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Biomedical subjects

M Ohtaki

Publications and source records attributed to M Ohtaki.

At least 73 records · Page 4Linked to original sources
PubMed1992

[Clinical experience with the omnicarbon valve prosthesis].

Between January 1985 and March 1990, isolated valve replacements with the Omnicarbon valve were performed in 90 patients aged 34-72 years. There were 53 aortic valve replacements (AVR) and 37 mitral valve replacements (MVR). The cumulative follow-up was 320 patient-year (py) with a mean follow-up of 3.7 +/- 1.4 years. There were 3 operative and hospital mortalities (3.3%), resulting from retrograde aortic dissection during cardiopulmonary bypass, postoperative renal failure, and rupture of infective pseudoaneurysm in ascending aorta. Seven patients died during the late postoperative period, 4 due to valve-related causes. Two of these patients died of prosthetic valve endocarditis (PVE), while the others died of thromboembolism (including valve thrombosis). The overall actuarial survival rate at 6 years was 86.3% (98.8% for AVR, and 82.1% for MVR). There were 2 thromboembolic events (one mesenteric artery thrombosis, and the other valve thrombosis). The linearized incidence of thromboembolism was 0.63%/py. PVE occurred in 3 patients (0.94%/py). One patient (0.31%/py) was found to have a valve dehiscence due to aortitis syndrome. There were no instances of anticoagulant-related hemorrhage, or valve-related hemolysis. The actuarial rate of freedom from valve-related mortality at 6 years was 93.5% (100% for AVR, and 88.1% for MVR). On the basis of a follow-up period of 6 years, good clinical results and a low incidence of valve-related complications can be demonstrated with Omnicarbon valve.

Adult↗
PubMed1991

Evaluation of cancer prevention strategies by computerized simulation model: an approach to lung cancer.

A computerized simulation model was developed to evaluate the potential impact of primary and secondary prevention on lung cancer mortality in Japan. The natural history of lung cancer was modeled as a Markovian stochastic process from cancer-free to preclinical, clinical, and finally to terminal states. The increase in mortality rate of lung cancer among males aged 75 to 79 years has been the major force of increase in the total number of lung cancer deaths in Japan. The simulation showed that this tendency would continue until the late 1990s, presumably due to the increase in the proportion of ever-smokers in that cohort, who started smoking at an earlier age than did prior generations. It was shown that the number of lung cancer deaths can be reduced either by smoking cessation or screening programs, and that the reduction is proportional to the increase in the annual smoking-cessation rate and to the annual increment in the screening rate. However, only two to three percent reduction of lung cancer deaths in the year 2001 can be expected when the annual smoking-cessation rate is raised from the current value of 0.46 percent to five percent during the period from 1991 to 2000 or when the screening rate is increased by three percent annually for the same period.

Adult↗
PubMed1990

A nonparametric method for estimating interaction effect of age and period on mortality.

In this paper we introduce a new model and develop an estimation strategy to analyze mortality data. The model we dealt with has the specific structure E[log qij] = mu + alpha i + beta j + rho ij subject to the linear restrictions sigma i alpha i/sigma 2i = sigma j beta j = sigma i pij/sigma 2i = sigma j rho ij = 0 for any i and j; here, qij denotes the mortality for the jth period category and ith age category, mu denotes the overall mean, alpha i denotes the ith age effect in antichronological order, beta j the jth period effect, rho ij the general interaction effect; and sigma 2i is the common error variance of log qij for the ith age group. We propose a combined technique of ANOVA and nonparametric smoothing for estimating these parameters. The methods described are illustrated by mortality data on rectum cancer in Japanese males and females between 1950-1986.

Age Factors↗
PubMed1990

Application of log-linear model in inference on karyotypic evolution in chronic myelocytic leukemia.

Relationships among additional chromosome abnormalities in chronic myelocytic leukemia (CML) with translocation 9;22 [Philadelphia chromosome (Ph1)-positive CML] were analyzed by log-linear models on 709 karyotypes reported in the literature. Additional abnormalities, such as the gain of chromosome 8 (+8), gain of Philadelphia chromosome (+Ph1), isochromosome of the long arm (q) of chromosome 17 [i(17q)], and the gain of chromosome 19 (+19), were frequently observed. A four-way 2 x 2 x 2 x 2 contingency table was considered with respect to the appearance of these four abnormalities, then the hierarchical log-linear models having at least four main effects were fitted to the observed contingency table. Akaike's information criteria of the models reflected the fitness of the model very well. Parameter estimates of the interaction terms indicated that the combinations of two abnormalities, '+8 and +19', '+Ph1 and +19', and '+8 and i(17q)' were positively associated, while '+Ph1 and i(17q)', and '+19 and i(17q)' were negatively associated. Based on the results of the data analysis, an inference was made on the route of karyotypic evolution in Ph1-positive CML; it statistically supports the hypothesis presented by Heim and Mitelman.

Aneuploidy↗
PubMed1989

Effect of tritiated water on female germ cells: mouse oocyte killing and RBE.

The relative biological effectiveness (RBE) of tritiated water (HTO) was investigated using mouse immature oocytes. Juvenile mice, having immature oocytes that are highly sensitive to radiation killing, were exposed to HTO, 137Cs gamma rays, 60Co gamma rays, or 252Cf fission neutrons. The 137Cs gamma rays were used to simulate the changing dose rate (but not the radiation quality) received from HTO (see section 2). On the 14th day after birth, female ICR strain mice were injected once in the abdominal cavity with HTO at levels of 1.70, 3.40, 6.81, or 10.21 MBq/10g body weight, and their ovaries were removed 2 weeks after the injection. (The cumulative doses are equivalent to 0.039, 0.077, 0.159 and 0.246 Gy, respectively.) The survival rate of oocytes was determined by light microscopy inspection of serial sections, and the results of the different exposures were compared. The number of surviving oocytes decreased exponentially with increasing dose of HTO or 137Cs, and RBEs of HTO compared to 137Cs gamma rays ranged from 1.1 to 3.5. The relative effectiveness of the different types of radiations was compared, and the results of the comparison, in order of increasing effectiveness, was 137Cs, 60Co, HTO, and 252Cf. The RBE of 252Cf compared to 60Co gamma rays ranged from 1.6 to 3.5.

Animals↗
PubMed1989

[Surgical treatment of Taussig-Bing malformation in an adult--a case report].

With the development of pediatric cardiac surgery, the surgical treatment of Taussig-Bing malformation has been common in frequency and a majority of these cases are reported. However, because the patient's condition is so critical in the early stage of life, the importance of adequate initial operation is emphasized, and this area is restricted to the operative cases of child patient. In this clinical study, the operation for 41-year-old adult patient with Taussing-Bing malformation was successfully performed using the Kawashima's procedure, and we would like to report the detailed operative procedure as well as its clinical courses. This patient was female of 41 years of age and at surgery, this case was found to be the Taussig-Bing malformation associated with pulmonic stenosis, and the operation for intracardiac repair was carried out using intracardiac conduit (5 x 4 cm) and also extracardiac conduit (5 x 3 cm). It is reported that there are many operative procedure available in child patients but we believe that Kawashima's procedure is probably the best choice of operation for adult patients because of its simplicity.

Adult↗
PubMed1989

Mortality statistics of major causes of death among atomic bomb survivors in Hiroshima Prefecture from 1968 to 1982.

A comparative study was made on mortality during a 15-year period from 1968 to 1982 between atomic bomb survivors resident in Hiroshima Prefecture and non-exposed controls. The mortality rate for all causes of death was lower in atomic bomb survivors than in the non-exposed, but the rate was higher among those directly exposed within about 1 km than in the non-exposed. The mortality rate for malignant neoplasms was higher in atomic bomb survivors than in the non-exposed, but that for cerebrovascular disease and heart disease was lower. In examining the rate for malignant neoplasms by site, the sites showing a high mortality rate among atomic bomb survivors were almost identical to the results of the Life Span Study. For these sites, the shorter the exposure distance the higher was the mortality rate. The rate for malignant neoplasms of the uterus and stomach, and leukemia was unnaturally high among early entrants whose period after issuance of atomic bomb survivor's health handbook was short. In observing the atomic bomb survivors by the level of family destruction due to the bombing as a socio-economic factor, a tendency was observed for the mortality rate for malignant neoplasms, diseases of blood and blood-forming organs, and peptic ulcer, to be higher among survivors with severe family destruction.

Cause of Death↗
PubMed1989

[Aortic dissection associated with percutaneous intra-aortic balloon pumping].

This is a case report of aortic dissection associated with percutaneous intraaortic balloon insertion, which was attempted for systolic unloading after repair of left ventricular rupture. But the hemodynamic condition gradually deteriorated in spite of IABP support and aortic dissection was suspected from the difference between monitoring pressures of bilateral radial arteries and balloon tip. The balloon was removed on the 3rd postoperative day, but the patient died from renal failure, liver dysfunction and D.I.C. on the 7th postoperative day. At postmortem examination, aortic dissection was found, which extended from left common iliac artery, all the way past right renal artery and ended just below origin of left subclavian artery. Therefore, acute renal failure was supposed to be followed by aortic dissection.

Aortic Dissection↗
PubMed1988

[Reconstruction of the venous outflow using a vein graft in dural arteriovenous malformation associated with sinus occlusion].

In some cases of dural arteriovenous malformations (dural AVMs) of the transverse-sigmoid sinuses, the presence of an occlusion or hypoplasia on the sinus contralateral to the affected side may significantly contribute to the development of intracranial hypertension. For these cases, closure of AV shunts or removal of the affected sinus may not be sufficient to improve intracranial hypertension. We encountered 2 cases of intracranial hypertension caused by dural AVMs at the transverse-sigmoid sinuses associated with disturbance of venous outflow contralateral to the lesion. Reconstruction of venous outflow using a saphenous vein graft was performed between the transverse sinus and the subclavian or external jugular vein after the dural AVMs were partially occluded by catheter embolization. Intracranial hypertension was relieved in both cases. In one case dural AVM was obstructed by both embolization and radical surgery after the bypass was confirmed unobstructed several weeks later. The bypass remained patent at the follow-up 4 months later. In the other case, patency of the bypass lasted only for approximately 1 month. In both cases clinical improvements were not remarkable. It is considered that the presence of AV shunt in the case of dural AVM may facilitate the patency of a graft placed between the venous systems. Reconstruction of the venous outflow may deserve further trial for the treatment of intracranial hypertension associated with some types of dural AVM.

Adult↗
PubMed1988

[A case of adenomatoid odontogenic tumor with intracranial extension].

A 49-year-old female of adenomatoid odontogenic tumor with intracranial extension was reported. She had 3 months history of left nasal obstruction and visual disturbance. Endocrinological examinations revealed a low basal level of serum cortisol and low level of urinary 17-OHCS. Neurological examinations revealed left anosmia and left visual disturbance (hand movement, marked afferent pupillary defect, and lower hemianopsia). Plain X-ray films and frontal tomograms of the skull showed a mass of soft tissue density in the left upper maxillary, left posterior ethmoid, and sphenoid sinuses with extensive destruction of the sella turcica, dorsum sellae, and anterior clinoid process. Plain axial CT scans demonstrated a low density mass filling up the left maxillary, left posterior ethmoid, and sphenoid sinuses and extending into the left middle fossa with bony destructions. Contrast-enhanced coronal CT scans demonstrated an extradural extension of the tumor into the left middle fossa and upward displacement of the pituitary complex. Left carotid angiograms showed a faint narrowing of the left internal carotid artery between the cisternal portion and the origin of the ophthalmic artery. Subtotal removal of the tumor and decompression of the optic canal and superior orbital fissure were performed via a left subtemporal extradural approach. Adenomatoid odontogenic tumor is a comparatively rare benign lesion which exhibits a slowly expansive growth without recurrence or metastasis after the surgical removal. No other case that recurred several times and extended into the intracranial space has been reported in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Neoplasms↗
PubMed1987

[Vascular compression neuropathy of the optic nerve by sclerotic internal carotid artery].

Although mechanical compression of the optic nerve by a dilated and/or tortuous sclerotic intracranial internal carotid artery is occasionally reported as an etiology for impairment of vision and visual field, early diagnosis of such condition has been hampered by the lack of characteristic neuro-ophthalmological and neuroradiological findings. The review of 35 previously reported cases (60 eyes) including ours showed that 41% out of the 34 operated eyes were improved neurologically by the decompressive procedure, while it was in 27% out of the 26 undecompressed or non-operated eyes. These unsatisfactory operative results are considered mainly due to the failure of early diagnosis. In order to investigate the relationship between the carotid artery and optic nerve, we proposed a method of angiographical projection consisting of the straight view along the long axis of the optic canal. By this projection, it is possible to detect a supero-medial enlargement and/or dislocation of the cisternal portion of the internal carotid artery. The addition of metrizamide CT cisternography which clarifies the relationship of the optic nerve, chiasm and internal carotid artery in the supersellar cistern may further provide an useful clue for the diagnosis of this condition.

Aged↗