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Biomedical subjects

J Azuma

Publications and source records attributed to J Azuma.

126 records · Page 7Linked to original sources
PubMed1977

Studies on pig serum lipoproteins. IV. Isolation and characterization of glycopeptides from pig serum low density lipoprotein.

Three glycopeptides were isolated from the pronase digest of the protein moiety of pig serum low density lipoprotein. The isolation procedure consisted of pronase digestion, gel filtration on Sephadex G-25 and G-50 columns, paper chromatography and DEAE-Sephadex A-50 column chromatography. Based on the carbohydrate analysis, the isolated glycopeptides were classified into two types. One type (GDI) consisted of mannose and N-acetylglucosamine residues in the molar ratio of 6:2 and had a molecular weight of about 2,300. The other type (GDII and GDIII) consisted of sialic acid, mannose, galactose, fucose, and N-acetylglucosamine residues in the molar ratio of 1:4:2:1:3 and 2:4:3:1:3, respectively. The molecular weights of GDII and GDIII were about 2,100 and 3,100, respectively. The results on the strong alkaline treatment of these glycopeptides suggested that all carbohydrate chains were linked to the peptide chains through N-acetylglucosaminyl-asparagine linkages. Of these glycopeptides and pig serum lipoproteins, only glycopeptide GDI and native LDL strongly interacted with concanavalin A.

Amino Acids↗
PubMed1977

A correlative study on the changes of cardiac dynamics and myocardial energy liberation in blood-let dogs.

Blood-letting of 450 to 1,000 ml with or without saline infusion was performed in dogs. In some dogs, right atrial pacing was carried out during blood-letting. Heart rate and isometric time-tension index were measured as the indicators of chronotropism and inotropism, respectively. After 60 min of blood-letting, dogs were sacrificed and mitochondria were isolated from the left ventricular myocardium. Mitochondrial respiration was measured polarographically and respiratory control index was calculated. As blood-letting advanced, the hearts revealed negative chronotropism with negative inotropism. Mitochondrial respiration was suppressed. When heart rate was forced to increase with atrial pacing, the hearts showed positive chronotropism with negative inotropism. Respiratory control index of mitochondria was deteriorated, showing uncoupling of oxidative phosphorylation. In consideration with our previous study on the ischemic heart, it is concluded that uncoupling of oxidative phosphorylation appeared in hypoxic myocardium when cardiac dynamics shifted to positive chronotropism with negative inotropism, though suppression of mitochondrial respiration was revealed when cardiac dynamics altered to negative chronotropism with negative inotropism.

Animals↗
PubMed1976

Vitamin B6 deficiency in patients with a clinical syndrome including the carpal tunnel defect. Biochemical and clinical response to therapy with pyridoxine.

Ten individuals having a severe clinical status associated with the carpal tunnel syndrome were selected for treatment with pyridoxine. The status of vitamin B6, as pyridoxal phosphate, was determined by the specific activities of the glutamic oxaloacetic transaminase of the erythrocytes (EGOT). Before treatment, the patients showed a deficiency of vitamin B6 as determined by 1) a comparison of the specific activities of EGOT with those of a control group (P less than 0.001); and 2) a differential assay based upon the principle of unsaturation and saturation of a Coenzyme-Apoenzyme System (CAS), as applied to EGOT. These patients were treated with pyridoxine, and the specific activities of EGOT were determined after 2 and 4 weeks. Not only was there a disappearance of the deficiency of pyridoxal phosphate, but the level of EGOT activity increased 55-68% during 2-4 weeks, respectively. More apoenzyme was apparently biosynthesized, because the specific activities were significantly higher than before therapy (P less than 0.001/4 wks). Clinical evaluation showed a great improvement in their status, and anticipated surgery for some of the patients became unnecessary. It is concluded that patients with a severe syndrome including the carpal tunnel defect have a deficiency of vitamin B6, and that both the syndrome and the deficiency are relived by therapy with pyridoxine.

Adult↗
PubMed1976

Apparent deficiency of vitamin B6 in typical individuals who commonly serve as normal controls.

Individuals who typically serve as normal controls were found by the differential assay of the glutamic oxaloacetic transaminase in their erythrocytes to have a deficiency (P less than 0.001) of enzyme activity as well as a deficiency (P less than 0.001) of pyridoxal phosphate. Contrary to the understanding that the diet provides an adequate intake of vitamin B6, the dietary intake of vitamin B6 of these controls was inadequate.

Adult↗
PubMed1975

Studies on pig serum lipoproteins. I. Separation and properties of low-density lipoproteins.

The low-density lipoproteins in pig serum were separated into two subclasses (LDL1 and LDL2) by 2 to 7% pore size gradient gel electrophoresis. Preparative gel electrophoresis in 2 to 4% gradient gel made it possible to isolate these components as distinct entities. After delipidation by chromatography on Sepharose 4B in the presence of SDS, both apo-LDL1 and apo-LDL2 were found to have a molecular weight of 2.6X10(5). However, when these apoproteins were incubated in 10% sodium dodecyl sulfate, fragmentation occurred and the minimum fragment molecular weight was estimated to be 2.4X10(4). No essential difference was found in the amino acid compositions or fragmentation patterns of the apoproteins. However, the amounts of carbohydrates in the two apoproteins were different (7.09% in apo-LDL1 and 5.08% in apo-LDL2). The carbohydrate composition was 0.8% sialic acid, 2.38% N-acetyl-glucosamine, and 4.01% neutral sugars in apo-LDL1 and 0.5, 1.75, and 2.83% in apo-LDL2, respectively. In both apoproteins, mannose, galactose, and fucose were present in almost the same molar ratio of 4-5 : 2-3 : 1.

Amino Acids↗
PubMedDate not supplied

Protective effect of taurine against isoprenaline-induced myocardial damage.

The effect of the sulfur amino acid, taurine, was examined on histological and biochemical changes induced by a toxic dose of isoprenaline in chick hearts. Isoprenaline treatment (80 or 240 mg/kg id twice daily for 4 days) caused a dose-dependent increase in heart weight and decrease in myocardial ATP. Isoprenaline administration (240 mg/kg id twice daily) produced necrotic changes in hearts, such as eosinophilic degeneration, myolysis, interstitial oedema, fibrosis, and inflammatory cell infiltration. Substantial accumulation of calcium was also observed. Taurine content of the heart was not significantly decreased. Parenteral administration of taurine (200 mg/day for 7 days) partially protected against these necrotic changes induced by isoprenaline. It is suggested that the protective effect of taurine against isoprenaline-induced myocardial injury might be due in part to the prevention of the massive overloading with calcium which is thought to cause myocardial cell necrosis.

Adenosine Triphosphate↗
PubMedDate not supplied

Beneficial effect of coenzyme Q on myocardial slow action potentials in hearts subjected to decreased perfusion pressure-hypoxia-substrate-free perfusion.

Coenzyme Q, an important component of the electron transfer system in mitochondria, plays a central role in energy production aerobically. The effect of pretreatment with coenzyme Q10 (Co Q) on myocardial slow action potentials (APs) and accompanying contractions and on myocardial high energy phosphate content was studied in perfused hearts subjected to decreased perfusion pressure-hypoxia-substrate-free. Post-hatched chicks were treated i.p. with 10 mg/kg of Co Q daily for 5 days. To study the slow APs exclusively, the fast Na+ channels were voltage-inactivated by elevated K+ (25 mM) Tyrode solution. The Ca++-dependent slow APs were induced by elevating [Ca]o to 5.4 mM; hearts were paced at a rate of 40 per min. Hearts which had been pretreated with Co Q were protected against the deleterious effect of decreased perfusion pressure - hypoxia - substrate-free perfusion on mechanical performance accompanying the slow Ca++-Na+ APs. The slow APs in hearts pretreated with Co Q were also less affected than were non-treated hearts. However, the myocardial ATP and total adenine nucleotides were not affected by exogenous Co Q. It was suggested that exogenous Co Q could protect against the decline of cardiac contractions via improved availability of slow APs during decreased perfusion pressure - hypoxia - substrate-free, independently of the cellular high energy phosphate level.

Animals↗
PubMedDate not supplied

Interaction of citrus juices with pranidipine, a new 1,4-dihydropyridine calcium antagonist, in healthy subjects.

OBJECTIVES: The study was conducted to investigate whether oral co-administration with citrus juices significantly affects the pharmacokinetics and/or pharmacodynamics of pranidipine, a new 1,4-dihydropyridine calcium antagonist, in healthy male subjects. Grapefruit juice and orange juice, which were both commercially available, were used in this study. METHODS: Sixteen healthy male Japanese subjects participated in this study and were divided into two groups for grapefruit juice and orange juice treatment. The study followed an open-labelled crossover design, comparing the effects of a single oral dose of 2 mg pranidipine taken together with 250 ml citrus juice or 250 ml water. Serum pharmacokinetics of pranidipine, adverse reactions, blood pressure, heart rate, 12-lead ECG, haematology, clinical chemistry and urinalysis were measured throughout the study. RESULTS: For grapefruit juice, mean Cmax and AUC0-24 h were significantly higher than those of water (P=0.0003 and 0.0005, respectively, ANOVA) with the ratios of log transformed values being 1.50 and 1.74, respectively. There were no differences in tmax and t1/2 between the juice and water treatments. A significant increase in heart rate (P=0.0240, ANOVA with repeated measurements) was observed in the juice treatment whereas there were no significant differences in systolic and diastolic blood pressure between the two treatments. For orange juice, a small decrease in mean Cmax was observed compared with water (P=0.0218, ANOVA) with the ratio being 0.86, but there was no significant difference in AUC0-24h between the two treatments. No marked differences were observed in tmax and t1/2. Oral pranidipine administration with orange juice did not affect heart rate, systolic and diastolic blood pressures or other parameters for safety evaluation. CONCLUSIONS: Oral co-administration with grapefruit juice and pranidipine was associated with increased bioavailability and changed the pharmacodynamics of pranidipine, particularly with regard to heart rate. Orange juice intake with pranidipine did not markedly affect the pharmacokinetics and no clinically significant changes were observed in the pharmacodynamics and safety evaluation.

Adult↗
PubMedDate not supplied

Circadian variation of the urinary 6beta-hydroxycortisol to cortisol ratio that would reflect hepatic CYP3A activity.

OBJECTIVES: Chronopharmacokinetics of drugs metabolized by cytochrome P450 3A (CYP3A) has been reported recently; however, little is studied on intra-individual circadian variation in CYP3A activity in human. The aim of this study was to assess the intra-individual diurnal variation and day-to-day variation of the urinary 6beta-hydroxycortisol to cortisol ratio, a noninvasive index of human CYP3A activity. METHODS: Urine samples from ten healthy Japanese men were collected over four time intervals (0900 hours to 1300 hours, 1300 hours to 1700 hours, 1700 hours to 2100 hours and 2100 hours to 0900 hours) on days 1, 5 and 14 to verify diurnal variation, and 24-h urine was collected to study day-to-day variation over 2 weeks. Urinary 6beta-hydroxycortisol and cortisol were determined by means of high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry. RESULTS: The ratio of urinary 6beta-hydroxycortisol to cortisol exhibited noteworthy diurnal variation intra-individually; 2.8-fold on average. However, day-do-day intra-individual variation of the ratio was not observed over 2 weeks; the coefficient of variation was 11.9 +/- 3.0%. CONCLUSION: The result indicates that imprudent use of random urine has a great risk of false evaluation in assessment of the 6beta-hydroxycortisol to cortisol ratio and that the ratio in 24-h urine samples provides a more robust measure of the inter-individual difference of this metabolic ratio, which to a certain but not complete extent represents the CYP3A activity.

Adult↗
PubMedDate not supplied

Protective effect of taurine against doxorubicin-induced cardiotoxicity in perfused chick hearts.

The ability of taurine to protect the isolated heart against doxorubicin cardiotoxicity was examined. Chick hearts perfused for 20 min with medium containing 17 microM doxorubicin exhibited a decrease in contractility, an increase in resting tension and a dramatic depletion in tissue high energy phosphate content. Addition of 20 mM taurine to the perfusate attenuated the increase in resting tension and the decrease in myocardial adenosine triphosphate content induced by doxorubicin. The present study confirms our previous in vivo observations that taurine partially prevents doxorubicin-induced cardiotoxicity.

Adenine Nucleotides↗
PubMedDate not supplied

An experimental study of the effect of glucose-insulin-potassium solution on energy metabolism of infarcted cardiac muscle.

The effect of GIK (glucose-insulin-potassium) infusion on the energy liberation of the infarcted heart muscle was studied experimentally in relation to epicardial electrocardiographic changes and cardiac dynamics. In the case of 30-min coronary ligation, the spread of the zone showing ST segment elevation was not depressed significantly, but the mean voltage values of ST elevations were suppressed in the peri-infarcted area, and the uncoupling of oxidative phosphorylation in the peri-infarcted area was also obscured by the GIK treatment. Cardiac dynamics did not change with GIK treatment. On the other hand, in the 60-min coronary ligation, the spread of the zone showing ST segment elevation was reduced significantly and the negative inotropism induced by coronary ligation was suppressed with GIK infusion. However, the uncoupling of oxidative phosphorylation in the infarcted area and in the peri-infarcted area did not show any significant improvement. Therefore, the disturbed energy metabolism of the peri-infarcted area of 30-min ligation might be improved by the effect of GIK infusion. These data suggested that the GIK infusion improved the energy liberation of the so-called twilight zone at 30 min after ligation, and then reduced the genuine infarcted zone after 60 min of ligation.

Animals↗
PubMedDate not supplied

Effects of the angiotensin II receptor antagonist, TCV-116, on blood pressure and the renin-angiotensin system in healthy subjects.

TCV-116 is a new, nonpeptide, angiotensin II type-1 receptor antagonist that acts as a specific inhibitor of the renin-angiotensin system. In this study, 36 healthy male volunteers were administered single and repeated oral doses of TCV-116 to investigate its effects on blood pressure and heart rate, and to evaluate the safety and pharmacokinetics of the drug. At single doses of 2.5 mg and greater, TCV-116 significantly lowered blood pressure even in normotensive subjects. This hypotensive effect was maintained during repeated administration on a once-daily regimen over an 8-day period. Serum concentration of M-1, an active metabolite of TCV-116, increased in a dose-dependent manner, reaching a peak 3 to 4 hours after administration. An amount of M-1 equivalent to approximately 10% of the administered dose of TCV-116 was excreted in the urine during the first 24 hours following administration. No accumulation of M-1 was observed in subjects receiving repeated administration of TCV-116. No adverse effects were observed except for mild headache in three subjects. These results suggest that the renin-angiotensin system plays a role in the regulation of blood pressure, even in normotensive subjects, and that TCV-116 may prove to be useful in the treatment of hypertension.

Adult↗