Search PubMed⌕ Search

Biomedical subjects

T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 1,243 records · Page 69Linked to original sources
PubMed1977

Echocardiogram in pulsus paradoxus. Respiration dependent cyclic changes in mitral and aortic valve motion: a case report.

The mechanism of production of pulsus paradoxus was echocardiographically studied in a 74-year-old male with subacute effusive-constrictive pericarditis which developed to constrictive pericarditis under the observation. Echocardiography disclosed the following phenomena during inspiration: 1) mitral valve did not open until the atrial systole, probably because of the lack of antegrade mitral flow during rapid filling phase (the E wave was not observed), 2) concomitantly, aortic valve opening decreased markedly in its grade, and 3) left ventricular ejection time (LVET) decreased and pre-ejection period (PEP) increased, resulting in a higher PEP/LVET ratio (up to 1.32). The opposite was true during expiration (PEP/LVET ratio was 0.40). This is probably the first case, in which the mechanism of pulsus paradoxus was investigated by aortic and mitral valve echograms.

Aged↗
PubMed1977

Studies on rat liver catalase. IX. Role of methionine in polypeptide chain inhibition.

Initiation with methionine of the synthesis of rat liver catalase [EC 1.11.1.6] has been investigated. Analysis of the N-terminal residue of nascent catalase peptides labeled in vivo with injected radioactive amino acids, including [3H]methionine, indicated a remarkably high content of methionine. By fractionating [3H]methionine-labeled nascent catalase according to chain length, it was found that peptides of shorter chain length contained more N-terminal methionine relative to total methionine incorporated. In addition, only a small amount of [3H]methionine was detected as the N-terminal amino acid when newly completed catalase was examined by Edman degradation. These results indicate that the synthesis of liver catalase is initiated with methionine, and suggest the presence of a mechanism for its subsequent removal from the N-terminal position. Catalase was also synthesized in a cell-free system directed by the catalase mRNA, using [3H]Met-tRNAf or [3H]Met-tRNAm. The results obtained in such in vitro experiments were in good agreement with those from in vivo studies, and further showed that the N-terminal methionine was provided by a specific initiator tRNA, i.e. tRNA Met f.

Animals↗
PubMed1976

Genesis of the third heart sound. Phonoechocardiographic studies.

To clarify the genesis of the third heart sound (IIIS), phonoechocardiographic analysis was made in 31 cases with apparent IIIS. The mitral valve, either anterior or posterior, showed no definite movement coincided with the IIIS. At the time of IIIS, mitral valve is in the closing process, but it is still widely open, and there was no evidence of the stretch or tension of the valve apparatus. On the other hand, the endocardial echoes, either of interventricular septum or of posterior wall of the left ventricle, almost always showed definite check point (point of inflexion) during (or exactly at the end of) rapid ventricular filling as manifested by the sudden change in the diastolic dimension of the left ventricle near the apex. The IIIS seems likely to originate from the abruptly arrested momentum of the moving mass of blood at this check point and then the vibration of the relaxed cardiohemic system.

Adult↗
PubMed1976

Giant T wave inversion as a manifestation of asymmetrical apical hypertrophy (AAH) of the left ventricle. Echocardiographic and ultrasono-cardiotomographic study.

Left ventricular scanning by echocardiography and ultrasono-cardiotomography was performed to search the possible muscular abnormality in 9 cases with giant T wave inversion without documented cause. The deeply inverted T wave was more than 1.2 mV (average was 1.63 mV) in the left precordial leads. All the cases had electrocardiographic left ventricular hypertrophy of obscure origin and ischemic episode was absent. Conventional echo beam direction to measure the short axis of the left ventricle disclosed almost normal thickness and movement of both interventricular septum (IVS) and the posterior wasll (PW), so that the report of these cases is frequently within normal limits. However, ultrasono-cardiotomography (sector B scan) disclosed the fairly localized hypertrophy near the left ventricular apex, and conventional echocardiography also revealed the same area of either IVS or PW or both below the insertion of the papillary muscles, when the scanning towards the apex was performed (asymmetrical apical hypertrophy: AAH). Control study of 9 cases with IHSS showed asymmetrical septal hypertrophy (ASH) with almost equally hypertrophied IVS from base to apex. All cases had inverted T waves, but these were of lesser degree. Three cases had relatively deep T wave compatible with those of AAH, and these cases also had the apical hypertrophy of considerable degree (unusual type of IHSS, i.e., intermediate type between AAH and ASH). The close relationship between the depth of the inverted T waves and the Apex/Mid wall thickness ratios suggests that the altered recovery process of the hypertrophied apical musculature is responsible for the giant T wave inversion of heretofore unsolved origin. Until the connective link of AAH to the other forms of hypertrophic cardiomyopathy is disclosed, the cases with such a T wave and the apical hypertrophy may be designated as asymmetrical apical hypertrophy (AAH).

Adult↗
PubMed1976

Radiation therapy in the treatment of glioblastoma.

A retrospective study of 127 cases irradiated for glioblastoma was made to assess the role of radiation therapy and to determine the optimal technique of radiation therapy. The over-all survival rates of our series were 52 percent at one year, 19 percent at three years, and twelve percent at five years after radiation therapy. Survival time of the patients is influenced by various factors other than treatment: age, sex, histologic grading, duration of symptoms, and location of tumor. Among these factors, the location of the tumor was the most important in our present series. Surgical treatment can extend the survival time. More extensive resection results in longer survival, provided that the location of the tumor allows such a surgical procedure. Radiation therapy can prolong the survival time of those with glioblastoma, but a high tumor dose of more than 6,000 rads or 1,700 rets is necessary to improve the prognosis significantly. Therefore, irradiation should be administered through generous fields according to the extent of the tumor under precise planning to determine the accurate localization and extent of the tumor.

Adolescent↗
PubMed1976

[Dura arteriovenous malformation of the posterior fossa-clinical and angiographical analysis of 6 cases].

Dural arteriovenous malformation of the posterior fossa was infrequently reported in the literatures. We presented 6 cases of dural arteriovenous malformation of the posterior fossa with the presentation of typical examples. Up to the end February, 1974, 119 cases of intracranial arteriovenous malformation were experienced in our clinic, in which there were 6 cases of dural arteriovenous malformation. The ages of our series ranged from 41 to 75 years old and 57 years old in average. Tinnitus and headache were two main symptoms which developed in most of the cases. As for the older symptoms, visual disturbance was seen in 4 cases, unilateral pulsating exophthalmos in 1 case and papilledema in 3 cases. There wers two cases which progressive dementia was developed by the cerebral anoxia due to arteriovenous shung. On examination, a pulsatile bruit was audible at the mastoid region in all cases and a thrill could be palpated along the occipital arteries. Many kinds of durl and/or tentorial arteries which were drained directly into the sinuses at the occipital portion as the feeding arteries were visualized angiographically. Moreover, the angiographical patterns of feeding arteries into the sinuses showed dynamic changes after the operation. As for the treatments, many kinds of surgery were carried out for the cases by the combination method of the next 6 ways. 1. ligation of external carotid artery 2. ablation of periosteum from occipital bone 3. occipital and/or suboccipital craniectomy 4. clipping of almost of all feeding arteries at dura mater and tentorium 5. ligation of threocervical trunk 6. ventriculo-atrial shunt or ventriculo-peritoneal shunt From our experiences, the most effective treatment is thought to be a direct closure of intradural arteriovenous shunt near the sinus at the occipital portion in the early stage.

Adult↗