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Biomedical subjects

K Fujita

Publications and source records attributed to K Fujita.

At least 73 records · Page 4Linked to original sources
PubMed2002

Effect of SMP-500, a novel acyl-coA:cholesterol acyltransferase inhibitor, on the cholesterol esterification and its hypocholesterolemic properties.

We investigated the effects of SMP-500, a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, on ACAT activities in the liver and intestine, and in macrophages. We measured its effects on the serum cholesterol levels and hepatic cholesterol content in mice, rabbits and hamsters. SMP-500 inhibited ACAT activities in rabbit liver and small intestine microsomes with IC(50) values of 72 and 84 nmol/l, respectively, and acted as a competitive inhibitor of rabbit liver ACAT. SMP-500 potently inhibited cholesterol esterification in rat peritoneal macrophages (IC(50) = 15 nmol/l). In high-fat and high-cholesterol diet-fed mice and in high-cholesterol diet-fed rabbits, SMP-500 reduced the serum cholesterol levels and the hepatic cholesterol content. SMP-500 also reduced the serum and hepatic cholesterol in normal chow-fed hamsters in a dose-dependent manner. In all the animal models, SMP-500 reduced the hepatic free cholesterol content as well as the total and esterified cholesterol. Administered orally, SMP-500 had a direct inhibitory effect on hepatic ACAT activity. These results indicate that SMP-500 is a potent and competitive ACAT inhibitor and may have a therapeutic potential for treating hypercholesterolemia and atherosclerosis.

Animals↗
PubMed2002

Contribution of HPLC mass screening for neuroblastoma to a decrease in mortality.

The aim of this study is the estimation of the contribution of HPLC mass screening for neuroblastoma to the decrease in deaths due to this disease. The mortality rates of malignant neoplasms of the adrenal glands (ICD 9, 1940; ICD 10, C74; virtually all the cases of these codes are neuroblastoma during childhood) at 1-4 years of age in cohorts born in 1979-1984, 1985-1988, and 1989-1992 in the whole of Japan were calculated, using data obtained from the Ministry of Health and Welfare. The numbers of infants screened by HPLC in the cohorts were estimated through the reports of the Ministry of Health and Welfare and the database of the Japanese Society for Mass-screening. The mortality of the cohort born in 1989-1992, in which 77.8% of the live births were screened by HPLC, was 1.73 per 100,000 live births. This is about half of that (3.26) of the cohort born in 1979-1984, in which few infants were screened. On the assumption that cases of the 1985-1988 and 1989-1992 cohorts died according to the mortality rate of the 1979-1984 cohort, the expected numbers of deaths were estimated; that for the 1985-1988 cohort was 178.51 (of them, that for the infants screened by HPLC was 39.65), and that for the 1989-1992 cohort was 159.78 (of them, that for the infants screened by HPLC was 124.33). The observed numbers of deaths were 145 and 85, respectively. Assuming that non-HPLC methods have no effects and using 2 unknown quantities x (contribution of HPLC) and y (other factors), simultaneous equations (1) 178.51 - 39.65x - 178.51y = 145 and (2) 159.78 - 124.33x - 159.78y = 85 were made. Solving them, x = 0.5041 and y = 0.0757 were obtained. In conclusion HPLC screening targeting infants aged 6 months reduces death of adrenal neuroblastomas at 1-4 years of age by about 50%.

Adrenal Gland Neoplasms↗
PubMed2002

Study on generation of oxygen-depleted water based on stochastically changing solar radiation intensity.

To examine the generation probability of oxygen-depleted sea water in Hakata Bay, possible 20 time-series of different hourly-solar-radiation intensities were generated stochastically, and a numerical simulation on dissolved oxygen was carried out for each time series. The results of the model calibration followed the seasonal variation of observed water quality well, and generated cumulative-frequency-distribution curves of daily solar radiation agreed well with the observed ones. The simulation results indicated that the exchange of sea water would have a great influence on the DO concentration, and that the concentration could change more than 1 mg/L in a day. This prediction method seems to be an effective way to examine a solution to minimize fishery damages when DO is depleted.

Animals↗
PubMed2001

Two stereoisomeric 3(I),2(II)-anhydro-alpha-cyclodextrins: a molecular dynamics and crystallographic study.

Regioselective epoxide ring opening of 2(I),3(I)-(2(I)S)-anhydro-alpha-cyclodextrin (1) through intramolecular attack of hydroxyl groups of neighboring glucose rings occurs in diequatorial fashion to yield 3(I),2(II)-anhydro-alpha-cyclodextrin (3) with a rigid glucopyranose-dioxane-glucopyranose tricyclic ring system, the usual diaxial opening and the gluco/altro-configured stereoisomer 2 cannot be detected. Molecular dynamic simulations in water were used to analyze the conformations of 1-3 and the stereochemical implications of this reaction. Due to the contracted 2,3-OH side of the torus, 3 features an inverted conicity compared to the parent alpha-cyclodextrin. A crystallographic study on the bis-3.3 n-PrOH nonahydrate not only displays little variations between the solid-state and solution geometries of 3, but also provides a molecular picture of a unique inclusion complex in which three n-propanol molecules are distributed in the cavity of a dimeric unit of 3 (monoclinic, space group P2(1), a=14.257(1), b=22.623(2), c=16.644(1) A, beta=104.82(1) degrees, all 19,278 reflections with I>2 sigma(I) yield R(F)=0.1017).

Computer Simulation↗
PubMed2001

Isolation and structural analyses of positional isomers of 6(1),6(n)-di-O-(N-acetyl-beta-D-glucosaminyl)cyclomaltoheptaose (n=2, 3, and 4) and 6-O-[6-O-(N-acetyl-beta-D-glucosaminyl)-N-acetyl-beta-D-glucosaminyl]cyclomaltoheptaose.

6-O-[6-O-(N-acetyl-beta-D-glucosaminyl)-N-acetyl-beta-D-glucosaminyl]cyclomaltoheptaose (beta CD) and three positional isomers of 6(1),6(n)-di-O-(N-acetyl-beta-D-glucosaminyl)cyclomaltoheptaose (n=2, 3, and 4) in a mixture of products from beta CD and N-acetylglucosamine by the reversed reaction of beta-N-acetylhexosaminidase from jack bean were isolated and purified by HPLC. The structures of four isomers of di-N-acetylglucosaminyl-beta CDs were determined by FABMS and NMR spectroscopy. The degree of polymerization of the branched oligosaccharides produced by enzymatic degradation with bacterial saccharifying alpha-amylase (BSA) was established by LC-MS methods.

Acetylglucosamine↗
PubMed2001

Role of human cytochrome P450 (CYP) in the metabolic activation of N-alkylnitrosamines: application of genetically engineered Salmonella typhimurium YG7108 expressing each form of CYP together with human NADPH-cytochrome P450 reductase.

The role of human cytochrome P450 (CYP) in the metabolic activation of N-alkylnitrosamines was examined by Ames test using genetically engineered Salmonella typhimurium (S. typhimurium)YG7108 cells expressing each form of human CYP together with human NADPH-cytochrome P450 reductase (OR). The relationship between the structure of N-alkylnitrosamines and CYP form(s) involved in the activation was evaluated. Eleven strains of S. typhimurium YG7108 cells expressing each form of CYP (CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4 or CYP3A5) were employed. Eight N-alkylnitrosamines including N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosodipropylamine (NDPA), N-nitrosodibutylamine (NDBA), N-nitrosomethylethylamine (NMEA), N-nitrosomethylpropylamine (NMPA), N-nitrosomethylbutylamine (NMBA) and N-nitrosoethylbutylamine (NEBA) were examined. Minimal concentration (MC) value of a promutagen was defined as the concentration of a chemical giving a positive result. Mutagen-producing capacity of CYP, as indicated by induced revertants/nmol promutagen/pmol CYP, for an N-alkylnitrosamine was determined for all forms of CYP. These N-alkylnitrosamines were mainly activated by CYP2E1, CYP2A6 and CYP1A1. N-alkylnitrosamines with relatively short alkyl chains such as NDMA and NMEA were primarily activated by CYP2E1 as judged by mutagen-producing capacity. With the increase of the number of the carbon atoms of the alkyl chains, the contribution of CYP2A6 increased. CYP2A6 played major roles in the activation of NDEA, NDPA, NMPA, NMBA and NEBA. Interestingly, CYP1A1 became a molecular form of CYP playing a major role in the metabolic activation of NDBA.

Aryl Hydrocarbon Hydroxylases↗
PubMed2001

Ventricular diverticulum at the posterior horn of the lateral ventricle presenting as aplasia cutis congenita.

Non-communicating hydrocephalus can cause rupture of the lateral or third ventricle, generally in the medial wall of the trigone or the posterior wall of the third ventricle, resulting in a cystic lesion known as ventricular diverticulum. In this paper, we describe a rare case of ventricular diverticulum located in the posterior horn of the lateral ventricle and expanding to bulge with a convexity reaching into the subdural space in a neonate. Aplasia cutis congenita and a bone defect were also present in the same neonate. Early surgical repair of the scalp defect and ventriculoperitoneal shunting were performed. In addition to illustrating the rare co-existence of a ventricular diverticulum at the posterior horn of the lateral ventricle and aplasia cutis congenita in a neonate, this case also offers new insights into the pathogenesis of these congenital anomalies.

Brain Diseases↗
PubMed2001

A factor of inducing IgE from a filarial parasite is an agonist of human CD40.

Immune responses to parasitic helminth are usually characterized by quite mysterious phenomena: dominance of Th2-like immunity and antigen-nonspecific IgE secretion. We previously purified a factor from Dirofilaria immitis that induces antigen-nonspecific IgE in rats and named it DiAg. In the presence of IL-4, DiAg induces mouse B cells to secrete IgE, which is antigen-nonspecific polyclonal antibody. We investigated the biochemical characteristics of DiAg as a factor of inducing IgE in this study. Recombinant DiAg (rDiAg) with interleukin (IL)-4 induced IgE synthesis in highly purified human normal B cells in vitro cell culture systems. The addition of recombinant human soluble CD40 IgG fusion protein (rsCD40-Ig) inhibited induction of IgE synthesis by rDiAg with IL-4. Monocyte cells were stimulated with rDiAg and recombinant human soluble CD40L (rsCD40L); IL-12 and TNF-alpha were induced. The addition of rsCD40-Ig to THP-1 cells activated with rDiAg and rsCD40L inhibited the production of IL-12. rDiAg bound to the monocyte cell membrane fraction and recombinant human soluble CD40; this binding of rDiAg was competitively inhibited by addition of rsCD40L. Moreover, in CD40-deficient mice, IgE production and MLN-B cell proliferation by rDiAg were completely absent. Based on these results, we concluded that DiAg is an agonist of CD40.

Animals↗
PubMed2001

Seroepidemiological survey of distemper virus infection in the Caspian Sea and in Lake Baikal.

Forty Caspian seals were surveyed seroepidemiologically between 1993 and 1998 around the times of mass mortality that occurred in 1997 in the Caspian Sea and seven Baikal seals were also surveyed in 1998. Virus neutralizing tests and ELISA clearly suggested that distemper virus epidemic was caused in Caspian seals before the spring of 1997 and that CDV infection continued to occur in Lake Baikal in recent years.

Animals↗
PubMed2001

A factor of inducing IgE from a filarial parasite prevents insulin-dependent diabetes mellitus in nonobese diabetic mice.

Parasitic helminth infections are characterized by eosinophilia and markedly elevated levels of circulating antigen-nonspecific immunoglobulin E (IgE), responses from which concern helminth protection. We previously purified a factor from Dirofilaria immitis that induces antigen-nonspecific IgE in mice and rats. Recombinant DiAg (rDiAg) has various biological activities. It is also known that parasitic helminth infection generates tremendous Th2 responses. The nonobese diabetic (NOD) mouse spontaneously develops Th1 cell-dependent autoimmune diabetes. Here we investigated the effects of rDiAg on the initiation and progression of this disease. rDiAg treatment of 6-week-old NOD females (the age at which insulitis typically begins) completely prevented insulitis and diabetes. Thus, rDiAg impaired the islet Ag-specific Th1 cell response in vivo, and the prevention of diabetes by rDiAg was associated with switching of the response from a Th1 to a Th2 profile. Since rDiAg clearly prevented insulitis by inhibiting the development and further accumulation of pathogenic Th1 cells to islets of Langerhans, we conclude that DiAg is a native Th2 inducer in filarial helminth and that Th1 responses are required for early events in the development of spontaneous autoimmune diabetes. In conclusion, the presence of parasitic helminth infections may play an important role as an immunomodulator in some autoimmune diseases or allergies.

Amino Acid Sequence↗
PubMed2001

Cooperative regulation of CYP3A5 gene transcription by NF-Y and Sp family members.

The purpose of this study was to clarify the mechanism(s) responsible for the transcriptional regulation of the human CYP3A5 gene. It was found that a region from nucleotides -90 to -40 was involved in the transcriptional activity of the CYP3A5 gene by transfection of a series of 5'-truncated promoter-luciferase chimeric genes into human hepatoma HepG2 cells. A gel shift assay using nuclear extracts prepared from HepG2 cells showed that nuclear factor-Y (NF-Y) and specificity protein (Sp) 1 and Sp3 bound to CCAAT box (-78/-68) and a basic transcription element (BTE) (-67/-46) in the CYP3A5 gene. Furthermore, introduction of mutations in the CCAAT box, the BTE, or both elements decreased the transcriptional activity to 10, 21, or 4% of that seen with the intact gene. Thus, we conclude that the transcription of the CYP3A5 gene is cooperatively regulated by NF-Y, Sp1, and Sp3 in HepG2 cells.

Base Sequence↗
PubMed2001

Inhibition by green tea catechins of metabolic activation of procarcinogens by human cytochrome P450.

Catechins, major polyphenol constituents of green tea, are potent chemopreventive agents against cancers caused by chemical carcinogens in rodents. The effects of four epicatechin derivatives, epigallocatechin gallate (EGCG), epicatechin gallate (ECG), epigallocatechin (EGC) and epicatechin (EC), on the metabolic activation of benzo[a]pyrene (B[a]P), 2-amino-1-methyl-6-phenylimidazo-[4,5-b]pyridine (PhIP) and aflatoxin B(1) (AFB(1)) by human cytochrome P450 (CYP) were examined. B[a]P, PhIP and AFB(1) were activated by respective human CYP1A1, CYP1A2 and CYP3A4 expressed in the membrane fraction of genetically engineered Salmonella typhimurium (S. typhimurium) TA1538 cells harboring the human CYP and human NADPH-CYP reductase (OR), when the membrane fraction was added to S. typhimurium TA98. Galloylated catechins, ECG and EGCG inhibited the mutagenic activation potently, while EGC and EC showed relatively weak inhibitory effects. Catechins also inhibited the oxidations of typical substrates catalyzed by human CYPs, namely ethoxycoumarin O-deethylation by CYP1A1, ethoxyresorufin O-deethylation by CYP1A2 and midazolam 1'-hydroxylation by CYP3A4. The IC(50) values of catechins for the inhibition of human CYP were roughly the same as those seen in the mutagenic activation. EGCG inhibited other forms of human CYP such as CYP2A6, CYP2C19 and CYP2E1, indicating the non-specific inhibitory effects of EGCG toward human CYPs. Furthermore, EGCG inhibited human NADPH-cytochrome CYP reductase (OR) with a K(i) value of 2.5 microM. These results suggest that the inhibition of the enzyme activity of CYP is accounted for partially by the inhibition of OR.

Aflatoxin B1↗
PubMed2001

A metabotropic glutamate receptor antagonist, alpha-methyl-4-carboxyphenylglycine, attenuates immediate early gene mRNA expression following traumatic injury in cultured rat cortical glial cells.

The effects of three glutamate receptor antagonists, (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]-cyclohepten-5,10-imine hydrogen maleate (MK-801) for the N-methyl-D-aspartate receptor, 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[f] quinoxaline-7-sulfonamide (NBQX) for the alpha-amino-3-hydroxy-5methyl-4-isoxazole propionate /kinate receptor and (S)-alpha-methyl-4-carboxyphenylglycine (MCPG) for the metabotropic receptor, on c-fos and c-jun mRNA expression were investigated in cultured cortical glial cells following traumatic scratch injury. Expression of the two genes along the edges of wounds detected by in situ hybridization was not affected by MK-801 and NBQX. However, 100 and 500 microM of MCPG remarkably reduced the hybridization signals for both c-fos and c-jun mRNAs. The present results suggest that group I metabotropic glutamate receptors might have some association with immediate early gene induction after in vitro traumatic injury in glial cells.

Animals↗
PubMed2001

Triethylborane-induced radical reactions with gallium hydride reagent HGaCl2.

[see reaction]. A gallium hydride reagent, HGaCl2, was found to act as a radical mediator, like tributyltin hydride. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source.

Journal Article↗
PubMed2001

Remote verification in radiotherapy using digitally reconstructed radiography (DRR) and portal images: a pilot study.

PURPOSE: To use digitally reconstructed radiography (DRR) and digitally compressed portal images in distant consultation using a telecommunications network, the verification performance of DRR and digitally compressed portal images on the image console was investigated. METHODS AND MATERIALS: A human thoracic phantom was scanned with computed tomography (CT). Radiotherapy was planned at 5 different anatomic locations. A digitally reconstructed radiograph was made; verification films of the phantom were then taken with 6-MV X-rays. The treatment center was intentionally dislocated. Fifty sets of DRR and portal images were seen by 7 doctors on a conventional view-box (view-box method) to judge whether the treatment center was dislocated. These image sets were digitalized by a film scanner, compressed to 1/10 Joint Photographic Experts Group (JPEG) format, and compared on an image console by the same physicians (image-console method). The verification performance of the image console method was compared with that of the view-box method by means of receiver operating characteristic (ROC) analysis. Clinically, 159 portal-image-sets were verified with the image-console method and the appropriateness of the decision was later assessed by the view-box method. RESULTS: The accuracy of the treatment verification was estimated to be 88.8% by the conventional view-box method and 88.3% by the image-console method. There was no statistically significant difference in the verification performances of the conventional method (Az = 0.86+/-0.02) and the image console method (Az = 0.84+/-0.07). Frequent digital image-processing modification was positively related to the accuracy of verification. Clinically, there were 3 (1.8%) major corrections, 31 (19.5%) minor corrections, and 123 cases with no correction. No further correction was called for by the re-evaluation using the view-box method. CONCLUSION: The verification performance of DRR and digitally compressed portal images on the image console was as accurate as the conventional method. Distant consultation using DRR and portal images through telecommunication is usable in clinical practice.

Humans↗
PubMed2001

Tryptophan-216 is essential for the transglycosylation activity of endo-beta-N-acetylglucosaminidase A.

Endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae (Endo-A) has a high level of transglycosylation activity. To determine which amino acids are involved in this activity, we employed deletion analysis, as well as random and site-directed mutagenesis. Using PCR random mutagenesis, 11 mutants with greatly decreased levels of enzyme activity were isolated. Six catalytically essential amino acids were identified by site-directed mutagenesis. Mutants E173G, E175Q, D206G, and D270N had markedly reduced hydrolysis activity, while mutants V109D, E173D, and E173Q lost all enzymatic activity, indicating that Val-109 and Glu-173 are important for the catalytic function. Moreover, we isolated a random mutation that abolished the transglycosylation activity without affecting the hydrolysis activity. The Trp-216 to Arg mutation was identified, by site-directed mutagenesis, as that responsible for the loss of transglycosylation activity. While other mutants of Trp-216 showed reduced activity, mutation to another positively charged residue (Lys) also abolished the transglycosylation activity. Sequence comparison with two other endo-beta-N-acetylglucosaminidases, that possess transglycosylation activity and that have been cloned recently, reveals a high degree of identity in the N-terminal regions of the three enzymes. These results indicate that the tryptophan residue at position 216 of Endo-A has a key role in the transglycosylation.

Amino Acid Sequence↗