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T Nii

Publications and source records attributed to T Nii.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cloning, functional expression and dietary regulation of the mouse neutral and basic amino acid transporter (NBAT).

The Na+-independent dibasic and neutral amino acid transporter NBAT is among the least hydrophobic of mammalian amino acid transporters. The transporter contains one to four transmembrane domains and induces amino acid transport activity via a b0,+-like system when expressed in Xenopus oocytes. However, the physiological role of NBAT remains unclear. Complementary DNA clones encoding mouse NBAT have now been isolated. The expression of mouse NBAT in Xenopus oocytes also induced an obligatory amino acid exchange activity similar to that of the b0,+-like system. The amount of NBAT mRNA in mouse kidney increased during postnatal development, consistent with the increase in renal cystine and dibasic transport activity. Dietary aspartate induced a marked increase in cystine transport via the b0,+ system in mouse ileum. A high-aspartate diet also increased the amount of NBAT mRNA in mouse ileum. In the ileum of mice fed on the aspartate diet, the extent of cystine transport was further increased by preloading brush border membrane vesicles with lysine. Hybrid depletion of NBAT mRNA from ileal polyadenylated RNA revealed that the increase in cystine transport activity induced by the high-aspartate diet, as measured in Xenopus oocytes, was attributable to NBAT. These results demonstrate that mouse NBAT has an important role in cystine transport.

Amino Acid Sequence↗
PubMed1997

Relative contributions of Na+-dependent phosphate co-transporters to phosphate transport in mouse kidney: RNase H-mediated hybrid depletion analysis.

Reabsorption of Pi in the proximal tubule of the kidney is an important determinant of Pi homoeostasis. At least three types (types I-III) of high-affinity Na+-dependent Pi co-transporters have been identified in mammalian kidneys. The relative roles of these three types of Na+/Pi co-transporters in Pi transport in mouse kidney cortex have now been investigated by RNase H-mediated hybrid depletion. Whereas isolated brush-border membrane vesicles showed the presence of two kinetically distinct Na+/Pi co-transport systems (high Km-low Vmax and low Km-high Vmax), Xenopus oocytes, microinjected with polyadenylated [poly(A)+] RNA from mouse kidney cortex, showed only the high-affinity Pi uptake system. Kidney poly(A)+ RNA was incubated in vitro with antisense oligonucleotides corresponding to Npt-1 (type I), NaPi -7 (type II) or Glvr-1 (type III) Na+/Pi co-transporter mRNAs, and then with RNase H. Injection of such treated RNA preparations into Xenopus oocytes revealed that an NaPi-7 antisense oligonucleotide that resulted in complete degradation of NaPi-7 mRNA (as revealed by Northern blot analysis), also induced complete inhibition of Pi uptake. Degradation of Npt-1 or Glvr-1 mRNAs induced by corresponding antisense oligonucleotides had no effect on Pi transport, which was subsequently measured in oocytes. These results indicate that the type II Na+/Pi co-transporter NaPi-7 mediated most Na+-dependent Pi transport in mouse kidney cortex.

Animals↗
PubMed1997

Three-dimensional spiral computed tomography angiography as an alternative imaging modality for a silent dissecting aortic aneurysm--a case report.

The authors report a patient with silent dissecting aortic aneurysm in whom three-dimensional spiral computed tomography (CT) angiography (3D-CTA) provided important imaging data. Images obtained by 3D-CTA were compared with the results of both conventional angiography and CT. They conclude that 3D-CTA was a powerful diagnostic modality for this patient, in addition to conventional CT and angiography.

Aortic Dissection↗
PubMed1997

Influence of diet on the single-dose pharmacokinetics of isosorbide 5-mononitrate and sustained-release isosorbide dinitrate.

The influence of diet on the single-dose pharmacokinetics of isosorbide 5-mononitrate (IS-5-MN) and sustained-release isosorbide dinitrate (ISDN) was studied in 8 healthy male volunteers. The subjects received either a low-calorie/low-fat diet (LCFD) or a high-calorie/high-fat diet (HCFD) according to a cross-over schedule and were administered the drug in tablet form after breakfast. The study was conducted first in 8 subjects who received a 20 mg IS-5-MN tablet and then in 6 of these individuals who received a 20 mg sustained-release ISDN tablet. After oral doses of IS-5-MN, the plasma drug levels declined monoexponentially and could be described by a one-compartment open model. There were no significant differences in the pharmacokinetic parameters for IS-5-MN between the LCFD and the HCFD. After administration of sustained-release ISDN, the plasma ISDN levels showed marked variations both between and within individuals. The increase in the mean AUC0-12 values for ISDN with the HCFD was found to exceed 60%, although there was no significant difference between the two diets.

Administration, Oral↗
PubMed1997

Long-term follow-up by coronary angiography in a patient with heterozygous familial hypercholesterolemia: a case report.

A 47-year-old man with heterozygous familial hypercholesterolemia was followed up by coronary angiography for 9 years. During these 9 years, he experienced inferior myocardial infarction twice, at segment 1 of the right coronary artery. A coronary atherosclerotic lesion (50% stenosis) was also present at segment 6 of the left anterior descending coronary artery. This lesion remained unchanged for the first 7 years, but then rapidly progressed to 90% stenosis in the 8th year. While the rate of the progression of coronary atherosclerosis is generally unpredictable, it may progress rapidly in this case of heterozygous familial hypercholesterolemia.

Angioplasty, Balloon, Coronary↗
PubMed1995

Acute myocardial infarction in a patient with primary coronary dissection and severe coronary vasospasm. A case report.

A case of myocardial infarction associated with coronary artery dissection in a thirty-five-year-old woman is reported. An emergent coronary angiogram revealed extensive dissection and thrombosis in the right coronary artery; in addition, severe vasospasm was observed in the left coronary artery on the next day. She was successfully treated with intracoronary thrombolysis and intra-aortic balloon pumping. The patient is alive and well two years after infarction.

Adult↗
PubMed1995

Reduced coronary vasodilation in patients with familial hypercholesterolemia following intracoronary injection of isosorbide dinitrate.

To clarify the relationship between the dilatation of angiographically non-stenotic coronary artery segments in response to isosorbide dinitrate (ISDN), and serum lipids, 5 coronary segments in 7 patients with familial hypercholesterolemia (FH) and 43 patients with non-familial hypercholesterolemia (non-FH), who had either 1- or 2-vessel coronary heart disease, were investigated. The serum total cholesterol level was significantly greater in FH than in non-FH. Before and after the direct intracoronary injection of ISDN, coronary diameter was measured by a computer-assisted coronary angiography analysis system. The order of the dilative responses in coronary segments in non-FH patients (segments: #5 > #11 > #6 > #13 > #7) was exactly the same as the order of their original diameters, while the ratio of the increase in diameter (after/before ISDN injection) did not differ among any of the segments (mean: 1.08-fold increase). In the non-FH group, no correlation was found between the serum total cholesterol, triglyceride, low-density lipoprotein-cholesterol, or high-density lipoprotein-cholesterol, and the ratio of the coronary diameter after and before injection of ISDN. Moreover, hypercholesterolemia in non-FH did not affect the coronary dilative response to ISDN injection. In the FH group, although the original diameter of each segment did not differ from that in the non-FH group, the ratio of the diameter after and before injection of ISDN was significantly smaller in FH than in non-FH (p < 0.01). These results suggest that a non-stenotic coronary artery in FH has a lower capacity for vasodilation in response to ISDN. Although hypercholesterolemia was excluded as a factor which may suppress the capacity for coronary dilation in non-FH, spontaneous hypercholesterolemia in FH may affect medial smooth muscle functions of the coronary artery.

Adult↗
PubMed1994

Coronary collateral circulation and diastolic function.

Patients with coronary artery disease reportedly have an impaired left ventricular filling. To evaluate the effects of coronary collaterals on diastolic function in patients with effort-induced angina, resting radionuclide ventriculography was performed in 14 patients with severe isolated (> or = 90% diameter) stenosis of the left anterior descending coronary artery and in seven normal subjects. Contrast ventriculography showed normal wall motion in all patients. Functional indices obtained by radionuclide ventriculography were compared between those patients with collateral vessels, Rentrop classification grades 1 (n = 7) and 3 (n = 1), and those patients without (n = 6) collateral vessels. Global peak filling rate was significantly (P < 0.01) reduced in the patients with collaterals. The septal, apical and lateral peak filling rates were also reduced in patients with collateral vessels, with the reduction in lateral peak filling rate being statistically significant (P < 0.05). The indices of systolic function and the temporal diastolic asynchronous index were similar, irrespective of the presence of collaterals. The exercise tolerance as evaluated by the rate-pressure product at peak treadmill exercise stress testing in 12 patients was significantly (P < 0.01) lower in those with collateral vessels. Angiographically visible collaterals could be a marker for more severe coronary stenosis in patients with effort-induced angina, and an indicator of the severity of deterioration in left ventricular diastolic function.

Aged↗
PubMed1994

Increased left ventricular non-uniformity in hypertensive patients with angina.

AIM: To determine how hypertension affects the left ventricular diastolic function of patients with effort angina. METHODS: We performed radionuclide ventriculography in 14 patients with isolated stenosis of the left anterior descending coronary artery and in seven healthy volunteers. RESULTS: Neither global nor regional peak filling rate differed significantly between the patients with (n = 6) and without (n = 8) hypertension, although the left ventricular asynchronous index was significantly increased (P < 0.05) in the hypertensive patients (87 +/- 20 ms), compared with the normotensive patients (59 +/- 22 ms). This index was significantly (P < 0.05) correlated with left ventricular mass index in all participants. CONCLUSIONS: Hypertension increased the diastolic non-uniformity of the left ventricle in patients with effort angina.

Aged↗
PubMed1993

Low serum apolipoprotein A-I level in patients with vasospastic angina.

The serum lipid and lipoprotein levels in 15 patients with vasospastic angina were compared with those in 33 patients with no angiographic coronary stenosis and no vasospastic angina after intracoronary acetylcholine infusion. The serum level of apolipoprotein A-I in patients with vasospastic angina (112 +/- 6 mg/dl) was significantly lower (p < 0.05) than that in patients without vasospasm (128 +/- 4 mg/dl). However, there were no differences between the two groups in the serum levels of cholesterol, triglycerides, high-density lipoprotein cholesterol, apolipoprotein A-II, and apolipoprotein B. Thus apolipoprotein A-I may play some role in the prevention of vasospastic angina.

Adult↗
PubMed1993

Role of left ventricular regional nonuniformity in hypertensive diastolic dysfunction.

OBJECTIVES: This study investigated 1) the role of left ventricular diastolic nonuniformity in hypertensive left ventricular diastolic dysfunction, and 2) the effects of a calcium channel antagonist on diastolic nonuniformity in hypertensive and normotensive subjects. BACKGROUND: Augmented left ventricular diastolic nonuniformity contributes to diastolic dysfunction in hypertrophic cardiomyopathy. Impaired left ventricular diastolic function with preserved systolic function has been recognized in hypertension. Therefore, abnormal ventricular regional nonuniformity might also be involved in hypertensive diastolic dysfunction in a milder form of hypertrophy. METHODS: Thirteen patients with established hypertension underwent radionuclide ventriculography before and after nifedipine administration. Indexes of left ventricular function were derived by computer analysis of the time-activity curve. After a computer subdivided the left ventricle into four regions, a time-activity curve of each region was constructed to determine an index of left ventricular diastolic nonuniformity. This index was calculated as the sum of the absolute values of time difference between global and regional peak filling in the septal, the apical and the lateral region. Ten normotensive subjects were studied for comparison. Echocardiography was performed in both groups. RESULTS: The two groups were matched for age, gender, heart rate, echocardiographic dimensions and systolic function. In the hypertensive group, left ventricular diastolic filling indexes were impaired, with a negative correlation between peak filling rate and the diastolic nonuniformity index. Although the change in ejection fraction after nifedipine administration was similar in the two groups, the increase in peak filling rate was larger in the hypertensive patients. The diastolic nonuniformity index decreased after nifedipine in the hypertensive but not in the control group. This decrease correlated with improved peak filling rate in the hypertensive group. CONCLUSIONS: In hypertensive patients with preserved systolic function, left ventricular diastolic nonuniformity increases, causing early diastolic dysfunction. Decreased diastolic nonuniformity after pharmacologic intervention contributes to lessened ventricular filling dysfunction, regardless of changes in loading conditions in hypertension. Thus, diastolic nonuniformity is an important determinant of left ventricular filling abnormality and might be a target of pharmacologic intervention in hypertensive patients.

Adult↗
PubMed1992

Cardiac effects of local angiotensin-converting enzyme inhibition in hypertensive patients.

1. The direct cardiac effects of angiotensin-converting enzyme (ACE) inhibitor in 22 hypertensive patients were investigated. Radionuclide ventriculography and echocardiography were performed to measure left ventricular function before and 60 min after administration of a subdepressor dose of captopril. 2. Since the response to ACE inhibitor is not uniform, patients were classified into 12 patients without significant blood pressure change following captopril (group I) and 10 patients with reduction of blood pressure (group II). 3. Clinical and baseline haemodynamic characteristics were similar for the two groups. 4. Ejection fraction (EF) increased without changes of heart rate and end-diastolic dimension after ACE inhibitor in group I as well as group II. The change of EF was not different for the two groups. No correlation was found between changes in EF and blood pressure in group I patients. 5. This study indicates that ACE inhibitor might directly influence left ventricular function independent of systemic haemodynamic changes.

Adult↗
PubMed1992

Reduced left ventricular diastolic asynchrony after captopril in single vessel coronary artery disease.

Impaired left ventricular diastolic function is often found preceding systolic functional abnormality in coronary artery disease. To assess whether captopril improves diastolic function, radionuclide ventriculography was performed before and 1 h after captopril administration in 10 stable effort angina patients with severe isolated stenosis of the left anterior descending coronary artery and in 8 controls. Resting global peak filling rate (PFR) was significantly (p < 0.05) reduced in association with significantly (p < 0.01) increased left ventricular diastolic asynchronous index (delta t) in patients with angina pectoris. Neither global PFR nor regional cardiac function was affected by captopril, although delta t was significantly (p < 0.05) reduced from 70 +/- 18 (SD) to 51 +/- 25 ms in patients with angina pectoris. A significant (p < 0.01) correlation was observed between percentage changes in peak ejection rate and in PFR in all subjects. Thus, captopril improves left ventricular asynchrony in patients with stable angina, although global diastolic function affected by systolic function remains unchanged.

Aged↗
PubMed1991

Normalization of reverse redistribution of thallium-201 with procainamide pretreatment in Wolff-Parkinson-White syndrome.

Stress thallium-201 myocardial perfusion imaging was performed in a patient with Wolff-Parkinson-White syndrome. Reverse redistribution phenomenon was observed in the absence of coronary artery disease. This seems to be the first report of normalization of this phenomenon in association with reversion of accessory pathway to normal atrioventricular conduction after pretreatment with procainamide.

Adult↗
PubMed1991

Diastolic filling abnormality modified by left ventricular asynchrony in essential hypertension.

Left ventricular (LV) asynchrony has been demonstrated to result in diastolic dysfunction. To test the hypothesis that altered LV synchrony interferes with LV diastolic function in essential hypertensive patients (HT), we performed radionuclide ventriculography and echocardiography in 38 HT and 11 normotensive subjects. LV diastolic asynchrony was measured as the sum (total delta t) of the absolute values of the time difference between global peak filling rate (PFR) and regional PFR. Global PFR and time to PFR were significantly reduced in HT. Although total delta t did not differ between two groups, total delta t significantly correlated with PFR (r = -0.44, p less than 0.01) in HT. Moreover, total delta t positively related to LV endsystolic stress and inversely related to LV ejection fraction in HT. Thus, LV asynchrony, in part, plays a role in early diastolic filling abnormality in hypertensive patients.

Adult↗
PubMed1987

Changes in hemodynamics and myocardial contractility during chronic sodium depletion in conscious dogs.

Chronic sodium depletion has been reported to decrease ejection fraction in anesthetized dogs. We tested the hypothesis that this reduction in cardiac performance is due to either hemodynamic or humoral factors. Seven mongrel dogs were fed a low sodium diet (less than 2 mEq Na+ per day) for 5 weeks. Echocardiographic and radionuclide techniques were used to monitor cardiac function. There was a gradual but significant (p less than 0.01) decrease in ejection fraction from 61 +/- 7% (SD) at baseline to 47 +/- 8% after 5 weeks of sodium depletion in association with a fall in left ventricular end-diastolic volume. Ejection fraction did not change in five control dogs fed 55 mEq Na+ per day throughout the 5-week follow-up period. Myocardial contractility did not change in either salt-depleted or control dogs. Plasma norepinephrine levels in the coronary sinus were twice as high in salt-depleted as in control dogs, but there were no significant differences in arterial norepinephrine concentration between the two groups. Therefore, we concluded that reduced ejection fraction during sodium depletion resulted from hemodynamic changes (decreased preload). The excess available norepinephrine failed to increase myocardial contractility, suggesting a dysfunction at the cardiac adrenergic neuroeffector junction.

Animals↗
PubMed1975

[Studies on P waves of mitral valvular diseases by the high-speed and magnified electrocardiograms].

Atrial waves of the electrocardiograms (ECG) of 50 cases of normal subjects and 113 cases of mitral valvular diseases (76 cases of mitral stenosis, 20 cases of mitral insufficiency and 17 cases of mitral steno-insufficiency) were studied by means of the high-speed and magnified electrocardiography. Leads II and V1 and three scalar leads of Frank system (X, Y and Z leads) were recorded by this method. Morphologic observations as well as the quantitative measurements of the amplitudes and the durations of P waves were carried out. Correlations among the various parameters of the P waves and hemodynamic data were examined. and the electrocardiographic criteria for the diagnosis of the left atrial overloading were investigated. The results obtained were as follows: 1) More detailed informations regarding to P waves were obtained by means of the high-speed and magnified ECG. 2) On statistical comparisons of the mean values of the P waves among the normal and the three groups of mitral valvular diseases, the amplitude, the duration and the peak time in lead II were larger in the latter, and the amplitude of positive and negative phases, the duration of negative phase of the diphasic P waves in lead V1 were learger in the latter, while the duration of positive phase was larger in the former. In leads X and Z of Frank system the findings were similar to those in leads II and V1 respectively. 3) The mean values of the instantaneous amplitudes of each 10 msec interval of P waves of scalar ECG of Frank system were compared among the normal and the three groups of the mitral valvular diseases..

Cardiac Volume↗