Search PubMed⌕ Search

Biomedical subjects

H Sakurai

Publications and source records attributed to H Sakurai.

At least 397 records · Page 22Linked to original sources
PubMed1993

Evaluation of delta-aminolaevulinic acid in blood of workers exposed to lead.

Exposure-effect and exposure-response relation between exposure to lead and delta-aminolaevulinic acid concentration in blood (ALA-B) were examined in 238 male workers exposed to lead. Concentrations of ALA-B ranged from 26 to 352 micrograms/l and lead concentrations in blood (Pb-B) from 7.1 to 86.0 micrograms/dl. Concentrations of ALA-B correlated closely with concentrations of Pb-B (r = 0.74), and increased ALA-B concentration occurred at Pb-B concentrations of around 30 micrograms/dl. Exposure-response curves indicated that the 50 percentile response doses were roughly 30, 40, and 50 micrograms/dl Pb-B when cut off points of ALA-B were set at 50, 60, and 70 micrograms/l respectively. The sensitivity and specificity of measurements of ALA-B concentrations for health screening were sufficiently high when the health based exposure limits of lead were set at 30-50 micrograms/dl. Moreover, a pronounced increase in ALA-B concentrations occurred when the inhibition rate of erythrocyte ALA dehydratase exceeded 85%. These findings suggest that ALA-B is a useful indicator for assessing the early effects of exposure to lead on haem biosynthesis.

Adult↗
PubMed1993

Toxicity of intraperitoneally administrated silicon tetraalkoxides in male ICR mice.

The toxicities of silicon tetraalkoxides, including tetramethoxysilane [Si(OCH3)4, TMOS], tetraethoxysilane [Si(OC2H5)4, TEOS], tetrapropoxysilane [Si(OC3H7)4, TPOS] and tetrabuthoxysilane [Si(OC4H9)4, TBOS], were investigated with intraperitoneal injection of 1,000 mg/kg of each compound. TMOS, as well as TEOS, caused acute tubular necrosis. Blood biochemical examination revealed elevation of blood urea nitrogen and creatinine in mice treated with TEOS, TPOS and TBOS, though TMOS treated mice died and therefore could not be examined. The severity of nephrotoxicity differs among these silicon tetraalkoxides. The spleens of mice treated with TMOS exhibited cytolysis in the white and red pulp, suggesting direct injury to the spleen. The kidney seems to be a common target organ of silicon tetraalkoxides.

Alkylation↗
PubMed1993

Study on high-strength plastic teeth. Tooth discoloration.

Conventional plastic teeth (CV teeth) are inferior to porcelain teeth in maintaining an adequate esthetic appearance with wear and discoloration, and thus have a shorter period of durability. Recently, high-strength plastic teeth (HS teeth) have been developed and applied to overcome the wear problems of CV teeth. Since HS teeth made of hard resin are still susceptible to staining with pigments, it has been observed that the esthetics of removable partial dentures made from such plastic teeth are gradually impaired in many patients. To investigate the susceptibility of HS teeth to pigments, we conducted an in vitro study by immersing three types of artificial teeth in three coloring liquids. It was found that the HS teeth tended to be less susceptible to the test pigments than the CV teeth to various degrees. In contrast, they showed markedly stronger susceptibility to the pigments than porcelain teeth. For all three artificial tooth types, daily tooth cleaning with an ultrasonic vibrator had a tendency to reduce the coloration in comparison with their counterparts without ultrasonic cleaning.

Acrylic Resins↗
PubMed1993

Study on the castability of Co-Cr alloy for cast plates. Part 3: Effects of alloy fusion temperature and the heating temperature of the cast ring.

Co-Cr alloy is used more frequently than Ni-Cr alloy as a non-precious alloy for cast plates in Japan. However, since the melting temperature of Co-Cr alloy is very high, about 1300 degrees C, and since it oxidizes easily, a vacuum-pressure casting machine capable of melting this alloy in a reduced atmosphere has recently been developed. Using this machine, the effects of fusion temperature and the heating temperature of the cast ring on the Co-Cr alloy were studied. It was found that in the vacuum-pressure casting method, both the fusion temperature of the Co-Cr alloy and the heating temperature of the cast ring had a significant effect (p < 0.01) on the castability of the Co-Cr alloy.

Chromium Alloys↗
PubMed1993

Testis function and feedlot performance of bulls actively immunized against gonadotropin-releasing hormone: effect of implants containing progesterone and estradiol benzoate.

The effect of implants containing anabolic steroid (Synovex) on testis function, feedlot performance, and carcass traits was evaluated in bulls, steers, and bulls actively immunized against gonadotropin-releasing hormone (GnRH). Ninety-one Hereford or Hereford x Red Angus bull calves were randomly assigned to a 3 x 2 factorial experiment. The treatments were: 1) unimmunized control (n = 30), 2) actively immunized against GnRH (n = 31), or 3) castrate (n = 30). The classes were 1) unimplanted (n = 45) or 2) implanted (n = 46) with Synovex. Animals in treatment Groups 2 and 3 were either immunized with a GnRH-keyhole limpet hemocyanin (KLH) conjugate or castrated at 3.6 +/- .1 mo of age. Animals assigned to Class 2 received Synovex-C at the time of initial treatment and Synovex-S at weaning and feedlot entry. Animals in treatment Group 2 received a booster immunization at feedlot entry. Anti-GnRH titer was evident at weaning and remained elevated to slaughter in all (31 of 31) immunized animals. Anti-GnRH titer was not evident in steers or unimmunized bulls. Immunization and (or) Synovex decreased (P < .05) serum concentrations of testosterone (T) and scrotal circumference (SC) at weaning. Similarly, SC, testis weight, and tissue concentrations of spermatozoa at slaughter were significantly reduced by immunization, Synovex, or the immunization/Synovex combination. Immunization, but not Synovex, reduced (P < .05) serum levels of T at slaughter. The masculinity of immunized bulls was less (P < .05) than that of control bulls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Evaluation of superoxide scavenging activities of hamamelis extract and hamamelitannin.

Hamamelitannin, which is a component of bark extract of hamamelis (Hamamelis virginior L.), was found to be a potent scavenger of superoxide anion radicals. Superoxide anion scavenging activity of the compound was evaluated by ESR-spin trap method using DMPO (5,5'-dimethyl-1-pyrroline-N-oxide) as a spin trapping agent. The IC50 value (the concentration producing 50% inhibition of superoxide anion radicals) of hamamelitannin was found to be 1.38 +/- 0.06 microM much lower than that of ascorbic acid (23.31 +/- 2.23 microM). Supporting the superoxide scavenging activity of hamamelitannin, the compound showed both suppressive ability against depolymelization of hyaluronic acid and protective ability against cytotoxicity induced by superoxide anion radicals. Hamamelitannin increased the survival rate of fibroblast to 85.5 +/- 3.3%, compared with that of control (27.2 +/- 4.3%).

Ascorbic Acid↗
PubMed1993

Differential immunohistochemical staining of cancerous cells with anti-single-stranded DNA antiserum in ordinary pathological paraffin section after DNA-denaturation by acid hydrolysis.

Based on the finding that the nuclear DNA of cancerous cells is much more unstable than that of non-cancerous cells, yielding a larger amount of single-stranded DNA by acid hydrolysis, we developed a new method of cancer cell detection in ordinary pathological sections by immunohistochemical staining with anti-single-stranded DNA antiserum after acid hydrolysis. Methylated bovine serum albumin was conjugated with heat-denatured calf thymus DNA and used as the antigen of single-stranded DNA, and white male rabbits were immunized with the antigen to obtain the polyclonal antiserum. Ordinary paraffin-embedded sections were prepared from the formalin-fixed biopsy specimens taken from 482 malignant tumors and 73 benign tumors of human epithelial and non-epithelial origins. Additional 82 biopsy specimens of borderline malignancy were also examined. The sections were immunohistochemically stained with the antiserum after RNase digestion and DNA denaturation by hydrolysis with 2 N HCl at 30 degrees C. The acid hydrolysis for 20-30 min was optimum for the specimens fixed with 10% buffered formalin at room temperature for 16-24 hrs, and all cancerous cells were specifically stained positive, in sharp contrast to the negative stainability of all non-cancerous cells including inflammatory cells. This new method gives us decisive help in making diagnosis of malignancy in daily pathological examination. The possibility of malignancy of borderline lesion was discussed.

Animals↗
PubMed1993

Polypoid adenosquamous carcinoma of the esophagus with prominent spindle cells. Report of a case with immunohistochemical and ultrastructural studies.

We report a case of spindle-cell adenosquamous carcinoma of the esophagus. This represents the third case in the worldwide literature in which an esophageal polypoid tumor contains adenosquamous carcinoma rather than the usual squamous cell carcinoma in addition to a prominent spindle-cell element. The spindle-cell component displayed positive immunoreaction for both keratin and vimentin, as expression of bidirectional differentiation within a single neoplasm.

Adenocarcinoma↗
PubMed1993

[Molecular analysis of new human endogenous retroviruses].

The genome of normal, uninfected animal cells contains gene sequences which are closely related to exogenous, infectious retroviral species. These genomes are called endogenous retrovirus, which have been isolated from a variety of vertebrates. The endogenous retrovirus genomes are stable genetic entities that are inherited in Mendelian fashion. In this study, we found the existence of many related endogenous retroviruses in human genomes, by cross-hybridization with human endogenous retrovirus, ERV3 env region. The ERV3-related endogenous retroviruses also contained a variety of restriction fragment length polymorphism (RFLP). We carried out molecular cloning of four retroviral fragments among their endogenous retrovirus genomes. The four retroviruses were named SY-1, SY-2, SY-3 and SY-4, respectively. A single copy of SY-1, 2 and 3 was integrated in human genome, whereas multi-copies of SY-4 were integrated. In sequence comparison, all of the four retroviruses were homologous with ERV3 pol-env region. SY-1 was located only on Y chromosome, and had the homologous sequence with human endogenous retrovirus NP-2 on Y chromosome. The flanking sequence of SY-1 as well as NP-2 might have an important role on investigating the origin and differentiation of Y chromosome. SY-2 was homologous with the endogenous retroviruses of not only primates but lower mammals such as mouse. It is suggested that SY-2 might be integrated into mammalian genome in early stage of evolutional process. SY-3 was a fragments of endogenous retrovirus, containing a sequence having homologies to U3 small nuclear RNA and other moderately repetitive sequences within the envelope region. SY-3 existed only in the genomes of human and rhesus monkey, but not in those of lower mammals.

Animals↗
PubMed1993

[Elution of lead and cadmium from imported gold-decorated glassware].

Lead and cadmium were known to be eluted from some imported gold-decorated glassware, which was bonded at a quarantine station. Elution of lead and cadmium was confirmed to be occurred from the gold-decorated portion, but not from glass itself. No elution of these heavy metals was observed from gold-decorated glassware in the market.

Cadmium↗
PubMed1993

Relation between exercise and absenteeism due to illness and injury in manufacturing companies in Japan.

The relation between exercise and absenteeism due to illness and injury was assessed in 21,924 male workers. Exercisers I (engaging in exercise less than once a week), II (once or twice a week), and III (more than three times a week) had a significantly lower incidence of absence than nonexercisers. The proportion of cases of absence in exercisers I, II, and III was 10%, 10%, and 14% lower, respectively, than that of nonexercisers. The number of days absent among exercisers I, II, and III was 48%, 43%, and 26% lower, respectively, than among nonexercisers. Controlling for confounding factors by logistic analysis, significantly reduced relative risk of absence persisted among exercisers I, II, and III versus nonexercisers at 0.88, 0.90, and 0.87, respectively. These findings indicate that worker exercise was associated with absence due to illness and injury.

Absenteeism↗
PubMed1992

DNA cleavage by hydroxyl radicals generated in a vanadyl ion-hydrogen peroxide system.

Vanadyl ion (+4 oxidation state) has been shown to be an effective agent for chemoprotection of cancers in animals. For understanding the mechanism, distribution of vanadium was studied. More vanadium was found to accumulate in the nuclei of the liver of rats when it was given as vanadyl sulfate than when it was given as sodium vanadate (+5 oxidation state). The reactivity of vanadyl ion with DNA was investigated by the DNA cleavage technique and the reaction mechanism by ESR spectroscopy. Incubation of double-strand DNA with vanadyl ion and hydrogen peroxide resulted in marked concentration- and pH-dependent DNA cleavage. Studies by the ESR spin-trap method demonstrated that hydroxyl radicals are generated during the reactions of vanadyl ion with hydrogen peroxide. Thus the antineoplastic action of vanadyl ion is proposed to be due to DNA cleavage by hydroxyl radicals generated in the cells.

Animals↗
PubMed1992

A rat model of human T lymphocyte virus type I (HTLV-I) infection. 1. Humoral antibody response, provirus integration, and HTLV-I-associated myelopathy/tropical spastic paraparesis-like myelopathy in seronegative HTLV-I carrier rats.

Human T lymphocyte virus type I (HTLV-I) can be transmitted into several inbred strains of newborn and adult rats by inoculating newly established HTLV-I-immortalized rat T cell lines or the human T cell line MT-2. The transmission efficiency exceeds 80%, regardless of strain differences or the age at transmission. The production of anti-HTLV-I antibodies significantly differs among the strains and depends on the age at the time of transmission. Rats neonatally inoculated with HTLV-I-positive rat or human cells generally become seronegative HTLV-I carriers throughout their lives, whereas adult rats inoculated with HTLV-I-positive cells at 16 wk of age become seropositive HTLV-I carriers. The HTLV-I provirus genome is present in almost all organs, regardless of whether the carriers are seronegative or seropositive. According to antibody titers to HTLV-I, there are three groups of inbred rat strains: ACI, F344, and SDJ (high responders); WKA, BUF, and LEJ (intermediate responders); and LEW (low responder). Three of three 16-mo-old seronegative HTLV-I carrier rats of the WKA strain developed spastic paraparesis of the hind legs. Neuropathological examinations revealed that the lesions were confined primarily to the lateral and anterior funiculi of the spinal cord. Both myelin and axons were extensively damaged in a symmetrical fashion, and infiltration with massive foamy macrophages was evident. The most severe lesions were at levels of the thoracic cord and continued from the cervical to the lumbar area. These histopathological features as well as clinical symptoms largely parallel findings in humans with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). These HTLV-I carrier rats, in particular the WKA rats described above, can serve as a useful animal model for investigating virus-host interactions in the etiopathogenesis of HTLV-I-related immunological diseases, particularly HAM/TSP.

Aging↗
PubMed1992

Copper-metallothionein induction in the liver of LEC rats.

Recently, copper (Cu) was found to be unusually accumulated, suggesting the induction of metallothionein (MT) in the liver of LEC rats (Long-Evans rats with a cinnamon-like coat color), which develop spontaneous jaundice with hereditary hepatitis. Thus, the direct relationship between the unusual Cu accumulation and the induction of Cu-MT was investigated by giving LEC rats Cu-overloaded or Cu-deficient diets. Results based on the determinations of Cu and MT levels in several organs, as well as the gel-filtration profiles of the cytosols of liver homogenates, showed that dietary Cu induced Cu-MT and development of hepatic injury associated with jaundice.

Animals↗
PubMed1992

Unusual accumulation of copper related to induction of metallothionein in the liver of LEC rats.

Copper (Cu), iron (Fe), zinc (Zn) and manganese (Mn) levels in organs of LEC rats (Long-Evans rats with a cinnamon-like coat color), which develop spontaneous jaundice with hereditary hepatitis, were determined by instrumental neutron activation analysis method. Unusual accumulations of Cu in the liver of LEC rats were found, depending on the age of the animals, the metal concentration being more than approximately 20-40 times those of normal LEA rats (Long-Evans rats with an agouti coat color). Fe and Zn were also accumulated, in addition to Cu, significantly in the LEC rats. The unusual Cu accumulations in the liver of LEC rats were associated with the induction of metallothionein, estimated by radioimmunoassay method, in the liver of LEC rats, rather than that of superoxide dismutase, estimated by electron spin resonance -spin trapping method. These findings suggest that the unusual Cu accumulation in LEC rats is involved in the development of jaundice, hepatic injury and hepatocellular carcinoma.

Aging↗