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Biomedical subjects

T Hirata

Publications and source records attributed to T Hirata.

At least 55 records · Page 3Linked to original sources
PubMed2001

Determination of the abundance of delta15N in nitrate ion in contaminated groundwater samples using an elemental analyzer coupled to a mass spectrometer.

A rapid method for measuring the delta15N of nitrate ion in water samples using an isotope ratio mass spectrometer coupled to an elemental analyzer system (EA-MS) was investigated. The water should be removed from the analytical sample before measurement with this system. We investigated the application of a super-absorbent polymer resin powder to various water samples. Each 1 mg of polymer resin powder can absorb about 50-100 mg of solution depending on the concentrations of major ions. Only samples which contain more than 100 mg l(-1) of nitrate-nitrogen are suitable to be absorbed by the polymer resin for the determination of delta15N of nitrate. Preconcentration by rotary evaporation was necessary for dilute samples but the temperature should be kept below 60 degrees C. The polymer resin (about 8 mg) containing the nitrate was directly analyzed using an EA-MS after being oven-dried at 80 degrees C. Good accuracy (precision +/- 0.3%) for delta15N measurements of nitrate-nitrogen in a sample without any isotope fractionation effects during pre-treatment was observed. Results for delta15N of nitrate in contaminated groundwater samples collected in the spring at a tea plantation area in Shizuoka, Japan, were from 9.8 to 10.6%, which were close to the delta15N abundance in organic fertilizers.

Mass Spectrometry↗
PubMed2001

Studies on polishing of Ti and Ag-Pd-Cu-Au alloy with five dental abrasives.

Titanium (Ti) and Ag-Pd-Cu-Au alloy were examined for their polishing behaviour by conducting manually controlled polishing tests using five dental abrasives [carborundum point (CR) and silicone points (R1 and R2)] driven by a high torque micromotor with rotational speeds ranging from 2000 to 15 000 r.p.m. Polishing of Ti resulted in less volume of removal upon polishing, a rougher surface and larger loss of abrasives, compared with polishing of Ag-Pd-Cu-Au alloy. Polishing of Ti with a rotational speed of 15 000 r.p.m. led to the largest volume of removal upon polishing, whilst that of 10 000 r.p.m. produced the optimal volume for Ag-Pd-Cu-Au alloy. It was concluded that Ti was much more difficult to polish, requiring special care (e.g. frequent exchange of abrasives). Development of new abrasives for polishing Ti is required.

Carbon Compounds, Inorganic↗
PubMed2001

A case of repetitive intrapleural cancer chemotherapy using INFUSE-A-PORT for malignant mesothelioma.

A 57-year-old man was diagnosed as having malignant pleural mesothelioma. We placed an implantable reservoir (INFUSE-A-PORT) into his pleural cavity to administer repetitive intrapleural chemotherapy. We administered intrapleural chemotherapy 7 times over a period of 10 months. The progression of the disease was very gradual; he could continue working during this time. INFUSE-A-PORT may be useful for repetitive intrapleural chemotherapy in outpatient treatment of malignant mesothelioma.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

Dynamic magnetic resonance imaging of femoral head perfusion in femoral neck fracture.

A prospective followup study of 36 femoral neck fractures according to the assessment of femoral head perfusion using dynamic magnetic resonance imaging is reported. Patients were divided into three groups based on the dynamic magnetic resonance imaging findings (dynamic curve pattern and relative enhancement ratio) that were conducted within 48 hours of the injury. Traction was used to achieve anatomic reduction and to prevent additional damage to vascularity until minimally invasive internal fixation could be done. The fractures of all 17 patients whose femoral head perfusion was normal (Type A; n = 11) or was impaired but not totally absent (Type B; n = 6) healed without complications. Among the 19 patients whose femoral head perfusion was absent (Type C), 15 had complications (osteonecrosis, n = 10; nonunion, n = 5). Assuming that fractures with a Type A or Type B curve pattern would unite successfully and that those with a Type C curve pattern would not, the sensitivity, specificity, and accuracy of the predictions of successful osteosynthesis of the femoral neck fractures using this method were 81%, 100%, and 89%, respectively. The current classification of femoral neck fractures using dynamic magnetic resonance imaging may be useful in selecting an appropriate treatment method for the fractures.

Adult↗
PubMed2001

[Clinical and bacteriological features of 12 cases of liver abscess caused by Streptococcus milleri group].

We described the clinical and bacteriological features of 12 cases of liver abscess caused by Streptococcus milleri group (SMG) during a 6-year period from 1993 to 1998. The gender was 11 males and 1 female with their ages ranging from 39 to 76 years old (mean: 53.4). The common symptoms were fever (100%), abdominal pain (67%), and appetite loss (58%). Nine cases had underlying diseases such as carcinomas and diabetes mellitus. Predominant causes of the liver abscess were cryptogenic (42%) and biliary tract disease (33%). Three patients died of an exacerbation of the carcinoma. Eight cases (67%) was single infection of SMG and no mixed infection with anaerobes. No strains isolated in this series showed resistance against penicillin G and ampicillin. SMG was highly isolated from the blood culture in eight of the 11 cases (73%). Liver abscess should be taken into consideration as one of the causes of SMG septicemia.

Adult↗
PubMed2001

Determination of pyrimidine dimers in Escherichia coli and Cryptosporidium parvum during UV light inactivation, photoreactivation, and dark repair.

UV inactivation, photoreactivation, and dark repair of Escherichia coli and Cryptosporidium parvum were investigated with the endonuclease sensitive site (ESS) assay, which can determine UV-induced pyrimidine dimers in the genomic DNA of microorganisms. In a 99.9% inactivation of E. coli, high correlation was observed between the dose of UV irradiation and the number of pyrimidine dimers induced in the DNA of E. coli. The colony-forming ability of E. coli also correlated highly with the number of pyrimidine dimers in the DNA, indicating that the ESS assay is comparable to the method conventionally used to measure colony-forming ability. When E. coli were exposed to fluorescent light after a 99.9% inactivation by UV irradiation, UV-induced pyrimidine dimers in the DNA were continuously repaired and the colony-forming ability recovered gradually. When kept in darkness after the UV inactivation, however, E. coli showed neither repair of pyrimidine dimers nor recovery of colony-forming ability. When C. parvum were exposed to fluorescent light after UV inactivation, UV-induced pyrimidine dimers in the DNA were continuously repaired, while no recovery of animal infectivity was observed. When kept in darkness after UV inactivation, C. parvum also showed no recovery of infectivity in spite of the repair of pyrimidine dimers. It was suggested, therefore, that the infectivity of C. parvum would not recover either by photoreactivation or by dark repair even after the repair of pyrimidine dimers in the genomic DNA.

Animals↗
PubMed2001

Eel urea transporter is localized to chloride cells and is salinity dependent.

Urea transporters (UTs) in the ureotelic vertebrates have been well-characterized, but little is known about those of the ammonotelic teleost fishes. To clarify the physiological roles of UTs in the ammonotelic teleosts, we determined the structure, tissue and cellular localizations, and regulation of expression of eel UT (eUT) by cDNA cloning, Northern analysis, and immunohistochemistry. A full-length cDNA (approximately 1.9 kb) coding for a UT of 486 amino acid residues was isolated from a seawater eel gill cDNA library. Sequence comparison with those of other species indicated that the eUT is a short isoform with 10 transmembrane spans and has longer NH2- and COOH-terminal cytoplasmic tails compared with the mammalian counterparts. Northern blot analysis demonstrated high expression of eUT mRNA confined in the gill and a substantial increase of its levels when eels were transferred from freshwater to seawater. Immunohistochemistry showed that eUT is localized on the basolateral membranes of the chloride cells, establishing, at the cellular level, the site of urea excretion in the eel, an ammonotelic teleost.

Amino Acid Sequence↗
PubMed2001

Addition of ATP and MgCl2 to the preservation solution attenuates lung reperfusion injury following cold ischemia.

BACKGROUND: In lung transplantation, reperfusion injury following cold ischemia is one of the crucial problems for recipients. OBJECTIVE: We evaluated the protective effect of adding a combination of ATP and MgCl2 to the preservation solution against lung reperfusion injury following cold ischemia. METHODS: Using an isolated rat lung perfusion model with fresh rat blood as the perfusate, the rats were divided into five groups (n = 6). In the fresh group, the study lungs were flushed with phosphate-buffered saline (PBS), then immediately reperfused for 120 min. In the control group, the study lungs were flushed with PBS, then cold ischemia was induced for 9 h (4 degrees C), after which reperfusion was performed. In the other three groups, the protocols were the same as for the control group except that ATP and/or MgCl2 were added to the PBS: ATP group (100 microM ATP), MgCl2 group (100 microM MgCl2) and ATP + MgCl2 group (100 microM ATP + 100 microM MgCl2). RESULTS: In the ATP + MgCl2 group, the intrapulmonary shunt fraction, peak airway pressure and wet to dry lung weight ratio were significantly lower than those in the control group. No improvement was observed in the ATP or MgCl2 groups. Histological examination supported these physiological results. In all groups, flush time and lipid peroxide levels in the lungs after cold ischemia did not show any significant differences. CONCLUSION: The addition of ATP and MgCl2 to the preservation solution attenuated reperfusion injury following cold ischemia in rat lungs.

Adenosine Triphosphate↗
PubMed2001

Adrenal insufficiency after incomplete resection of pituitary macrocorticotropinoma of Cushing's disease: role of high molecular weight ACTH.

A 15-year-old girl with Cushing's disease exhibited adrenal insufficiency following incomplete trans-sphenoidal resection of a large pituitary corticotropinoma, approximately 35 mm in diameter. Within two weeks following surgery, her plasma ACTH level decreased from 42 to 13 pmol/l, while, her plasma cortisol levels and urinary excretion of free cortisol decreased from 607 nmol/l and 1112 nmol/day to 94 nmol/l and 55 nmol/day, respectively. Immunoreactive ACTH was characterized in plasma using Sephadex G-75 column chromatography and measuring ACTH with immunoradiometric assay (IRMA) and radioimmunoassay (RIA) to determine additional peaks, other than the one demonstrated for 1-39 ACTH. In particular, when measured with RIA, a broad peak including the high molecular weight ACTH was detected as well as 1-39 ACTH. The bioactivity of the high molecular weight ACTH in patient plasma was lower than the reference range of 1-39 ACTH, which is determined by the ability of dispersed rat adrenocortical cells to secrete corticosterone. The large pituitary corticotropinoma found in this patient secreted not only 1-39 ACTH but also high molecular weight proopiomelanocortin (POMC)-derived peptides, which could be detected by measuring with IRMA and RIA for ACTH. Based on the results of biological activity and molecular ratios, no positive evidence could be found to support the hypothesis that the high molecular weight ACTH induced any postoperative adrenal insufficiency in this patient. However, based on this study, the possibility of adrenal insufficiency should be carefully monitored, even when post-operative remnant tumor tissue is clearly present in patients with Cushing's disease, accompanied by macrocorticotropinoma.

Adenoma↗
PubMed2001

Expression of E-cadherin and lymph node metastasis in resected non-small-cell lung cancer.

This study was conducted to clarify the relationship between E-cadherin expression on tumor and lymph node metastasis as well as its prognostic roles in resected non-small-cell lung cancer. Two hundred forty-nine patients, who underwent surgical resection (stage I-IIIA), were examined. Paraffin-embedded sections of the primary tumors in all cases and of the metastatic lymph nodes in stage IIIA disease were stained with a monoclonal antibody against E-cadherin. Decreased expression of E-cadherin correlated with pathologic stage, tumor size, lymph node metastasis, and histological grade. The 5-year survival rate of E-cadherin-negative patients with stage IIIA disease was significantly lower than that of E-cadherin-positive patients. Multivariate analysis in stage IIIA disease indicated that E-cadherin was an independent prognostic factor. In the patients with clinical N0 tumors, the frequency of pathological N2 tumors was significantly higher in cases where the primary tumor was recognized as E-cadherin expression negative than in cases where the primary tumor was recognized as positive. Decreased E-cadherin expression showed correlation with presence of lymph node metastasis in resected non-small-cell lung cancer and with the prognosis of patients with stage IIIA disease.

Journal Article↗
PubMed2001

[Prediction of the need for mechanical ventilation after transsternal thymectomy in patients with myasthenia gravis].

Between June 1992 and May 2000, transsternal extended thymectomy was performed for 70 patients with myasthenia gravis in our hospital. We were able to evaluate 64 of them in terms of prediction of the need for postoperative mechanical ventilation using the score systems reported by Leventhal et al., Kimura et al. and the criteria of Adachi et al.. For these systems, the rates of agreement between predictions and results were 85.9%, 82.8%, and 64.1%, respectively. The two former systems had some false negative cases (i.e., they predicted that ventilation would not be needed when in fact it was), but the last one gave no false negatives. We recommend Adachi's criteria for clinical safety. In our cases the patients whose value of %VC multiplied by FEV1.0% was less than 7,000 (Adachi's criterion is less in 8,300), especially, needed careful management with regard to respiratory crisis.

Adolescent↗
PubMed2001

The effect of temperature on the efficacy of ozonation for inactivating Cryptosporidium parvum oocysts.

Examination of the effects of water temperature on the inactivation of Cryptosporidium parvum oocysts with ozone, ozonation experiments were conducted in a semi-batch mode with a wide temperature range of 3-30 degrees C. Inactivation was assessed in terms of mice infectivity and in vitro excystation. The temperature dependency of the CT products by a reduction in infectivity of 2 log10 could be described successfully by the Arrhenius equation, 1/CT = 1.086 x 10(18)e-12520/K where CT is the integrated ozone concentration over the contact time (mg/min/L) and K is the Kelvin temperature of water. As for the reduction in viability assessed by the excystation assay, protocol B, the obtained regression equation, 1/CT = 1.802 x 10(18)e-12640/K, was almost identical to that observed for the infectivity. Thus, the CT products required for a 2 log10 reduction in both infectivity and viability increased by an average factor of 4.2 for every 10 degrees C decrease in water temperature. Additionally, our findings suggested that the viability, as determined by protocol B, could substitute for animal infectivity in evaluating the effects of environmental factors on the efficacy of ozonation.

Animals↗
PubMed2001

Occurrence of Cryptosporidium oocysts and Giardia cysts in a conventional water purification plant.

A one-year monitoring of Cryptosporidium oocysts and Giardia cysts was conducted at a water purification plant. A total of thirteen 50 L samples of river source water and twenty-six 2,000 L samples of filtered water (treated by coagulation-flocculation, sedimentation and rapid filtration) were concentrated using a hollow fibre ultrafiltration membrane module at a purification plant. Cryptosporidium oocysts were detected in all raw water samples with a geometric mean concentration of 400 oocysts/m3 (range 160-1,500 oocysts/m3). Giardia cysts were detected in 12/13 raw waters (92%) with a geometric mean concentration of 170 cysts/m3 (range 40-580 oocysts/m3). Probability distributions of both Cryptosporidium oocysts and Giardia cyst concentration in raw water were nearly log-normal. In filtered water samples, Cryptosporidium oocysts were detected in 9/26 samples (35%) with a geometric mean concentration of 1.2 oocysts/m3 (range 0.5-8 oocysts/m3) and Giardia cysts in three samples (12%) with 0.8 cysts/m3 (range 0.5-2 oocysts/m3). The estimated removal of Cryptosporidium oocysts and Giardia cysts was, respectively, 2.54 log 10 and 2.53 log10 on the basis of geometric means, 3.20 and 3.57 log10 on the basis of 50% observation level and 2.70 and 2.90 log10 on the basis of 90% observation level.

Animals↗
PubMed2001

[Anterior chest wall reconstruction with myocutaneous flap after open drainage for infectious bulla and empyema following T4 lung cancer resection via anterior approach].

A 48-year-old man with T4 lung cancer underwent resection of the right upper lobe, chest wall, and superior vena cava, and reconstruction of the last 2 tissues via anterior approach after induction chemo-radiotherapy. However, a bulla in the apical segment of the lower lobe divided by stapling was infected after the operation, and open drainage through the anterior chest wall was mandatory due to massive air leak and spread of infection to the pleural space. As the incision were fortunately restricted in the anterior chest, he could undergo successful reconstruction of a full-thickness defect of the anterior chest wall using a serratus anterior muscle flap and a myocutaneous flap of lattissimus dorsi with minimum rib resection after 2 months. He has in regular work with a small limitation of raising the right upper extremitus these 7 years.

Carcinoma, Large Cell↗
PubMed2001

Comparison of changes in hemodynamics between unilateral and bilateral lung volume reduction for pulmonary emphysema.

This study was aimed to compare changes in hemodynamics between unilateral (UL) or simultaneous bilateral (BL) lung volume reduction surgery (LVRS) for chronic obstructive lung disease. Sixteen patients underwent LVRS by stapler resection with neodymium: yttrium-alminum-garnet (Nd: YAG) laser ablation; five underwent BL-LVRS (four by median sternotomy and one by thoracoscopy) and 11 underwent UL-LVRS by thoracoscopy. Four patients had multiple bullae within pulmonary emphysema. At preoperation and 6, 12, 24, and 48 hours postoperatively, hemodynamics and right ventricular performance were evaluated. UL- and BL-LVRS reduced afterload of the right and left ventricle postoperatively. Although the pulmonary arterial resistance increased after surgery, the total pulmonary resistance decreased (p=0.001) in association with the reduced systemic vascular resistance (p=0.001). These reductions improved cardiopulmonary circulation, resulting in increased stroke volume and cardiac output (p=0.003). The right ventricular ejection fraction showed minimal change 48 hours postoperation. Two patients died of pneumonia caused by persistent air leakage. In conclusion, both the UL- and BL-LVRS showed similar effectiveness in terms of improvement in the systemic and cardiopulmonary circulation after LVRS, if there were no postoperative complications. We concluded that we had to reduce and repair the persistent air leakage after LVRS.

Aged↗
PubMed2000

P-Selectin glycoprotein ligand 1 (PSGL-1) is a physiological ligand for E-selectin in mediating T helper 1 lymphocyte migration.

P-selectin glycoprotein ligand 1 (PSGL-1) is a sialomucin expressed on leukocytes that mediates neutrophil rolling on the vascular endothelium. Here, the role of PSGL-1 in mediating lymphocyte migration was studied using mice lacking PSGL-1. In a contact hypersensitivity model, the infiltration of CD4(+) T lymphocytes into the inflamed skin was reduced in PSGL-1-deficient mice. In vitro-generated T helper (Th)1 cells from PSGL-1-deficient mice did not bind to P-selectin and migrated less efficiently into the inflamed skin than wild-type Th1 cells. To assess the role of PSGL-1 in P- or E-selectin-mediated migration of Th1 cells, the cells were injected into E- or P-selectin-deficient mice. PSGL-1-deficient Th1 cells did not migrate into the inflamed skin of E-selectin-deficient mice, indicating that PSGL-1 on Th1 cells is the sole ligand for P-selectin in vivo. In contrast, PSGL-1-deficient Th1 cells migrated into the inflamed skin of P-selectin-deficient mice, although less efficiently than wild-type Th1 cells. This E-selectin-mediated migration of PSGL-1-deficient or wild-type Th1 cells was not altered by injecting a blocking antibody to L-selectin. These data provide evidence that PSGL-1 on Th1 cells functions as one of the E-selectin ligands in vivo.

Adjuvants, Immunologic↗
PubMed2000

Neocortical origin and tangential migration of guidepost neurons in the lateral olfactory tract.

The early-generated neurons designated as lot cells specifically mark the future site of the lateral olfactory tract (LOT) and guide LOT axons. We investigated the mechanism of how lot cells develop and get localized in the LOT position. Lot cells differentiated from neuroepithelial cells in all regions of the neocortex but not from those in the ganglionic eminence in culture. Cell tracing analyses demonstrated that lot cells generated from the neocortex subsequently followed a tangential migration stream ventrally toward the LOT position. Mutant mouse embryos lacking the function of transcription factor Gli3 showed disturbances of the migration stream and translocation of lot cells in the dorsal telencephalon. These results reveal a new type of neuronal migration in the telencephalon and introduce an unexpected dramatic feature of the earliest regionalization of the telencephalon.

Animals↗