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Biomedical subjects

K Mabuchi

Publications and source records attributed to K Mabuchi.

At least 73 records · Page 4Linked to original sources
PubMed1996

Studies of the mortality of atomic bomb survivors. Report 12, Part I. Cancer: 1950-1990.

This continues the series of periodic general reports on cancer mortality in the cohort of A-bomb survivors followed by the Radiation Effects Research Foundation. The follow-up is extended by the 5 years 1986-1990, and analysis includes an additional 10,500 survivors with recently estimated radiation doses. Together these extensions add about 550,000 person-years of follow-up. The cohort analyzed consists of 86,572 subjects, of which about 60% have dose estimates of at least 0.005 Sv. During 1950-1990 there have been 3086 and 4741 cancer deaths for the less than and greater than 0.005 Sv groups, respectively. It is estimated that among these there have been approximately 420 excess cancer deaths during 1950-1990, of which about 85 were due to leukemia. For cancers other than leukemia (solid cancers), about 25% of the excess deaths in 1950-1990 occurred during the last 5 years; for those exposed as children this figure is nearly 50%. For leukemia only about 3% of the excess deaths in 1950-1990 occurred in the last 5 years. Whereas most of the excess for leukemia occurred in the first 15 years after exposure, for solid cancers the pattern of excess risk is apparently more like a life-long elevation of the natural age-specific cancer risk. Taking advantage of the lengthening follow-up, increased attention is given to clarifying temporal patterns of the excess cancer risk. Emphasis is placed on describing these patterns in terms of absolute excess risk, as well as relative risk. For example: (a) although it is becoming clearer that the excess relative risk for those exposed as children has declined over the follow-up, the excess absolute risk has increased rapidly with time; and (b) although the excess relative risk at a given age depends substantially on sex and age at exposure, the age-specific excess absolute risk depends little on these factors. The primary estimates of excess risk are now given as specific to sex and age at exposure, and these include projections of dose-specific lifetime risks for this cohort. The excess lifetime risk per sievert for solid cancers for those exposed at age 30 is estimated at 0.10 and 0.14 for males and females, respectively. Those exposed at age 50 have about one-third these risks. Projection of lifetime risks for those exposed at age 10 is more uncertain. Under a reasonable set of assumptions, estimates for this group range from about 1.0-1.8 times the estimates for those exposed at age 30. The excess life-time risk for leukemia at 1 Sv for those exposed at either 10 or 30 years is estimated as about 0.015 and 0.008 for males and females, respectively. Those exposed at age 50 have about two-thirds that risk. Excess risks for solid cancer appear quite linear up to about 3 Sv, but for leukemia apparent nonlinearity in dose results in risks at 0.1 Sv estimated at about 1/20 of those for 1.0 Sv. Site-specific risk estimates are given, but it is urged that great care be taken in interpreting these, because most of their variation can be explained simply by imprecision in the estimates.

Adolescent↗
PubMed1996

Incidence of salivary gland tumors among atomic bomb survivors, 1950-1987. Evaluation of radiation-related risk.

A wide-ranging search for benign and malignant tumors of the major and minor salivary glands among members of the Life Span Study sample of the Radiation Effects Research Foundation identified 41 malignant and 94 benign incident tumors, including 14 malignant and 12 benign tumors of the minor salivary gland, plus 10 major gland tumors of unknown behavior. Dose-response analyses found statistically significant increases in risk with increasing A-bomb dose for both cancer and benign tumors. Estimated relative risks at 1 Sv weighted tissue kerma (RR1Sv, with 90% confidence interval in parentheses) were 4.5 (2.5-8.5) for cancer and 1.7 (1.1-2.7) for benign tumors. When analyzed by histological subtype within these two broad groups, it appeared that most of the dose response for malignant tumors was provided by an exceptionally strong dose response for mucoepidermoid carcinoma [11 exposed cases with dose estimates, RR1Sv = 9.3 (3.5-30.6)], and most or all of that for benign tumors corresponded to Warthin's tumor [12 cases, RR1Sv = 4.1 (1.6-11.3)]. There was a marginal dose response for malignant tumors other than mucoepidermoid carcinoma [RR1Sv = 2.4 (0.99-5.7)] but no significant trend for benign tumors other than Warthin's tumor [RR1Sv = 1.3 (0.9-2.2)]. Re-examination of the original data from published studies of other irradiated populations may shed new light on the remarkable type specificity of the salivary tumor dose response observed in the present study.

Dose-Response Relationship, Radiation↗
PubMed1996

Feasibility of using decades-old archival tissues in molecular oncology/epidemiology.

Archival tissues are a bountiful resource for various studies. Polymerase chain reaction permits the use of such tissues for molecular biological analyses of disease causation. However, a comprehensive study using a large number of decades-old samples (20 or more years) for molecular oncology/epidemiology has never been shown to be feasible. We have relied upon the unique tumor registry of atomic bomb survivors to show that such studies are possible using 275 hepatocellular carcinoma and 41 skin cancer cases. We used 23 relatively recent thyroid papillary carcinoma cases from persons living in the vicinity of the Chernobyl nuclear reactor accident for comparison. Degradation of DNA is severe in autopsy hepatocellular carcinoma samples but can be compensated for by decreasing the polymerase chain reaction product size. Increasing the amount of DNA that is used by a factor of 8 improved amplification efficiency from approximately 60 to 80%. Age of the samples was not as great a problem as was the source of procurement. The extracted DNA can be used for all types of assays that require polymerase chain reaction amplification, such as restriction fragment length polymorphism, single-strand conformation polymorphism, and direct sequencing.

Base Sequence↗
PubMed1996

Mortality study of atomic-bomb survivors: implications for assessment of radiation accidents.

To determine the possible late effects of atomic-bomb radiation, the Life Span Study (LSS) cohort of about 120,000 individuals, including 93,000 atomic bomb survivors and 27,000 non-exposed controls, was established by the Radiation Effects Research Foundation (RERF). Mortality in this cohort has been under study since 1950. Deaths are routinely identified through the family registry system and ascertainment is virtually complete. Cancer incidence data for the LSS cohort are also available from the Hiroshima and Nagasaki population-based tumour registry established in 1958. The central finding of the LSS is an increase in cancer risk. Besides the well-known increase in leukaemia, increases in solid cancer such as cancers of the lung, breast, stomach and thyroid have also been demonstrated. Radiation-induced leukaemia occurred 2 to 3 years after exposure, reached its peak within 6 to 8 years after the bombing, and has since declined steadily. However, this has not been true of solid cancer. Radiation-induced solid cancer begins to appear at later ages than such cancer is normally prone to develop, and continues to increase proportionally with the increase in mortality or incidence in the control group as it ages. Survivors who were exposed in the first or second decade of life have just entered the cancer-prone age and have so far exhibited a high relative risk in association with radiation dose. Whether the elevated risk will continue or will fail with time is not yet clear. It is important to continue long-term follow-up of this cohort to document the changes with time since exposure. Beyond cancer risk, increased risk of non-cancer mortality is also suggested, although it is not conclusive.

Adult↗
PubMed1995

Incidence of benign gastrointestinal tumors among atomic bomb survivors.

Using the Hiroshima and Nagasaki tumor and tissue registries, benign tumors of the stomach, colon, and rectum were identified among members of the Life Span Study cohort of atomic bomb survivors. During the period 1958-1989, a total of 470 cases with histologically confirmed benign gastrointestinal tumors (163 stomach, 215 colon, and 92 rectum) were identified among approximately 80,000 Life Span Study members with known radiation doses, who were alive in 1958. Restricting the analysis to adenomatous tumors not detected at autopsy, a dose-response relation was observed for stomach tumors (excess relative risk at 1 sievert (ERR1Sv) = 0.53; 95% confidence interval (CI) -0.01 to 1.43). However, there was little evidence of a dose response for colon tumors (ERR1Sv = 0.14; 95% CI -0.20 to 0.76), and no evidence was present for rectal tumors (ERR1Sv = -0.25; 95% CI undetermined to 0.80). The excess relative risk (ERR) for benign tumors of the stomach is consistent with the excess found for stomach cancer. For cancer of the rectum, the dose response was not significant, but the point estimate of the excess relative risk was positive. The excess relative risk for benign colon tumors is less than that reported for colon cancer (ERR1Sv = 0.72). The authors observed a dramatic increase in colon tumors detected after 1985, suggesting that the relatively recent introduction of colonoscopy may be influencing these results.

Cohort Studies↗
PubMed1995

Physical characterization of calponin. A circular dichroism, analytical ultracentrifuge, and electron microscopy study.

Calponin is a thin filament-associated smooth muscle protein that has been suggested to play a role in the regulation of smooth muscle contraction. We have used circular dichroism spectroscopy, electron microscopy, and analytical ultracentrifugation to study the physical properties of recombinant chicken gizzard alpha-calponin. The alpha-helix content of alpha-calponin was estimated from its circular dichroism spectrum to be approximately 13%, alpha-Calponin melts with a single sharp transition at approximately 57 degrees C. Rotary shadowing electron micrographs of alpha-calponin reveal diverse shapes ranging from elongated rods to collapsed coils. The lengths of the rod-shaped structures are approximately 18 nm. Analytical ultracentrifugation studies found alpha-calponin to be homogeneous with a monomer molecular mass of 31.4 kDa, and a s20,w value of 2.34 S. These data could be used to model alpha-calponin as a prolate ellipsoid of revolution with an axial ratio of 6.16, a length of 16.2 nm, and a diameter of 2.6 nm. Taken together, our results indicate that calponin is a flexible, elongated molecule whose contour length is sufficient to span three actin subunits along the long pitch helix of an F-actin filament.

Animals↗
PubMed1995

Radiation studies.

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Government Agencies↗
PubMed1995

Prospective cohort study of risk factors for primary liver cancer in Hiroshima and Nagasaki, Japan.

We investigated risk factors for primary liver cancer among a cohort of 36,133 residents in Hiroshima and Nagasaki, Japan, originally established to examine the association between exposure to atomic bomb radiation and disease. A mail survey to study the late effects of atomic bomb radiation was conducted among the cohort between 1978 and 1981. During the subsequent follow-up period (average 8.61 years), 242 cases of primary liver cancer were identified through population-based tumor registries in the two cities. The relative risk (RR) of liver cancer was 2.23 [95% confidence interval (CI) = 1.53-3.23] for tobacco smokers compared with those who had never smoked. Alcohol use was slightly positively associated with the risk of liver cancer, and men who had quit drinking had an RR of 2.33 (95% CI = 1.34-4.07) compared with those who never drank. Among alcohol drinkers, an inverse relation between years of abstinence and the rate of liver cancer was found, possibly attributable to a confounding effect of preclinical disease. The use of female hormone preparations was modestly associated with the risk of liver cancer (RR = 1.29; 95% CI = 0.59-2.84). Other risk factors included a self-reported history of radiation therapy (RR = 1.79; 95% CI = 1.31-2.43).

Adult↗
PubMed1995

Basic study to develop the undulation pump for practical use: antithrombogenicity, hemolysis, and flow patterns inside the pump.

The undulation pump (formerly called the precessional displacement pump) is a continuous flow displacement-type blood pump that is being developed as an implantable total artificial heart. A new undulation pump was developed for chronic use and was examined with animal experiment and flow visualization studies. In the animal experiment using a left ventricular bypass in goats, severe hemolysis occurred. After driving for 12 h, thrombus formation inside the pump was found. In the flow visualization studies, the flow pattern showed that the flow inside the pump was a very complicated turbulent flow. Improvement of hemolysis and thrombus formation is important to realize implantable total artificial hearts using undulation pumps.

Animals↗
PubMed1995

New version of flow-transformed pulsatile total artificial heart with no electrical switching valve.

The flow-transformed pulsatile total artificial heart (FTPTAH) is a new pulsatile total artificial heart that consists of a single continuous flow rotary blood pump and blood flow switching valves. It can perfuse the pulmonary and the systemic circulation alternately with pulsatile flow. A new version of the FTPTAH, which consists of one undulation pump (UP), 4 jellyfish valves, and a compensatory chamber, has been proposed. The UP is a reversible continuous flow blood pump, and flow transformation is caused by switching the direction of the motor rotation so that no electrical flow switching valve is needed. A prototype model could perfuse alternately pulmonary and systemic circulation with 3.0 L/min in a mock circulation. Unoxygenated blood in the UP at the end of pulmonary circulation will be stored in the compensatory chamber by shifting a flexible membrane to the direction of the left atrium (LA); therefore, the blood is not sent to the systemic circulation.

Atrial Function↗
PubMed1995

Development of a new apparatus to observe microcirculation chronically in continuous flow blood pump research.

To observe microcirculation chronically is an important key to the successful evaluation of the continuous flow blood pump. In this study, we succeeded in developing a new apparatus by which microcirculation could be observed chronically without a microscope in a conscious animal. The apparatus utilizes a charge coupled device (CCD). A thin living tissue, such as mesentery, is put directly on a highly integrated CCD and is lit up through the tissue with a light-emitting diode (LED). The vascular nets in the tissue are projected onto the CCD like a contact photograph, which is then sent to a television screen and which can be used to analyze their motion and function. A 0.5-inch CCD having 250,000 pixels was used in this study. The cover glass of the CCD was removed, and a fiber optic plate was fixed onto the surface of the CCD for the tissue to be able to contact with the apparatus surface without clearance. The CCD as well as the LED were molded with epoxy resin for electrical insulation. The apparatus was 35 mm wide and 12 mm high with a micro stand for an LED, which can be easily implanted into an animal. The apparatus was implanted into a rabbit for 12 h. The configuration of arterioles and venules, tens of micrometers in diameter, and their motions in subcutaneous tissue could be observed.

Animals↗
PubMed1995

Anti-Human T-lymphotropic virus type-I antibodies in atomic-bomb survivors.

Adult T-cell leukemia (ATL), induced by human T- lymphotropic virus type-I (HTLV-I), is endemic in Nagasaki, Japan. To investigate the effects of atomic-bomb radiation on development of this specific type of leukemia, 6182 individuals in the Radiation Effects Research Foundation (RERF) Adult Health Study sample in Hiroshima and Nagasaki were examined for positive rate of HTLV-I antibody. Several lymphocyte parameters were also studied for 70 antibody- positive subjects in Nagasaki. The HTLV-I antibody-positive rate was higher in Nagasaki (6.36%) than in Hiroshima (0.79%) and significantly increased with increasing age, but no association was observed with radiation dose. Whether relationship existed between antibody titer levels and radiation dose among antibody-positive subjects was not The frequency of abnormal lymphocytes tended to be higher in antibody-positive subjects than in antibody-negative subjects, and higher in females than in males regardless of radiation dose. The lymphocyte count was lower in antibody-positive subjects than in antibody-negative subjects and lower in female than in male subjects. No evidence was found to suggest that atomic-bomb radiation plays an important role in HTLV-I infection.

Adult↗
PubMed1995

[Auditory disturbance induced by carbamazepine administration in a patient with secondary generalized seizure].

We report on an 18-year-old woman with secondary generalized seizure, who developed an auditory disturbance (flat a tone) after carbamazepine (CBZ) administration. She used to have brief episodes of conjugate deviation of the eyes to the right, head heaviness, teleopsia, and visual hallucination since 16 years of age. At the age of 18 years, she developed a tonic-clonic seizures during sleep, and was placed on CBZ 400 mg/day. Immediately after taking the medication, she developed auditory disturbance while she played the musical instruments: she felt as if she played the musical note almost a half tone lower. On admission, neurological examinations and magnetic resonance images of the brain were normal. Electroencephalogram at rest was normal. However, intravenous diphenhydramine injection induced spikes in the left temporo-occipital region, followed by diffuse spike and wave complex. Although the serum CBZ level was reduced to the therapeutic level by lowering CBZ administration from 200 to 150 mg/day, she continued to have the same auditory disturbance. When CBZ administration was discontinued, the symptoms also disappeared. It remains unknown whether such a subtle side effect of CBZ is a common thing, or it can be recognized only by persons who are well trained in music.

Adolescent↗
PubMed1995

Thyroid cancer after exposure to external radiation: a pooled analysis of seven studies.

The thyroid gland of children is especially vulnerable to the carcinogenic action of ionizing radiation. To provide insights into various modifying influences on risk, seven major studies with organ doses to individual subjects were evaluated. Five cohort studies (atomic bomb survivors, children treated for tinea capitis, two studies of children irradiated for enlarged tonsils, and infants irradiated for an enlarged thymus gland) and two case-control studies (patients with cervical cancer and childhood cancer) were studied. The combined studies include almost 120,000 people (approximately 58,000 exposed to a wide range of doses and 61,000 nonexposed subjects), nearly 700 thyroid cancers and 3,000,000 person years of follow-up. For persons exposed to radiation before age 15 years, linearity best described the dose response, even down to 0.10 Gy. At the highest doses (> 10 Gy), associated with cancer therapy, there appeared to be a decrease or leveling of risk. For childhood exposures, the pooled excess relative risk per Gy (ERR/Gy) was 7.7 (95% CI = 2.1, 28.7) and the excess absolute risk per 10(4) PY Gy (EAR/10(4) PY Gy) was 4.4 (95% CI = 1.9, 10.1). The attributable risk percent (AR%) at 1 Gy was 88%. However, these summary estimates were affected strongly by age at exposure even within this limited age range. The ERR was greater (P = 0.07) for females than males, but the findings from the individual studies were not consistent. The EAR was higher among women, reflecting their higher rate of naturally occurring thyroid cancer. The distribution of ERR over time followed neither a simple multiplicative nor an additive pattern in relation to background occurrence. Only two cases were seen within 5 years of exposure. The ERR began to decline about 30 years after exposure but was still elevated at 40 years. Risk also decreased significantly with increasing age at exposure, with little risk apparent after age 20 years. Based on limited data, there was a suggestion that spreading dose over time (from a few days to > 1 year) may lower risk, possibly due to the opportunity for cellular repair mechanisms to operate. The thyroid gland in children has one of the highest risk coefficients of any organ and is the only tissue with convincing evidence for risk about 1.10 Gy.

Adolescent↗