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Biomedical subjects

T Sakamaki

Publications and source records attributed to T Sakamaki.

At least 37 records · Page 2Linked to original sources
PubMed1999

Loculated pericardial effusion due to congestive heart failure: an unusual case of vanishing tumor--a case report.

Loculation of a pleural effusion within an interlobar fissure as a result of congestive heart failure is a well-known entity. It has been termed "vanishing" or "phantom" tumor because its roentgenographic appearance simulates a pulmonary tumor and resolves with treatment of the congestive heart failure. The authors describe an 89-year-old man with a loculated pericardial effusion on the left cardiac border on chest roentgenogram. This was initially thought to represent an occult metastatic malignancy; however, its etiology became obvious when it disappeared with therapy of heart failure. Loculated pericardial effusion should be included in the differential diagnosis of roentgenographic densities in the chest when seen on the left cardiac border.

Aged↗
PubMed1999

Steroid therapy is effective in a young patient with an inflammatory abdominal aortic aneurysm.

We report a successful resection of an inflammatory aneurysm following treatment with steroids in a 23-year-old man. Suffering from fever and severe lumbago, he was admitted to our hospital. An ultrasound and computed tomography of the abdomen revealed an infrarenal abdominal aortic aneurysm surrounded by dense perianeurysmal fibrous tissue. We diagnosed it as an inflammatory abdominal aortic aneurysm based on a symptomatic inflammatory reaction and the findings of ultrasound and computed tomography. Since the aneurysmal wall strongly adhered to the surrounding tissues and surgery was ruled out when it proved impossible to expose the vessels sufficiently to obtain vascular control, steroid therapy was started to control fever and severe lumbago. Five months later, we undertook surgery. Our conclusion is that steroid therapy was very effective against a young patient with inflammatory abdominal aortic aneurysm.

Adult↗
PubMed1998

Type V phosphodiesterase inhibition modulates endogenous immunoreactivities of endothelin-1 and endothelial nitric oxide synthase in pulmonary arteries in rats with monocrotaline-induced pulmonary hypertension.

We evaluated the effects of oral administration of E4021 (100 mg/kg/day), a type V phosphodiesterase inhibitor, on immunoreactivities of endothelin-1, endothelin receptors, and nitric oxide synthases in pulmonary arteries in a rat model of pulmonary hypertension. Immunoreactivities of endothelin-1 and endothelial nitric oxide synthase were observed significantly less frequently, together with significant reduction of right ventricular overload and medial thickening in rats treated with E4021 than in the control with monocrotaline on day 28. The levels of plasma endothelin-1 and serum nitrite and nitrate were significantly lower in rats that received E4021 than in the control with monocrotaline. Oral administration of E4021 modulates endogenous immunoreactivities of endothelin-1 and endothelial nitric oxide synthase with the improvement or right ventricular overload and medial thickening.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1998

Characteristics of UVA-induced delayed tanning: seasonal variation.

We studied seasonal variation in UVA-induced delayed tanning and compared it to that in UVA + B-induced delayed tanning. The minimal tanning dose (MTD) and the minimal melanogenic dose (MMD) were determined one week after UVA exposure or UVA + B exposure, respectively. The MTD determined in the summer (June to August) was significantly higher than that in winter (December to February). In addition, while MTD in the winter correlated well with skin color, there was no correlation between MTD and skin color in summer. MTD tended to correlate with self-reported tanning history at the initiation of tanning in the winter, but they were not correlated with each other in the summer. The MMD measured in the summer was significantly lower than that in the winter. MMD correlated well with skin color in both seasons; the lighter the skin, the smaller the MMD. Also, a correlation was detected between MMD and self-reported tanning history. These results suggest that the susceptibilities of delayed tanning to UVA and UVA + B are affected by different factors.

Adult↗
PubMed1998

Decreased basal production of nitric oxide in patients with heart disease.

STUDY OBJECTIVES: The pathophysiologic role of nitric oxide (NO) released in the lung is not well understood. To determine whether the production of endogenous NO is correlated with any hemodynamic parameters, we measured the amount of NO released from the lung tissue of patients with heart disease. METHODS: Twenty patients (14 with ischemic heart disease, 4 with dilated cardiomyopathy, and 2 with mitral stenosis) and 16 normal control subjects were enrolled in the study. We measured exhaled air samples by using a method developed in our laboratory. The NO release rate from the lungs was calculated from the amount of exhaled NO and the duration of the exhalation. RESULTS: The rate of NO release was significantly lower in the patients with moderate-to-severe heart failure (New York Heart Association [NYHA] II or III) than in those with mild heart failure (NYHA I) or in normal control subjects. The rate of NO release was positively correlated with the cardiac index (r=0.50, p<0.05), and was negatively correlated with either the systemic (r= -0.58, p<0.01) or pulmonary vascular resistance (r=-0.45, p<0.05). In the patients with moderate-to-severe heart failure, the amount of NO released and the oxygen tension in the pulmonary artery were significantly lower compared with those parameters in patients with mild heart failure. CONCLUSIONS: Results suggest that the basal production of endogenous NO in the lung tissue of patients with heart failure is impaired, perhaps leading to the elevated pulmonary vascular tone seen in patients with moderate-to-severe heart failure.

Adult↗
PubMed1998

The somatostatin analog, octreotide, inhibits in vitro outgrowth of smooth muscle cells from canine coronary and carotid atherosclerotic plaque tissues.

Restenosis is caused by excessive neointima formation resulting from smooth muscle cell (SMC) proliferation and migration from the arterial media into the subendothelial space, stimulated by growth factors. A long-acting somatostatin analog, octreotide, activates protein tyrosine phosphatases and can inhibit the stimulatory effects of growth factors. In this study, we evaluated the effect of octreotide on SMC outgrowth from in vitro explants of both coronary and carotid arterial tissues in a canine endothelium-injury model. After 6 days of culture, SMC grew out of 33.3% and 58.3% of the explants from the injured canine carotid and coronary arterial tissues, respectively. In contrast, SMC outgrowth was not observed from any of the explants from normal canine carotid arterial tissue. Octreotide completely inhibited SMC outgrowth from injured canine carotid arterial tissue at a concentration of 10(-6) M. This agent also inhibited SMC outgrowth from injured canine coronary arterial tissue by 57% and 71% of the control value at concentrations of 10(-8) M and 10(-6) M, respectively. We conclude that our explant cell-culture model may prove to be valuable for assessing the effect of agents designed to reduce intimal proliferation, and that the use of the somatostatin analog octreotide in clinical settings may modify the high incidence of restenosis after coronary interventions by reducing SMC proliferation.

Animals↗
PubMed1997

Stretch-induced hypertrophic growth of cardiocytes and processing of brain-type natriuretic peptide are controlled by proprotein-processing endoprotease furin.

When hypertrophic growth is induced in neonatal rat cardiocytes by stretching, the cardiocytes express high levels of brain-type natriuretic peptide (BNP) and the proprotein-processing enzyme furin. A BNP precursor, gammaBNP, possesses a furin-cleavable Arg-X-X-Arg motif, which is cleaved when gammaBNP is processed to form BNP-45. The Arg-X-X-Arg motif is found in many precursors of growth factors and growth-related proteins. To determine if furin converts gammaBNP to BNP-45 as well as other unidentified growth-promoting protein precursors to their active form that may induce hypertrophic growth in cardiocytes, we used two protease inhibitor systems, synthetic peptidyl chloromethyl ketones (CMK) (dec-Arg-Val-Lys-Arg-CMK and dec-Phe-Ala-Lys-Arg-CMK; where dec is decanoyl) and vaccinia vector-integrated native and variant alpha1-antitrypsins. The furin-specific inhibitors, dec-Arg-Val-Lys-Arg-CMK and variant alpha1-antitrypsin with the inhibitory determinant Arg-X-X-Arg, suppressed the stretch-induced hypertrophic growth of cardiocytes as well as the processing of gammaBNP to BNP-45. The other serine protease inhibitors and variant alpha1-antitrypsin against elastase, or thrombin, however, neither suppressed the hypertrophic growth nor prevented the processing of gammaBNP to BNP-45. Thus, we suggest that furin catalyzes the conversion of gammaBNP to BNP-45 as well as growth-promoting proproteins to their active form, which might induce hypertrophic growth in cardiocytes.

Animals↗
PubMed1997

Co-elevation of brain natriuretic peptide and proprotein-processing endoprotease furin after myocardial infarction in rats.

We investigated the expression of the yeast Kex2 family endoproteases furin and PACE4, and brain natriuretic peptide (BNP) in the atrium and ventricle after infarction as well as the conversion of the BNP precursor gammaBNP to BNP-45. In a rat heart failure model, plasma BNP rose in two phases--first at day 3, and again at day 14. BNP mRNA, as measured by Northern blot analysis, increased strongly at day 3, then at days 14 and 28 less strongly in the atrium, and in the ventricle it increased weakly at day 3, then strongly at days 14 and 28. Furin mRNA showed the same pattern of expression as that of BNP message, whereas PACE4 message stayed unchanged after the infarction. Both furin and BNP were immunostained in the myocardium adjacent to the infarcted tissue. We suggest that after myocardial infarction, furin is co-expressed with BNP in both the atrium and ventricle, and that furin may be responsible for the conversion of gammaBNP to BNP-45.

Animals↗
PubMed1997

Chronic blockade of nitric oxide synthesis increases urinary endothelin-1 excretion.

OBJECTIVES: Our objective was to determine the effect of nitric oxide (NO) inhibition on renal synthesis of endothelin-1 (ET-1) in vivo. DESIGN AND METHODS: Rats were administered 500 mg/l NG-nitro-L-arginine methyl ester (L-NAME) in their drinking water or its vehicle for 2 weeks (2W-L-NAME, n = 10; 2W-CONT, n = 10) or for 6 weeks (6W-L-NAME, n = 13; 6W-CONT, n = 11). We measured the levels of albumin, NO metabolites and ET-1 both in their blood and in 24 h urine samples, and determined the expression of preproET-1 messenger RNA in the renal cortex and the inner medulla. We also examined renal histology. RESULTS: L-NAME administration for 6 weeks reduced NO metabolites both in serum (21.5 versus 3.66 nmol/ml in 6W-CONT) and in urine (5.72 versus 22.53 nmol/24 h in 6W-CONT), raised the systolic blood pressure (228 versus 162 mmHg in 6W-CONT), and the increased urinary excretion of albumin (24.29 +/- 11.66 versus 0.60 +/- 0.08 mg/day in 6W-CONT) and of ET-1 (112.0 +/- 38.3 versus 35.8 +/- 4.4 pg/day in 6W-CONT). There were no significant differences between the plasma levels of ET-1 in the control and L-NAME groups. Expression of preproET-1 messenger RNA increased in the renal cortex but not in the inner medulla in the 6W-L-NAME group. Bleeding and marked arteriolar narrowing were observed in the renal cortex of the 6W-L-NAME group. CONCLUSIONS: Prolonged inhibition of NO synthesis increases urinary excretion of ET-1 and albumin without having any effect on plasma ET-1 levels. These results do not support the hypothesis that NO plays an inhibitory role in the regulation of ET-1 in the systemic circulation, although it is possible that such a role could exist in renal tissue. However, in view of the albuminuria, a more likely explanation is that increased urinary ET-1 is secondary to L-NAME-induced renal hyperfiltration injury.

Albuminuria↗
PubMed1997

Magnetic resonance imaging in diagnosis of right coronary arteriovenous fistula--a case report.

We describe a patient with a right coronary arteriovenous fistula in whom magnetic resonance imaging (MRI) was useful in establishing the diagnosis. In a 36-year-old woman, T1 spin echo MRI demonstrated a massively dilated coronary arteriovenous fistula connecting the right coronary artery to the right atrium. The cine field echo technique showed a continuous shunt flow within the fistula as documented by the flow void throughout the cardiac cycle. These findings were confirmed by cardiac catheterization. We conclude that MRI is useful not only in detecting a coronary arteriovenous fistula but also in identifying its origin and the drainage site.

Adult↗
PubMed1997

Flow-mediated vasodilation of a conduit artery in relation to downstream peripheral tissue blood flow during reactive hyperemia in humans.

Arterial conduit vessels dilate in response to increased blood flow stimuli. Our objective was to determine precisely how a change in large arterial diameter results in a change in peripheral tissue blood flow. Using high-resolution ultrasound Doppler echography, we measured the diameter of the right femoral artery at rest, during reactive hyperemia, and after administration of 2.5 mg of sublingual isosorbide dinitrate in 10 healthy young men. Reactive hyperemia was induced by distal circulatory arrest followed by reperfusion of the leg ipsilateral (right) or contralateral (left) to the side of arterial diameter measurements. Femoral arterial blood flow was calculated by simultaneous measurement of femoral arterial diameter and blood velocity. The change in skin blood flow was also analyzed simultaneously by laser Doppler flowmetry. Reactive hyperemia induced a 2-fold increase in femoral arterial blood velocity 30 sec after cuff release. During this flow augmentation, the femoral artery dilated. The peak of skin blood flow was coincident with the peak of femoral arterial vasodilation. The time required for the return of arterial diameter to baseline was longer than that for blood flow in both the conduit artery and the peripheral skin tissue. Equivalent cuff occlusion and release of the contralateral limb had no effect on ipsilateral arterial diameter. Isosorbide dinitrate induced dilation in all subjects, despite the absence of a significant increase in blood velocity. These results indicate that the human femoral artery dilates in response to increased blood velocity, and that the flow-mediated vasodilation of a large conduit artery is involved in the adjustments of blood flow in the downstream peripheral tissue.

Adult↗
PubMed1997

Long-term evaluation of combined antihypertensive therapy with lisinopril and a thiazide diuretic in patients with essential hypertension.

For the treatment of hypertension, the combination of an angiotensin-converting enzyme (ACE) inhibitor and a thiazide diuretic is supported by multiple lines of evidence, because these drugs have synergistic action and are expected to cancel out each other's adverse side effects. However, the long-term outcome of this combination antihypertensive therapy is not entirely clear. In the present multicenter open trial, we investigated the long-term efficacy and safety of combined antihypertensive therapy with an ACE inhibitor, lisinopril, and a thiazide diuretic, trichlormethiazide. A total of 466 patients with essential hypertension were treated with lisinopril alone (monotherapy group, n = 360) or with a combination of lisinopril with trichlormethiazide (combination therapy group, n = 106) for 1 year. The average blood pressure was effectively lowered to below 150/90 mmHg in both the monotherapy and the combination therapy groups throughout the study period. The average maintenance dose of lisinopril was lower when combined with thiazide than when given alone (9.8 vs. 11.5 mg/day, p < 0.001). Dry cough was the major side effect of lisinopril; no severe adverse effects were observed. The incidence of cough was not significantly different between the monotherapy group (13.1%) and the combination therapy group (11.3%). The increase in serum potassium observed in the monotherapy group was reversed by the concurrent use of the thiazide diuretic in the combination therapy group. Fasting blood glucose was significantly reduced in the monotherapy group; the reduction observed in the combination therapy group was not significant. Thus, the present results provide useful information as to the effectiveness and safety of combined antihypertensive therapy with lisinopril and a thiazide in comparison with monotherapy with lisinopril.

Adult↗
PubMed1997

Transient hypertension due to adrenal hemorrhage in a patient with von Recklinghausen's disease.

A 29-year-old man with von Recklinghausen's disease suddenly developed severe epigastric pain and was admitted to hospital. Physical examination revealed elevated blood pressure (200/130 mmHg) and tachycardia (162 bpm). Initially, he was suspected to have appendicitis, and appendectomy was performed immediately; however, appendicitis was not demonstrable pathologically. Retroperitoneal hematoma was found incidentally during the operation. Further clinical and laboratory examination demonstrated a marked increase in the urinary excretion of catecholamines. There was no evidence of pheochromocytoma on computed tomography or magnetic resonance imaging; however, these imaging studies simply showed a hematoma at the right adrenal gland. Transient hypertension and tachycardia, resembling pheochromocytoma, was caused by adrenal hemorrhage.

Adrenal Gland Diseases↗
PubMed1997

Association of HLA-DR, DQ genotype with different beta-cell functions at IDDM diagnosis in Japanese children.

Japanese IDDM patients have been demonstrated to have unique and different HLA associations from white patients. To elucidate the effect of HLA-associated genetic factors on the clinical heterogeneity of IDDM in Japanese people, HLA-DRB1, DQA1, and DQB1 genotypes in 88 childhood-onset Japanese IDDM patients were examined by polymerase chain reaction-sequence-specific oligonucleotide (PCR-SSO) or sequence-specific primers (SSP). Of the 88 IDDM patients, 26 (29.5%) had DRB1*0405-DQA1*0302-DQB1*0401/X (DR4-DQ4/X), 38 (43.2%) had DRB1*0901-DQA1*0302-DQB1*0303/X (DR9-DQ9/X), and 9 (10.2%) were DR4/9-DQ4/9 heterozygous in the present study (X does not contain protective alleles). Clinical heterogeneity such as age distribution at onset, prevalence and serum level of anti-GAD antibodies (GADAb), and residual pancreatic beta-cell function after diagnosis were compared between patients with HLA-DR4-DQ4 and DR9-DQ9. The frequency of DR9-DQ9 genotype was significantly higher in the younger (0-10 years) than in the older (11-16 years) age-group of onset, but the frequency of DR4-DQ4 was higher in the older (11-16 years) age-group. Although no association of DR-DQ genotypes with the prevalence and serum level of GADAb was found among newly diagnosed patients, long-standing DR9-DQ9 patients had significantly higher levels of GADAb than those with DR4-DQ4. While no difference in time course of serum C-peptide (CPR) levels was detected between GADAb+ and GADAb- patients, a remarkable difference was demonstrated between DR9-DQ9 and DR4-DQ4 patients. The residual pancreatic beta-cell function was retained more in patients with DR4-DQ4 than in those with DR9-DQ9 at diagnosis through 12-18 months after diagnosis. These results suggest that the DR9-DQ9 genotype may induce stronger autoimmune destructive response (T-helper 1 function) against target beta-cells than the DR4-DQ4 genotype does. Our findings may warrant further studies on the association of diabetogenic autoimmune response with HLA class II molecules and contribute to a clarification of interracial differences in HLA-encoded susceptibility to IDDM.

Adolescent↗
PubMed1997

Immunosuppressive drugs inhibit the production of interleukin-6 and interleukin-8 in cultured cardiac myxoma cells.

Cardiac myxoma cells produce large amounts of interleukin (IL)-6 and IL-8. To determine whether immunosuppressive agents could be used to treat cardiac myxoma, we tested the effects of dexamethasone and three of the newer second-generation immunosuppressive drugs, cyclosporin A, tacrolimus, and deoxyspergualin, on the production of IL-6 and IL-8 in these cells. Cultured cardiac myxoma cells were used as in vitro model of cardiac myxoma. Cells were tested for 24 hours with 10(-7) M dexamethasone, 10(-6) M cyclosporin A, 10(-8) M tacrolimus, and 10(-6) M 15-deoxyspergualin, with aliquots of conditioned medium being assayed for cytokine levels at 0, 6, 12, and 24 hours. Cardiac myxoma cells isolated from 4 patients all produced quantities of IL-6 and IL-8. The concentrations of IL-6 in the medium after 7 days in culture ranged from 79,000 to 2,740,000 pg/ml, and the concentrations of IL-8 ranged from 40,000 to 1,000,000 pg/ml. Exposure of cyclosporin A and dexamethasone almost completely inhibited the production of IL-6 and IL-8 after 24 hours of treatment. Tacrolimus inhibited the production of both cytokines by 55%, while 15-deoxyspergualin reduced IL-6 levels by 24% and IL-8 levels by 48% after separate 24 hour treatments. These results suggest that these newer immunosuppressive agents may be useful in reducing the production of IL-6 and IL-8 in patients with cardiac myxoma.

Aged↗
PubMed1997

Reduced serum T3 level in a patient with nodular goiter and cardiac myxoma.

We report the unusual case of an 87-year-old woman with cardiac myxoma and adenomatous goiter. She exhibited slight elevations of serum interleukin-6 (IL-6), but levels of thyroid hormones such as T3, free T3 and free T4 were all abnormally low. Interleukin-6 may potentiate the alteration of thyroid metabolism.

Aged↗