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Biomedical subjects

T Higashi

Publications and source records attributed to T Higashi.

At least 163 records · Page 9Linked to original sources
PubMed1996

Alzheimer-type pathology in a patient with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS).

A 53-year-old Japanese woman with a point mutation in mitochondrial DNA (tRNALeu(UUR), nt3243) consistent with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) and Alzheimer-type brain pathology is reported. This woman had suffered myopathy and psychosis without any clinical evidence of, stroke-like episodes during the last 10 years of her life, and had died after an accident. At autopsy 30 h post mortem, a part of the brain was snap frozen for biochemical and histochemical studies, and the remaining part was processed for a routine examination and electron microscopy. In the brain there were no ischemic lesions. Instead, primitive/diffuse senile plaques were found throughout the brain, predominantly in the frontal and temporal lobes, while Alzheimer neurofibrillary tangles were found only in the parahippocampal gyrus. These plaques were positive for beta-protein and mostly negative for tau protein, ubiquitin, neurofilaments, alpha-choline acetyltransferase, and acetylcholinesterase. Mutations in codon 331 of the ND2 gene as well as codons 693, 713 and 717 of the beta-amyloid precursor protein gene, known to be responsible for some cases of familial Alzheimer disease, were not found. Furthermore, coincidental Down syndrome was ruled out by chromosome analysis. The results suggest a possible correlation between this mitochondrial DNA abnormality and Alzheimer-type pathology.

Alzheimer Disease↗
PubMed1996

Release of fructose and hexose phosphates from perivascular cells induced by low density lipoprotein and acceleration of protein glycation in vitro.

We investigated whether low density lipoprotein (LDL) under oxidative stress might induce the release of fructose, glucose-6-phosphate and fructose-6-phosphate from perivascular cells, and also whether these substances might accelerate the formation of advanced glycation end products (AGE) from proteins in vitro. When vascular smooth muscle cells were incubated with LDL in Ham's F10 at 37 degrees C for 48 h. release of all these substances was increased dose-dependently by oxidized LDL. Fructose release was increased in a dose-dependent manner by glucose. Indomethacin (20 microM) significantly (P < 0.01) suppressed the release of fructose (25.4 +/- 15.7% of control) and hexose phosphates (29.4 +/- 4.0) with the inhibition of release of lactate dehydrogenase (35.5 +/- 4.9) as well as probucol, whereas an aldose reductase inhibitor, epalrestat, significantly (P < 0.001) inhibited only the fructose release (0.9 +/- 0.8). Release of fructose and hexose phosphates from vascular endothelial cells was also induced by oxidized LDL. AGE immunoreactivities and AGE-related fluorescence formed from proteins and glucose were significantly increased (P < 0.001) in the presence of small amounts of the cellular glucose metabolites (6.6%) with glucose (93.4%). These data suggest that release of potent AGE initiators, fructose and hexose phosphates, from perivascular cells induced by oxidized LDL may be an important phenomenon for vascular complications.

Aldehyde Reductase↗
PubMed1996

High concentrations of cholecystokinin octapeptide suppress protein kinase C activity in guinea pig pancreatic acini.

In pancreatic acini, calcium-mobilizing agents increase intracellular calcium and stimulate the production of diacylglycerol, and then activate protein kinase C (PKC). However, there are few studies which have examined the activation of PKC in intact acini. To examine the activation of PKC in intact acini by calcium-mobilizing agents, we measured the binding of [3H]phorbol-12,13-dibutyrate (PDBu) to intact acini. Acini were incubated with 10 nM [3H]PDBu at 25 degrees C with or without agents. The binding reactions were terminated by filtration. The filters were counted by a scintillation counter after washing. Acini possessed a single class of binding sites to PDBu, with Kd = 70 nM. CCK-8 and carbachol upregulated the binding affinity of PKC to PDBu in the acini. The ability of calcium-mobilizing agents to increase binding of [3H]PDBu to the acini had a close correlation to their ability to stimulate the amylase secretion from the acini, and higher concentrations of CCK-8 for amylase secretion suppressed binding of [3H]PDBu to the acini. 8Br-cAMP, 8Br-cGMP, and calcium ionophore did not inhibit the maximal activation of PKC induced by CCK-8. The calmodulin inhibitor W7 did not reverse the inhibitory effect of higher concentrations of CCK-8 on PKC activation. These results indicate that calcium-mobilizing agents upregulate the binding affinity of PKC to PDBu in intact acini, and that higher concentrations of CCK-8 for amylase secretion may activate the intracellular mechanism that inhibits PKC activity in acini. This inhibitory mechanism was mediated by some other mechanism other than cAMP-, cGMP-, calcium- and calmodulin-dependent mechanisms.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1996

Influence of particle size of hydroxyapatite as a capping agent on cell proliferation of cultured fibroblasts.

The influence of particle size of biomaterials on cell reaction and cell proliferation was studied by means of coculturing fibroblasts with calcium phosphate ceramics. Both dense and porous hydroxyapatite ceramics obtained under different sintering conditions were selected, and two particle sizes of 300 and 40 micrometers were used to examine cell reaction. The four materials were each cocultured with dental pulp-derived fibroblasts for 7 days. Cell reaction was observed by phase-contrast microscopy and scanning electron microscopy. Cell proliferation was measured by counting the number of trypsinized cells in 7-day-old culture. On the seventh day, the dense 300-micrometer particles of hydroxyapatite were completely covered by cultured cells that had proliferated on the dish surface. On the other hand, the porous and dense 40-micrometer particles were captured or gathered by the cultured cells, which seemed not to proliferate. The porous 300-micrometer particles were accompanied by numerous small broken pieces on the dish surface, and the cells proliferated only around the large particles. From these results, the dense 300-micrometer particles of hydroxyapatite can be considered the most appropriate biomaterial.

Biocompatible Materials↗
PubMed1996

Characteristics and effects of calcified degenerative zones on the formation of hard tissue barriers in amputated canine dental pulp.

The purpose of this research was to study under undecalcified conditions the presence, ultrastructural features, and contributions of the degenerative zone beneath the necrotic zone and whether it had effects on the formation of reparative dentin in canine incisors and premolars. The research was conducted over a period of 14 days after experimental pulpotomy using calcium hydroxide as a pulp-capping agent. On the first day following pulp exposure and capping with calcium hydroxide, electron-dense spherical bodies were observed under the necrotic zone. Energy dispersive X-ray point analysis confirmed that these electron-dense deposits contained calcium and phosphorus. By the third day, varying amounts of minute von Kossa-positive granules could be observed light-microscopically between the two zones of necrosis and underlying vital pulp tissue. Migration and proliferation of pulpal cells, most probably mesenchymal cells, were observed adjacent to the von Kossa-positive zone. The ultrastructure of the von Kossa-positive zone consisted of degenerated cells, electron-dense spherical bodies, and electron-dense shortened dilating fibrils. By the seventh day, short cylindrical-shaped cells collected at the coronal end of the vital pulp tissue. By the fourteenth day, the specimens having a uniform von Kossa-positive zone exhibited rapid differentiation of odontoblasts and tubular dentin formation. In contrast, only some specimens having an irregular von Kossa-positive zone exhibited osteodentin formation and the beginning of odontoblast differentiation beneath the osteodentin. These findings suggest that this calcified degenerative zone has an important effect on the reparative process of pulp tissue after pulpotomy.

Animals↗
PubMed1996

Influence of particle size of calcium phosphate ceramics as a capping agent on the formation of a hard tissue barrier in amputated dental pulp.

The purpose of this research was to compare the effect of two different particle sizes of hydroxyapatite and beta-tricalcium phosphate as capping agents on hard tissue barrier formation after experimental pulpotomy in canine dental pulp. By the thirtieth day after pulp exposure and capping with hydroxyapatite-300 (particle size, 300 microns), a hard tissue barrier was formed in 8 of 17 specimens. A newly formed barrier was seen around the hydroxyapatite particles and connecting neighboring particles. Capping with tricalcium phosphate-300 (particle size, 300 microns) led to the formation of a hard tissue barrier surrounding the particles in 11 of 17 specimens. In contrast, using hydroxyapatite-40 (particle size, 40 microns) and beta-tricalcium phosphate-40 (particle size, 40 microns), hard tissue barrier formation was poor and almost all pulp tissues showed infiltrations of inflammatory cells or abscess formation. These findings suggest that the particle size of hydroxyapatite and beta-tricalcium phosphate is an important factor in reparative hard tissue formation.

Animals↗
PubMed1996

Electron microscopic study on interodontoblastic collagen fibrils in amputated canine dental pulp.

The purpose of this research was to study the presence and the ultrastructural features of interodontoblastic collagen fibrils and their contribution to the formation of reparative dentin in dog incisors and premolars for a period of 30 days following experimental pulpotomy. On the seventy day after pulp exposure and capping with calcium hydroxide, short cylindrical-shaped cells collected at the coronal end of the vital pulp tissue. Many collagen fibrils were synthesized in the intercellular spaces and in the direction of the long axis of these cells. On the fourteenth day, large bundles of collagen fibrils were observed in the intercellular spaces of young odontoblasts. These bundles spread out in a fan-shaped arrangement. On the thirtieth day, the odontoblasts formed a tubular dentin matrix. Small numbers of twisted collagen bundles crossed the distal junctional complex of the odontoblast cell bodies and entered the dentin matrix.

Animals↗
PubMed1996

Cellular distribution of transcripts for tissue inhibitor of metalloproteinases 1 and 2 in human hepatocellular carcinomas.

The cellular distribution of tissue inhibitor of metalloproteinases (TIMP)-1, and TIMP-2 was studied by using in situ hybridization in surgically removed human hepatocellular carcinomas (HCCs) and cholangiocellular carcinomas (CCCs). The purpose of this study was to characterize the protein involvement of TIMPs in the development of HCCs and CCCs. All HCCs and CCCs expressed TIMPs. The distribution of transcripts for TIMPs in the tumors was mostly homogeneous. Expression of TIMP in cancer cells was more intense than that in the surrounding noncancerous liver (either, cirrhosis, chronic hepatitis, or normal), and expression of TIMP-1 was stronger than that of TIMP-2. Expression of TIMPs varied among HCC nodules, but there was no obvious association between the expression level of TIMPs and differentiation stages or invasiveness of the HCCs. Transcripts for TIMPs were clearly demonstrated in the metastatic HCC nodules in the lung. Expression of TIMP-1 CCC was strong, and small nodules of CCC were recognized in the liver. Immunohistochemical study for TIMP-1 revealed a consistent staining of the TIMP protein with the transcripts. In the peritumoral histologically normal liver, which was not infected with either hepatitis B or C virus, expression of TIMP-1 was found in various cell types, but that of TIMP-2 was weak. Expression of TIMP-1 in hepatocytes revealed clear zonal distribution. These results suggest that TIMPs may act on modulating the matrix/tumor interaction and may play an important role in growth and invasion of HCCs and CCCs. Expression of TIMP-1 can be a marker of HCC metastasis to the lung, and also that of the extent of CCC invasion. Furthermore, the consistent expression of TIMPs in many cell types of the noncancerous liver suggests some unknown functional role that must be clarified.

Aged↗
PubMed1996

Activities of an occupational health organization in Japan, in special reference to services for small- and medium-scale enterprises.

This paper reports the activities of occupational health organizations in Japan, taking Nishinihon Occupational Health Service Center, one of the largest scale occupational health service providers, as an example. The organizations, at the request of enterprises, provide occupational health services on a profit basis especially for small- and medium-scale enterprises which lack the human resources and/or facilities to meet legal requirements on occupational health. The main services include: (1) providing various types of medical examinations for workers, (2) measuring work environment, (3) occupational physicians and occupational health nurses providing a comprehensive service. Among these services, legally required health examinations and work environment measurements are well served even for small-scale enterprises. Less effective are the health promotion and occupational health service by the occupational health staffs. In the future, these service will be better provided by a newly developed network system to support occupational heath activities in small-scale enterprises.

Industry↗
PubMed1996

Isolation and characterization of mitochondrial nucleoids from the yeast Pichia jadinii.

Mitochondrial (mt) nucleoids were isolated with a high degree of purity from the yeast Pichia jadinii, in which the mitochondrial DNA (mtDNA) is linear. Field-inversion gel electrophoresis (FIGE) revealed that significant amounts of mtDNA could be isolated intact, as linear molecules of 41 kbp, from the isolated mt-nucleoids. Fifteen different proteins were detected in the mt-nucleoid fraction and, eight of these proteins bound to DNA. The patterns of mt-nucleoid proteins and of the DNA-binding proteins after gel electrophoresis in the presence of SDS were somewhat different from those of such proteins from Saccharomyces cerevisiae. The corresponding proteins isolated from the mt-nucleoids of four other species of yeast in the genera Pichia and Williopsis also differed from one another in terms of electrophoretic mobility in the presence of SDS. In immunoblotting experiments, antibodies that had been raised against the 67-kDa protein of mt-nucleoids from S.cerevisiae and the YMN-1 monoclonal antibody that is specific for a 48-kDa protein in the mt-nucleoids from S. cerevisiae did not recognize any proteins in the mt-nucleoids from Pichia jadinii and four other species of yeast. The results suggest the considerable diversity of the proteins in the mt-nucleoids of yeasts.

Animals↗
PubMed1996

Evaluation of multi skin test in colorectal cancer patients and effects of serum immunosuppressive factor and cytokine production of peripheral mononuclear cells.

Decreased skin reactions using five kinds of recall antigens correlate d with the stage of colorectal cancer. Immunosuppressive factors in the serum (IS index) increased with the progression of the stage in cancer patients, but interleukin (IL)-I and IL-2 production in peripheral mononuclear cells (PBMC) did not correlate with the advance of the disease. In patients with low immunosuppressive factors, the score of skin reactions was significantly higher than that in patients with high immunosuppressive factors. Increased serum immunosuppressive factors seem to reduce skin reactions in the patients. Furthermore, significant difference in skin reaction score was observed between patients with high IL-1 production of PBMC and patients with low IL-1 production of PBMC. These results suggest that skin reaction might be controlled by serum immunosuppressive factors and IL-1 production of PBMC, and that the score of skin reaction using multirecall antigens is a useful parameter to learn the host immunity in colorectal cancer.

Adult↗
PubMed1996

Apoptosis and proliferation of human hepatocellular carcinoma.

To investigate the contribution of apoptosis, a major mechanism of cell death, in the growth of hepatocellular carcinoma, we analyzed both apoptosis and cell proliferation in human hepatocellular carcinoma. We used the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling method and proliferative cell nuclear antigen staining, respectively. Among 21 hepatocellular carcinoma specimens examined, four were well, ten were moderately, and seven were poorly differentiated hepatocellular carcinoma. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cells in hepatocellular carcinoma were scattered individually or were sometimes clustered in the tumors. The terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling indices were 0.35 +/- 0.09, 0.81 +/- 0.29, and 1.9 +/- 0.94 in well, moderately, and poorly differentiated hepatocellular carcinoma, respectively. The proliferative cell nuclear antigen labeling indices were 6.6 +/- 0.9, 13.1 +/- 3.5, and 26.7 +/- 6.3 in hepatocellular carcinoma in the same respective order of differentiation. The differences in both terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling indices and proliferative cell nuclear antigen labeling indices (p < 0.05) were significant between well, moderately and poorly differentiated hepatocellular carcinoma. There was a positive correlation between the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and proliferative cell nuclear antigen labeling indices in hepatocellular carcinoma (r = 0.84, p < 0.001). This study showed that the proliferation rate and the incidence of apoptosis increased as the differentiation grade of hepatocellular carcinoma was lowered, suggesting a rapid turnover of cancer cells in the lower differentiation grades. Apoptosis may thus play an important role in the growth of hepatocellular carcinoma.

Apoptosis↗
PubMed1996

Telomere length in human liver diseases.

To determine the role of telomere-mediated gene stability in hepatocarcinogenesis, we examined the telomere length of human liver with or without chronic liver diseases and hepatocellular carcinomas (HCC). The mean telomere restriction fragment (TRF) length of normal liver (n = 13), chronic hepatitis (n = 11), liver cirrhosis (n = 24) and HCC (n = 24) was 7.8 +/- 0.2, 7.1 +/- 0.3, 6.4 +/- 0.2 and 5.2 +/- 0.2 kb, respectively (mean +/- standard error). TRF length decreased with a progression of chronic liver diseases and that in HCC was significantly shorter than that in other chronic liver diseases (p < 0.05). The ratios of TRF length of HCC to that of corresponding surrounding liver of well differentiated (n = 7), moderately differentiated (n = 10) and poorly differentiated (n = 4) HCCs were 0.83 +/- 0.06, 0.75 +/- 0.05 and 0.98 +/- 0.09, respectively. The ratio of poorly differentiated HCC was significantly higher than that of moderately differentiated HCC (p < 0.05). A comparison between the size and telomere length ratio of moderately differentiated HCCs revealed a decrease of the ratio with size until it reached 50 mm in diameter. In contrast, the ratio increased as the size enlarged over 50 mm. These findings suggest that the gene stability of the liver cells mediated by the telomere is reduced as chronic liver disease progresses and that telomerase is activated in poorly differentiated HCC and moderately differentiated HCC over 50 mm in diameter.

Adolescent↗
PubMed1996

A bibliometric study of the trend in articles related to epidemiology published in occupational health journals.

OBJECTIVES: To study the role assumed by epidemiology in occupational health literature and characterise its change over the years. METHODS: A bibliometric study was conducted with a MEDLINE search to evaluate 9024 articles published in eight representative occupational health journals for the period 1980-93. Articles related to epidemiology were found by descriptors indexed in the articles and their numbers and proportions among all published articles was tabulated for the study period. RESULTS: The proportion of source items indexed by epidemiology as a descriptor increased over threefold from 7.9% (42/534) in 1980 to over 25% after 1990. Epidemiology was indexed most frequently as a subheading associated with other descriptors-for example, occupational diseases-epidemiology. Cohort studies had the largest increase in the descriptors that indicated epidemiological type of studies during the period studied. CONCLUSION: Epidemiology is assuming increasing importance in occupational health literature. This was shown quantitatively and qualitatively by the use of descriptors in the MEDLINE database.

Abstracting and Indexing↗
PubMed1996

Comparison of Two Questionnaires on Respiratory Symptoms in a Nicaraguan Population: Value in Diagnosis of Chronic Bronchitis.

Two questionnaires about respiratory symptoms were evaluated for reliability and ability to diagnose chronic bronchitis in a study population of 129 Nicaraguans (110 workers and 19 patients with chronic bronchitis). The first questionnaire (AQ) had symptom questions that were based on British Medical Research Council (MRC) questions, adapted to local Spanish. The second questionnaire (MRCQ) contained MRC symptom questions translated directly into Spanish. The reliability of the questions was measured in a test-retest procedure. The questionnaire-based diagnosis of chronic bronchitis was compared with the diagnosis made by a physician (for workers) or from the hospital records (for patients). The questions concerning symptoms in both questionnaires were of acceptable reliability. For the diagnosis of chronic bronchitis in workers, the AQ showed similar sensitivity, a somewhat higher specificity, and a substantially higher positive predictive value (90%) than the MRCQ (57%). Among the patients, the AQ identified 17 patients as positive (sensitivity 89%), while the MRCQ identified 15 (sensitivity 79%). respiratory questionnaire; reliability; chronic bronchitis; Nicaragua Hanley & Belfus, Inc. Int J Occup Environ Health 1077-3525 2 2 1996 April/June Chronic Exposure to Cigarette Smoke Inhibits the Stimulating Effects of Mineral Fibers on the Production of Tumor Necrosis Factor by Alveolar Macrophages of Rats 95 98 EN Yasuo Morimoto Department of Environmental Health Engineering, University of Occupational and Environmental Health, Japan 1-1, Iseigaoka, Yahatanishiku, Kitakyushu 807, Japan. Ziro Nambu Hajime Hori Tohru Tsuda Hiroshi Yamato Toshiaki Higashi Yasuyuki Yokosaki Masamitsu Kido Isamu Tanaka The objective of this study was to evaluate the chronic combined effects of mineral fibers and cigarette smoke on the production of tumor necrosis factor (TNF) by alveolar macrophages. The authors chronically exposed ten rats to cigarette smoke in vivo and measured the production of TNF by alveolar macrophages in the presence of mineral fibers in vitro. For smoke exposure, rats were divided into two groups. Five rats were exposed daily to a concentration of 10 mg/m(3) of cigarette smoke for six hours a day, five days a week, for four weeks, and five rats (control) were not exposed to smoke. A broncho-alveolar lavage was performed after the smoke exposure, and the recovered alveolar macrophages were incubated with either chrysotile or ceramic fibers on a microplate for 24 hours. TNF activity in the supernatant was determined by the L929 bioassay. When alveolar macrophages were not stimulated by mineral fibers, TNF production tended to be lower in smoke-exposed alveolar macrophages than in unexposed ones, although the difference was not significant statistically. When alveolar macrophages were stimulated in vitro by chrysotile or ceramic fibers, both fibers stimulated TNF production, but TNF production in smoke-exposed alveolar macrophages was lower than that in unexposed macrophages. These results revealed that long-term exposure to cigarette smoke inhibited the stimulating effect of mineral fibers on the production of TNF.

Journal Article↗
PubMed1996

Should Petasospora BOIDIN et ABADIE (Saccharomycetaceae) be retained?--the phylogeny based on the partial sequences of 18S and 26S ribosomal RNAs.

The six strains of the Pichia species, once classified in the genus Petasospora, were examined for their 18S (positions 1451-1618, 168 bases) and 26S (positions 1611-1835, 225 bases and 493-622, 130 bases) rRNA partial base sequencings. In the 18S rRNA partial base sequencings, the type species of the genus Petasospora (Petasospora rhodanensis) was found to be closely related to Pichia anomala (identical to Hansenula anomala, type species of genus Hansenula) with base differences of two, but not to Pichia membranaefaciens, the type species of the genus Pichia, with base differences of ten. However, the species was not so closely related to P. anomala in the 26S rRNA partial base sequencings with base differences of twelve and 68 percent similarity. The genus Petasospora was known to be a very heterogeneous taxon phylogenetically with base differences of thirty-one to three and ninety-two to eight and with 40 to 83 percent similarities. The sequence data obtained here and the phenotypic features described previously indicate that the type species of the genus Petasospora (Pet. rhodanensis, identical to Pichia rhodanensis) is adequate to be accommodated temporarily in the genus Pichia, a heterogeneous taxon, until the precise taxonomic position of the type species is defined.

Base Sequence↗
PubMed1996

Cathepsin B in the growth of colorectal cancer: suppressive effect of leupeptin on the growth of DMH-induced rat colon neoplasm.

Cathepsin B, a thiol protease, has been reported to be involved in cancer progression and metastasis. The suppressive effects of two kinds of protease inhibitors, leupeptin and dietary camostate (FOY-305), on tumorigenesis and progression in 1, 2-dimethylhydrazine (DMH)-induced rat colon neoplasm were examined in relation to tissue cathepsin B activity. Male Donryu rats were treated with leupeptin or FOY-305 during or after the administration of DMH. There were no significant differences in average tumor numbers among all DMH-treated groups. However, the percentage of small tumors was significantly higher in the group in which leupeptin was supplied during DMH administration. This trend was not recognized in the FOY-305-treated groups. The ratio of cathepsin B activity in the tumors to that in the tumor-bearing tissue (T/Tb) was significantly increased with increasing tumor size (P = 0.009). The cathepsin B activity levels in the tumor-bearing mucosa in the groups which received leupeptin or FOY-305 following DMH treatment were both significantly lower than that in the group which received neither protease inhibitor (P = 0.046 and P = 0.0067, respectively). The results obtained indicate that leupeptin may have suppressed tumor growth by lowering the tissue cathepsin B activity.

1,2-Dimethylhydrazine↗