Biomedical subjects

Y Azuma

Publications and source records attributed to Y Azuma.

At least 91 records · Page 5Linked to original sources

PubMed1998

Cholesterol-lowering effects of NTE-122, a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, on cholesterol diet-fed rats and rabbits.

Pharmacological characterization of NTE-122 (trans-1,4-bis[[1-cyclohexyl-3-(4-dimethylamino phenyl)ureido]methyl]cyclohexane), a novel acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, was performed with both in vitro and in vivo assay systems. NTE-122 inhibited microsomal ACAT activities of various tissues (liver of rabbit and rat, small intestine of rabbit and rat, and aorta of rabbit) and cultured cells (HepG2 and CaCo-2), with IC50 values from 1.2 to 9.6 nM. The inhibition mode of NTE-122 was competitive for HepG2 ACAT. NTE-122 had no effect on other lipid metabolizing enzymes, such as 3-hydroxy-3-methylglutaryl-CoA reductase, acyl-CoA synthetase, cholesterol esterase, lecithin:cholesterol acyltransferase, acyl-CoA:sn-glycerol-3-phosphate acyltransferase and cholesterol 7alpha-hydroxylase up to 10 microM. When NTE-122 was administered to the cholesterol diet-fed rats, serum and liver cholesterol levels were markedly reduced with an ED50 of 0.12 and 0.44 mg/kg/day, respectively. In the cholesterol diet-fed rabbits, NTE-122 significantly lowered plasma and liver cholesterol levels at more than 2 mg/kg/day. These results indicate that NTE-122 is a potent, selective and competitive inhibitor of ACAT, making it a worth while therapeutic agent for hypercholesterolemia and atherosclerosis.

1-Acylglycerol-3-Phosphate O-Acyltransferase↗

PubMed1998

[Predictability of Gleason score and reduction time (tau) of prostatic volume after castration for the prognosis of prostatic cancer].

PURPOSE: The efficacy of the reduction time (tau) after castration as a prognostic factor was examined by comparing to Gleason score. MATERIALS AND METHODS: The change of prostatic volume after castration was observed from the castration to 3 months after in 24 cases of prostatic cancer. Prostatic volume was examined by transrectal ultrasonography of the prostate. Survival curves was calculated by Kaplan-Meier method. Differences among survival curves were analyzed using Cox-Mantel test. RESULTS: tau had a close relationship to the prognosis of each case (Wilcoxon test: p < 0.05, Cox-Mantel test: p < 0.05). Gleason score had a weak relationship to prognosis (Wilcoxon test: N. S., Cox-Mantel test: p < 0.05). CONCLUSIONS: tau was efficient as prognostic factor compared to Gleason score.

Aged↗

PubMed1998

Effects of continuous alendronate treatment on bone mass and mechanical properties in ovariectomized rats: comparison with pamidronate and etidronate in growing rats.

Alendronate is a potent inhibitor of bone resorption. To investigate the relationship between antiresorptive activity and bone-related side effects, we studied the effect of 2 months of daily alendronate (0.04, 0.2, 1.0 or 5.0 mg/kg/day) treatment on the strength of the femoral shaft and neck and on the bone mass of ovariectomized rats. The p.o. administration regimen began immediately after ovariectomy at 6 weeks of age, and the results were compared with pamidronate (0.2, 1.0 or 5.0 mg/kg/day) or etidronate (5.0, 25.0 or 125.0 mg/kg/day) treatment. In the femoral epiphysis and neck, a preventive effect of alendronate on loss of bone mineral density was observed at the dose of 1.0 mg/kg. The alendronate-treated group did not show significant alteration of the breaking load or the cross-sectional shape of the femoral midshaft. Similar results were obtained in the femoral neck strength and femoral neck geometry. In histomorphometric analysis of tibial metaphyses, alendronate inhibited the ratio of osteoid volume to tissue volume and the mineral apposition rate at a dose of 0.2 mg/kg compared with the ovariectomized control. In contrast, etidronate tended to increase osteoid volume/bone volume at 125 mg/kg. From these results, we conclude that p.o. alendronate-treatment prevented the decrease in bone mineral density and maintained the mechanical properties of bone after ovariectomy without impairing of bone mineralization in growing rats.

Alendronate↗

PubMed1998

[SLE with interstitial pneumonia during cyclophosphamide pulse therapy].

A 49 year-old man was admitted for edema and renal impairment due to SLE. Since he did not improve with predonisolone and methylprednisolone pulse therapy, cyclophosphamide pulse therapy (300 mg div.) was administered. The patient subsequently developed a fever, dyspnea and cough, and interstitial regions of the lungs exhibited shadows on X-ray and CT. The patient also suffered hypoxemia and poor lung function. Since several culture tests and viral antibody tests were negative for infection, antibiotics were not effective, and TBLB indicated interstitial pneumonia, which we speculated was induced by cyclophosphamide. However, this was such a severe case of interstitial pneumonia that it could not be cured merely by discontinuing the cyclophosphamide, but it did improve immediately after starting methylprednisolone pulse therapy. The incidence of cyclophosphamide-induced interstitial pneumonia is very low, but the mortality rate is high. Since cyclophosphamide pulse therapy is often used to treat SLE, attention should be focused on the incidence of interstitial pneumonia.

Cyclophosphamide↗

PubMed1997

Association between the short-term natural history of diabetic macular edema and the vitreomacular relationship in type II diabetes mellitus.

PURPOSE: The authors ascertain the association between the short-term natural history of untreated diabetic macular edema and the vitreomacular relationship. METHODS: The authors prospectively studied 82 type II diabetic patients with clinically significant macular edema over a six-month period. They used multiple linear regression analysis to evaluate the effect of ten variables on the short-term natural history of macular edema 6 months after diagnosis: age; gender; diabetes duration at diagnosis of macular edema; hemoglobin A1; insulin use; presence of proteinuria; presence of systemic hypertension, cardiac disorders, or both; degree of diabetic retinopathy; history of panretinal photocoagulation; and vitreomacular relationships, as determined by present lens biomicroscopy. RESULTS: At study entry, 22 (27%) eyes had vitreomacular separation and 60 (73%) eyes did not. Macular edema spontaneously resolved in 27 (33%) eyes 6 months after diagnosis. Of the 22 eyes with vitreomacular separation at study entry, 12 (55%) had spontaneous resolution of macular edema after 6 months, whereas only 15 of 60 (25%) of the eyes with vitreomacular adhesion at study entry had spontaneous resolution (P = 0.01). Stepwise regression analysis indicated that vitreomacular separation (P = 0.01) and diabetes duration (P = 0.03) contribute to resolution of macular edema. Of the 27 eyes with resolved macular edema, 17 (63%) had improved visual acuity of more than two lines, whereas no eyes had improved visual acuity if macular edema persisted. The prevalence of improved visual acuity of more than two lines was significantly higher in eyes with vitreomacular separation at study entry (36%, 8/22) than in eyes without (15%, 9/60; P = 0.04). CONCLUSION: Our findings suggest that vitreomacular separation may promote the spontaneous resolution of diabetic macular edema and consequently improve visual acuity.

Adolescent↗

PubMed1997

Phosphorylation of Srp1p, the yeast nuclear localization signal receptor, in vitro and in vivo.

Srp1p, the protein encoded by SRP1 of the yeast Saccharomyces cerevisiae, is a yeast nuclear localization signal (NLS) receptor protein. We have previously reported isolation of a protein kinase from yeast extracts that phosphorylates Srp1p complexed with NLS peptides/proteins. From partial amino acid sequences of the four subunits of the purified kinase, we have now identified this protein kinase to be identical to yeast casein kinase II (CKII). It was previously thought that autophosphorylation of the 36 kDa subunit of the yeast enzyme was stimulated by the substrate, GST-Srp1p. However, with the use of a more refined system, no stimulation of autophosphorylation of the 36 kDa subunit of yeast CKII was observed. Biochemical and mutational analyses localized the in vitro phosphorylation site of Srp1p by CKII to serine 67. It was shown that, in the absence of NLS peptides/proteins, phosphorylation of the intact Srp1p protein is very weak, but deletion of the C-terminal end causes great stimulation of phosphorylation without NLS peptides/proteins. Thus, the CKII phosphorylation site is apparently masked in the intact protein structure by the presence of a C-terminal region, probably between amino acids 403 and 516. Binding of NLS peptides/proteins most likely causes a change in protein conformation, exposing the CKII phosphorylation site. Mutational alterations of serine 67, the CKII phosphorylation site, to valine (S67V) and aspartic acid (S67D) were not found to cause any significant deleterious effects on cell growth. Analysis of in vivo phosphorylation showed that at least 30% of the wild type Srp1p molecules are phosphorylated in growing cells, and that the phosphorylation is mostly at the serine 67 CKII site. The ability of Srp1p purified from E coli and treated with calf intestinal phosphatase to bind a SV40 T-antigen NLS peptide was compared with that of Srp1p which was almost fully phosphorylated by CKII. No significant difference was observed. It appears that NLS binding does not require any phosphorylation of Srp1p, either by CKII or by some other protein kinase.

Amino Acid Sequence↗

PubMed1997

Positive correlation between prolonged potentiation of binding of double-stranded oligonucleotide probe for the transcription factor AP1 and resistance to transient forebrain ischemia in gerbil hippocampus.

Gel retardation electrophoresis revealed that binding of a radiolabelled double-stranded oligonucleotide probe for the nuclear transcription factor activator protein-1 was markedly potentiated in the CA1 and CA3 subfields and the dentate gyrus of the hippocampus of the gerbils with transient forebrain ischemia for 5 min, which is known to induce delayed death of pyramidal neurons exclusively in the CA1 subfield. The potentiation was transient in the vulnerable CA1 subfield, but persistent up to 18 h in the resistant CA3 subfield and dentate gyrus. However, no significant alteration was detected in endogenous levels of cyclic AMP response element binding protein phosphorylated at serine133 in these three different hippocampal structures 3 h after the reperfusion. On the other hand, hypothermia during ischemia which is known to protect the CA1 subfield against ischemic damages, led to a prolonged elevation of the activator protein-1 binding up to 9 h after the reperfusion in this vulnerable subfield at least in part through expression of c-Fos protein. Moreover, activator protein-1 binding was significantly elevated in the CA1 subfield up to 12 h after forebrain ischemia for 2 min which is shown not to induce marked damages to the vulnerable subfield. These results suggest that prolonged elevation of DNA binding activity of activator protein-1 may be responsible for molecular mechanisms underlying the unique vulnerability and/or resistance of particular subfields to a transient ischemic insult in the gerbil hippocampus.

Adaptor Protein Complex 1↗

PubMed1997

Inhibition by anti-RCC1 monoclonal antibodies of RCC1-stimulated guanine nucleotide exchange on Ran GTPase.

Nine monoclonal antibodies to RCC1, the guanine nucleotide exchange factor on Ran GTPase, were obtained using recombinant RCC1 as the antigen. Epitopes of three monoclonal antibodies, which did not inhibit RCC1 function, were localized in the N-terminus outside the RCC1 repeat, while epitopes of the other 6 monoclonal antibodies were localized within the RCC1 repeat. Three of the latter 6 monoclonal antibodies, 2B6, 6C3, and 8D9, inhibited RCC1-stimulated nucleotide release. Two of them, 2B6 and 6C3, recognized the same amino acid residues in the N-terminus of the second RCC1 repeat, Tyr89, Ser90, Phe91, and Gly92, of which one, Gly92, is conserved in Saccharomyces cerevisiae and mutated in an rcc1(-) strain, mtr1-2. The monoclonal antibody 8D9 recognized two amino acid residues, Arg320 and Ala321, downstream of Gly319 in the N-terminus of the 6th RCC1 repeat, which corresponds to Gly92 in the second RCC1 repeat. The monoclonal antibodies which inhibited RCC1 function bound to RCC1 in homogeneous solution and stained cellular RCC1. We propose that the N-terminus of the RCC1 repeat is exposed at the surface of RCC1 on the coated plate or in fixed cells, and is involved in the RCC1-stimulated nucleotide exchange on the Ran GTPase.

Amino Acid Sequence↗

PubMed1997

A candidate case for lymphocytic infundibulo-neurohypophysitis mimicking a neurohypophysial tumor.

A 56-year-old Japanese man presented with a 2-month duration of polyuria and polydipsia. The diagnosis of diabetes insipidus was confirmed by water deprivation and vasopressin injection. The secretory function of the adenohypophysis was estimated as normal by a variety of provocative tests. Magnetic resonance imaging (MRI) displayed the loss of the hyperintense signal of the neurohypophysis and a tumor-like lesion confined to the neurohypophysis. The tissue specimen resected at transsphenoidal surgery showed diffuse lymphocytic infiltration. These findings suggest that this is a candidate case for lymphocytic infundibuloneurohypophysitis (LIN) that is not identical to classical lymphocytic hypophysitis. This patient will be followed up to determine whether this case simply represents an early stage of classical hypophysitis or a different clinical entity.

Diabetes Insipidus↗

PubMed1997

The effect of occlusal appliances and clenching on the temporomandibular joint space.

It has been suggested that stabilization appliances and mandibular anterior repositioning appliances work by decompressing the temporomandibular joint. To indirectly test this assumption, tomograms of right temporomandibular joints of seven subjects were taken during comfortable closure and maximum clenching in maximum intercuspation and on the two types of occlusal appliances. Outlines of the condyle and the temporal fossa were automatically determined by an edge detection protocol. Upon comfortable closure, the anterior joint space dimension was reduced with stabilization appliances and mandibular anterior repositioning appliances. Upon maximum clenching, the minimum joint space dimension on stabilization appliances was equivalent to that seen in maximum intercuspation, while that on mandibular anterior repositioning appliances was substantially less (P < .05). Findings do not indicate that these appliances induce an increase in joint space during clenching.

Adult↗

PubMed1997

[Interstitial tubercle in Chinese and Japanese young adults]

A comparative study on the incidence of interstitial tubercle from standardized stone casts of 160 Chinese and 190 Japanese young adults,ages from 20-30.The following results were obtained:(1)No significant difference in the incidence of interstitial tubercle on maxillary first premolar between Chinese and Japanese groups(P>0.05),but on maxillary second premolar,Japanese is higher than Chinese(P<0.05).(2)The incidence of interstitial tubercle on maxillary first premolar is higher than second premolar in two groups(P<0.05).(3)The intestitial tubercle occurs in unilateral more frequently than in bilateral.The incidence of maxillary first premolar in mesial of occlusal is higher than in distal.No difference between mesial and distal on occlusal of maxillary second premolar in the Chinese group,and the incidence in mesial is higher than in distal in the Japanese group.

Journal Article↗

PubMed1997

Sequence-selective RNA scission by oligoamine--DNA conjugates (1).

Ethylenediamine and diethylenetriamine, which are active for RNA hydrolysis, are attached to the 5'-ends of synthetic oligonucleotides by urethane linkages. The resultant artificial ribonucleases selectively hydrolyze the substrate RNA at the target phosphodiester linkage. Acid/base cooperation in the oligoamines for the catalysis is confirmed in terms of kinetic evidences.

Base Sequence↗

PubMed1996

Dis3, implicated in mitotic control, binds directly to Ran and enhances the GEF activity of RCC1.

Using the two-hybrid method, we isolated a Saccharomyces cerevisiae cDNA encoding a protein homologous to Schizosaccharomyces pombe protein Dis3sp, using as bait, human GTPase Ran. The DIS3 gene is essential for viability and complements S.pombe mutant dis3-54 which is defective in mitosis. Although Dis3sc has no homology to RanBP1, it bound directly to Ran and the S.cerevisiae Ran homologue Cnr1, but not to the S.cerevisiae RCC1 homologue Srm1. Upon binding to Ran with a 1:1 molar ratio, Dis3sc enhanced a nucleotide-releasing activity of RCC1 on Ran. In the presence of Dis3sc, the K(m) of RCC1 on Ran decreased by half, while the kcat was unchanged. In vivo, Dis3sp was present as oligomers of M(r) 670-200 kDa as previously reported, and the 200 kDa oligomer of Dis3sp was found to include Spi1 and Pim1, the S.pombe homologues of Ran and RCC1, respectively. Although the biological function of the heterotrimeric oligomer consisting of Dis3, Spi1 and Pim1 is unknown, our results indicate that Dis3 is a component of the RCC1-Ran pathway.

Amino Acid Sequence↗

PubMed1996

Change in electric characteristics of membranes in response to taste stimuli with increasing amount of lipids in membrane matrix of PVC and plasticizer.

Changes in membrane electric potential in response to taste substances were studied for membranes containing differing amounts of negatively charged lipids in the membrane matrix of polyvinyl chloride and plasticizer. Responses to quinine showing bitterness decreased systematically with increasing the quantity of charged lipids contained in the membrane, whereas the response did not depend on differences in the hydrocarbon chains of lipids. The mechanism is discussed qualitatively in terms of hydrophobicity and hydrophilicity of the membranes.

Journal Article↗

PubMed1996

Premature chromatin condensation induced by loss of RCC1 is inhibited by GTP- and GTPgammaS-Ran, but not GDP-Ran.

RCC1 is a guanine nucleotide exchanging factor acting on nuclear G protein Ran. Premature chromatin condensation occurs in the temperature-sensitive rcc1- mutant of the BHK21 cell line, tsBN2, at the restrictive temperature. This observation can be explained if the premature activation of MPF is normally inhibited by GTP-Ran. In the absence of RCC1, GDP-Ran predominates, resulting in MPF activation. However, experiments with Ran mutants to determine whether GTP- or GDP-Ran prevents activation of MPF have yielded conflicting results. In order to clarify this point, we have microinjected nucleotide-bound Ran, instead of mutated Ran, into the nuclei of tsBN2 cells treated to reduce RCC1-mediated guanine nucleotide exchange. GTP-Ran, GTPgammaS-Ran, and GDP-Ran all inhibited chromatin condensation. However, the inhibition of chromatin condensation by GDP-Ran could be completely abolished by co-injection with GDP, but not GTP. Thus, we conclude that GTP-Ran blocks the activation of MPF and that hydrolysis of GTP is not required to prevent MPF activation.

Animals↗

PubMed1996

Simultaneous determination of binding of a variety of radioligands related to ionotropic excitatory amino acid receptors in fetal and neonatal rat brains.

Expression of ionotropic excitatory amino acid receptors was assessed by membrane binding assays using a variety of radioligands in fetal and neonatal rat brains. In fetal rat brain, receptors sensitive to N-methyl-D-aspartate (NMDA) exhibited delayed onset of expression during the last 7 days before birth as compared with those insensitive to NMDA. In addition, developmental increases in agonist-preferring sites preceded those in antagonist-preferring sites within the first 7 postnatal days in particular brain structures with respect to each domain on the NMDA receptor complex. Growth of animals led to drastic increments of [3H](+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d] cyclohepten-5,10-imine (MK-801) binding to the NMDA channel in telencephalic regions until 21 to 28 days after birth, with concomitant desensitization to inhibition by protons of [3H]MK-801 binding in cortical membranes. By contrast, three different agonists were invariably effective in more potently potentiating [3H]MK-801 binding in cortical membranes of 14- and 28-day-old rats than in those of 5-day-old rats. These results suggest that the NMDA-sensitive subclass may play more critical roles in mechanisms underlying postnatal development of rat telencephalon than do the NMDA-insensitive subclasses.

Animals↗

PubMed1996

In vivo microautoradiography of [3H]1,24(OH)2D3 (tacalcitol) following topical application to normal rats and in vitro metabolism in human keratinocytes.

This study was conducted to investigate the mechanism of topical absorption of [3H]1,24(OH)2D3 (1,24-dihydroxyvitamin D3; tacalcitol) by applying an ointment containing 4 micrograms2/g [3H]1,24(OH)2D3 to the skin of rats using an occlusion method. Microautoradiography of the skin at the application site 1 h after topical treatment showed a high concentration of radiolabel in the stratum corneum, the epidermis and around the hair follicles. Radiolabel was also seen in the epidermis and hair follicle areas 8 h and 24 h after application. The radiolabel was distributed to a minor extent to the subcutaneous fat layer. Microautoradiography showed two routes of purcutaneous absorption of 1,24(OH)2D3: through the stratum corneum and epidermis into the microvessels, and through hair follicle areas into the bloodstream. After topical application of an ointment containing 4 micrograms/g or 40 micrograms/g [3H]1,24(OH)2D3 to the shaved neck skin of rats, the absorption rate, estimated by excretion in the urine and faeces, was about 30% of the total applied radioactivity. The main excretion route after topical application was in the faeces. Furthermore, 1,24(OH)2D3 added to human adult keratinocytes was not metabolized into other compounds, and only the unchanged compound was detected. These findings strongly suggest that 1,24(OH)2D3 distributed into the epidermis acts on epidermal keratinocytes. Topical application of 1,24(OH)2D3 appears to be a possible approach to the treatment of psoriasis and other skin diseases through its action on the 1,25(OH)2D3 receptor, which reportedly plays a very important role in the regulation of proliferation and differentiation of keratinocytes.

Absorption↗

PubMed1996

Differentiation by magnesium ions of affinities of nuclear proteins for consensus core nucleotide element of the transcription factor c-Myc in murine brain.

The addition of divalent cations such as Mg(2+) and Ca(2+) ions markedly reduced binding of a radiolabeled double stranded oligonucleotide probe for the transcription factor c-Myc in the presence of 100 mM KCl in nuclear extracts of the mouse whole brain. Irrespective of the addition of MgCl(2), binding was selectively competed with the unlabeled probe for c-Myc having a double stranded conformation. Treatment with V8 protease differentially modulated binding of the probe for c-Myc determined in the presence and absence of added MgCl(2). Introduction of irreversible covalent bonding between the radiolabeled probe and nuclear proteins led to retarded mobility of the radioactive probe/protein complex in the presence of MgCl(2) on sodium dodecyl sulfate electrophoresis regardless of treatment with DNase. However, an antibody against the c-Myc protein affected neither mobility nor intensity of the radioactive band on gel retardation electrophoresis. Moreover, regional distribution was different from each other in mouse brain when determined in the presence and absence of added MgCl(2). These results suggest that magnesium ions may have an ability to differentiate between nuclear c-Myc family proteins with different affinities for the consensus core nucleotide element CACGTG in murine brain.

Animals↗