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Biomedical subjects

S Hirakawa

Publications and source records attributed to S Hirakawa.

At least 19 recordsLinked to original sources
PubMed1995

Modulation of noradrenaline release through presynaptic alpha 2-adrenoceptors in congestive heart failure.

Stimulation of presynaptic alpha 2-adrenoceptors inhibits the release of noradrenaline from sympathetic nerve endings; however, the extent to which it operates in patients with congestive heart failure is still unknown. To investigate the degree of negative feedback to the release of noradrenaline via presynaptic alpha 2-adrenoceptors at sympathetic nerve endings, we measured plasma noradrenaline levels before and after the injection of phentolamine (i.e., plasma noradrenaline concentration at rest, plasma noradrenaline concentration after phentolamine injection [NAph], and the phentolamine-induced increase in plasma noradrenaline [delta NAph]). Plasma noradrenaline concentration at rest, NAph, and delta NAph increased in a stepwise manner from New York Heart Association class I to class III. A positive correlation was found between the plasma noradrenaline at rest and delta Naph (n = 123, r = 0.697, p < 0.001). These results suggest that the enhanced release of plasma noradrenaline is substantially buffered by the mechanism of noradrenaline release-inhibitory presynaptic alpha 2-adrenoceptors in patients with congestive heart failure, and this buffer serves to protect organs such as the heart from excess sympathetic stimulation.

Aged↗
PubMed1995

Alternations in atrial natriuretic peptide release after DC cardioversion of non-valvular chronic atrial fibrillation.

The response of atrial natriuretic peptide (ANP) release to haemodynamic influences after cardioversion of atrial fibrillation has not been fully examined. We measured plasma concentrations of ANP and assessed haemodynamic changes 60-120 min after DC cardioversion in 22 patients with non-valvular chronic atrial fibrillation. Passive leg elevation to enhance volume expansion was performed 60 min after DC cardioversion. Sinus rhythm was restored in 18 of the 22 patients (successful DC cardioversion group). The control group consisted of seven patients with non-valvular chronic atrial fibrillation who did not undergo DC cardioversion (atrial fibrillation control group). In the successful DC cardioversion group, the mean pulmonary artery wedge pressure decreased significantly 15 min after cardioversion (P < 0.05) and then remained unchanged. Plasma concentrations of ANP also decreased significantly 15 min after cardioversion (P < 0.05). Furthermore, there was an additional significant decrease in ANP levels for up to 60 min after cardioversion (P < 0.05 from 15 min). Passive leg elevation for 15 min led to an increase in the mean pulmonary artery wedge pressure (P < 0.01) and right atrial pressure (P < 0.05), but did not result in increased plasma concentrations of ANP (47.1 +/- 27.6 vs 43.9 +/- 34.4 pg.ml-1, mean +/- SD, P = ns). In the atrial fibrillation control group, passive leg elevation increased the mean pulmonary artery wedge pressure (P < 0.01), the mean right atrial pressure (P < 0.05) and plasma concentrations of ANP (139.9 +/- 85.8 vs 168.1 +/- 108.2, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Human pulmonary vascular and venous compliances are reduced before and during left-sided heart failure.

Human pulmonary vascular and venous compliances were measured in 41 patients with or without left-sided heart failure. Two methods were used. Method 1 was based on analysis of pulmonary capillary wedge (PCW) pressure tracings according to Cv,PCW = (SF/100)(0.075PCW + 0.90)SV/[(v - d)PCW + 1], where Cv,PCW is compliance of pulmonary venous system, SF is systolic fraction of pulmonary venous flow [related to pulmonary capillary wedge pressure (PCW) as SF = 82 - 2.01PCW], (v - d)PCW is pulse pressure in PCW position, and SV is stroke volume. The (0.075PCW + 0.90) term equals k", i.e., systolic run-off ratio. Method 2 was used to measure to pulmonary vascular volume-pressure (V-P) relationship and pulmonary vascular compliance (Cvasc) and is based on measurement of pulmonary blood volume (PBV) and its increase with passive elevation of the legs to calculate Cvasc. Assuming the proportion of blood entering pulmonary venous system (in increase of PBV) during passive leg elevation to be 0.8, pulmonary venous compliance (Cv,PBV) was calculated as Cv,PBV = 0.8Cvasc. Cv,PCW correlated fairly closely with Cv,PBV (r = 0.81, coefficient of variation = 31%). This fair agreement between two independent methods suggests strongly that both methods may be valid, although other interpretations are possible. Cv,PCW, Cvasc, and Cv,PBV decreased going from New York Heart Association class I to classes II and III. When PBV was plotted vs. PCW, average V-P line for class II patients was flatter and shifted downward to the right compared with that for class I. This suggests pulmonary vasoconstriction as well as other factors. Average V-P line for class III patients is flatter but not displaced compared with that for class II. Another previously reported series of 50 patients, most of whom had ischemic heart disease, are included in this study.

Blood Pressure↗
PubMed1995

Apoptosis in thyroid diseases: a histochemical study.

Recent studies demonstrate that apoptosis is an important process in physiological and pathological cell death. We examined the apoptotic phenomena in thyroid tissues by two methods: immunohistological and in situ end-labeling of fragmented DNA (ISEL). In thyroid tissues from patients with Hashimoto's thyroiditis and thyroid cancer, fragmented nuclear DNA and LeY (apoptosis associated antigen) were observed. In tissues from patients with Graves' disease, LeY and bcl-2 oncoprotein were expressed, but no ISEL positive cells were observed. In contrast, thyrocytes in normal thyroid tissues were not stained with ISEL or anti-LeY antibodies (Abs). Fas antigen (Ag) was expressed in various thyroid tissues, including normal subjects. The clinical meaning of this was not determined. These results suggest that the apoptotic process takes place in Hashimoto's thyroiditis and thyroid cancer, and is overcome in Graves' disease by bcl-2 expression.

Apoptosis↗
PubMed1995

Thrombotic thrombocytopenic purpura and myoglobinuric acute renal failure following radiation therapy in a patient with polymyositis and cervical cancer.

A 73-year-old woman was admitted to receive radiation treatment for uterine cervical cancer, however a complex series of events ensued, leading to death. She developed an acute exacerbation of polymyositis complicated by thrombotic thrombocytopenic purpura, rhabdomyolysis and acute renal failure. Radiation therapy may have produced an immune disturbance leading to the acute exacerbation of polymyositis. Auto-immune-mediated endothelial damage might have triggered a series of events leading to thrombotic thrombocytopenic purpura. Rhabdomyolysis seemed to be the main cause of acute renal failure.

Acute Kidney Injury↗
PubMed1995

Plasma adrenaline modulates alpha 1-adrenoceptor mediated pressor responses and the baroreflex control in patients with borderline hypertension.

Plasma level of adrenaline has been reported to be elevated in borderline hypertension. However, its role in developing and maintaining hypertension is still not completely understood. This study aimed to estimate the role of plasma adrenaline in developing hypertension. Ten patients with borderline hypertension (BHT) and 10 age-matched normotensive subjects were included. We infused at least three graded doses of phenylephrine, an alpha-adrenoceptor agonist, into the antecubital vein of subjects lying quietly in a supine position. Mean blood pressure was measured continuously through the right radial artery. Cardiac output was measured by the thermodilution method before and after the administration of each dose of phenylephrine infusion. We obtained dose-response curves for mean blood pressure and total peripheral resistance to phenylephrine. Baroreflex sensitivity was calculated by plotting the longest R-R intervals against the elevated peak mean blood pressure after the infusion of each dose of phenylephrine. Plasma noradrenaline and adrenaline concentrations at rest were measured by high performance liquid chromatography coupled with trihydroxyindole fluorimetric detection. The plasma adrenaline level at rest was higher in patients with BHT than in normotensive subjects. With graded infusion of phenylephrine, both the pressor responses and the changes in total peripheral resistance were greater in patients with BHT than in normotensive subjects. The plasma adrenaline level was positively correlated with the slope of dose response curves for the increments of mean blood pressure to phenylephrine (r = 0.60, p < 0.01). Baroreflex sensitivity was reduced in patients with BHT as compared with normotensive subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-1 Receptor Antagonists↗
PubMed1994

Usefulness of the pulmonary vein flow velocity-time profile as an estimate of left atrial storage fraction.

During ventricular systole, the left atrium (LA) stores a certain amount of ventricular stroke volume; this is defined as an LA storage volume. From cineangiocardiograms, an LA storage fraction is obtained as the ratio of the LA storage volume to left ventricular stroke volume. From the pulmonary vein (PV) flow velocity-time profile, the LA storage fraction may be estimated as a ratio of the PV flow velocity-time integral during systole (Sa) to a sum of that during systole and diastole (Sa+Da), namely, Sa/(Sa+Da), provided that the PV cross-sectional area remains relatively unchanged during one cardiac cycle and that the PV flow velocity-time profile is similar in any of the PVs draining to the LA. To evaluate usefulness of Doppler echocardiographic method of estimating the LA storage fraction, the authors measured the LA storage fraction from the left upper PV flow velocity-time profile by transesophageal Doppler echocardiography and compared it with the LA storage fraction from conventional cineangiocardiographic volumes. Subjects were 23 patients with a variety of cardiac diseases in normal sinus rhythm, ranging from eighteen to seventy-four years of age. The LA storage fraction was 0.58 +/- 0.12 (mean +/- SD) from cineangiocardiography and 0.64 +/- 0.08 from Doppler echocardiography larger than that from cineangiocardiography (P < 0.01), the correlation was good (r = 0.643). The authors conclude that the left upper PV flow velocity-time profile appears to provide a better correlation with that by cineangiography and may be used as a reliable quantitative estimate of the LA storage fraction.

Adult↗
PubMed1994

Stimulation of the biosynthesis of interleukin 8 by interleukin 1 and tumor necrosis factor alpha in cultured human chorionic cells.

Human chorion, but not amnion, tissue explants produced substantial quantities of neutrophil chemoattractant in response to interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF alpha). This suggested that chorion is one of the chemoattractant producing tissues. Therefore, the biochemical properties and the regulation of a chemoattractant in human chorionic cells were examined. IL-1 alpha and TNF alpha stimulated human chorionic cells to produce neutrophil chemotactic factor in both a dose- and time-dependent manner. This chemotactic factor was a heat-stable and trypsin-sensitive protein with an apparent molecular weight of 10000, and it was also immunologically identified as a chemotactic cytokine of the human IL-8 family. Immunohistochemical observations with IL-1 alpha- and TNF alpha-treated chorion explants indicated that trophoblasts and stromal cells, including fibroblast-like and macrophage-like cells, but not endothelial cells, were characterized as IL-8-producing cells. From these observations, it is very likely that both IL-1 and TNF alpha may participate in the production of chemotactic factor/IL-8 in pre-term parturition, accompanied by an intraamniotic infection, along with their known promotive effect on the production of matrix metalloproteinases, which is connected with the destruction of matrix components of fetal membranes.

Amnion↗
PubMed1993

The change of membrane complement regulatory protein in chorion of early pregnancy.

Research on membrane complement inhibitors (DAF, MCP, and CD59) has led to understanding of the regulation of complement system; however, their precise role and distribution remain speculative. In this study, we used an indirect fluorescent immunostaining to investigate the distribution of complements, MCP, DAF, and CD59, in the villi before the 10th week of pregnancy in 18 women. DAF and MCP were observed at the surface of syncytiotrophoblasts (ST) and extravillous trophoblast (EVT) in all subjects. They were observed in villous cytotrophoblast (VCT) in the subjects before the 8th week of pregnancy but were not observed in any subject after the 9th week. However, CD59 appeared in ST but never in VCT. MCP, DAF, and CD59 were observed in EVT. These findings indicated that these complement inhibitors played an important role in early pregnancy, and that CD59 continued to appear in early pregnancy, whereas the expression of MCP and DAF depended on the stage of pregnancy.

Antigens, CD↗
PubMed1993

Electrophysiological study of superficial abdominal reflexes in normal men.

We studied the superficial abdominal reflexes of 83 normal men, using as stimuli a train of electrical pulses or a needle scratch. Electrical stimulation delivered to the midline of the abdominal wall evoked, almost symmetrically on both sides, two reflex discharges: an early response having an oligophasic wave form, and a late response of polyphasic wave form. The threshold of the early response significantly exceeded that of the late response. With repetitive stimulation, the late response generally revealed habituation. Electrical stimulation of the unilateral abdominal wall evoked two responses on the stimulated side, whereas it evoked only the late response on the contralateral side. A needle scratch on the unilateral abdominal wall evoked one reflex discharge with a long latency and a polyphasic wave form. This response occurred generally on the stimulated side and became habituated to repeated scratching. These observations suggest that the superficial abdominal reflexes elicited by electrical stimulation are composed of two reflex discharges with a different reflex arc. They appear to closely resemble the blink reflex. The response elicited by needle scratching is thought to correspond to the late response of the electrically elicited abdominal reflexes.

Adult↗
PubMed1993

Individual difference in toxic diffuse goiters assessed by heme-based specific activity and Km value.

Thyroid peroxidase (TPO) was purified from each thyroid of 10 patients (experiment 1) and 4 patients (experiment 2) with toxic diffuse goiter by a simplified method with monoclonal anti-TPO antibody-assisted immunoaffinity column chromatography. The final preparations were used to measure the heme concentration based on the cyanide difference spectrum, and to determine the Km and kcat values from double reciprocal plots in the assay employing guaiacol and iodide as the second substrates. The heme-based specific activities of TPO purified from thyroids in experiment 1 were higher than those in experiment 2, which were probably impaired by freezing-thawing, and those of porcine TPO previously reported. There were some differences in the kinetic properties between experiment 1 and experiment 2, but the individual differences within each group were relatively small, the values for CV (= SD/mean) being 0.16-0.48.

Adolescent↗
PubMed1993

The effects of thyroid-stimulating hormone and thyroid microsomal antibody on thyroid peroxidase activity in human follicular cells: a mini organ culture study.

Thyroid peroxidase (TPO) is an essential enzyme involved in thyroid hormone synthesis and is closely related to the microsomal antigen which is the target of thyroid microsomal antibody. There have been several reports on direct inhibition of peroxidase activity by thyroid microsomal antibody. We prepared a mini organ culture of thyroid glands obtained at operation, and investigated the localization of thyroid peroxidase activity in follicular cells proliferated around the thyroid tissue blocks by electron microscopy. The development of microvilli containing TPO activity on the cell surface facing the culture medium was observed when normal thyroid tissue or Graves' thyroid tissue was incubated with TSH but in the TSH-free group the development of microvilli was poor and TPO activity was very much decreased. After the addition of serum positive for thyroid microsomal antibody, the TPO activity of the microvilli was retained in 4/6 tissue samples, but it disappeared in 2 cases. Our findings suggested that thyroid peroxidase activity is regulated by thyroid stimulating substances such as TSH and by TPO in tissue.

Adolescent↗
PubMed1993

Ultrastructural substrates for increased lung water content in experimental pulmonary edema.

We examined the relationship between the incidence of ultrastructural changes in the alveolar septum and the extravascular lung water content. Pulmonary edema was induced in 18 mongrel dogs by either dextran (n = 12) or alloxan (n = 6) administration. Six other dogs served as controls. Extravascular lung water content was measured by the thermal-dye double indicator dilution method. Specimens of lung tissue were examined with an electron microscope, and the incidence of 13 types of pathological changes in the alveolar septum was studied. For each type of pathological change, the incidence was correlated with the magnitude of lung water content. The following results were obtained. The incidence of edematous changes in the alveolar interstitium (widening of the interstitial space, and dispersion and disarray of collagen fibres in the interstitial space) was well correlated with lung water content (r = 0.78, p < 0.01, and r = 0.84, p < 0.01, respectively). The correlation was not significant in the remaining types of changes. We conclude that the incidence of the pathological changes in the alveolar septum is increased along with the increase in the content of lung water in both dextran- and alloxan-induced experimental pulmonary edema in dogs.

Alloxan↗
PubMed1992

Age-related increase in systolic fraction of pulmonary vein flow velocity-time integral from transesophageal Doppler echocardiography in subjects without cardiac disease.

The pulmonary vein flow velocity-time profile would be equivalent to the pulmonary vein flow volume-time profile, provided that the cross-sectional area of the pulmonary vein remains unchanged during 1 cardiac cycle. The systolic fraction of the pulmonary vein flow velocity-time integral, a ratio of velocity-time integral of the S wave to the sum of velocity-time integrals of the S and D waves, represents the ratio of left atrial storage volume to left ventricular stroke volume. This systolic fraction may help early filling of the left ventricle through an appropriate storage of blood and generation of driving pressure in the left atrium. Because early filling of the left ventricle is progressively impaired with age, it was hypothesized that this systolic fraction is increased with age. Forty-four noncardiac surgical patients (age range 17 to 70 years) who underwent transesophageal Doppler echocardiography under general anesthesia were studied, and left upper pulmonary vein flow and mitral inflow velocities were recorded. The ratio of peak velocity of the E wave to that of the A wave of mitral inflow velocity-time profile (y) decreased with age (y = -0.0245 x age + 2.41; r = -0.672, p < 0.01). Systolic fraction (y) increased with age (y = 0.00373 x age + 0.514; r = 0.656, p < 0.01). The age-related increase in the systolic fraction of pulmonary vein flow velocity-time integral may account for the compensation for impaired early filling of the left ventricle in elderly patients.

Adolescent↗
PubMed1992

Coronary angioplasty using an over-the-wire balloon catheter through a new 6 French guiding catheter.

A new 6 French (F) guiding catheter with a large, teflon-coated internal lumen (4.2F) was developed, permitting use of the standard ultralow profile (less than 3F) over-the-wire system. This small coronary angioplasty system (6F-PTCA) was evaluated in 48 lesions in 45 of 137 patients (33%) who underwent coronary angioplasty between September 1990 and January 1991. The mean age was 64 years (range 49 to 82); 37 (82%) were male. The procedure was via the brachial artery in 28 patients (62%). The overall primary success rate was 96%. It was 100% via the brachial artery and 90% via the femoral artery. There were no major complications. The puncture compression time with the 6F-PTCA via the brachial artery and via the femoral and with 8F-PTCA via the femoral was 3.8, 9.6, and 16.9 hr, respectively (P less than 0.001), although the procedure time of the 6F-PTCA via brachial and via femoral and of the 8F-PTCA was not significantly different. The mean hospital stay was 3.1, 4.5, and 5.5 days, respectively (P less than 0.01). A small hematoma occurred in 2 patients (4.4%) after the 6F-PTCA and in 3 (3.3%) after 8F-PTCA, and a large hematoma (greater than 5 cm) was noted in 7 patients (7.6%) after 8F-PTCA. These results indicate that coronary angioplasty using the over-the-wire system through the new 6F guiding catheter is technically feasible. Moreover, this approach, especially when advanced via the brachial artery, could shorten the hemostasis time and facilitate early ambulation.

Aged↗
PubMed1992

Increase in serum cardiac myosin light chain I associated with elective percutaneous transluminal coronary angioplasty in patients with ischemic heart disease.

Changes in serum myosin light chain I (MLCI) due to elective percutaneous transluminal coronary angioplasty (PTCA) were studied after PTCA (0, 8 and 48 hours) in 57 patients with old myocardial infarction (MI group) and 20 patients with angina pectoris (AP group). The AP group showed no increase after PTCA. In contrast, in the MI group there were 16 patients in whom MLCI at 48 hours was increased by 1.0 ng/ml or more (MI1 group) and another group of 41 patients who showed no increase in MLCI (MI2 group). The MI1 group had a significantly higher incidence of (1) non-Q wave myocardial infarction (62.5% vs. 17.1%, p < 0.01), (2) 99% stenosis of a coronary artery (50.0% vs. 12.2%, p < 0.01), and (3) redistribution in a hypoperfusion area found in the delayed image of resting thallium-201 (201Tl) myocardial scintigraphy (85.7% vs. 15.8%, p < 0.01). The left ventricular ejection fraction (LVEF) was significantly improved in the MI1 group, 3 to 4 months later (from 0.49 +/- 0.12 to 0.58 +/- 0.11, p < 0.01), in contrast to the patient of MI2 group who did not show any improvement. The AP group was not considered to have a bulk of myocardium impaired enough to show a release of MLCI due to PTCA-associated transient coronary occlusion. In the MI1 group, however, MLCI was probably released from the chronically under-perfused, but still salvageable, portion of the myocardium. This is consistent with the improvement in LVEF observed 3 to 4 months after the relief of severe coronary stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗