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I Shimokawa

Publications and source records attributed to I Shimokawa.

72 records · Page 4Linked to original sources
PubMed1990

Leu-7 immunoreactivity in human and rat embryonic hearts, with special reference to the development of the conduction tissue.

The distribution pattern of Leu-7 (HNK-1) in developing human embryonic hearts and rat hearts was studied by immunohistochemistry. Human and rat embryos at Streeter's stages XIII approximately XX and fetus stage I were used. Leu-7, which is absent in the newborn rat heart, is expressed transiently in the embryo and fetus I stages. The earliest embryonic heart shows two incomplete circular structures with immunoreactivity in the myocardium along the primitive atrioventricular cushion and bulboventricular canal. These two structures become localized topographically in the definitive atrioventricular node and atrioventricular bundle after rearrangement and partial disappearance during embryonic development. At Streeter's stages XVIII approximately XX, Leu-7 immunoreactivity appears to localize topographically in almost all the pathways of the conduction system, although some discontinuities are observed in the atrioventricular junction and atrial internodal tracts. Thereafter, immunoreactivity decreases gradually and differentially by site and stage. The precise nature of Leu-7 immunoreactive cells, that is, whether or not they are neurogenic or myogenic, is not revealed by this study. The present observations are discussed in connection with the hypothesis that specialized ring tissue is the primordium of the conduction system.

Animals↗
PubMed1990

[Incidence of multiple myeloma in Nagasaki City, with special reference to those subjected to atomic bomb exposure].

In order to observe the incidence of multiple myeloma in the population of Nagasaki City from 1973 to 1982, and to assess any influence caused by A-bomb exposure, 85 cases of myeloma have been collected and analysed. Informatively, 48 cases of this number were A-bomb survivors. Among the middle-aged cases, the crude incidence rates of myeloma in the exposed group were found to be higher than those in the non-exposed group. Further, the relative risk of myeloma was higher in A-bomb survivors and this tendency become more pronounced in the those who were within 2 km of the epicenter of the blast. The age-adjusted relative risk in male and female A-bomb survivors was 1.59 and 1.68 respectively, but no significant differences were noted.

Adult↗
PubMed1990

[Trends in the incidence of uterine cancer in Nagasaki city, with special reference to previous atomic bomb exposure, 1973-1982].

An epidemiological study has been conducted to elucidate the trend in the incidence of uterine cancer, a with a reference also to previous A-bomb exposure. Studied were 783 cases (345 exposed and 438 nonexposed) of uterine cancer that were handled from 1973 to 1982. The incidence rate of cervical cancer was significantly higher among the population who came into Nagasaki city within two weeks after exposure. A comparison between the incidence rate of '73-'77 and '78-'82 revealed a decreasing trend of cervical cancer and an increasing trend of corpus cancer. The increasing rate of corpus cancer was higher in the younger group of a-bomb survivors (less than 59 years old) than in the other survivors.

Adult↗
PubMed1989

A sequential ultrastructural and histoautoradiographic study of early neoplastic lesions in ethylnitrosourea-induced rat glioma.

A sequential study of the early stage of development of ethylnitrosourea (ENU)-induced glioma in the rat was performed by electron microscopy and [3H]thymidine histoautoradiography. Hyperplasia, the earliest neoplastic change that was detectable morphologically, consisted of a few or several immature oligodendroglia-like cells which were connected with one another or with preexisting neural tissue by junctional apparatus, and showed no reactive changes in the astrocytes or microglia. The labelling index of hyperplastic cells was 2.6%. Foci of early neoplastic proliferation (ENP) showed mild destructive changes in the neighboring neural tissue, and their major constituent cells had characteristics of immature oligodendroglias. The labelling index of cells showing ENP was 3.3%. The intercellular spaces exhibited slight enlargement with accumulation of extracellular matrix and a decrease in the number of junctional apparatus on the neoplastic cells. Microtumors showed apparent destruction of the preexisting neural tissue to form a tumor mass with an increase in the extracellular matrix. Constituent cells of the microtumors were similar to those of the ENP, although reactive astrocytes and microglias occurred more frequently. The labelling index was 9.6% in the central area of microtumors and 5.3% in the peripheral area. These findings suggest that in the initial or very early stages of glial cell neoplastic proliferation, it is necessary for the neoplastic cells to maintain contact with the neurons for metabolic purposes, and that after losing contact, these cells can proliferate autonomously with the accumulation of extracellular matrix.

Animals↗
PubMed1989

A case of hypoxic brain damage consequent to ligature strangulation.

A case of delayed death following strangulation is reported. A 43-year-old woman died 18 days after being subjected to strangulation. The autopsy and neuropathological findings are presented. Informatively, enzymatic immunohistochemical techniques were used for the neuropathological investigation.

Adult↗
PubMed1988

An electron microscopic examination of age-related changes in the rat liver. The influence of diet.

The influence of age and diet on the ultrastructure of hepatocytes is reported. The following dietary manipulations were investigated: Group 1, fed ad libitum a diet containing 21% protein; Group 2, fed a similar diet but restricted to 60% of the intake of Group 1 from 6 weeks of age onwards; Group 3, restricted from 6 weeks to 6 months of age and thereafter fed ad libitum; Group 4, restriction started at 6 months of age; Group 5, fed ad libitum a diet containing 12.6% protein. In all groups the size of hepatocytes was found not to increase during adult life. The size of hepatocytes in Groups 2 and 4 was the same as or larger than that of the other groups; thus food restriction resulted in a decreased number of hepatocytes. Changes in the structure of some organelles and the accumulation of lipofuscin granules occurred with advancing age and the extent of these age-related changes was less in Groups 2 and 4 than in the other groups. These morphologic findings in conjunction with our previously reported metabolic findings provide a new view of the action of food restriction on the aging process.

Aging↗
PubMed1987

[The nature of immunohistochemically defined astrocytic cells in rat gliomas].

The nature of astrocytic cells in rat gliomas induced by ethylnitrosourea (ENU) was studied by means of immunohistochemically demonstrating glial fibrillary acidic protein (GFAP), vimentin and beta-subunit of S 100 protein (S 100 beta) on paraffin sections. A special attention was paid to elucidating whether astrocytic cells would be neoplastic or not. The astrocytic cells in tumors were compared with astrocytes in normal rat brains and reactive astrocytes around a stab wound for their morphology, distribution and immunohistochemical characteristics. GFAP positive astrocytic cells in tumors were roughly divided into astrocytic cells and hypertrophic cells that showed morphologically similar appearance to fibrous astrocytes and hypertrophic reactive astrocytes around a stab wound respectively. A few multi-nucleated pleomorphic cells regarded as a kind of hypertrophic cells were also noted in gross tumors. GFAP positive cells were diffusely distributed in early neoplastic proliferations and microtumors, while in gross tumors they tended to be localized at the periphery. The GFAP positive cells were scattered among negative cells of tumors, forming no tumor mass. These findings suggest that the GFAP positive cells show no neoplastic growth, even though histopathologically they exhibit atypism or pleomorphism. The quantitative analysis of GFAP positive cells in tumors indicated more than 8% in most tumors in the white matter, whereas less than 8% in tumors in the gray matter and approximately 5% in gross tumors. The predominance of GFAP positive cells in the white matter was also observed in lesions induced by a stab wound.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Epidemiological studies on malignant lymphoma in Nagasaki City, especially in relation to atomic bomb exposure].

One hundred and eighty-two (182) cases of malignant lymphoma registered at the Nagasaki Tumor Registry from 1973 to the end of 1977 were studied in relation to atomic bomb exposure. No significant difference in the incidence of malignant lymphoma was found between the exposed and nonexposed groups. One hundred and thirty-one (131) cases excluding Hodgkin's disease and mycosis fungoides were histologically reviewed and classified according to Lymphoma Study Group (L.S.G.) and Working Formulation (W.F.) Classifications. Using the L.S.G. Classification, the three histological types (diffuse large cell, diffuse pleomorphic, and diffuse medium sized cell) occupied 72.7% and 69.0% of the exposed and nonexposed groups respectively. No significant difference in histological type between the exposed and nonexposed groups could be found with an exception of a slightly higher incidence of the diffuse medium sized cell type in the exposed group than in the nonexposed group. An evaluation of these results was made in comparison with the results in Hiroshima.

Age Factors↗
PubMed1984

[Epidemiological studies of colon cancer in Nagasaki City with special reference to radiation exposure].

Epidemiological studies were conducted on 223 cases of colon cancer registered at the Nagasaki Tumor Registry from 1973 to 1977, with particular emphasis on the relation to radiation exposure. The incidence in atomic bomb survivors was not significantly different as compared with nonexposed persons. By site, cancer of the sigmoid colon was more frequent in males than in females, especially in older people, but no difference was seen by exposure status. Histologically, about 90% was relatively differentiated adenocarcinoma and showed no difference by age, sex or exposure status.

Adenocarcinoma↗
PubMed1984

[Epidemiology of lung cancer in Nagasaki--especially in relation to radiation exposure].

We investigated the present incidence of lung cancer and its distribution by histologic type in Nagasaki City using Nagasaki Tumor Registry data from the years 1973-1977. The risk of radiogenic lung cancer did not increase significantly in either sex. The difference in relative distribution by histologic type between the exposure and non-exposure groups was not significant. Further analyses should be carried out on the risk present for individuals who were young at the time the bomb was dropped and the effect of exposure distance on the incidence and histologic types of lung cancer in A-bomb survivors.

Adenocarcinoma↗
PubMed1984

[Epidemiological studies on multiple primary malignant tumors in Nagasaki City].

Ninety-four cases of multiple primary malignant tumors registered at the Nagasaki Tumor Registry during the period from 1973-1977 were studied. The crude incidence rate tended to be higher in atomic bomb survivors although the difference was not significant. The male:female ratio was 1:1.19. Cases in the sixth decade of life were dominant, the average age was somewhat lower in females than in males. Stomach cancer was observed in 48 patients (51.1%; triple malignancies in 8 cases (8.5%).

Adult↗
PubMed1984

[Epidemiological studies on gastric cancer in Nagasaki].

One thousand-four hundred and twenty-four cases of gastric cancer registered at the Nagasaki Tumor Registry between 1973 and 1977 were studied. The incidence of gastric cancer tended to be higher in persons exposed to the atomic bomb within 2.0 km from the hypocenter, especially in young persons, than in non-exposed individuals, but the difference was not statistically significant. Compared with the nonexposed, the corrected relative risk of gastric cancer in persons exposed within 2.0 km from the hypocenter was 1.28 in males and 1.11 in females. In terms of histologic type or location, the incidence of gastric cancer showed no statistically significant difference between the exposed and nonexposed persons.

Adult↗
PubMed1984

[Epidemiological studies on thyroid cancer in Nagasaki City].

We studied 89 cases of thyroid cancer registered at the Nagasaki Tumor Registry during the period from 1973--1977. The incidence of thyroid cancer tended to be higher in persons exposed to the atomic bomb, especially women, than in the nonexposed population. Compared with nonexposed individuals, the relative risk for thyroid cancer was increased in distally as well as proximally exposed persons, but not in early entrants to the bombed city. In 83 histologically examined patients, papillary carcinomas were highly predominant, they were more prevalent in the exposed than in the nonexposed population.

Adenocarcinoma↗
PubMedDate not supplied

Physical activity as a factor in the action of dietary restriction on aging: effects in Fischer 344 rats.

Dietary restriction (DR) slows the rate of aging in laboratory rodents but the mechanism of action is unknown. DR is known to induce beneficial effects in a variety of tissues and organ systems. DR also maintains high levels of physical activity over the life span. We tested the hypothesis that lifelong physical activity is an important component of the anti-aging action of DR. Male specific pathogen-free Fischer 344 rats were divided into 4 groups at 6 weeks of age: A: fed old libitum; AE: fed ad libitum and in cages with running wheels; B: fed 60% ad libitum; BE: fed 60% ad libitum and in cages with running wheels. Running activity and spontaneous cage activity were measured over 24 hours and over the life span. Metabolic rate was measured indirectly by analysis of air entering and leaving cages. AE rats exhibited low levels of running activity and ran very little beyond 6 months of age. In contrast, BE rats sustained high running levels even after all A and AE rats had died. High levels of wheel running did not decrease spontaneous cage activity. Median life span (50% survival) was in the order A = AE < B < BE. Ten percent survival was in the order A = AE < B = BE. BE rats had greatest median life span and also highest specific metabolic rate. Exercise and DR altered pathology: At death BE rats had a high incidence of cardiomyopathy, whereas A and AE rats had high incidence of chronic nephropathy and pituitary tumors. The data indicate that increased physical activity is probably not an important factor in the action of DR on aging.

Aging↗
PubMedDate not supplied

Morphometric analysis of somatotrophs: effects of age and dietary restriction.

We investigated changes in the cell number of somatotrophs in the anterior pituitary of male F344 rats caused by age and lifelong dietary restriction (DR). Morphometric and immunohistochemical techniques were performed on the pituitary gland at 6, 18, and 24 months of age. In ad lib fed (AL) rats, cell density of somatotrophs progressively decreased with age. However, when normalized according to the increased volume of the anterior lobe, which occurs during aging, the total number of somatotrophs remained constant until 18 months, then decreased. In contrast, the cell density of DR rats was not affected to the same extent as that of AL rats, and the total number of cells seemed to remain constant through 24 months, thus, retarding the age-related numerical changes. However, the cell number in DR rats, when normalized by body weight, was larger than that found in AL rats. We also found that average cell volume of somatotrophs shows little age or dietary restriction effects, but the nucleus volume significantly increases at 24 months in both groups. The numerical changes which occur in somatotrophs during the aging process may be associated with the aging phenomena found in GH secretion.

Aging↗
PubMedDate not supplied

Malignant peripheral nerve sheath tumors developing multifocally in the central nervous system in a patient with neurofibromatosis type 2.

We describe autopsy findings of multifocal malignant peripheral nerve sheath tumors (MPNSTs) appearing in the central nervous system in a 45-year-old Japanese female with neurofibromatosis type 2. Multiple MPNSTs were detected in both III and VIII, left IV, and V cranial nerves, and a number of nerve roots of the spinal cord. Neurofibromata were on the other hand evident on some nerve roots of the spinal cord and femoral and sciatic nerves. Our results suggest that a mutation of p53 gene may have played a role in the malignant transformation of nerve tumors in this patient since p53 protein was immunohistochemically detected in MPNST cells but not in tumor cells of the neurofibromata.

Fatal Outcome↗