Biomedical subjects

T Nakata

Publications and source records attributed to T Nakata.

At least 235 records · Page 13Linked to original sources

PubMed1990

[A case of pheochromocytoma with an AMI-like ECG change corrected by an alpha-blocking agent].

A 59 year-old housewife was admitted to the emergency service with a sudden onset of chest pain and nausea. Initially she was treated as an acute myocardial infarction, but conventional treatments were not effective, and she was sent to our hospital for further evaluation. Her ECG showed several abnormal findings including T-wave inversion, atrial flutter, QT-time prolongation, ST-segment depression or elevation, and frequent ventricular ectopic beats. The echocardiogram, 201thallium scintigram and coronary angiography were almost normal. Both urinary and plasma levels of catecholamines were remarkably increased, and the plasma epinephrine was extremely high during attacks. Abdominal echotomography and CT-scanning showed a large left adrenal tumor. The 131MIBG scintiscan revealed a high accumulation in this tumor. Then the patient was diagnosed as having pheochromocytoma and catecholamine-induced myocarditis. The administration of phentolamine (10 mg) normalized the inversion of T-wave and the high blood pressure. But when propranolol (2 mg) was administrated in addition to phentolamine, the ECG showed a biphasic low T-wave change. According to these phenomena, we supposed that the alpha-adrenergic receptor was involved in the development of the ST-T changes of the ECG, and the alpha-adrenergic receptor of this patient might be sensitive under excessive catecholamines, according to the inhibition of the beta-receptor by propranolol.

Adrenal Gland Neoplasms↗

PubMed1990

Clear and colorless fluid observed during percutaneous transhepatic gallbladder drainage.

Twelve patients with discharge of clear colorless fluid during percutaneous transhepatic gallbladder drainage (PTGBD) were encountered during a period of 4.5 years. On the average, the fluid appeared on the 12th day after PTGBD and continued to flow until the completion of observation. The volume was usually less than 60ml per day. It flowed in an alternating pattern with normal yellow color bile each day. The fluid was observed in patients in whom satisfactory patency of the biliary system was confirmed by cholangiography and/or cholangio-fiberscopy. Biochemical examinations of the fluid revealed lower biliary lipids but a similar electrolyte composition compared to bile of normal color. It was alkaline. These observations indicate that the clear colorless fluid is different from what is known as "white bile", which is produced when there is an obstruction of the biliary tree. The fluid may be secreted from the gallbladder epithelium or the bile duct epithelium. The significance was not clarified in this study. Further investigation is necessary to elucidate the clinical implications of the clear and colorless fluid secretion.

Bile↗

PubMed1990

Are reperfusion-induced arrhythmias caused by disinhibition of an arrhythmogenic component of ischemia?

Isolated rat hearts were used to examine whether reperfusion-induced arrhythmias may be caused by washout of substances accumulating during ischemia. This was achieved by subjecting hearts to 10 min of regional ischemia and rendering them transiently inexcitable during the first 1.5 min of reperfusion. Transient inexcitability was induced by switching to cold solution (4 degrees C) shortly before reperfusion (-1.5 min). In controls (no hypothermia), the incidences of ventricular tachycardia (VT) and ventricular fibrillation (VF) were 83% and 92%, respectively, during the first 1.5 min of reperfusion. Transient hypothermia caused inexcitability and asystole, impaired recovery of coronary flow and abolished VT and VF (all P less than 0.05). On subsequent rewarming to 37 degrees C, coronary flow and sinus rate recovered in all hearts. However, VT and VF occurred in only 58% and 25%, respectively (P less than 0.05). These values were similar to those of new episodes of VT and VF occurring in controls during the equivalent period. Therefore arrhythmias had been abolished during transient hypothermia, not merely delayed. The relative contributions of transient impairment of recovery of coronary flow and transient asystole to the antiarrhythmic effects were examined in a further 10 groups of hearts (n = 12/group) in which reperfusion conditions were transiently manipulated. We utilized combinations of hypothermia, ventricular pacing, acetylcholine (ACh) 55 microM (to cause asystole and impairment of recovery of coronary flow), and right atrial excision and left atrial pacing (to permit bradycardia to be transiently induced during reperfusion by temporarily switching off the pacemaker). The results indicated that transient hypothermia was antiarrhythmic as a result of a reduction of excitability, not because of bradycardia or impairment of recovery of flow. The data support the hypothesis that reperfusion unmasks (disinhibits) latent arrhythmogenic components of ischemia (particularly during the first 1.5 min of reperfusion) and that, by inducing inexcitability, transient hypothermia allows these substances to be washed out without their arrhythmogenic effects being manifested. The identities of the arrhythmogenic and antiarrhythmic substances remain to be determined; we suggest that cyclic AMP and potassium, respectively, are likely candidates.

Acetylcholine↗

PubMed1990

Microdialysis in the posterior hypothalamus: sodium chloride affects norepinephrine release, mean arterial pressure, heart rate and behavior in awake rats.

A microdialysis probe, implanted in the posterior hypothalamus (PH) was used to examine changes of extracellular norepinephrine (NE) in freely moving rats from which mean arterial pressure (mAP) and heart rate (HR) were continuously monitored. Artificial cerebrospinal fluid (aCSF) was pumped through the probe and 10-microliters dialysate samples were collected at 5-minute intervals and analyzed for NE by radioenzymatic assay. High sodium chloride (NaCl)-aCSF solution elicited pressor and tachycardiac responses and locomotor activity coupled with significant increases in levels of dialysate NE. The latter and the associated cardiovascular effects were significantly attenuated by perfusate lidocaine (0.5%). When alpha-adrenergic receptors in PH were blocked by phenoxybenzamine (0.165 M), high NaCl-aCSF released NE but the associated cardiovascular effects were attenuated. In addition, intravenous ganglionic blockade with hexamethonium (25 mg/kg) also attenuated cardiovascular responses during the high NaCl-aCSF perfusion of PH. These results indicate that PH is one of the important areas for central actions of NaCl and that the cardiovascular and locomotor responses produced by central NaCl, in part, depend on neuroadrenergic activity in PH.

Animals↗

PubMed1990

Conformational change and localization of calpactin I complex involved in exocytosis as revealed by quick-freeze, deep-etch electron microscopy and immunocytochemistry.

Calpactin I complex, a calcium-dependent phospholipid-binding protein, promotes aggregation of chromaffin vesicles at physiological micromolar calcium ion levels. Calpactin I complex was found to be a globular molecule with a diameter of 10.7 +/- 1.7 (SD) nm on mica. When liposomes were aggregated by calpactin, quick-freeze, deep-etching revealed fine thin strands (6.5 +/- 1.9 [SD] nm long) cross-linking opposing membranes in addition to the globules on the surface of liposomes. Similar fine strands were also observed between aggregated chromaffin vesicles when they were mixed with calpactin in the presence of Ca2+ ion. In cultured chromaffin cells, similar cross-linking short strands (6-10 nm) were found between chromaffin vesicles and the plasma membrane after stimulation with acetylcholine. Plasma membranes also revealed numerous globular structures approximately 10 nm in diameter on their cytoplasmic surface. Immunoelectron microscopy on frozen ultrathin sections showed that calpactin I was closely associated with the inner face of the plasma membranes and was especially conspicuous between plasma membranes and adjacent vesicles in chromaffin cells. These in vivo and in vitro data strongly suggest that calpactin I complex changes its conformation to cross-link vesicles and the plasma membrane after stimulation of cultured chromaffin cells.

Adrenal Medulla↗

PubMed1990

Clonidine abolishes exaggerated pressor responses to shaker stress in spontaneously hypertensive rats.

To determine whether clonidine would attenuate exaggerated pressor responses to stress in spontaneously hypertensive rats (SHR), pressor responses to shaker stress were recorded following intracerebroventricular (icv) injections of clonidine in conscious SHR. Pressor responses to shaker stress were significantly larger in SHR than in Wistar-Kyoto rats (WKY). Increased sympathetic nerve responses to shaker stress were also significantly greater in SHR than in WKY. Exaggerated pressor responses in SHR were partly attenuated by adrenalectomy and abolished by clonidine (icv). By contrast, 1-Sar,8-Ile angiotensin II (icv) was ineffective. These findings suggest that in SHR, the alpha-adrenergic system in the brain may contribute to exaggerated pressor responses to shaker stress, but not the brain renin-angiotensin system.

1-Sarcosine-8-Isoleucine Angiotensin II↗

PubMed1990

Species differences in vulnerability to injury by oxidant stress: a possible link with calcium handling?

STUDY OBJECTIVE: The aim was to exploit species- and age dependent differences in calcium handling to assess the role of calcium as a mediator of oxidant stress induced injury in the mammalian heart. DESIGN: Hearts from immature and mature rats and rabbits were perfused aerobically with buffer containing rose bengal which was photoactivated by illumination--a process that generates singlet oxygen and superoxide. This oxidant stress rapidly leads to electrocardiographic abnormalities, ultrastructural injury, and a redistribution of calcium. EXPERIMENTAL MATERIAL: Isolated perfused hearts from mature (60-90 d old) and immature (4-6 d old) rats, and mature (60-90 d old) and immature (7-10 d old) rabbits. MEASUREMENTS AND MAIN RESULTS: In hearts (n = 6 per group) from mature rats, aerobic perfusion and photoactivation for 5 min with buffer containing rose bengal (250 and 1000 nmol.litre-1) had no significant effect upon heart rate (until the onset of arrhythmias) but did result in a dose dependent transient increase in coronary flow. ECG abnormalities appeared within less than 30 s and these deteriorated to ventricular premature beats (VPB) and ventricular tachycardia (VT) in most hearts. By contrast, in identical studies with comparable sized hearts from young rabbits, ECG changes and arrhythmias occurred later, and the incidence of VT and the mean number of VPB were lower. Although arrhythmias were less severe in rabbit hearts, photoactivation of rose bengal caused both coronary flow and heart rate to fall in a dose dependent manner. Increasing the concentration of rose bengal to a value (2500 nmol.litre-1), which would be highly toxic in the rat heart, increased the severity of injury in the rabbit heart, the nature of which differed from that in the rat heart. To assess whether developmental state, as opposed to species, was a factor determining the differences in vulnerability to injury, hearts from immature rats and adult rabbits were perfused with various concentrations of rose bengal (250-2500 nmol.litre-1) with the intensity of illumination (1400-6600 Lux) adjusted to account for the size of the heart. Under these conditions rabbit hearts were found to be less vulnerable to injury and arrhythmias than rat hearts, and hearts from immature rats were found to be less vulnerable than those from adult rats. CONCLUSIONS: The results of this and other studies suggest that species and developmental differences in calcium handling (sarcolemmal v sarcoplasmic reticulum control) might explain the differences in vulnerability to arrhythmias.

Age Factors↗

PubMed1990

Chronic central GABAergic stimulation attenuates hypothalamic hyperactivity and development of spontaneous hypertension in rats.

To determine whether chronic central gamma-aminobutyric acid (GABA) stimulation would attenuate development of hypertension, tail-cuff systolic pressures were measured in male spontaneously hypertensive rats (SHR) treated with either an inhibitor of GABA breakdown (valproate, VPA), or a GABA-receptor agonist (muscimol). When VPA was injected intraperitoneally (i.p.) daily for 4 weeks, tail-cuff systolic pressures were decreased during the last 2 weeks. On the other hand, continuous infusion of muscimol into the lateral cerebral ventricle for 14 days using an osmotic minipump decreased systolic pressures throughout the 10-day observation period. During terminal experiments under urethane anesthesia, pressor and sympathetic nerve responses to electrical stimulation of the ventromedial hypothalamus were reduced in VPA- or muscimol-treated SHR. Pressor responses to intravenously (i.v.) injected norepinephrine (NE) were unaltered by either treatment, indicating that diminished pressor responsiveness to hypothalamic stimulation was not due to diminished cardiovascular reactivity. Regardless of either VPA acid or muscimol treatment, basal blood pressure (BP), heart rate (HR), and responses to hypothalamic stimulation were lower in normotensive Wistar-Kyoto controls (WKY) than in SHR. In addition, chronic treatment with either drug had weaker hypotensive and hypothalamic depressant effects in WKY than in SHR. Our results suggest that in SHR the central GABAergic system is impaired and that chronic treatment with GABAergic stimulants can attenuate development of spontaneous hypertension by reducing hypothalamic overactivity.

Animals↗

PubMed1990

[Assessment of infarct-related coronary arteries using the bull's eye view method and unfolded surface mapping in thallium-201 myocardial tomography].

Infarct-related coronary lesions and collaterals were assessed by the bull's eye view and the unfolded surface map derived from thallium-201 myocardial tomography (Tl-201 SPECT) in 25 patients with anterior myocardial infarction. The patients were categorized in six groups according to their cine-angiographic findings: locations of stenosis (proximal or distal portions of the first diagonal branch or distal site of the first septal branch), and the presence or absence of collaterals. The anterior half of the left ventricle on the bull's eye view map was divided into eight regions from the anterior septum to the lateral wall and from the apex to the cardiac base. Tl-201 SPECT images were expressed as functional maps using maximum-count circumferential profile analysis: an "extent image" showing the extent of perfusion defect, and a "severity image" demonstrating the degree of hypoperfusion. The following results were obtained: 1. Perfusion defect of the "extent image" at the basal portion of the anterior septum reflected poor collaterals, with a sensitivity of 81.3%, a specificity of 77.8%, and a diagnostic accuracy of 80.0%. 2. Coronary stenosis at segment 6 (AHA classification) was differentiated from that at segment 7 by detecting hypoperfusion at the basal septum on the "severity image", with a sensitivity of 71.4%, a specificity of 77.8%, and a diagnostic accuracy of 75.0%. 3. Perfusion defect at the basal section of the proximal portion of the anterior wall on the "extent image" indicated stenosis at the proximal segment 6, with a sensitivity of 57.1% and a specificity of 88.9%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

[Cytotoxicity of lymphocytes sensitized by autologous tumor cells in vitro, against autologous lung cancer cell lines].

In order to obtain killer lymphocytes that would have a strong cytotoxicity against autologous tumor cells, we conducted a cytotoxic assay of effector cells cultured from human peripheral blood lymphocytes (PBL) using 10 cultured lung cancer cell lines as target cells. We present this result. (1) Lymphocytes obtained by 17 days mixed lymphocyte tumor cell culture (MLTC: Fresh PBL from lung cancer patients was mixed with irradiated autologous tumor cells in a medium, and cultured for 3 days. Irradiated allogeneic lymphocytes were then added, and cultured for 14 days) were cytotoxic against 4 of the 10 autologous lung cancer cell lines. (2) Lymphocytes obtained by 14 days MLTC and 3 more days culture in a medium containing interleukin 2 were cytotoxic against all 10 of the autologous lung cancer cell lines. These lymphocytes proliferated to 4.13 times of the original cell number, and their surface marker was OKT3+. These killer lymphocytes are expected to be effective in adoptive immunotherapy as effector cells.

Adult↗

PubMed1990

[A case of pulmonary metastasis from adenoid cystic carcinoma of the trachea].

A 33-year-old woman with adenoid cystic carcinoma of the trachea was treated by resection of the upper and mid-trachea, plus total laryngectomy, subtotal thyroidectomy, partial resection of the cervical esophageal muscle layer and mediastinal tracheostomy. This tumor invaded directly into the thyroid gland, the larynx, the recurrent laryngeal nerve and the cervical esophagus. Three years after the operation, metastases developed in the right lung (S10, S2) and partial resection of the lung was performed. This patient is now free from disease. Aggressive surgical resection is important for the improvement of survival in this condition, although this tumor shows low grade malignancy and is slowly growing.

Adult↗

PubMed1990

[Hepatic artery reconstruction grafting with the right gastroepiploic artery for surgical treatment of upper bile duct cancer].

The right gastroepiploic artery (GEA) was used as hepatic artery graft in 2 patients with advanced upper bile duct cancer. The pedicle, including the right GEA and surrounding tissues, was mobilized along greater curvature of the stomach. The GEA pedicle was raised up beyond the gastric pylorus and was anastomosed to the distal right hepatic artery by interrupted suture technique using 7-0 monofilament-nylon stitches. The patients recovered well without evidences of anastomotic dehiscence of hepatico-jejunostomy and prolonged liver dysfunction beyond three postoperative days. Angiograms at one week after operation showed good patency of the GEA graft. The method of hepatic artery grafting with the right GEA is very simple and useful for surgical treatment of upper bile duct cancer.

Aged↗

PubMed1990

[Treatment of invasive thymoma with myasthenia gravis: a case report responsive to azathioprine and methylprednisolone].

The treatment of invasive thymomas associated with autoimmune diseases, such as myasthenia gravis (MG) and pure red cell aplasia, has not been established. In this paper, we report a 37-year-old patient with post thymectomy myasthenia gravis, who underwent subtotal resection of invasive thymoma with residual lesions of intrathoracic implants. He was treated with azathioprine (AZP) and methylprednisolone (MP). During two months from the start of this therapy, the clinical symptom was improved apparently and the recurrent tumor was reduced. Lasting 18 months of the treatment, he had to stop it because of the renal failure, but now he has no sign of the recurrence. Further studies with this combined regiments are warranted in the treatment of the invasive thymomas associated with autoimmune disease.

Adult↗

PubMed1990

[A recurrent gastric cancer improved by radiation therapy].

In March, 1988, a 65 year-old male underwent a total gastrectomy for a gastric cancer (Borrmann 3: a poorly differentiated adenocarcinoma; IIc: signet ring cell carcinoma). In October that year, however, an anastomotic recurrence of this tumor was found. Thus, from November, 1988 to January, 1989, to treat this recurrence, the patient received a course of radiation therapy frontally, towards the upper abdomen, with a total dose of 46.5 Gy (linac X-ray). His symptoms improved, and a CT, an upper gastrointestinal barium study, and an endoscopic examination indicated that the tumor had disappeared. No further recurrence was found until January, 1990, when the patient died of a metastasis that had spread throughout his body.

Adenocarcinoma↗

PubMed1989

Quantification of area and percentage of infarcted myocardium by single photon emission computed tomography with thallium-201: a comparison with serial serum CK-MB measurements.

In order to quantify the size of the infarcted myocardium, two kinds of data processing techniques were applied to single photon emission computed tomography (SPECT) with thallium-201 and its clinical reliability was evaluated by comparing it with the infarct sizing procedure with the serial serum creatine kinase-MB measurements in 14 patients with acute myocardial infarction. After maximum-count circumferential profile analysis, short axis images were reformatted into an unfolded surface map and a bull's eye view map. The SPECT-determined infarct size was defined as the area or the percentage of hypoperfused myocardium of which the profile count was less than the mean minus 2SD derived from 8 normal subjects. The infarct area was calculated from the number of pixels with an abnormal count and expressed in an unfolded surface map. The percentage was calculated from the number of abnormal profile points and displayed in a bull's eye view map. A high linear correlation was observed between the enzymatically determined infarct size and the infarct area or the percentage (r = .947, r = .872, respectively), despite underestimations in 2 patients with accompanying right ventricular infarction and overestimations in 2 patients with prior anterior infarction. Moreover, a close negative correlation was found between the left ventricular ejection fraction and the infarct area or the percentage (r = .836, r = .821, respectively). Thus, the semiautomatic techniques for processing thallium-201 SPECT images might contribute to the quantitative estimation and display of infarcted myocardium and have high clinical reliability.

Adult↗

PubMed1989

Availability of 111In-labeled platelet scintigraphy in patients with postinfarction left ventricular aneurysm.

Eighteen patients with postinfarction left ventricular aneurysms (LVAs) were examined with Indium-111-labeled autologous platelet scintigraphy to identify intracardiac thrombi and to investigate the effect of antithrombotic agents on thrombogenesity within their LVAs. Left ventriculography (LVG), and two-dimensional echocardiography were also carried out to assess the diagnostic ability of the platelet imaging. Indium-111-platelet scintigraphy for the detection of LVA mural thrombi had a sensitivity of 60% and a specificity of 100%. Four of six patients with false-negative scintigraphic studies had been under antiplatelet therapy. Eight of the nine patients who had showed active platelet deposition on initial examination had not received antiplatelet therapy. Thereafter, five of these nine were treated with tichlopidine (300 mg/day) for 29.8 +/- 5.0 days. On the second platelet study, two had resolution and the other three had interruption of intra-aneurysmal deposition, which remained positive. In only one patient of the three, the third platelet study was performed after warfarin therapy. It took two weeks after beginning the therapy to completely interrupt platelet deposition within the LVA in this patient. ECG gated radionuclide ventriculography and Thallium-201-myocardial scintigraphy were also performed to assess left ventricular wall motion of left ventricular ejection fraction (LVEF) and myocardial blood perfusion. Thallium-201-SPECT showed apical or anteroapical perfusion defects and the radionuclide ventriculography correctly identified all 18 apical and anteroseptal aneurysms which were confirmed by LVG methods. The comparison between the thrombus positive group and the thrombus negative group was carried out on both the LVEF and the period from the last myocardial infarction to the initial platelet scanning study. There were no statistical differences in the LVEF and the interval (34.5 +/- 12.5% vs 37.3 +/- 14.6%, 39.6 +/- 52.6 days vs 89.6 +/- 108.3 days) between the two groups. These results suggest that Indium-111-labeled platelet scintigraphy can be a reliable method for the identification of active left ventricular mural thrombi and a practical method of judging antiplatelet and anticoagulant therapy.

Adult↗

PubMed1989

Scintigraphic imaging of a case of congenitally corrected transposition of the great vessels and an adult case of single atrium and single ventricle.

We report on the clinical utility of radionuclide angiography and gated blood pool single emission computed tomography (gated blood pool SPECT) in two patients having congenital heart disease. Both conventional equilibrium radionuclide angiography and gated blood pool SPECT demonstrated the connection of the great vessels with both ventricles in a 15-year-old male patient with a congenitally corrected transposition of the great vessels. In particular, the latter procedure could provide very useful information about the ventricular morphology and inversion which is important for diagnosing this disorder. The second case is an extremely rare 42-year-old female patient with a single atrium and single ventricle. She underwent first-pass and multiple gated blood pool angiography from the anterior, right and left oblique views. The combination of these scintigraphic techniques revealed an insufficiency in anatomical correlations among the single atrium, atrioventricular valve, single ventricle and the great vessels in addition to the connection of superior vena cava with the single atrium, and the atrioventricular valve. Thus, conventional equilibrated angiography from multiple views and gated blood pool SPECT seems to be very reliable not only for anatomical evaluation but also for clinical course observation in patients with complicated congenital heart disease.

Abnormalities, Multiple↗

PubMed1989

Paraventricular nucleus lesions attenuate the development of hypertension in DOCA/salt-treated rats.

To determine whether paraventricular nucleus (PVN) can play a role in the hypertension in DOCA/salt-treated rats, DOCA/salt hypertension was produced in PVN lesions and sham-operated rats. In lesioned rats, the development of hypertension was significantly attenuated (day 7: 132 +/- 3 v 157 +/- 5 mm Hg, P less than 0.01; day 14: 132 +/- 3 v 157 +/- 5 mm Hg, P less than 0.01; day 21: 189 +/- 2 v 224 +2- 6 mm Hg, P less than 0.01). Lesions lowered systolic blood pressure in even control rats. Mean blood pressure (mBP) from awake free moving rats was also significantly lower in lesioned DOCA/salt-treated rats than those of sham-operated DOCA/salt-treated rats (155 +/- 14 mm Hg v 193 +/- 13, P less than 0.01), while mBP was not different between lesioned and sham-operated control rats. The reduction of mBP by hexamethonium injections was significantly larger in sham-operated DOCA/salt-treated rats than those of lesioned DOCA/salt rats. (-53 +/- 3% v -45 +/- 2, P less than 0.05). Plasma norepinephrine and epinephrine were significantly elevated in DOCA/salt-treated rats, however, PVN lesions inhibited significantly those elevations. 1-Deaminopenicillamine, 4-valine, 8-D-arginine Vasopressin (dPVDAVP) injections did not affect BP and heart rate in all rats. Body weight, water intake, urine volume, urine Na, K, and vasopressin excretion, and urine osmorality were not altered by lesions. These findings suggest that PVN contributes to development of hypertension in DOCA/salt-treated rats with sympathetic nervous activations.

Animals↗