Search PubMed⌕ Search

Biomedical subjects

H Hata

Publications and source records attributed to H Hata.

At least 199 records · Page 11Linked to original sources
PubMed1989

Ketopantoyl lactone reductase is a conjugated polyketone reductase.

Ketopantoyl lactone reductase (EC 1.1.1.168) of Saccharomyces cerevisiae was found to catalyze the reduction of a variety of natural and unnatural conjugated polyketone compounds and quinones, such as isatin, ninhydrin, camphorquinone and beta-naphthoquinone in the presence of NADPH. 5-Bromoisatin is the best substrate for the enzyme (Km = 3.1 mM; Vmax = 650 mumol/min/mg). The enzyme is inhibited by quercetin, and several polyketones. These results suggest that ketopantoyl lactone reductase is a carbonyl reductase which specifically catalyzes the reduction of conjugated polyketones.

Alcohol Oxidoreductases↗
PubMed1989

Sister chromatid exchange analysis in lymphocytes of workers exposed to hexavalent chromium.

To investigate the usefulness of sister chromatid exchange (SCE) analysis in lymphocytes as an indicator for mutagenic effects after in vivo exposure to hexavalent chromium (Cr), SCE frequency was analysed in lymphocytes of 44 Cr platers occupationally exposed to hexavalent Cr and 47 controls. Although urinary Cr analysis confirmed that the Cr platers were exposed to Cr, no effects of the exposure on SCE frequency were found. Smokers, both Cr platers and controls, had a significantly higher SCE frequency than non-smokers. These results suggest that SCE analysis in human lymphocytes is not a good indicator of possible mutagenic effects of exposure to hexavalent Cr.

Adult↗
PubMed1989

Phagocytic multiple myeloma with disseminated intravascular coagulation.

We describe an atypical case of IgG lambda multiple myeloma in a 28-year-old patient. He developed multiple cutaneous plasmacytomas, and the terminal event, leukemic conversion by phagocytic plasma cells and disseminated intravascular coagulation. Secretion of monoclonal immunoglobulin (IgG lambda) from myeloma cells was demonstrated by plaque-forming cell assay. Electron microscopy showed myeloma cells with well-developed rough endoplasmic reticulum and erythroid cells or platelets in intracytoplasmic vacuoles.

Adult↗
PubMed1989

[Clinical evaluation of low viscosity composite resin].

This study was to evaluate clinically low viscosity composite resin. The subjects of the present study were 121 children aged 2 to 10 years who visited the Pedodontic clinic of Tohoku University Dental Hospital and 53 children aged 2 to 8 years who visited the clinic of the general practitioners in Sendai. A total of 451 cavities (343 at the clinic of the University Hospital, 108 at the clinic of the general practitioners) were treated with Clearfil SC-II (Kuraray). The observation period varied from 1 month to 33 months after treatment. The restorations were examined with regard to spacing or stepped abrasion in the marginal region of the fillings, fracture, loss, attrition and discoloration of the fillings, and recurrent caries and/or pulpal involvement of the treated teeth. The following findings were obtained. 1) The restoration cases treated at the clinic of the University Hospital were evaluated as clinically acceptable in 254 cases (74.1%), while those treated at the clinic of the general practitioners in 76 cases (70.4%). 2) Of the 343 restorations treated at the clinic of the University Hospital, 73 (21.3%) exhibited poor restorative conditions, while of the 108 restorations treated at the clinic of the general practitioners, 15 (13.9%) showed such conditions. 3) The incidences of poor restorative conditions for anterior restorations were 39.7% and 8.3% respectively at the clinics of the University Hospital and general practitioners. 4) The incidences of poor restorative conditions for posterior restoration were 16.9% and 17.7% respectively at the clinics of the University Hospital and general practitioners. 5) Among the poor restorative conditions, the spacing or stepped abrasion and recurrent caries in the marginal region of the restorations occurred more frequently. 6) The incidences of spacing or stepped abrasion and recurrent caries in the marginal region of the restorations increased in the cases of class II and III cavities.

Child↗
PubMed1989

[Responsiveness and mechanisms of action of steroid hormones in human endometrial adenocarcinoma cells].

The responsiveness and action mechanisms of steroid hormones and epidermal growth factor on human endometrial carcinoma cells are analyzed by using in vitro culture system. 1) The Ishikawa cells, derived from a well differentiated endometrial adenocarcinoma and possess ER and PR, are shown to respond to estrogens by increasing a variety of parameters, viz cell proliferation, PR levels, ALP and DNA polymerase activities. 2) ER and PR of those cells are localized in the nuclei by immunocytochemical staining using the monoclonal antibodies against to ER and PR, confirming the correctness of Gorski and Greene's one step theory involving the action mechanisms of steroid hormones. 3) Progestins reduced the ER level and stimulate E2DH activities and glycogen content, which are completely abolished by anti-progestin (RU486), suggesting that PR of those cells should be functional. 4) These responses to steroid hormones of Ishikawa cells are synergistically enhanced or appeared earlier by addition of EGF. 5) The main metabolite of E2 incubated with Ishikawa cells is E2-3-sulfate instead of E1, indicate that the higher estrogenic status may be persisted in endometrial cancer tissues.

Adenocarcinoma↗
PubMed1989

[Mechanical characteristics of ultrasonic device for root canal treatment].

Recently, many studies have demonstrated the superiority of the ultrasonic devices in endodontic treatment, while other reports did not recognize the advantage of the ultrasonic instrumentation over hand instrumentation. This disagreement in opinion might be due to the fact that the mechanical characteristics of ultrasonic devices have not been clarified. Therefore, some factors which might contribute to the mechanical characteristics of ultrasonic device for root canal treatment were examined. These factors were: (a) applied force on file; (b) angle of connector; (c) position of substrate material being cut; (d) filing speed; and (e) resonance of file. These factors were examined by measuring the cutting depth on acrylic wafer using the cutting efficiency testing apparatus. This apparatus with a push-pull stroke approximately 4 mm in length, was propelled the root canal instruments in linear motion. The filing speed was adjusted to 100 strokes per minute. The results were as follows: 1. The greater load was given to the file, the higher was the cutting ability of ultrasonic device. But cutting efficiency of #15, #25 and #35 files were inhibited over the load of 50, 60 and 70g each. It was considered that the adequate load for filing utilized ultrasonic device was #15:50g, #25:60g and #35:70g. 2. The file attached to the angled connector had a cantilevered vibration. And the cutting ability was effected by connector angle. The 120 degree-type connector was more effective than straight type (180 degree-type connector). 3. Substrate materials were made deeper cut when it was applied against the vibrating direction of the file than were applied at right angle to vibrating direction of the file. 4. Cutting efficacy of ultrasonic device was evaluated under the conditions as filing speed of 25, 50 and 100 strokes/min by comparing each ratio of cutting depth per total number of filing strokes after 20 minutes. The ultrasonic vibration showed tighter cutting ability when this ultrasonic device was operated 25 strokes/min. 5. Cutting efficiency of two methods was examined under the same amplitude. One was to set up the file length slightly shifted from the resonance point and to give the amplitude to file using resonance phenomenon. The other was to set up the file length of nonresonance condition and to give the amplitude by power supplying from the device. The latter showed higher cutting ability without the risk of the file fracture.(ABSTRACT TRUNCATED AT 400 WORDS)

Equipment Design↗
PubMed1989

Susceptibility of inbred mice to Paragonimus miyazakii infection.

Differences in the susceptibility among inbred strains of mice to Paragonimus miyazakii infection were examined. Recovery of worms varied among the strains used. More were recovered from BALB/c mice than from any of the other strains; whereas, the fewest were recovered from C57BL/6 and C57BL/10. No worm formed a cyst in the lung or matured in any of the strains.

Animals↗
PubMed1989

[Mechanism of action of endocrine therapy of endometrial carcinoma].

The mechanism of action of sex steroid hormones on endometrial carcinoma was analyzed by a cell culture system. 1) Estrogenic actions such as enhancement of ALP activity, PR level and cellular growth were confirmed in Ishikawa endometrial carcinoma cells which possess ER. 2) ER and PR are both localized immunocytochemically in the nuclei of Ishikawa cells, confirming the correctness of Gorsky and Greene's theory in endometrial carcinoma. 3) In Ishikawa cells with PR, progestins stimulated E2DH activity and glycogen synthesis and reduced ER level, thus proving the existence of their hormonal action. We cannot, however, rule out the pharmaceutical action of progestin, because a decrease in nucleic acid syntheses and ALP activity, alteration in electron microscopic observation and finally cellular death were observed in endometrial cancer cells without PR. 4) Conversely, Tamoxifen, anti-estrogen, stimulated the cellular growth in serum-free environment of culture. We must therefore be careful in using it clinically.

Adenocarcinoma↗
PubMed1989

[Late results after heart valve surgery in the elderly].

Heart valve surgery was performed in 133 patients over the age of 60 between 1976 and 1981. There were 54 men and 79 women. Their ages ranged from 60 to 74 years (mean age 64.3 years). In this study, 54 valve prostheses (15 porcine and 39 mechanical) in the aortic position, 79 prostheses (69 porcine and 10 mechanical) in the mitral position and 3 prostheses (3 porcine) in the tricuspid position were implanted in 121 patients. Fifteen patients (11.3%) died in the hospital. The hospital mortality was high in the cases of MVR (14.6%), MVR + TAP (12.5%) and emergency (50%). The mean follow-up was 37.2 months (range 4 to 129 months, total 367.3 patient-years). There were 10 late deaths (8.5%). Actuarial survival for hospital survivors at 5 years was 89.2 per cent. At follow-up, 95.8% of the surviving patients were in New York Heart Association functional class I or II. Valve-related complications were thromboembolism (2.0% pt/year), periprosthetic leak (1.7% pt/year), primary tissue failure (0.5% pt/year) and thrombosed valve (0.3% pt/year). Anticoagulant-related hemorrhage necessitating hospitalization occurred in 2 patients (1.0% pt/year). The freedom from all events at 5 years was 72.8 per cent. This study suggests that heart valve surgery in the elderly can be performed with an acceptable mortality. Advanced age alone should not be a contraindication to surgical management.

Aged↗
PubMed1988

Ectopic production of salivary-type amylase by a IgA-lambda-type multiple myeloma.

A patient with IgA-lambda-type multiple myeloma who appeared to be secreting salivary-type amylase ectopically is reported. Both the patient's serum and urine contained high levels of amylase. Amylase activity in the supernatant of cultured myeloma cells, obtained from the patient's pleural effusion while he had malignant pleuritis, increased almost linearly from the time of cell seeding. The presence of IgA and S-type amylase in the myeloma cells was demonstrated cytochemically and by immunoelectron microscopy. These observations showed that amylase was produced by these human myeloma cells.

Amylases↗
PubMed1988

A novel fungal enzyme, NADPH-dependent carbonyl reductase, showing high specificity to conjugated polyketones. Purification and characterization.

A novel enzyme which specifically catalyzes the reduction of conjugated polyketones was purified to homogeneity from cells of Mucor ambiguus AKU 3006. The enzyme has a strict requirement for NADPH and irreversibly reduces a number of quinones such as p-benzoquinone, alpha-naphthoquinone and acenaphthenequione. The enzyme also reduces polyketones such as isatin and ketopantoyl lactone, and their derivatives. The apparent Km values for isatin and ketopantoyl lactone are 49.9 microM and 714 microM, respectively. The reduction of ketopantoyl lactone proceeds stereospecifically to yield L-(+)-pantoyl lactone. The pro-S (A) hydrogen at C-4 of NADPH is transferred to the substrate. The enzyme is not a flavoprotein and consists of two polypeptide chains with an identical relative molecular mass of 27,500. Quercetin, dicoumarol and some SH reagents inhibit the enzyme activity. 3-Methyl-1,2-cyclopentanedione and 1,3-cyclohexanedione are uncompetitive inhibitors with Ki values of 80.9 microM and 64.5 microM, respectively, to ketopantoyl lactone.

4-Butyrolactone↗
PubMed1988

Involvement of spinal alpha adrenoceptors in mediation of the hypotensive action of guanabenz in rats.

The effects of intrathecal, intracisternal and intravenous injections of yohimbine (10 micrograms) on hypotensive and bradycardic responses to the alpha agonist guanabenz (10 micrograms/kg, i.v.) were studied in anesthetized rats. The depressor response to guanabenz was inhibited by intrathecal pretreatment with yohimbine, while this pretreatment did not affect the bradycardic response to guanabenz. Intracisternal pretreatment with yohimbine inhibited both cardiovascular responses to guanabenz, whereas intravenous pretreatment with yohimbine affected neither. Guanabenz (1 microgram) decreased blood pressure when injected intrathecally but did not affect it when injected intravenously. These results suggest that in rats spinal alpha adrenoceptors are involved in mediation of the hypotensive action of the alpha agonist guanabenz injected systemically.

Animals↗
PubMed1988

Comparison of compact colony-forming activity and paracoagulation activity of strains of Staphylococcus aureus in serum and plasmas of various animals.

Using 20 strains of Staphylococcus aureus isolated from clinical specimens, the compact colony-forming activity (CCFA) in serum-soft agar (SSA) in sera from various animals and the paracoagulation (PC) activity of the compact colony-forming active substance (CCFAS) extracted from these strains were investigated. The results of this comparative study revealed that the CCFA and PC of S. aureus for sera from various animals in SSA were different, not only among different strains but also in the same strains. In addition, the effect of galactose and calcium ions on the PC activity of these strains in experiments employing human fibrinogen permitted the recognition of these groups of S. aureus strains. In one group, PC activity was decreased by galactose but unaffected by calcium ions, in the second group PC activity was unaffected by galactose but increased by calcium ions, while in the third group it was unaffected by both. These results suggest the possibility of heterogeneity of CCFA among different strains of S. aureus.

Animals↗
PubMed1988

Schistosoma japonicum and Paragonimus ohirai: antagonism between S. japonicum and P. ohirai in Oncomelania nosophora.

Antagonistic interactions between Schistosoma japonicum and Paragonimus ohirai were examined in the snail host, Oncomelania nosophora. When P. ohirai-infected snails were exposed to S. japonicum miracidia at intervals of 4 to 18 weeks post-first exposure, only a few snails (0-7%) were found to be superinfected with S. japonicum sporocysts. Sporocysts were fewer in number than those of single infected controls. Mature S. japonicum cercariae were not observed. Furthermore, when the snails were examined at intervals of 14 to 18 weeks post-second exposure, neither sporocysts nor cercariae of S. japonicum were found. On the other hand, when the snails were exposed to miracidia of S. japonicum and P. ohirai simultaneously, they were easily infected with both parasites. At 26 weeks after simultaneous exposure, however, the infection rate of S. japonicum was significantly lower than that of controls. In contrast, when S. japonicum-infected snails were exposed to P. ohirai miracidia, they were superinfected with P. ohirai, although the infection rate was somewhat lower than that of controls. These results indicate the existence of antagonism between S. japonicum and P. ohirai in O. nosophora. Furthermore, P. ohirai was dominant over S. japonicum in the antagonistic interactions in this snail host.

Animals↗
PubMed1988

Epidemiologic studies on schistosomiasis japonica in a newly found habitat of Oncomelania snails in Japan.

Epidemiologic studies' on schistosomiasis japonica were carried out in the Obitsu River basin of central Boso Peninsula, a newly found habitat of Oncomelania snails in Japan. Forty-five (4.1%) of 1,102 schoolchildren and 64 (10.4%) of 618 junior high school students were positive for the skin test with veronal buffered saline-extracted Schistosoma japonicum antigen. None was positive by the enzyme-linked immunosorbent assay, complement fixation test, double diffusion test in agar, and circumoval precipitin test. About one fifth of 356 adult inhabitants showed positive reactions in the enzyme-linked immunosorbent assay and complement fixation test as well as in the skin test, although only 25 individuals (7%) were positive for the circumoval precipitin test. All of 70 individuals who had shown positive reactions in at least two of the immunological tests were negative for a series of 5 stool examinations with the AMS III method. Release of S.japonicum cercariae was not observed in 15,000 O. hupensis nosophora collected in this area. Repeated examinations by dipping mice into irrigation ditches were negative. These observations, with the fact that all of 15 patients reported from nearby hospitals to have schistosome eggs in their tissues were over 45 years old, suggest that schistosomiasis has become a disease of the past in this area.

Adolescent↗
PubMed1988

Establishment and characterization of an amylase-producing human myeloma cell line.

Two stable lines of IgA lambda-producing plasma cells (KHM-1A and KHM-1B) that were free of the Epstein-Barr virus were established from a patient with multiple myeloma complicated by hyperamylasemia. Surface marker studies of the two cell lines showed that the cells had no surface immunoglobulins but were positive for cytoplasmic immunoglobulins (IgA lambda) and for HLA-DR and PCA-1. Secretion of IgA monoclonal immunoglobulin by the two lines was detected by a plaque-forming cell assay and by an enzyme-linked immunosorbent assay of culture media. KHM-1B cells also secreted alpha-amylase, but no such activity was detected in the culture-conditioned supernatant fluid of KHM-1A.

Amylases↗