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Biomedical subjects

Y Tamura

Publications and source records attributed to Y Tamura.

At least 451 records · Page 25Linked to original sources
PubMed1991

Inhibition of human immunodeficiency virus forward and reverse transcription by PC6, a natural product from cones of pine trees.

We have previously shown that PC6, a natural product extracted from cones of Pinus parviflora Sieb et Zucc, can inhibit the replication of human immunodeficiency virus type 1 (HIV-1) in CD4+ T cells and in monocyte/macrophage cell lines. Here, we show by immunoprecipitation of HIV-1 proteins with a specific pooled serum that PC6 inhibited the expression of all HIV-1 proteins in CEM cells. PC6 did not affect the posttranslational processing of the HIV-1 proteins. Northern, Southern, and kinetics analyses revealed that PC6 inhibited HIV-1 reverse and forward transcription in CEM cells. Transient transfection of CEM cells with HIV-1 long terminal repeat (LTR) linked CAT DNA also showed that PC6 inhibited LTR-driven gene expression at the transcriptional level.

Antiviral Agents↗
PubMed1991

Vitamin B-12 deficiency increases the specific activities of rat liver NADH- and NADPH-linked aquacobalamin reductase isozymes involved in coenzyme synthesis.

Rat liver contains both NADH- and NADPH-linked aquacobalamin reductases, which are involved in the synthesis of the vitamin B-12 coenzymes and are distributed in both the mitochondrial and microsomal membranes. To clarify the physiological roles of these hepatic enzymes, vitamin B-12-deficient rats were used to study the effect of the deficiency on the enzyme activities. Male rats fed a vitamin B-12-deficient diet for 11 wk developed a severe vitamin B-12 deficiency with a high urinary methylmalonate excretion (214.3 +/- 115.2 mumol/d) and approximately 96% lower hepatic vitamin B-12 content. Tissues of the vitamin B-12-deficient rats were assayed for NADH- and NADPH-linked aquacobalamin reductase activities. The specific activities of both enzymes in homogenates of liver, kidney or upper intestine were shown to be three- to 20-fold greater in the vitamin-deficient rats than in the control rats. In liver, the vitamin deficiency specifically elevated the specific activities of the mitochondrial NADH-linked and microsomal NADPH-linked enzymes. These are likely the isozymes involved in vitamin B-12 coenzyme synthesis.

Animals↗
PubMed1991

A high frequency of detection of Helicobacter pylori in whitish exudate of gastric ulcer.

Helicobacter pylori has been implicated in the pathogenesis of chronic gastritis and peptic ulcer. However, no report to date has been made on the presence of H. pylori in the whitish exudate of peptic ulcers. We examined the biopsy specimens of 52 patients (42 men and 10 women, aged 29-78, not taking steroids or nonsteroid antiinflammatory drugs), and evaluated the frequency of detecting the organism in the whitish exudate of gastric ulcers in comparison with that in the ulcer border, gastric fundic gland, and pyloric gland using microaerobic culture and acridine-orange stain. H. pylori was detected in high rates: 38 (73%) of 52 cases by culture, and 50 cases (96%) by staining of the whitish exudate, 42 (81%) of 52 cases by culture, and 46 cases (88%) by staining of the ulcer border. The frequency for the other regions were 81% by culture and 90% by staining of the fundic gland, and 81 and 90% of the pyloric gland, respectively. Of all sites studied by the staining method, H. pylori was detected at the highest frequency in the whitish exudate. The fact that many H. pylori live in the whitish exudate of gastric ulcer, suggests a causal relationship between H. pylori and gastric ulcer.

Acridine Orange↗
PubMed1991

Cardioprotective effects of amlodipine in animal models of ischemia and reperfusion.

The protective effect of amlodipine was studied in isolated blood-perfused cat hearts made globally ischemic for 60 min followed by reperfusion for 60 min. Ischemia-induced alterations of left ventricular developed pressure and compliance were monitored. Amlodipine produced significant decreases in myocardial oxygen consumption (6.2 +/- 0.4 to 4.4 +/- 0.4 ml of oxygen/min/100 g) and coronary vascular resistance, as assessed by changes in perfusion pressure (120 +/- 1 to 100 +/- 4 mm Hg). When administered before the onset of global ischemia, amlodipine decreased the development of ischemic contracture as reflected by a progressive increase in resting left ventricular diastolic pressure. The return of contractile function, 60 min after reperfusion, was improved significantly in amlodipine-treated hearts compared to controls and there was better maintenance of the tissue concentration of Na+, Ca2+, and K+. In a canine model of regional myocardial ischemia (6 h) followed by reperfusion, amlodipine at 150 microg/kg, administered 15 min before reperfusion (90 min), reduced infarct size expressed as a percentage of the area at risk (34.5 +/- 3.8% vs. 45.9 +/- 2.8%, p = 0.027). We conclude that amlodipine reduces myocardial ischemic injury by mechanism(s) that may involve a reduction in myocardial oxygen demand as well as by positively influencing transmembrane Ca2+ fluxes during ischemia and reperfusion.

Amlodipine↗
PubMed1991

Cardiovascular and renin responses to desmopressin in humans: role of prostacyclin and beta-adrenergic systems.

To investigate the involvement of prostacyclin and the sympathetic nervous system in cardiovascular responses to 1-desamino-8-D-arginine vasopressin (DDAVP), a selective V2-receptor agonist, in normal subjects, DDAVP (0.4 micrograms/kg) was infused with or without indomethacin, a cyclooxygenase inhibitor, or propranolol, a beta-adrenoceptor antagonist. A decrease in blood pressure and increases in pulse rate and plasma renin activity (PRA) were observed by DDAVP infusion. Indomethacin did not influence the DDAVP-induced changes in blood pressure and pulse rate but suppressed the increases in PRA and urinary 6-ketoprostaglandin F1 alpha excretion after DDAVP infusion. Even with propranolol administration, DDAVP produced a similar decrease in blood pressure with a reduction of the increased pulse rate. The DDAVP-induced increase in PRA was not affected either. Indomethacin or propranolol alone did not affect the basal levels of the parameters. DDAVP stimulated the in vitro renin release from rabbit renal cortical slices. The stimulation was inhibited by indomethacin or d(CH2)5[D-Ile2,Ile4]AVP, a selective V2-receptor antagonist. These findings suggest that DDAVP primarily elicits vasodilation, probably through the prostacyclin-independent endothelium-derived relaxation and DDAVP also causes an increase in renin release, which would be partly attributed to the increased synthesis of prostacyclin due to vasculoendothelial V2-like receptor activation but not mainly due to an increase in sympathetic nerve activity.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

Long-term administration of highly purified eicosapentaenoic acid provides improvement of psoriasis.

Nine patients with chronic stable psoriasis (4 males and 5 females) were entered in this trial. Eicosapentaenoic acid (EPA) ethylester (90% pure) without docosahexaenoic acid (DHA) in gelatin-coated capsules at a daily dose of 3.6 g was administered to 9 patients for 3 months, 7 patients for 6 months and 6 patients for 12 months. The clinical changes of skin lesions of the patients with 12 months of treatment were as follows: marked improvement 1, improvement 3, relative improvement 1, no change 1. A clinical improvement of skin lesions was first observed 2-3 months after EPA treatment. The supplementation of highly purified EPA caused a significant increase in the content of plasma EPA and docosapentaenoic acid without affecting that of arachidonic acid (AA) and DHA. EPA decreased the production of leukotriene B4 (LTB4) and increased the formation of leukotriene B5 (LTB5) and 5-hydroxyeicosapentaenoic acid significantly in A23187-stimulated neutrophils. The LTB5/LTB4 ratio positively correlated with the plasma EPA/AA ratio and was directionally related to the clinical score, although the directional data were not statistically significant. We could not observe any side effects of EPA over 1 year. Although its effects are modest, it is nontoxic and its favorable effect appears to continue for the duration of its usage, indicating that EPA could be beneficial for the long-term treatment of psoriasis.

Adult↗
PubMed1991

Sudden appearance of coronary thrombus observed by angiography--a case report.

A sudden coronary thrombus formation was documented by chance during cardiac catheterization in a patient with postinfarction angina. The thrombus was successfully treated with intravenous urokinase and heparin infusions, and thereafter, coronary angioplasty was performed without any complication.

Angina, Unstable↗
PubMed1991

Aortitis syndrome, coronary artery ectasia, and mid-ventricular obstruction.

A 46-year-old Japanese woman, who had been diagnosed as having aortitis syndrome 4 years earlier, was admitted to our hospital in May 1989. The diagnosis of aortitis syndrome was confirmed by intravenous digital subtraction angiography which showed stenotic lesions in each subclavian artery, the left common carotid artery, and the descending aorta. Coronary arteriography revealed diffuse and prominent dilatation of entire coronary artery segments. Moreover, a left ventriculogram showed complete obstruction of the mid-ventricle during systole. Thus, we diagnosed this case as aortitis syndrome complicated by coronary artery ectasia and mid-ventricular obstruction. The causal relations of these findings are discussed.

Adult↗
PubMed1991

Potent bactericidal activity of bovine lactoferrin hydrolysate produced by heat treatment at acidic pH.

A hydrolysate of bovine lactoferrin produced by heat treatment under acidic conditions had antibacterial activity at concentrations of 10 micrograms/ml in the culture medium. The optimal degree of hydrolysis for this activity was about 10%. Heat-treated lactoferrin, treated at pH 2.0 and 120 degrees C for 15 min and degree of hydrolysis of about 10%, had no Fe-binding capacity (0%) and less antigenicity (about 10(-6) than untreated lactoferrin. Heat-treated lactoferrin increased in antibacterial activity, and the activity was maintained in an Fe-rich medium. After fractionation of heat-treated lactoferrin by reverse-phase HPLC, several peptide fractions were found that had strong antibacterial activity. It was suggested that lactoferrin latently contains at least one bactericidal domain that is activated upon release by limited acid hydrolysis of the protein. The bactericidal activity of the peptide fragments of lactoferrin was shown to have no relation to Fe chelation, in contrast with the antibacterial mechanism of native lactoferrin.

Animals↗
PubMed1991

[Clinical study of operative therapy for renal cell carcinoma. 1. Nephrectomy].

A study was made on treatment-related factors, notably prognosis, in 148 patients treated by surgical resection of the primary lesion among 170 consecutive patients who were admitted to the Department of Urology, Gunma University for the treatment of renal cell carcinoma during the period from September 1961 through August 1989. Operative procedures used in this series were radical nephrectomy in 100 patients, simple nephrectomy in 46, partial nephrectomy in 1 and tumor enucleation in 1, lymph node dissection being performed in 53 of the 100 patients treated by radical nephrectomy. The patients receiving surgical resection of the primary lesion were stratified according to sex, PS, disease stage, surgical procedure, lymph node dissection and weight of renal substance resected and comparisons were made on survival rate and recurrence rate among patients in different strata in an effort to observe if these factors are determinant of postoperative prognosis. No significant difference in survival rate was observed between sexes. Patients displaying a PS value of 0 had a significantly higher survival rate than those having a PS value of 1 or above. Whereas a significant difference in survival rare was noted between stage IIIA + IIIB + C disease patients, no significant difference was observed among stage I, II and III patients, thus stages up to IIIA being considered low stage. Radical nephrectomy was associated with a significantly higher survival rate than simple nephrectomy in low stage (stage I-II) disease patients. However, there was no significant difference in survival rate between stage I-II disease patients with vs. without lymph node dissection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[The quantitative evaluation of myocardial blood flow and myocardial FDG uptake in the infarcted lesions with Q-wave and without Q-wave determined by O-15 water, FDG and PET].

Cardiac PET elicits an accurate relationship between myocardial blood flow (MBF) and tissue viability, which is evaluated by myocardial FDG uptake (MFU). To differentiate reversible tissue from necrotic tissue after the ischemic event, we from necrotic tissue after the ischemic event, we measured absolute MBF and MFU in patients with myocardial infarction. The MBF obtained by O-15 water and dynamic PET was accurately corrected by employing a tissue fraction (a) for the partial volume effect, including wall-motion effect. MFU was also corrected by using the tissue fraction. The subjects consisted of 5 patients with non-Q-wave infarction and 7 patients with Q-wave infarction. The regions of interest were selected from the infarcted area, each corresponding to regions with Q-wave or non-Q-wave. The MBFs in regions with Q wave (0.36 +/- 0.14 ml/min/g) were lower than those without Q wave (0.74 +/- 0.29 ml/min/g) (p less than 0.005). MFUs in regions without Q-wave (0.061 +/- 0.028) were higher than those with Q-wave (0.038 +/- 0.017) (p less than 0.05). The highest threshold of MBF in regions where Q-wave was detected was 0.55 ml/min/g. It is concluded that we will able to find the threshold of electrophysiological dysfunction in the infarcted region with this method.

Aged↗
PubMed1991

Characterization of antisense DNA derivatives having stereoisomeric linkages.

The isomer separation of oligonucleoside phosphoramidates (OPA) by RPLC was studied. All stereoisomers of OPA-tetramer (dATCG) modified with isopropylamine could be separated and they showed different CD spectra each other. OPA-decamer (dGGGCATCGTC) modified with 3-amino-1-propanol could be separated into five fractions. Each fraction was found to have different ability to form hybrids with its complementary oligonucleotide, indicating that it is possible to exclude stereoisomers which can hardly bind to target nucleic acids.

Amides↗
PubMed1991

Unusual signal broadening in NMR of oligonucleotides.

Solution structure of single-stranded small oligonucleotides (up to pentamer) has been studied by 1H-NMR (600 MHz) and it has been found that when those having some specific base sequences produce unusual broadening of the lines attributed to the protons of guanine residues. These broadened signals did not become sharp even at elevated temperature. This extremely unusual behavior has been attributed to the interaction between the guanine residues.

Hydrogen-Ion Concentration↗
PubMed1991

[Elevation of 11-dehydro-thromboxane B2 levels in unstable angina].

To evaluate in vivo platelet activation, 11-dehydro-thromboxane B2 levels in plasma and urine were measured in 9 patients with unstable angina and 11 with stable angina using radioimmunoassay modified by the extraction method of Kawano et al. The 2 groups were matched for age, sex, coronary risk factors, medications or atherosclerotic lesions in coronary angiography. Although there was no difference in the plasma level between the 2 groups in the usual state, urinary 11-dehydro-thromboxane B2 amount in unstable angina was significantly increased compared to the stable angina group (865.5 +/- 238.7 vs 535.9 +/- 177.4 pg/mg creatinine (mean +/- SD), p < 0.01). There was no correlation between the 11-dehydro-thromboxane B2 level and the degree of coronary atherosclerosis in either group. The plasma level increased during the attacks in 2 patients with unstable angina. The amount of urinary 6-keto-PGF1 alpha did not differ between the 2 groups. These findings suggest that platelet activation in vivo is more pronounced in unstable angina than in stable angina, and that the measurement of urinary 11-dehydro-thromboxane B2 may be useful for evaluating and treating angina.

Angina Pectoris↗
PubMed1991

Tissue distribution of type VIII collagen in human adult and fetal eyes.

The type VIII collagen tissue distribution in human adult (32-78 yr of age) and fetal (16-27 weeks of gestation) eyes was studied immunohistochemically using a monoclonal antibody to type VIII collagen. Type VIII collagen was distributed in a linear or fibrous fashion in adult eyes in Descemet's membrane of the cornea, the trabecular meshwork, the walls of Schlemm's canal, Bruch's membrane, the choroidal stroma, the sclera, the cribriform plates of the optic nerve, and the intima of the central retinal artery. The staining in the central retinal artery was similar to that of type IV collagen. No distinct positive staining was seen in other blood vessels. When fetal eyes were examined, significant differences in positive staining were found between adults and fetuses in the sclera. In fetal eyes, the posterior sclera was strongly stained; however, the positive staining gradually decreased, and in the equatorial area it disappeared. The cribriform plates of the lamina cribrosa and the presumptive Bruch's membrane in fetal eyes did not react with the antibody. The trabecular meshwork and Descemet's membrane, but no other part of anterior section of fetal eyes, reacted with the antibody.

Adult↗