[Lecithin-cholesterol acyltransferase (LCAT)].
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Humans↗
Biomedical subjects
H Itakura
Publications and source records attributed to H Itakura.
Dementia and advance-care planning: perspectives from three countries on ethics and epidemiology.
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Advance Care Planning↗
Domain organization and functional analysis of Thermus thermophilus MutS protein.
MutS protein binds to DNA and specifically recognizes mismatched or small looped out heteroduplex DNA. In order to elucidate its structure-function relationships, the domain structure of Thermus thermophilus MutS protein was studied by performing denaturation experiments and limited proteolysis. The former suggested that T. thermophilus MutS consists of at least three domains with estimated stabilities of 12.3, 22.9 and 30.7 kcal/mol and the latter revealed that it consists of four domains: A1 (N-terminus to residue 130), A2 (131-274), B (275-570) and C (571 to C-terminus). A gel retardation assay indicated that T.thermophilus MutS interacts non-specifically with double-stranded (ds), but not single-stranded DNA. Among the proteolytic fragments, the B domain bound to dsDNA. On the basis of these results we have proposed the domain organization of T. thermophilus MutS and putative roles of these domains.
Adenosine Triphosphatases↗
Probucol treatment attenuates the aortic atherosclerosis in Watanabe heritable hyperlipidemic rabbits.
We examined the effect of probucol on the aortic atherosclerosis already developed in Watanabe heritable hyperlipidemic (WHHL) rabbits at the initiation of treatment. In WHHL rabbits treated with probucol for 5 months from 8 months old, the lesion area in the aorta was significantly (P < 0.05) reduced when compared with that in untreated animals as well as animals at age 8 months. In contrast, plasma cholesterol levels in the probucol-treated group and untreated group during the experiment were not significantly different. LDL prepared from rabbits receiving probucol for 5 months showed resistance to oxidation by copper ions. Plasma CETP activity was significantly (P < 0.05) increased by probucol treatment. An immunohistochemical study showed that macrophages were abundant in the atherosclerotic lesions of untreated rabbits whereas smooth muscle cells were predominant in lesions of probucol-treated rabbits. These results suggest that the atherosclerotic lesion in WHHL rabbits can regress when treated by probucol and that the attenuation of atherosclerosis in this animal involves effects of probucol other than a decrease in plasma cholesterol, for example anti-oxidant activity.
Actins↗
Inhibitory effects of Dai-saiko-to (Da-Chai-Hu-Tang) on the progression of atherosclerotic lesions in Kurosawa and Kusanagi-hypercholesterolemic rabbits.
The inhibitory effects of the traditional herbal medicine Dai-saiko-to (Da-Chai-Hu-Tang) on the progression of the atherosclerotic lesions were studied using the spontaneous familial hypercholesterolemia (FH) model, Kurosawa and Kusanagi-hypercholesterolemic (KHC) rabbits. Changes in blood chemistry, pathology and low-density lipoprotein (LDL) oxidation were measured in a control group and a Dai-saiko-to-treated group. In the control group, the area of atheromatous plaques of the aorta progressed between week 12 (29.1%) and 26 (51.5%). This progression of atherosclerotic lesions did not happen in the Dai-saiko-to-treated group between week 12 (26%) and 26 (27.4%). Antioxidative effects on LDL were seen in the Dai-saiko-to-treated group in weeks 16 and 18. Dai-saiko-to did not improve the hypercholesterolemia in the KHC rabbits. These results suggest that Dai-saiko-to has inhibitory effects on the development of atheromatous plaque formation in spontaneous FH model rabbits. It is possible that the antioxidative effects of Dai-saiko-to on LDL led to the beneficial effects observed in this study.
Animals↗
Effect of 20 days' bed rest on the reverse cholesterol transport system in healthy young subjects.
OBJECTIVES: To study the effects of 20 days of bed rest on HDL cholesterol, lipoprotein lipase, hepatic triglyceride lipase, cholesterol ester transfer protein and lecithin-cholesterol acyltransferase. DESIGN: A 20-day intervention study. SETTING: Makita general hospital. SUBJECTS: Five male and five female healthy participants, mean age 20.4 years, range 19-24 years. INTERVENTIONS: Twenty days of bed rest. MAIN OUTCOME MEASURES: Lipid, lipoprotein, lipoprotein lipase, hepatic triglyceride lipase, cholesterol ester transfer protein and lecithin-cholesterol acyltransferase. RESULTS: Fasting HDL, HDL2 and HDL3 cholesterol levels decreased from 1.748 to 1.404 mmol L(-1) (P < 0.01), from 0.807 to 0.628 mmol L(-1) (P < 0.01) and from 0.939 to 0.784 mmol L(-1) (P < 0.05), respectively, while VLDL triglyceride levels increased from 0.365 to 0.754 mmol L(-1) (P < 0.05). Plasma post-heparin lipoprotein lipase activity decreased from 0.494 to 0.418 micromol mL(-1) h(-1) (P < 0.01), but plasma post-heparin hepatic triglyceride lipase activity and cholesterol ester transfer protein activity did not change during bed rest. Lecithin-cholesterol acyltransferase activity increased from 72.5 to 84.8 nmol mL(-1) h(-1) (P < 0.001). CONCLUSIONS: Twenty days of bed rest induced a decline in HDL cholesterol levels and an increase in VLDL triglyceride levels. When considering lipoprotein lipase, hepatic triglyceride lipase, cholesterol ester transfer protein and lecithin-cholesterol acyltransferase as factors in the decreased HDL cholesterol, the contribution of lipoprotein lipase is suggested.
Adult↗
A comparison of epidemiologic, histologic, and virologic studies on Hodgkin's disease in western Kenya and Nagasaki, Japan.
Rapid progress in molecular technologies has enabled the detection of several oncogenic viruses in various types of tumors. The pathogenesis of Hodgkin's disease is suggested to have a strong association with Epstein-Barr virus (EBV). However, Hodgkin's disease related to EBV shows a wide geographic variation in epidemiology. These variations among different populations suggest an interaction of environmental factors and a direct role of EBV infection. Therefore, we performed a comparative study on epidemiologic, histologic, and virologic features of Hodgkin's disease among those in the western part of Kenya and in Nagasaki, Japan. The age distribution of Hodgkin's disease showed a distinct peak in the 0-9-year-old age group in Kenya, and a higher and lower peak in the 60-69- and 30-39-year-old age groups, respectively, in Japan. The most common subtype of Hodgkin's disease in both countries was mixed cellularity, followed by nodular sclerosis, lymphocyte depletion, and lymphocyte predominance. Mixed cellularity showed a significantly high prevalence among Kenyan children nine years of age or younger. Using the in situ hybridization method, EBV-encoded RNA (EBER-1) was detected in 79% of the Kenyan cases and 59% of the Japanese cases, with the mixed cellularity subtype showing a strong correlation with EBER-1. There was 100% positivity in both countries in those less than nine years old. These results suggest that EBV plays a more direct role in the pathogenesis of Hodgkin's diseases in Kenya, especially in cases among young children and also in Japanese children. Environmental and/or genetic factors may have a role, in addition to EBV, in the pathogenesis of Hodgkin's disease, especially in Nagasaki, Japan.
Adolescent↗
A candidate high density lipoprotein (HDL) receptor, HB2, with possible multiple functions shows sequence homology with adhesion molecules.
High density lipoprotein (HDL), an antiatherogenic lipoprotein comprises several subclasses differing in composition and metabolic function. This physiological complexity appears to be matched with the growing number of candidate HDL receptors, since several HDL binding proteins have recently been identified in various tissues. Because these putative receptors may signal different pathways it is important to identify their structure and potential role in HDL metabolism. We review recent progress in the cloning and characterization of HB2, one of a pair of HDL binding proteins (HB1 and HB2) first purified from rat liver. The structure of HB2 is consistent with a receptor role for this membrane protein and when expressed in cells, increases HDL binding 2 fold. HB2, minimally present in THP-1 cells, is substantially upregulated in macrophages and appears sensitive to cholesterol loading of these cells. The protein shows high homology with adhesion molecules ALCAM and BEN and the possibility that HDL by binding to HB2, reduces adhesion induced arterial wall injury, is discussed in the context of the known protective role of HDL against atherosclerosis. The possible functions of HB2 are also compared with other recently cloned HDL receptors.
Animals↗
Binding mode of benzhydroxamic acid to Arthromyces ramosus peroxidase shown by X-ray crystallographic analysis of the complex at 1.6 A resolution.
The crystal structure of Arthromyces ramosus peroxidase (ARP) in complex with benzhydroxamic acid (BHA) as determined by X-ray analysis at 1.6 A shows unambiguously how BHA binds to ARP. BHA is located in the distal heme pocket. Its functional groups are held by three hydrogen bonds to His56N(epsilon), Arg52N(epsilon), and Pro(154)O, but are too far away to interact with the heme iron. The aromatic ring of BHA is positioned at the entrance of the channel to the heme pocket, approximately parallel to the heme group. Most water molecules at the active site of the native enzyme are replaced by BHA, leaving a ligand, probably a water molecule, at the sixth position of the heme. Results are compared with spectroscopic data.
Binding Sites↗
Cloning and characterization of HB2, a candidate high density lipoprotein receptor. Sequence homology with members of the immunoglobulin superfamily of membrane proteins.
The protection against coronary artery disease attributed to high density lipoprotein (HDL) may be associated with several functions, including its central role in reverse cholesterol transport, possible antioxidant and antithrombotic properties and others not yet identified which may depend on specific interactions between HDL and cell receptors. Several HDL-binding proteins have been identified including two candidate liver HDL receptors, HB1 and HB2 recently purified in this laboratory. We now report the cloning, sequencing, and some properties of HB2, the most abundant of the pair. It shows significant homology with the adhesion molecules ALCAM and BEN of the immunoglobulin superfamily and the cDNA, when transfected into HepG2 or COS cells, caused specific HDL3 binding to increase by 80-100%. Further, ligand blotting of glycoproteins isolated from phorbol 12-myristate 13-acetate-treated THP-1 cells or from transfected HepG2 and Chinese hamster ovary cells also provided evidence of increased binding of HDL3 to HB2. Differentiation of THP-1 cells into macrophages resulted in a striking increase in HB2 mRNA which was attenuated if cells were cholesterol-loaded by incubation with acetylated low density lipoprotein. If the interaction between HDL and HB2 reduces the adhesion-induced inflammatory cellular events that characterize arterial wall injury, thereby achieving the protection associated with higher plasma levels of HDL, these findings may provide a clue to one mitigating effect of HDL in heart disease.
Activated-Leukocyte Cell Adhesion Molecule↗
A role for macrophage scavenger receptors in atherosclerosis and susceptibility to infection.
Macrophage type-I and type-II class-A scavenger receptors (MSR-A) are implicated in the pathological deposition of cholesterol during atherogenesis as a result of receptor-mediated uptake of modified low-density lipoproteins (mLDL). MSR-A can bind an extraordinarily wide range of ligands, including bacterial pathogens, and also mediates cation-independent macrophage adhesion in vitro. Here we show that targeted disruption of the MSR-A gene in mice results in a reduction in the size of atherosclerotic lesions in an animal deficient in apolipoprotein E. Macrophages from MSR-A-deficient mice show a marked decrease in mLDL uptake in vitro, whereas mLDL clearance from plasma occurs at a normal rate, indicating that there may be alternative mechanisms for removing mLDL from the circulation. In addition, MSR-A-knockout mice show an increased susceptibility to infection with Listeria monocytogenes or herpes simplex virus type-1, indicating that MSR-A may play a part in host defence against pathogens.
Animals↗
Binding of iodide to Arthromyces ramosus peroxidase investigated with X-ray crystallographic analysis, 1H and 127I NMR spectroscopy, and steady-state kinetics.
The site and characteristics of iodide binding to Arthromyces ramosus peroxidase were examined by x-ray crystallographic analysis, 1H and 127I NMR, and kinetic studies. X-ray analysis of an A. ramosus peroxidase crystal soaked in a KI solution at pH 5.5 showed that a single iodide ion is located at the entrance of the access channel to the distal side of the heme and lies between the two peptide segments, Phe90-Pro91-Ala92 and Ser151-Leu152-Ile153, 12.8 A from the heme iron. The distances between the iodide ion and heme peripheral methyl groups were all more than 10 A. The findings agree with the results obtained with 1H NMR in which the chemical shift and intensity of the methyl groups in the hyperfine shift region of A. ramosus peroxidase were hardly affected by the addition of iodide, unlike the case of horseradish peroxidase. Moreover, 127I NMR and steady-state kinetics showed that the binding of iodide depends on protonation of an amino acid residue with a pKa of about 5.3, which presumably is the distal histidine (His56), 7.8 A away from the iodide ion. The mechanism of electron transfer from the iodide ion to the heme iron is discussed on the basis of these findings.
Crystallography, X-Ray↗
Smoking cessation increases the resistance of low-density lipoprotein to oxidation.
The effects of smoking cessation on the susceptibility to oxidation of low-density lipoprotein (LDL) was investigated in 14 men who quit smoking for 3 months. LDL was isolated and susceptibility of LDL to V-70 (4-methoxy-2,4-dimethylvalerinitrile)-mediated oxidation was assessed by measuring conjugated diene production at 234 nm, the lag phase being a measure of the resistance of LDL to oxidation. The mean duration of the lag phase became 1.9-fold longer after 3 months (P < 0.001). The result suggests that the increase in resistance of LDL to oxidation contributes to the reduction of the risk of coronary heart disease by smoking cessation.
Adult↗
Cholate inhibits high-fat diet-induced hyperglycemia and obesity with acyl-CoA synthetase mRNA decrease.
The effects of sodium cholate on high-fat diet-induced hyperglycemia and obesity were investigated. Insulin resistance was estimated by measuring 2-deoxyglucose uptake in epitrochlearis muscles incubated in vitro. Addition of 0.5% cholate to high-safflower oil diet completely prevented high fat-induced hyperglycemia and obesity in C57BL/6J mice with a slight decrease of energy intake but with no inhibition of fat absorption. Furthermore, the addition of cholate decreased blood insulin levels and prevented high-fat diet-induced decrease of glucose uptake in epitrochlearis. However, there was no change in the unsaturation index of fatty acids in skeletal muscles and in GLUT-4 levels by cholate. In liver, cholate addition resulted in cholesterol accumulation and completely prevented high-fat diet-induced triglyceride accumulation. The changes of triglyceride level in the liver were paralleled to the changes of acyl-CoA synthetase (ACS) mRNA. ACS catalyzes the formation of acyl-CoA from fatty acid, and acyl-CoA is utilized for triglyceride formation in liver. ACS has a sterol-responsive element 1 in its promoter region. These data indicate that the favorable effects of cholate could be partly the result of downregulation of ACS mRNA.
Analysis of Variance↗
Effects of antioxidants on the oxidative susceptibility of low-density lipoprotein.
An important event in the pathogenesis of atherosclerosis is believed to be the oxidative modification of low-density lipoprotein (LDL) initiated by a free radical-driven lipid peroxidation process. Vitamin E acts as a lipophilic chain-breaking antioxidant, while water-soluble chain-breaking antioxidants such as vitamin C or uric acid suppress the oxidation of LDL initiated by aqueous radicals. In this study, we established a new method of measuring the lag time of inhibited lipid peroxidation using the lipophilic azo radical initiator V-70:2-2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) and investigated in vitro the susceptibility of LDL to oxidation using this method when lipid- and water-soluble antioxidants were added. When the lipid-soluble antioxidant, vitamin E, was added to LDL, the lag time was extended whereas a higher dose of vitamin E led to a shortened lag time of V-70-induced lipid peroxidation in LDL. These results suggest that vitamin E radicals (tocopheroxyl radicals) act as prooxidants during the autoxidation of LDL. It was also shown that the shortened lag time induced by higher doses of vitamin E was restored when lipid- and water-soluble antioxidants were added simultaneously, which suggests that vitamin E radicals derived from vitamin E are subsequently reduced by vitamin C to regenerate vitamin E. Thus, the interaction between lipid- and water-soluble antioxidants provides an important function in maintaining LDL resistance to oxidation.
Adult↗
[The clinical study of radical cystectomy for lymph node positive bladder cancer].
BACKGROUND: The impact of pelvic lymph node dissection on the survival of patients with lymph node positive bladder cancer is controversial. We analyzed the records of the bladder cancer patients treated with radical cystectomy. METHODS: Between 1976 and 1993, 84 patients with transitional cell carcinoma of the bladder were treated with radical cystectomy at Tokyo Metropolitan Komagome General Hospital. Sixteen patients (19.0%) had pathologically proved nodal metastases. These patients' records were reviewed with regard to pathological status, and the outcome compared with negative lymph node patients. The two patients with pN3, which we could not completely undergo lymph node dissection of, were excluded from the analyses for recurrence and survival. RESULTS: There were 10 males and 6 females, aged between 47 and 83 with a mean of 68.3 years. There were significant differences between the patients with positive lymph node and negative in the rate of grade 3 and the rate of infiltration of cancer to the vein and lymphatics of the bladder walls. The frequency of the patients of positive lymph node was 5.3% in pT1, 10.0% in pT2, 28.6% in pT3a, 32.0% in pT3b, 50.0% in pT4, and none in pTis, pTa and pT4is. The five-year survival rates estimated by the Kaplan-Meier method were 68.6% over all 82 patients, 75.7% for the patients with negative lymph node and 30.7% for positive. Of the patients with positive lymph node, two-year survival was 80.0% for pT2-3a, versus 0% for pT3b-4. This difference was highly significant (p < 0.01). But survival analysis for pT2-3a showed no significant difference between the lymph node negative patients and positive. The recurrence rate was 57.1% (8 of 14) in patients with positive lymph node and seven patients suffered from distant metastases. All the patients which had recurrent tumors died by bladder cancer. CONCLUSION: Radical cystectomy with lymph node dissection can provide favorable outcome in lymph node positive patients with low stage (pT2-3a). But the patients with high stage (> or = pT3b) were poor prognosis. Most of the patients died by distant metastases.
Aged↗
The effects of 20 days bed rest on serum lipids and lipoprotein concentrations in healthy young subjects.
The effects of 20 days bed rest (BR) on serum lipids and lipoprotein concentrations were investigated in 23 healthy young subjects (13 males and 10 females, aged 19 to 25 yr.). After 20 days BR, VO2max was reduced in both genders, but body composition did not change. The ratio of glucose area to insulin area during an oral glucose tolerance test decreased gradually throughout BR, which suggested a decrease in insulin sensitivity. Estimated changes in plasma volume from the beginning of BR were largest at day 3 of BR (-9.1% in females and -3.4% in males) and seemed to return the initial level at the end of BR in both genders. The increase in serum triglycerides and the decrease in high density lipoprotein (HDL) cholesterol, and apolipoprotein AI were observed in both genders during BR. In a smaller study of 4 males and 5 females, 20 days BR was associated with a decrease in HDL, cholesterol, a decrease in apolipoprotein AI and apolipoprotein AII, decrease in a plasma postheparin lipoprotein lipase activity and an increase in very low density lipoprotein triglyceride. Overall, the data suggested that the decrease in lipoprotein lipase activity and insulin sensitivity may contribute to the impairment in HDL metabolism.
Adult↗
Novel elements located at -504 to -399 bp of the promoter region regulated the expression of the human macrophage scavenger receptor gene in murine macrophages.
The expressions of type I and type II macrophage scavenger receptors (MSRs) are highly specific in macrophages and related cell types. Although some reports have described the regulation of MSR gene expression and proposed some cis-elements related to cell-specific expression, the regulation of MSR remains largely unclear. This is due, in part, to an unacceptably low efficiency of transfection into monocyte/ macrophage cells. In the present study, we optimized the conditions of electroporation in murine macrophage (P388D1) cells. The efficiency of electroporation was increased 20-fold compared with previous methods. Using the optimized method, we focused on studying the regulation of the human MSR promoter in macrophages. We presently demonstrate that: a) the proximal -10 to +50 bp human MSR promoter region is necessary for the cell type-specific expression of human MSR; b) the 6.5 kbp upstream sequence suppresses the expression of human MSR; c) a promoter region extending from -504 to -399 bp produced the greatest increase in transcriptional activity; d) macrophage cell-specific transcription factors bind to the region as determined by electrophoretic mobility shift assay (EMSA) and a footprint assay; and e) mutations of the region reduced about 40-75% of the promoter activity in a transfecting assay. We concluded that novel elements located at the -504 to -399 bp region may play an important role in the regulation of the MSR gene expression in macrophages. We speculate that macrophage-specific factors binding to those elements may be responsible for the transcription regulation of the MSR gene in macrophages.
Animals↗