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Biomedical subjects

T Nakata

Publications and source records attributed to T Nakata.

At least 253 records · Page 14Linked to original sources
PubMed1989

Transection of aortic depressor nerve fails to raise blood pressure in spontaneously hypertensive rats.

Although central resetting via the aortic depressor nerve (ADN) has been known to occur in spontaneously hypertensive rats, the function of the ADN is not yet clear in these animals. To determine whether a baroreflex via the ADN can act to regulate blood pressure during hypertension, blood pressures were measured following ADN transection in spontaneously hypertensive and normotensive rats, and the reflex changes of heart rate and the sympathetic nerve activity were recorded during the pressor response to phenylephrine infusions. Blood pressures were significantly raised 1 day after ADN transections in normotensive rats and continued so for 7 d. Blood pressures were not changed in sham operated rats. In spontaneously hypertensive rats, ADN transections did not alter blood pressures in comparison with sham operated controls. On the seventh day after transections, all rats were anaesthetised with urethane and pressor responses to phenylephrine were examined. Bradycardic and sympathoinhibitory responses to the elevation of blood pressure caused by phenylephrine infusions were significantly smaller in ADN transectioned normotensive rats than in sham operated controls. In spontaneously hypertensive rats, the bradycardic and sympatho-inhibitory responses were not reduced by ADN transections. These findings suggest that the impaired baroreflex via the ADN can contribute to the development of hypertension in the spontaneously hypertensive rat.

Animals↗
PubMed1989

Central baroreflex regulation by the renal nerves in anesthetized rats.

To determine whether the renal nerves affect central baroreflex regulation, the aortic depressor nerve (ADN) was stimulated electrically, while blood pressure, heart rate, and splanchnic nerve activity were recorded in renal denervated and sham-operated rats anesthetized with urethane. Tail cuff systolic pressure fell 6 days after renal denervation, but mean blood pressure recorded after anesthetizing with urethane did not differ between renal denervated and sham-operated rats. Urinary sodium excretion was greater in renal denervated than in sham-operated rats. ADN stimulation produced frequency-dependent falls in blood pressure accompanied by inhibitions of sympathetic nerve activity and heart rate. Depressor and sympathetic inhibitory responses to ADN stimulation were significantly smaller in renal denervated than in sham-operated rats. These findings suggest that the renal nerves can regulate baroreflexes centrally.

Anesthesia↗
PubMed1989

[Respiratory regulations of pulmonary vagal nerves under hypercapnic conditions; effects of J-receptor].

We studied ventilatory responses under hypercapnic condition in 9 lightly anesthetized dogs, using a vagal nerve cooling technique. One side of the cervical vagosympathetic trunks of dogs were previously severed, and a copper cooler was attached to the other side. When the cervical nerve was cooled below 7 degrees C, the Hering-Breuer inflation reflex ceased. We found that when the vagal nerve was not cooled or cooled to 7 degrees C, the respiratory frequency increased significantly in relation to hypercapnic gas inhalation. However, the increment of respiratory frequency was reduced by bilateral cervical vagotomy. We concluded that the J-receptor is responsible for the increase in respiratory frequency under hypercapnic gas inhalation.

Animals↗
PubMed1989

[A case report of sacral chordoma].

Sacrococcygeal chordoma is one of the retrorectal tumors. Relative rarity and anatomical location of this may lead to difficulty in diagnosis and surgical treatment. We report a case of sacrococcygeal chordoma successfully treated by high sacral resection by a posterior approach, in which the co-operative efforts of gastroenterological surgeons and an orthopedic surgeon were employed. A 64-year-old man with a long term continued vague anal pain was referred to our hospital. Digital rectal examination revealed an elastic hard mass presacrally. Plain sagittal radiograph, CT, barium enema showed a retrorectal mass and sacral destruction. Diagnosis was confirmed histologically by the specimen taken by open biopsy. Surgical resection was carried out in prone position with the buttocks elevated. The skin incision was upward arched transverse. The lower sacral vertebrae, including S3, were removed en block with the tumor. Bilateral S3 sacral nerve roots were preserved. Postoperative disturbances of the urination and defecation were not seen. High dose radiation therapy, 80 Gray, was done after surgery. Radiation ulcer of the skin was treated by free skin graft, but radiation proctocolitis was not seen. Now he is free from the disease.

Biopsy↗
PubMed1989

[Electrophysiologic and histopathologic investigations in children with idiopathic ventricular arrhythmias].

Between April 1984 and December 1987, electrophysiological studies and endomyocardial biopsy were performed in 14 pediatric patients, aged from 7 to 15 years, with idiopathic ventricular arrhythmias in whom diagnostic evaluation had revealed no structural heart disease. They were 8 boys and 6 girls. Cardiac catheterization revealed regional wall motion abnormalities of the left ventricle in 3 patients, one of whom showed decreased ejection fraction (EF). Electrophysiologic examination showed sinus node dysfunction in 21%. AV nodal dysfunction in 14% and dual AV nodal pathway in 21%. Histopathologic examination by endomyocardial biopsy showed myocellular hypertrophy, degeneration of myocytes, interstitial fibrosis and endomyocardial thickness in 86%, 36%, 35% and 14%, respectively. Since idiopathic ventricular arrhythmias in pediatric age group included relatively high electrophysiologic and histopathologic abnormalities, which were suggestive of occult myocardial disease and might be the early stage of cardiomyopathy, careful follow-up should be required.

Adolescent↗
PubMed1989

[A case of WPW syndrome with slow Kent documented by ATP injection].

A 46-year-old woman with chest tightness and palpitation at exercise was admitted to Sapporo Medical College Hospital for the evaluation of the ST-T changes on stress electrocardiogram. In this patient, PQ time was 0.14 second and pre-exitation was not clearly documented on electrocardiogram at rest. Bolus injection of 10 mg of adenosine-5'-triphosphate (ATP) demonstrated deltawave through the elongation of antegrade conduction of atrio-ventricular (AV) node. Electrophysiological study also showed left lateral accessory pathway with slow antegrade conduction, slow Kent. Stress 201-T1 myocardial scintigraphy using bicycle ergometer did not show the existence of ischemic region in spite of the ST-T changes on electrocardiogram. In this case, it seemed that a false positive ST-T changes might be caused by ventricular pre-exitation through slow Kent fiber. From these findings, it was suggested that the transient interruption on conduction through AV node by ATP bolus injection may be a useful diagnostic method in borderline pre-exitation syndrome.

Adenosine Triphosphate↗
PubMed1989

[Electrophysiological study on the atrophied pectoralis major muscle after modified radical mastectomy].

In order to clarify the cause of the atrophy of the pectoral muscles after modified radical mastectomy, twenty patients who had had the operation at Nagasaki Chuo National Hospital 40 days to 2 years prior to this study, were investigated by electromyography. Of 20 subjects, 11 had the operation to preserve the pectoralis major muscle and 9 had the operation to preserve both the pectoralis major and minor muscles. The results were as follows: 1) Electromyography revealed some damages to the pectoral nerves in 16 cases of 20 (80%). In 12 cases, development of fibrillation potentials was observed at rest, while motor unit potentials disappeared during voluntary contraction. These findings suggest the damage to the nerves including neutrotomy. 2) The regions with macroscopic muscular atrophy remarkably coincided with those with neurogenic changes on electromyography. This suggests that the atrophy of the pectoralis major after modified radical mastectomy might be mainly caused by the damage to the pectoral nerves. 3) The mastectomy preserving only the pectoralis major tends to cause damage to nerves innervating the sternocostal part of the pectoralis major more frequently than the mastectomy preserving both the pectoralis major and minor muscles. The abdominal part was frequently damaged irrespective of the types of the operation.

Action Potentials↗
PubMed1989

[Lung transplantation as a treatment method in terminal respiratory failure].

Lung transplantation is the last treatment for terminal respiratory failure due to irreversible pulmonary disease such as fibrosis and emphysema. In this paper we reported the results of our studies on three major problems for conducting clinical lung transplantation sefely, including lung preservation, early diagnosis of lung allograft rejection and bronchial anastomotic healing. We have developed a method for 48- and 96-hour lung preservation. Under simple hypothermic preservation using phosphate buffered solution resembling extracellular fluid, 48-hour storage of the lung becomes possible. Immunologic monitoring is feasible for early detection of postoperative rejection of the lung transplant. In this study subset and spontaneous blastogenesis of lymphocyte obtained from bronchoalveolar lavage fluid were measured in orthotopic rat lung allotransplantation. Lung allograft rejection is closely connected with wound healing of the bronchial anastomosis in lung transplantation. It seems that clinical applications of single and double lung transplantation is now possible for patients with terminal respiratory disease in our country.

Bronchoalveolar Lavage Fluid↗
PubMed1988

Central attenuation of baroreflex by angiotensin II in normotensive and spontaneously hypertensive rats.

To determine whether angiotensin II (A II) can modify baroreflex centrally and contribute to the central resetting of baroreflex in spontaneously hypertensive rats (SHRs), the aortic depressor nerve (ADN) was electrically stimulated following intracerebroventricular (ICV) administration of A II and/or A II analog in urethane-anesthetized normotensive Wistar rats (WKYs) and SHRs. Electric stimulation of the ADN elicited frequency-dependent depressor, bradycardic, and sympatho-inhibitory responses. Angiotensin II, administered ICV, dose-dependently attenuated these responses induced by ADN stimulation in normotensive rats. We found, however, these attenuations could be abolished by ICV pretreatment with A II analog. Vasopressin (ICV) did not change any responses to ADN stimulation. The vasopressor and sympatho-inhibitory responses to ADN stimulation were significantly less in SHRs when compared with those in WKYs: In SHRs, A II analog completely cancelled the A II-attenuated responses to ADN stimulation. These findings suggest that A II can centrally attenuate baroreflex, which might be independent from vasopressin, and in the brain A II can contribute to the central resetting of baroreflex in SHRs.

Angiotensin II↗
PubMed1988

Central attenuation of baroreflex precedes the development of hypertension in DOCA-salt-treated rats.

To determine whether baroreflex is changed centrally before the development of hypertension in DOCA-salt treated rats, aortic depressor nerve was stimulated electrically 5 days after DOCA-salt treatment in urethane-anesthetized rats: compared with those of sham-operated control rats, blood pressure was not elevated in either awake or anesthetized rats. Aortic depressor nerve (ADN) stimulation elicited frequency-dependent vasodepressor, bradycardiac, and sympatho-inhibitory responses in both DOCA-salt-treated and control rats. However, the responses to ADN stimulation were significantly smaller in DOCA-salt-treated rats. These findings suggest that baroreflex is attenuated centrally before the development of hypertension and this attenuation may contribute to the pathogenesis of DOCA-salt hypertension.

Animals↗
PubMed1988

Increased extracellular concentration of norepinephrine in the hypothalamus by sinoaortic denervation.

To determine whether baroreflex can affect the norepinephrine system in the hypothalamus, the extracellular concentration of norepinephrine were measured by the brain dialysis technique in sinoaortic denervated rats (SAD). Twenty-four hours after sinoaortic denervation, systolic blood pressure and heart rate were significantly elevated, and norepinephrine concentration in perfusate of the posterior hypothalamus was significantly higher in SAD rats than in sham-operated rats. These results suggest that baroreflex could modify the activity of noradrenergic neuron projecting to the posterior hypothalamus.

Animals↗
PubMed1988

Central attenuation of aortic baroreceptor reflex in prehypertensive DOCA-salt-loaded rats.

To determine whether the arterial baroreceptor reflex can act to oppose the development of hypertension, deoxycorticosterone acetate (DOCA)-salt hypertension was produced in sinoaortic-denervated and sham-operated rats. Systolic blood pressure measured by tail cuff started to increase in both sinoaortic-denervated and sham-operated rats 7 days after DOCA treatment, and the hypertension developed identically in both denervated and sham-operated rats. These findings suggest that the baroreceptor reflex cannot act against the development of hypertension. To determine whether the baroreceptor reflex is attenuated before the development of hypertension, bradycardiac and sympathoinhibitory responses to i.v. injections of norepinephrine were examined. Bradycardic and sympathoinhibitory responses were significantly smaller in DOCA-salt-treated rats in both prehypertensive (5th day after DOCA-salt treatment) and hypertensive stages (21st day after treatment). In urethane-anesthetized DOCA-loaded and control rats on the 5th day after treatment, aortic depressor nerve stimulation elicited frequency-dependent depressor and bradycardic responses accompanied by inhibition of sympathetic nerve activity in both DOCA-loaded and control rats. However, those responses were significantly smaller in DOCA-loaded rats than in control rats. These results suggest that the central component of the baroreceptor reflex mediated by the aortic depressor nerve is impaired before hypertension develops and that this impairment may contribute to the development of hypertension in DOCA-salt-treated rats.

Animals↗
PubMed1988

Morphological assessment of left ventricular wall and ventricular aneurysm by thallium-201 myocardial emission computed tomography.

To evaluate the influence of left ventricular (LV) aneurysm on non-infarcted ventricular wall, the shape of the left ventricular wall was assessed by thallium-201 single photon emission computed tomography (SPECT). From the morphology of the ventricular wall close to the apex, the rest images along the transaxis, horizontal long axis and vertical long axis were classified into 4 types: convergent, parallel, divergent and completely defective. LV aneurysm was detected by 2-dimensional echocardiography and/or contrast left ventriculography in 39 of 80 patients with previous myocardial infarction. Although convergence in the normal configuration of ventricular walls close to the apex, 4 of 39 patients with LV aneurysm showed this pattern. The divergent type was very specific (100%) and the most sensitive (56.4%) of the 4 for identifying LV aneurysm. Moreover, the parallel configuration indicated aneurysm in cases of inferoposterior infarction and all the completely defective cases exhibited this abnormality. Thus, thallium-201 SPECT is suitable for observing the morphology of the ventricular wall and can provide highly reliable information for detecting postinfarction ventricular aneurysm with a sensitivity of 89.7%, a specificity of 87.8% and a diagnostic accuracy of 88.8%.

Adult↗
PubMed1988

Effects of salt and DOCA on hypothalamic and baroreflex control of blood pressure.

Cardiovascular and sympathetic nerve responses to electrical stimulation of either the aortic depressor nerve (ADN) or the posterior hypothalamus were recorded from rats treated with salt, DOCA, or DOCA/salt and compared with those from untreated controls. By the 7th day, tail-cuff systolic pressures were significantly elevated in rats treated with salt or DOCA/salt. And by the 21st day, all treated rats (i.e. with salt, DOCA, or DOCA/salt) had elevated pressures together with attenuated ADN responses and augmented hypothalamic responses. After 5 days, DOCA/salt treated rats already had attenuated responses to ADN stimulation and augmented responses to hypothalamic stimulation even though their systolic pressures were still unaltered. These findings suggest that combined treatment with salt and DOCA altered central blood pressure regulation even before hypertension developed.

Animals↗
PubMed1988

[Carcinoembryonic antigen, alpha-fetoprotein and hepatoma alkaline phosphatase in gastric carcinoma].

Reported here is a 38-year-old woman who had a gastric cancer accompanied with liver metastasis. Abnormal serum levels of a carcinoembryonic antigen, alpha-fetoprotein, and an alkaline phosphatase isozyme were observed persistently after a gastrectomy. The properties of this alkaline phosphatase isoenzyme were identical to a hepatoma alkaline phosphatase type. Histologic findings of the stomach revealed a poorly differentiated adenocarcinoma. The patient died on the 180th postoperative day.

Adenocarcinoma↗