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Biomedical subjects

M Amenomori

Publications and source records attributed to M Amenomori.

At least 19 recordsLinked to original sources
PubMed2006

Anisotropy and corotation of galactic cosmic rays.

The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments.

Journal Article↗
PubMed2004

Observation by an air-shower array in Tibet of the multi-TeV cosmic-ray anisotropy due to terrestrial orbital motion around the Sun.

We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the Sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g., the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made.

Journal Article↗
PubMed1999

Observation of Multi-TeV Gamma Rays from the Crab Nebula using the Tibet Air Shower Array.

The Tibet experiment, operating at Yangbajing (4300 m above sea level), is the lowest energy air shower array, and the new high-density array constructed in 1996 is sensitive to gamma-ray air showers at energies as low as 3 TeV. With this new array, the Crab Nebula was observed in multi-TeV gamma-rays and a signal was detected at the 5.5 sigma level. We also obtained the energy spectrum of gamma-rays in the energy region above 3 TeV which partially overlaps those observed with imaging atmospheric Cerenkov telescopes. The Crab spectrum observed in this energy region can be represented by the power-law fit dJ&parl0;E&parr0;&solm0;dE=&parl0;4.61+/-0.90&parr0;x10-12&parl0;E&solm0;3 TeV&parr0;-2.62+/-0.17 cm-2 s-1 TeV-1. This is the first observation of gamma-ray signals from point sources with a conventional air shower array using scintillation detectors.

Journal Article↗
PubMed1999

Analysis of genetic changes in intrahepatic cholangiocarcinoma induced by thorotrast.

Thorotrast, a colloidal suspension of radioactive (232)ThO(2) that emits alpha particles, was used as a radiographic contrast agent in the 1930s-1950s. Several decades after injection, Thorotrast causes liver cancers, among which intrahepatic cholangiocarcinoma (ICC) is prominent. We investigated mutations of the RAS and the TP53 genes in archival sections of ICC induced by Thorotrast. Compared to ICC that was not associated with Thorotrast, the frequency of mutation of the KRAS gene was lower, while that of the TP53 gene was more than two times higher. The most common mutation of the TP53 gene was A-G transitions. Interestingly, TP53 mutations were also found in noncancerous areas of livers in which Thorotrast had been deposited. Furthermore, mutations tended to accumulate in tissues from more advanced tumors. These results suggest that deposited Thorotrast continuously damages DNA in liver cells in some way, resulting in A-G transitions of the TP53 gene. However, we have not been able to rule out the possibility that genetic insults occur indirectly in the proliferating cells adjacent to the necrosis rather than being a direct effect of alpha particles.

Aged↗
PubMed1998

Spontaneous remission of hypertrophic lymphocytic gastritis associated with hypoproteinemia.

A 54-year-old woman came to our office because of pretibial edema. She had no gastrointestinal symptoms. Laboratory tests revealed severe hypoproteinemia. Upper gastrointestinal endoscopy demonstrated enlarged gastric folds and multiple aphthoid nodules on the body and the fornix of the stomach. The biopsy specimen revealed a large number of CD8 positive intraepithelial T-lymphocytes infiltrating the gastric mucosa. Both serum total protein and the gastric lesions improved eight months after her first visit without any therapy for peptic ulcer or eradication of Helicobacter pylori. The data suggest that spontaneous remission may occur in lymphocytic gastritis without any gastrointestinal symptoms.

Biopsy↗
PubMed1998

Incidence and characteristics of thyroid dysfunction following interferon therapy in patients with chronic hepatitis C.

Thyroid functions were analyzed before, during and after interferon (IFN) therapy in patients with chronic hepatitis C. According to the results of routine thyroid function tests and measurements of the levels of anti-thyroid autoantibody prior to the therapy, patients were divided into 2 groups; Group A (19 patients) had at least one abnormal finding related to the thyroid, and Group B (40 patients) did not show any abnormality. Five patients (26%) in Group A and 4 (10%) in Group B showed thyroid dysfunctions which were very clearly reflected by thyrotropin (TSH) measurements. Interestingly, the time of peak TSH elevation in Group A (mean +/- SD, 4.3 +/- 0.8 months) was significantly earlier than that in Group B (6.8 +/- 0.8). Most patients in Group B were diagnosed as having destructive thyroiditis. These findings may suggest that the pathogenesis of IFN-induced thyroid dysfunction consists not only of exacerbation of pre-existing thyroid autoimmunity but also of de novo destructive changes even in the intact thyroid before IFN therapy.

Adult↗
PubMed1995

Sensitive detection of circulating hepatocellular carcinoma cells in peripheral venous blood.

BACKGROUND: This study was performed to develop a sensitive method for the detection of circulating hepatocellular carcinoma (HCC) cells in peripheral blood, in advance of the diagnosis of distant metastasis of HCC by conventional means. METHODS: Peripheral blood (5 ml) samples were obtained from 64 patients with HCC and from 48 control subjects (31 patients with benign liver disease, 8 with metastatic liver cancer, and 9 with normal liver function). To identify HCC cells in peripheral blood, liver-specific human alpha-fetoprotein (hAFP) mRNA was amplified from total RNA extracted from whole blood by reverse transcriptase-polymerase chain reaction. RESULTS: Human alpha-fetoprotein mRNA was detected in 23 blood samples from the HCC patients (23/64, 36%), in 17 patients in whom there was no clinical evidence of distant metastasis. In contrast, there were no control patients whose samples showed detectable hAFP mRNA in the peripheral blood. The presence of hAFP mRNA in blood seemed to be correlated with the stage (by TNM classification) of HCC, the serum hAFP value, and the presence of intrahepatic metastasis, portal vein thrombosis, and/or distant metastasis. CONCLUSIONS: Reverse-transcriptase polymerase chain reaction is a very sensitive method for detecting circulating HCC cells. With this technique, important information for the management of HCC can be acquired, such as the indications for orthotopic liver transplantation in HCC patients. Moreover, use of this detection method may encourage investigation of the mechanism of metastasis in HCC.

Adult↗
PubMed1994

Amplification and overexpression of the cyclin D1 gene in aggressive human hepatocellular carcinoma.

We analyzed the genetic alterations of the cyclin D1 and INT-2 genes in hepatocellular carcinomas (HCCs) from 45 patients. Among these, expression of the cyclin D1 mRNA was also analyzed in 18 of them by Northern blotting. The cyclin D1 gene was amplified 3-16 fold in five HCCs (11%); among these, the INT-2 gene was also amplified 2-10 fold in four HCCs. We analyzed the mRNA of cyclin D1 in four HCCs with gene amplifications, and 6-10 fold overexpressions were detected in all of them. Because the cyclin D1 gene was amplified in patients at an advanced stage of HCC with rapid tumor growth, it appeared to be associated with the aggressive behavior of tumors. Studies on loss of heterozygosity on chromosome 13q, where the retinoblastoma (RB) gene is located, indicated that all HCCs with an amplified cyclin D1 gene retained heterozygosity on chromosome 13q. These results suggest that amplification and overexpression of the cyclin D1 gene result in the rapid growth of a subset of HCC, even though the function of the RB gene is retained.

Carcinoma, Hepatocellular↗
PubMed1994

A case of lipoprotein glomerulopathy successfully treated with probucol.

A 54-year-old woman presented proteinuria and severe hyperlipoproteinemia, She had type III hyperlipoproteinemia with the phenotype E2/2. Renal biopsy specimen revealed lipoprotein thrombi within the glomerular capillary lumina without tubulointerstitial lesion and deposition of IgA in the mesangium and peripheral capillary loops, indicating lipoprotein glomerulopathy with IgA nephropathy. Treatment with probucol resulted in the improvement of both hyperlipoproteinemia and proteinuria with the disappearance of the lipoprotein thrombi in the glomerular capillary without any change in the mesangial IgA deposition. The data suggest that probucol may be effective against the early stage of lipoprotein glomerulopathy with less lipoprotein thrombi and without tubulointerstitial damage.

Female↗
PubMed1992

Interleukin-5 in eosinophilic gastroenteritis.

During a 4-year period a 28-year-old female had 4 episodes of eosinophilia of over 10,000/mu 1; these episodes were associated with nausea, vomiting, diarrhea, and abdominal pain. On one occasion, she had ascites and pleural effusion which contained numerous mature eosinophils. On each occasion, these attacks disappeared within several weeks without any specific treatment. A diagnosis of eosinophilic gastroenteritis was made. A plasma sample obtained during the eosinophilia generated in vitro eosinophilic colonies when added to granulocyte/macrophage-progenitor (CFU-GM) cultures without exogenous growth factors. Colony formation was inhibited by anti-interleukin-5 (IL-5) antibody but not by antibodies toward IL-3, granulocyte colony-stimulating factor (G-CSF) or GM-CSF. A high plasma interleukin-5 (IL-5) level was noted when measured by enzyme-linked immunosorbent assay, while IL-3, G-CSF, and GM-CSF were undetectable. During remission the plasma gave negative results both for colony formation and IL-5 level. These results indicate that the eosinophilia of this disease is mediated by IL-5.

Adult↗
PubMed1988

A new prostaglandin E1 analogue (TFC-612) prevents a decrease in motor nerve conduction velocity in streptozocin-diabetic rats.

A new prostaglandin E1 analogue (TFC-612) was orally given to streptozocin-diabetic rats for 4 weeks after the induction of diabetes and its effects on motor nerve conduction velocity were studied. The compound significantly prevented a decrease of the velocity but did not reverse abnormal sorbitol and myo-inositol contents of the sciatic nerve. The results suggest that TFC-612 has a potent effect on diabetic nerve dysfunction via other mechanism than the correction of sorbitol and myo-inositol metabolisms and could be a potential compound for therapy of diabetic polyneuropathy.

Alprostadil↗