination, PRCA was diagnosed and treated with blood transfusion and immunosuppressive drug (cyclosporin: CYA) administration but anemia had not been improved. The chest computed tomography displayed a 3 cm in a diameter of thymoma located in the anterior mediastinum. The extended thymothymectomy had been performed in February 1998, pathological detection disclosed Masaoka classification stage I, type AB was diagnosed due to the World Health Organization (WHO) classification. PRCA had not obtained an immediate remission during the postoperative-early term, while, adjuvant therapy (CYA 300 mg/day) has been continued and it brought a complete remission of PRCA in August 2001 (after the postoperative 3 years and 6 months later). CONCLUSIONS: Even though only thymothymectomy for thymoma with PRCA showed no effectiveness for the postoperative-early remission of PRCA, however, the combination of thymectomy and the postoperative adjuvant therapy (CYA) should bring a better outcome, and the continuous follow-up would be required for a long postoperative term.

Cerebral motor control in patients with gliomas around the central sulcus studied with spatially filtered magnetoencephalography.

OBJECTIVE: Application of spatially filtered magnetoencephalography (MEG) to investigate changes in the mechanism of cerebral motor control in patients with tumours around the central sulcus. METHODS: MEG records were made during a repetitive hand grasping task in six patients with gliomas around the central sulcus and in four control subjects. Power decreases in the alpha (8-13 Hz), beta (13-30 Hz), and low gamma bands (30-50 Hz) during the motor tasks (event related desynchronisation, ERD) were analysed statistically with synthetic aperture magnetometry. The tomography of ERD was superimposed on the individual's magnetic resonance image. RESULTS: beta ERD was consistently localised to the contralateral primary sensorimotor cortex (MI/SI) in control subjects, whereas the alpha and low gamma ERD showed considerable intersubject variability. beta ERD in patients during non-affected side hand movement was also localised to the contralateral MI/SI, but exclusively to the ipsilateral hemisphere during affected side hand movement. CONCLUSIONS: The altered pattern of ERD in the patient group during affected side hand movement suggests recruitment of diverse motor areas, especially the ipsilateral MI/SI, which may be required for the effective movement of the affected hand.

Stereotactic radiofrequency ablation for sessile hypothalamic hamartoma with an image fusion technique.

BACKGROUND: Radiosurgery has been advocated as a primary treatment for hypothalamic hamartoma (HH), but it has a risk of damaging the surrounding structures and does not have an immediate effect for refractory epilepsy, endocrinological and mental disorders. METHOD: We report on a 13-year-old boy with a large and sessile HH who presented with intractable seizures, precocious puberty and aggressiveness. Stereotactic radiofrequency ablation (SRA) combined with an image fusion technique was performed to make a maximum ablative lesion within the HH via multiple trajectories. FINDINGS: After surgery, we observed rapid cessation of the gelastic seizures and aggressiveness. The ophthalmological function did not get worse, and the hypothalamopituitary function improved. INTERPRETATION: SRA in combination with an image fusion technique is a viable alternative treatment for HH, because it provides precise preoperative simulation and immediate improvement of symptoms can be obtained.

Progressive neuronal loss in the ventral posterior lateral and medial nuclei of thalamus in Niemann-Pick disease type C mouse brain.

Niemann-Pick disease type C (NP-C) disease is a progressive and fatal neurological disorder characterized by accumulation of cholesterol and glycosphingolipids in peripheral tissues and that of glycosphingolipids in the brain. A C57BL/KsJ-npc1(spm) mutant strain is a genetically authentic model of NP-C. This study investigated neuronal cell loss and lipid accumulation in the npc1(spm) mouse brain. Nissl-staining revealed abundant swollen neurons in the neocortex, piriform cortex, hippocampus and basal ganglia at 3-4 wk of age. In addition to loss of the Purkinje cells, we found a conspicuous cell loss in the ventral posterial lateral (VPL) and medial (VPM) nuclei of thalamus, which became apparent after 4-5 wk. Biochemical analyses revealed no increase of cholesterol in the lipid extracts whereas a substantial accumulation of cholesterol was detectable in most of the large neurons by filipin staining in the brain of homozygous mice. In contrast to the diffuse staining pattern in normal brains, the neuropils of the neurons in the brain of homozygous mice were stained in a punctate pattern. The ubiquitous accumulation excludes a direct role of cholesterol in the progressive neuronal loss in the Purkinje cell layer and in the VPL and VPM of the thalamus.

Genetic polymorphisms and functional characterization of the 5'-flanking region of the human CYP2C9 gene: in vitro and in vivo studies.

OBJECTIVE: Genetic polymorphisms were identified in the 5'-flanking region of the human CYP2C9 gene, and their effects on the phenotype were evaluated on the basis of the luciferase reporter gene assay and the in vivo pharmacokinetics of phenytoin. METHODS: Genetic polymorphisms were screened by polymerase chain reaction-single-strand conformational polymorphism analysis, following sequencing with DNA samples obtained from 50 healthy volunteers and 133 adult epileptic patients. HepG2 hepatoma cells were cotransfected with various sequence patterns of 5'-flanking region-luciferase reporter gene constructs. Pharmacokinetic parameters of phenytoin in relation to the corresponding sequence patterns were estimated by the Bayesian method, and the results were compared with in vitro activities. RESULTS: Genetic analysis revealed the existence of 7 single nucleotide polymorphisms (SNPs). Allele frequencies of T-->C transition at position -1912 (T-1912C), C-1886G, C-1566T, G-1538A, C-1189T, G-982A, and A-162G were 0.019, 0.019, 0.077, 0.019, 0.579, 0.019, and 0.003, respectively. Some mutations occurred simultaneously, and a total of 6 sequence patterns (patterns 1-6) were observed. The luciferase reporter gene assay indicated that the presence of mutation(s) resulted in a reduction in luciferase activity of 41.4% (pattern 2) to 86.8% (pattern 5) compared with the activity of the wild-type construct. The calculated intrinsic clearance of phenytoin was also lower (up to a 40% reduction for pattern 2) when a mutation(s) was present. CONCLUSION: In addition to the two major mutations in the coding region (CYP2C9*2 and CYP2C9*3 ), mutations in the 5'-flanking region of the human CYP2C9 gene appear to contribute to the large interindividual variability in drug metabolism activity.

Isolation of NPC1-deficient Chinese hamster ovary cell mutants by gene trap mutagenesis.

Chinese hamster ovary cell mutants defective in the NPC1 gene (NPC1-trap) were generated by retrovirus-mediated gene trap mutagenesis from a parental cell line JP17 expressing an ecotropic retrovirus receptor. Insertion of the gene trap vector in the NPC1 gene and the absence of the gene product were verified by 5'RACE and immunological analyses, respectively. NPC1-trap cells showed intracellular accumulation of low-density lipoprotein (LDL)-derived cholesterol and had an increased level of unesterified cellular cholesterol. Cholesterol biosynthesis through the mevalonate pathway was upregulated in the mutant cells as assessed by [(14)C]acetate incorporation into cellular sterols. When JP17 cells were depleted of lipoproteins and then loaded with LDL, cell surface LDL receptors were promptly downregulated and the mature form of the sterol regulatory element-binding protein-1 disappeared from the nucleus. These responses to LDL were obviously retarded in NPC1-trap cells, suggesting an impaired response of the cholesterol-regulatory system to LDL. NPC1-trap cells will be a useful tool to study the regulation of cellular cholesterol homeostasis and the pathogenesis of Niemann-Pick disease type C.