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Biomedical subjects

H Toyoshima

Publications and source records attributed to H Toyoshima.

At least 127 records · Page 7Linked to original sources
PubMed1990

Secondary structure of the human T-cell leukemia virus type 1 rex-responsive element is essential for rex regulation of RNA processing and transport of unspliced RNAs.

Rex protein of human T-cell leukemia virus type 1 (HTLV-1) induces cytoplasmic expression of unspliced gag/pol mRNA and singly spliced env mRNA and thus is essential for replication of the virus. This regulation requires a cis-acting rex-responsive element (RXE), located in the 3' region of the viral RNA. By external deletion, we have identified RXE composed of 205 nucleotides. The secondary structure of RXE was confirmed by studies on its susceptibility to nuclease digestions to consist of four stem-loops and a long stretch of stem structure. Substitution and deletion mutations revealed that two regions of the stem-loops and their secondary structures are essential for rex regulation. Similar secondary structures were found in the corresponding regions of HTLV-2, bovine leukemia virus and human immunodeficiency virus. Furthermore, a sequence of 11 nucleotides in the RXE was found to be conserved in the secondary structures of HTLV-1, HTLV-2, and bovine leukemia virus. These observations suggest that the secondary structure as well as the conserved sequence may be important in expression of unspliced RNA even with diverged sequences as observed in these viruses.

Base Sequence↗
PubMed1990

[Detection of activated oncogenes in hematological malignancies using RT-PCR method and its clinical applications].

Recently, a new and simple method of PCR has been developed and its application is extending widely including clinical research. We are using this method to detect various activated oncogenes within clinical samples from hematological malignancies. We now attempt to use these results as supporting evidences in clinical diagnosis. Here we report several successful results we have obtained through the study of activated RAS oncogenes.

Adult↗
PubMed1990

[Nuclear DNA content in the cells of squamous cell carcinoma and Bowen's disease. I. Relationship between nuclear DNA content and grade of clinical and histological malignancy].

Nuclear DNA content of squamous cell carcinoma (SCC) was assayed by use of microfluorometry in an attempt to know the relationship between the content and grade of malignancy. As the results, we found that polyploid cell (greater than 4C) population tends to increase with advancing histological malignancy. However, the population of polyploid cells of grade 1, 2 and 3 SCC was almost the same. The number of polyploid cell of recurred lesion of SCC was increased than that of primary lesion. And polyploid cell (greater than GC) population in the primary lesion of the recurred case was higher than that in the tumor of non-recurred case. From these findings, it may be concluded that the polyploid cell population in SCC was proportional to clinical and histopathological malignancy in some extend.

Aged↗
PubMed1990

[Nuclear DNA content in the cells of squamous cell carcinoma and Bowen's disease. II. A study on DNA contents of deeply invaded cells in comparison with non-invading cells at the upper dermis].

To know the variation of DNA contents of SCC cells due to invasion activity, cytophotometric assay was used. The specimens for this study were paraffin-embedded tissue section of SCC stained with azocarmin G for blocking the non-specific fluorescence. By comparing the nuclear DNA content of tumor cells at the upper dermis and at the subcutaneous fat tissue, it was found that polyploid cells (greater than 4C and greater than 6C) populations in deep tissue was significantly higher than those in the upper dermis. This finding suggests that SCC cells capable to invade deeply are having larger amount of nuclear DNA that cells at the upper dermis.

Aged↗
PubMed1990

[A primary choriocarcinoma of the stomach with a review of 45 cases in Japan].

A case of a primary choriocarcinoma of the stomach is reported together with review of 44 cases in the Japanese literature. The patient, a 79-year-old male complaining of severe anemia, was admitted to hospital. As a result of a gastric endoscopy, a carcinoma was diagnosed and a laparotomy was performed. Because of an extensive metastasis, however, the surgery was limited to a palliative proximal gastrectomy. Pathologically, the tumor was a choriocarcinoma, and the HCG in the blood was slightly elevated. Immunohistologically, however, no HCG was detected. Although most cases reported in Japan support the theory of differentiations in gastric carcinomas, this choriocarcinoma suggests a separate type of differentiation in both the function and the morphology or a morphological mimicking.

Aged↗
PubMed1989

[Effects of serum lipid concentrations and smoking and drinking habits on serum vitamin A and E levels].

Serum retinol and tocopherol concentrations in 419 males and 478 females, aged 10 to 49 years, were determined by an HPLC method. Then their relationships to serum lipid concentrations and smoking and drinking habits were examined. Retinol levels were higher in males than in females but tocopherol showed little difference by sex. The sex differences in age-related serum levels of retinol and triglyceride (TG) were similar to those of tocopherol and total cholesterol (TC), respectively. Retinol had a significant correlation with TC and TG, with coefficients of 0.20-0.29 (p less than 0.001). These were smaller than those of tocopherol (R = 0.32-0.52, p less than 0.001) both in males and females, suggesting that it had a higher susceptibility to factors other than serum lipids than tocopherol did. Both the retinol and tocopherol levels were significantly higher in the groups with smoking and drinking habits than in the groups without them among the males aged 30 years and over. Furthermore, the retinol level was positively dependent on the daily consumption of both cigarettes and alcohol, whereas tocopherol was dependent on the consumption of alcohol. Multiple regression analysis showed that smoking and drinking habits had statistically significant effects on the serum retinol level independent of other factors and that their effects were greater than those of TC and TG. Tocopherol was affected most by TC and TG and then by drinking habit. Less significant but similar results were obtained for the females of the same age group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Recanalization of experimental thrombotic arterial occlusion by radiofrequency thermal angioplasty: an angioscopic observation.

The efficacy of radiofrequency (RF) angioplasty for recanalization of arterial thrombosis was assessed angioscopically in five dogs. A thrombus was induced by balloon injury of the left femoral artery. Within two hr, thrombi led to total occlusion of the artery in three dogs, subtotal occlusion in one, and about 70% obstruction in one. A metal-tipped catheter, with a tip size of 2.0 mm x 5.7 mm, was advanced into the thrombus and RF at 13.56 MHz was delivered repeatedly with gradually increased energies. The arterial lumina were recanalized or enlarged in all dogs. The thrombus surface had a shaggy appearance, and were dark (charring), or mixed dark and white in color. There were relatively large variations in the energies required; 140 J in one, 200 J in two and 250 J in two. The present results suggest that thrombotic arterial occlusion, such as acute occlusion complicating balloon angioplasty, can be treated with RF thermal angioplasty. Angioscopy provided detailed information about thrombus surfaces. The variations in required energies indicate the inability to control the thermal effect by energy settings alone. A more sophisticated method such as measurement of tip temperature will be able to overcome this difficulty.

Angioplasty, Balloon↗
PubMed1989

[Aging of epidermis. I. Morphological changes and their quantitative analysis].

Morphological changes in the epidermis caused by aging and sun exposure were studied by light microscopy and micrometric techniques. The following findings were obtained. 1. Corneocytes of the sun exposed skin of young healthy subjects were smaller than those of aged persons. 2. The epidermal rete ridges of the sun-exposed skin of old subjects disappeared and flattened. 3. The thinning and flattening of the epidermis of old subjects were more prominent in sun exposed skin than in sun protected skin. These data suggest that sun exposure accelerates some morphological changes of epidermis considered due to aging.

Adolescent↗
PubMed1989

HTLV-1 rex and HIV-1 rev act through similar mechanisms to relieve suppression of unspliced RNA expression.

Human retroviruses, human T cell leukemia viruses (HTLV) and human immunodeficiency viruses (HIV), express two classes of mRNAs; fully spliced mRNA in the early phase and intron-containing mRNA in a later phase. The expressions of HTLV-1 rex and HIV rev by early mRNAs are essential for the later phase of expression of intron-containing gag and env mRNAs. Each two cis-acting sequences seem to be involved in these regulations: HTLV-1 rex depends on a splice donor (SD) and a responsible element (RXE) at the 3' end, whereas HIV rev depends on a specific repressive sequence (CRS) and a responsible element (RRE) in the intron, but does not require an SD. For analyses of these cis-acting sequences, we inserted an HIV element RRE into an HTLV-1 construct and tested the responses to HTLV-1 rex and HIV rev regulations. The results indicated that both rex and rev could regulate RNA expression of these chimeric constructs responding to an HIV RRE. A repressive element (CRS) was dispensable, and the intronic or exonic location of RRE was not important. These observations suggest that rex and rev could be functionally equivalent to induce cytoplasmic expression of unspliced RNA which expression is suppressed either by an SD or CRS depending on the construction.

Cell Line↗
PubMed1989

[Influences of polychlorinated dibenzofuran on experimental carcinogenesis in mice].

To ascertain whether 2,3,4,7,8-pentachlorodibenzofuran (PCDF) has the possibility of cocarcinogen, three different concentrations of 0.5, 1 and 5 ppm PCDF was evaluated in the course of experimental carcinogenesis in mice. Concerning the difference of total number of tumors occurred among the groups of mice with various treatments, the mice treated with 0.5 ppm PCDF and 20-methylcholanthrene (MC) have produced twice as many tumors as those of the other groups. Then the adequate concentration of PCDF to be a promoter was supposed to be 0.5 ppm. Two kinds of tumors were seen in mice which were treated by MC with or without PCDF, and there was no difference of tumors between the groups by appearance and pathologically. One is a benign papilloma, and the other is a squamous cell carcinoma which tends to keratinize and looks like a keratoacanthoma. The latter had a tendency to arise much more four weeks after the treatments had been done, even though the number of the former increased gradually. There was no evidence that PCDF of these concentrations could permeate through the skin and could be toxic. Furthermore PCDF seemed to neither stay nor act directly on the follicular epithelium, since there was no acne formation on the back skin of mice. One of the possible factors to cause malignant changes of epidermal cells was supposed to be a prolonged inflammation of the skin.

Animals↗
PubMed1988

Renal amyloidosis. Correlations between morphology, chemical types of amyloid protein and clinical features.

Sixty-one autopsy cases of renal amyloidosis were reviewed to assess the relationship of renal pathology to chemical types of amyloid and clinical features. Glomerular amyloid deposition was divided on the basis of morphological characteristics, into four types: a mesangial nodular type showing nodular mesangial deposits with sparse capillary wall involvement (25 cases), a mesangio-capillary type disclosing diffuse amyloid deposition in the mesangium and along both sides of the glomerular basement membrane (19 cases), a perimembranous type principally involving the subepithelial side of the basement membrane invariably characterized by exuberant spicular arrangement (6 cases), and a hilar type showing amyloid deposits almost exclusively in hilar arterioles (11 cases). Twenty-four of 25 cases of mesangial nodular type (96%) showed amyloid protein of AA type. However, mesangio-capillary and perimembranous types were associated with deposition of AL amyloid protein in 15 of 19 (79%) and all 6 cases, respectively. Nephrotic syndrome was more frequent in patients with AL amyloidosis; notably, all patients with perimembranous type had nephrotic syndrome irrespective of the extent of glomerular amyloid deposits. Chronic renal failure and renal death appeared more common in mesangial nodular type in which the extent of glomerular amyloidosis correlated with that of vascular amyloid deposits. The results obtained suggest that the chemical type of glomerular amyloid protein (AA vs AL) is associated with significant differences in the morphological, clinical and prognostic features of the renal involvement.

Adult↗
PubMed1988

Rapid regression of renal medullary granular change during reversal of potassium depletion nephropathy.

Structural changes were studied on the kidney of a potassium-depleted man and on rat kidneys during potassium depletion and repletion. Light and electron microscopy revealed rapid disappearance of intracytoplasmic granules in the renomedullary cells after potassium repletion in our patient as well as in rats. In potassium-depleted rats a series of ultrastructural changes, which were similar to those observed in the human kidney were seen with potassium repletion. Most of the granules were reduced in size and number, with loss of internal structure, shrinkage and condensation of their contents, and were almost totally eliminated by 72 h of potassium repletion. In some endothelial and interstitial cells, the granules were seen to be in the process of being extruded through an area of gap in the plasma membrane. The results indicate that most of the intracytoplasmic granules in the renal medulla rapidly disappeared by intracytoplasmic digestion and the rest of them were probably eliminated by exocytosis during reversal of potassium depletion nephropathy in man and rats.

Adult↗
PubMed1987

zero.1-T human fat/water separation by SIDAC.

High-resolution human fat/water separated images were obtained in 17 min at a static magnetic field strength as low as 0.1 T. The sequence used was based on SIDAC (spectroscopic imaging by dephasing amplitude changing), which employs a stepwise changing dephase gradient for the separation of spectral and spatial information of magnetic spins.

Adipose Tissue↗