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N Hamada

Publications and source records attributed to N Hamada.

At least 91 records · Page 5Linked to original sources
PubMed1997

Thromboxane A2, released by the anti-tumour drug irinotecan, is a novel stimulator of Cl- secretion in isolated rat colon.

1. A camptothecin derivative, irinotecan (Cpt-11), is a topoisomerase I inhibitor and has a strong activity against a broad range of human cancer. One of the side-effects of this drug is diarrhoea. Here, we tried to determine the mediator of the irinotecan-induced Cl- secretion which may underlie this diarrhoea, using isolated mucosae of rat distal colon. 2. Irinotecan increased Cl- secretory current in a concentration-dependent manner across the mucosa, set between Ussing chambers. Thromboxane A2 (TXA2) has not been reported to date as a physiological stimulant of Cl- secretion in the distal colon. However, the major part of the present irinotecan-induced current was inhibited by selective thromboxane A2 receptor antagonists (KW-3635 and ONO-3708), and a selective thromboxane synthase inhibitor (Y-20811). In fact, we found that irinotecan stimulated the release of TXA2 in a concentration-dependent manner from the isolated mucosa into the bathing solutions. 3. Furthermore, 9,11-epithio-11,12-methano-thromboxane A2 (STA2), a stable analogue of TXA2, induced Cl- secretion, which was almost completely inhibited by the TXA2 receptor antagonists. 4. In single cells of isolated crypts, STA2 depolarized the cell and increased the membrane conductance, indicating that STA2 opened the apical Cl- channel of the crypt cells. 5. We conclude, therefore, that the irinotecan-induced endogenous TXA2 is a novel stimulant of the Cl- secretion from the crypt cells of distal colon.

Animals↗
PubMed1997

Local muscimol disinhibits mesolimbic dopaminergic activity as examined by brain microdialysis and Fos immunohistochemistry.

Infusion of muscimol (5 X 10[-5] M, 60 min) into the nucleus accumbens (NAC) through a dialysis membrane caused a significant increase in extracellular dopamine (DA) and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC). Fos-like immunoreactivity induced by intra-NAC infusion of muscimol was seen ipsilaterally in many accumbofugal target areas, but no Fos-positive neurons were seen in the vicinity of the dialysis membrane in the NAC. Sequential staining of Fos and tyrosine hydroxylase (TH) immunoreactivities revealed that a portion of A10 dopaminergic neurons were double-labelled. These results suggest that muscimol in the NAC disinhibits mesolimbic DA neuronal activity possibly through activity of the accumbofugal GABA neuron system.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

High-performance liquid chromatographic separation of Porphyromonas gingivalis fimbriae.

Fimbriae are responsible for the adherence of many bacterial species to the surfaces they eventually colonize. Porphyromonas gingivalis is an important pathogenic agent involved in periodontal disease. Fimbriae of P. gingivalis have been thought to mediate binding of the bacterium to oral surfaces. In order to study the role of fimbriae in microbial adhesion, it is important to purify fimbriae to homogeneity. A simple and rapid reverse-phase high-performance liquid chromatography (HPLC) method is developed to purify P. gingivalis fimbriae. The crude fimbriae were precipitated from sonic extract of P. gingivalis cells with the 40% ammonium sulfate precipitation. The dialyzed crude fimbriae preparation was subjected to reverse-phase HPLC separation. The purity and size of purified fimbrial proteins were confirmed by SDS-polyacrylamide gel electrophoresis(SDS-PAGE) followed by Western immunoblot using polyclonal antibodies against fimbriae. The purified major fimbrial protein from strain 33277 of P. gingivalis had apparent molecular mass of 41 kDa. The method is useful for analytical as well as preparative purification with 25% yields from the ammonium sulfate-precipitated crude fimbriae preparation, and represents increased speed and efficiency over earlier published methods.

Bacterial Proteins↗
PubMed1997

Isolation and characterization of fimbriae from a sparsely fimbriated strain of Porphyromonas gingivalis.

Porphyromonas gingivalis W50 (ATCC 53978) possesses the gene for fimbriae; however, the surface-expressed fimbriae are sparse and have not been previously isolated and characterized. We purified fimbriae from strain W50 to homogeneity by ammonium sulfate precipitation and reverse-phase high-performance liquid chromatography [H. T. Sojar, N. Hamada, and R. J. Genco, Protein Expr. Purif. 9(1):49-52, 1997]. Negative staining of purified fimbriae viewed by electron microscopy revealed that the fimbriae were identical in diameter to fimbriae of other P. gingivalis strains, such as 2561, but were shorter in length. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, the apparent molecular weight of isolated fimbrillin from strain W50 was found to be identical to that of the fimbrillin molecule of strain 2561. Unlike 2561 fimbriae, W50 fimbriae, under reducing condition, exhibited a monomeric structure on SDS-PAGE at room temperature. However, under nonreduced conditions, even at 100 degrees C, no monomer was observed. In immunoblot analysis as well as immunogold labeling of isolated fimbriae, polyclonal antibodies against 2561 fimbriae, as well as antibodies against peptide I (V-V-M-A-N-T-G-A-M-E-V-G-K-T-L-A-E-V-K-Cys) and peptide J (A-L-T-T-E-L-T-A-E-N-Q-E-A-A-G-L-I-M-T-A-E-P-Cys), reacted. However, antifimbrial antibodies against strain 2561 reacted very weakly compared to anti-peptide I and anti-peptide J. Negative staining of whole W50 cells, as well as immunogold electron microscopy with anti-peptide I and anti-peptide J, showed fimbriae shorter in length and very few in number compared to those of strain 2561. Purified fimbriae showed no hemagglutinating activity. Amino acid composition was very similar to that of previously reported fimbriae of the 2561 strain.

Amino Acid Sequence↗
PubMed1997

A role for fimbriae in Porphyromonas gingivalis invasion of oral epithelial cells.

Isogenic mutants of Porphyromonas gingivalis which differ in the expression of fimbriae were used to examine the contribution of fimbriae in invasion of a human oral epithelial cell line (KB). At a multiplicity of infection of 100, the wild-type P. gingivalis strains 33277, 381, and A7436 exhibited adherence efficiencies of 5.5, 0.11, and 5.0%, respectively, and invasion efficiencies of 0.15, 0.03, and 0.10%, respectively. However, adherence to and invasion of KB cells was not detected with the P. gingivalis fimA mutants, DPG3 and MPG1. Adherence of P. gingivalis wild-type strains to KB cells was completely inhibited by the addition of hyperimmune sera raised to the major fimbriae. Examination by electron microscopy of invasion of epithelial cells by the P. gingivalis wild-type strain 381 revealed microvillus-like extensions around adherent bacteria; this was not observed with P. gingivalis fim mutants. Taken together, these results indicate that the P. gingivalis major fimbriae are required for adherence to and invasion of oral epithelial cells.

Antibodies, Blocking↗
PubMed1997

Retrohepatic cavoatrial shunt with a ringed polytetrafluoroethylene graft for the Budd-Chiari syndrome. A case report.

This report describes a patient with Budd-Chiari syndrome who was operated on successfully by means of shunt formation with polytetrafluoroethylene graft between the inferior vena cava (IVC) and right atrium. The patient is a sixty-two-year-old woman suffering from persistent edema of the lower limbs for four years. The examination disclosed complete obstruction of the IVC at the level of the diaphragm with a patent right inferior hepatic vein. Following the operation, edema of the limbs disappeared, hypersplenism improved, and the serum ammonium concentration decreased to the normal range. In conclusion, a retrohepatic cavoatrial shunt is feasible and useful in treating a patient with the Budd-Chiari syndrome who has patent major hepatic veins.

Blood Vessel Prosthesis↗
PubMed1997

Appearance of TSH receptor antibody and hyperthyroidism associated with metastatic thyroid cancer after total thyroidectomy.

We report here on a patient who was diagnosed with follicular carcinoma in 1985, and who was treated with total thyroidectomy. Two years later, when metastasis was found in his neck lesion, lung, pelvis and right femur, the patient received 131I treatment. Six years after receiving 131I treatment, the patient presented with hyperthyroidism. Whole-body scan with 131I revealed functioning metastasis in his right femur and pelvis. There was no hot spot in the neck region, confirming that no thyroid tissue remained. Blood panels revealed an increase in both TSH binding inhibitory immunoglobulin (TBII. 36.2%; normal. -10 approximately 10%) and thyroid stimulating antibody (TSAb, 176%; normal, less than 145%). Treatment with antithyroid drugs, dexamethasone and radioisotope therapy rapidly resolved his hyperthyroidism. Thyrotoxicosis and positive TRAb occurred in the absence of thyroid tissue, and many years after the completion of R1 therapy. The overproduction of thyroid hormone can therefore only be attributed to some mechanism of activity in the metastatic tumor tissue.

Adenocarcinoma, Follicular↗
PubMed1997

Risk factors for unsatisfactory intraocular pressure control in combined trabeculectomy and cataract surgery.

BACKGROUND AND OBJECTIVE: Trabeculectomy combined with posterior chamber intraocular lens (PC IOL) insertion is often chosen for the treatment of glaucoma combined with cataract. In this study, the clinical prognostic indicators for late intraocular pressure (IOP) control in combined procedures were investigated. PATIENTS AND METHODS: The clinical records of 60 eyes that underwent trabeculectomy combined with PC IOL implantation were retrospectively analyzed using the Cox proportional hazards model. All of the patients received postoperative 5-fluorouracil injections. RESULTS: Extracapsular cataract extraction (ECCE) was found to be a statistically significant risk factor for unsatisfactory late IOP control (hazard ratio 2.54; P < .01) and for unsatisfactory filtering bleb appearance (hazard ratio 5; P < .001). The frequency of fibrin formation and the incidence of a transient IOP spike (> or = 25 mm Hg) were significantly lower in the phacoemulsification and aspiration (PEA) group than in the ECCE group. In the PEA group, the probability of IOP control (< or = 15 mm Hg) without medication was 54%, and the probability of persistent filtering bleb appearance was 80% at 18 months. CONCLUSION: The PEA technique, not ECCE, should be employed in combined trabeculectomy and PC IOL implantation.

Aged↗
PubMed1997

[The outcome of adjusted accumulation dose of treatment of Graves' disease].

We evaluated the outcome of 131I treatment of Graves' disease in two different protocols (old and new protocol) of adjusted accumulation dose from 1988 to 1995. Adjusted accumulation doses of patients with above 50 g thyroid weights were increased by 5-20 Gy/g tissue in new protocol compared to those in old one. In 166 patients treated with single and plural doses of 131I treatment in 1990 (Group In), the therapeutic doses were calculated according to new protocol and in 130 patients in 1988 (Group Io), according to old one, modification of Quimby's formula. The patients treated with plural doses were classified as hyperthyroidism because the efficacies of the first treatments with 131I were insufficient. At the 5-yr follow up, the incidence of hypothyroid in Group In was 9%, subclinical hypothyroid 17%, euthyroid 30%, subclinical hyperthyroid 7%, hyperthyroid 37%. In Group Io, 11% of the patients were hypothyroid, 6% subclinical hypothyroid, 29% euthyroid, 3% subclinical hyperthyroid, 51% hyperthyroid. The incidence of hyperthyroid in Group In was lower than that in Group Io (p < 0.05). There were no significant differences in hypothyroid and euthyroid. In conclusion, we suggest that an adjusted dose of 131I in relation to the patients' thyroid weight shows some room for improvement.

Adult↗
PubMed1997

Expression of fas (CD95/APO-1) antigen induced by radiation therapy for diffuse B-cell lymphoma: immunohistochemical study.

Most malignant lymphomas show relatively high degrees of radiosensitivity, in which apoptosis has been shown to play an important role. Recently, the Fas (CD95/APO-1)/Fas ligand system has been identified as a key regulator of apoptosis in some types of lymphoma cell lines. In this study, we aimed to determine whether Fas antigen expression is induced by radiotherapy for malignant lymphoma and to clarify its possible correlation with the therapeutic effect of radiation therapy. Fifty-six patients with tumors of the tongue, oropharynx, and maxillary sinus were examined; four were confirmed as malignant lymphoma, and the rest were identified as squamous cell carcinoma. After obtaining the patients' informed consent, biopsies were performed before treatment and at doses of 4, 10, and 20 Gy of radiotherapy, and specimens were preserved in liquid nitrogen until further examination. Serial sectioning of 6 micrometer was performed using a cryostat, and samples were immunohistochemically stained using the streptoavidin-biotin peroxidase method and a monoclonal antibody against Fas. Two of the four patients with malignant lymphoma showed Fas antigen expression on their tumor tissue at 4 and 10 Gy of radiotherapy. These tumors showed high radiosensitivity and disappeared at a dose of 20 Gy of radiotherapy. In samples from these two patients, DNA ladder formation was identified at 10 Gy. In 52 squamous cell carcinomas, staining for the Fas antigen showed negative or only slightly positive results. However, in one of the cases of squamous cell carcinoma, lymphocytes infiltrating into cancer tissue showed Fas antigen expression at 4 Gy of irradiation, and these lymphocytes disappeared on the tumor tissue at 10 Gy. Therefore, the high radiosensitivity of malignant lymphoma among our samples could be explained by the overexpression of Fas antigen induced by small doses of radiation therapy, and Fas ligand could be produced by infiltrating lymphocytes or may be expressed simultaneously on the lymphoma cells.

Aged↗
PubMed1997

Immunohistochemical study of c-fos-positive lymphocytes infiltrated into human squamous cell carcinomas of the head and neck during radiation therapy and its clinical significance.

C-fos has been reported to be one of the immediate early genes in signal transduction systems after many kinds of stresses, including ionizing radiation. Changes in c-fos expression induced by radiation therapy in tumor tissues have not yet been reported. In this study, we have attempted to determine whether c-fos expression is induced by radiotherapy in human squamous cell carcinomas of the head and neck and to establish a possible correlation between c-fos expression and the therapeutic effects of radiation therapy. Twenty-seven patients with tumors of the oral cavity, oropharynx, and maxillary sinus were examined, all of which were confirmed as squamous cell carcinomas. After obtaining the patients' informed consent, biopsies were performed before treatment and at doses of 4, 10, and 20 Gy of radiotherapy, and the specimens were preserved in liquid nitrogen for further examination. Serial sectioning of 6 micrometer was performed using a cryostat, and samples were immunohistochemically stained using the streptoavidin-biotin peroxidase method and a monoclonal antibody against c-fos. Three of the 27 patients with squamous cell carcinoma showed slight expression of c-fos in their tumor cells before and/or at 4 or 10 Gy of radiotherapy. The tumors showed high radiosensitivity. Concerning tumor-infiltrating lymphocytes, the rate of moderate or remarkable grades of c-fos-positive lymphocytes before radiotherapy and at radiation doses of 4, 10, and 20 Gy was 8.0, 29.2, 4.8, and 0%, respectively. The relationship between the immunohistochemical findings and the antitumor effect at a radiation dose of 20 Gy was examined on the corresponding H&E-stained sections. In patients whose infiltration of c-fos-positive lymphocytes into tumor tissues were moderate or remarkable at 4 Gy of radiotherapy, the tumors responded significantly well to radiation therapy (P < 0.025, chi2 test), and the patients took a significantly favorable clinical course (P < 0.05, chi2 test). In a sample from one of the patients, c-fos-positive lymphocytes were identified as CD4 positive and CD8 negative. Therefore, the high radiosensitivity of squamous cell carcinomas in our samples could be explained by an overexpression of c-fos in the tumor-infiltrating lymphocytes induced by small doses of radiation therapy, and these activated lymphocytes exerted a cytotoxic effect against the cancer cells.

Adult↗
PubMed1996

In vivo effect of OPC15161, a superoxide scavenger, on anti-Thy1 nephritis.

The in vivo effect of 6-(1 H-indol-3-ylmethyl)-5-methoxy-3-(2-methylpropyl)-2(1 H)-pyrazinone, 4-oxide (OPC15161), a superoxide scavenger, was studied in rats with anti-Thy1 nephritis. Rats were divided into 4 groups: G-1, normal control; G-2, anti-Thy1 nephritis; G-3 anti-Thy1 nephritis and treated with OPC15161 (50 mg/kg/day) starting at day 0; and G-4, anti-Thy1 nephritis and treated with OPC15161 starting 3 days before antibody injection. At weeks 2 and 8, rats were killed for morphological study and at week 8 for renal clearance. Results were compared among the 4 groups. OPC15161 suppressed urinary albumin/day. Total glomerular cells, mesangial cells, ED-1-positive cells/glomerulus and glomerular volume all increased and the increases were suppressed by OPC15161. Tubulointerstitial index, assessed by point counting, was improved by OPC15161 (P < 0.05 G-3, 4, vs. G-2, not significant vs. G-1). Glomerular filtration rate decreased in all nephritic animals, but the decrease in renal blood flow was less in the treated groups. These findings indicate a favorable effect of OPC15161 on the glomerular and interstitial lesions of anti-Thy1 nephritis.

Albuminuria↗
PubMed1996

Intestinal neuromuscular function after preservation and transplantation.

While it is well known that prolonged preservation of the intestinal graft causes severe mucosal damage after transplantation, little is known about the effect on neuromuscular function. The entire small intestine of adult hound dogs was flushed and preserved with cold lactated Ringer's solution and autotransplanted either immediately (n = 6) or after 24 hr (n = 6). Animals undergoing sham operation (n = 4) were used as a control. Fasting motility and the response of the intestinal smooth muscle and enteric nerves to bethanechol (100 microg/kg/0.5 hr, iv) and cisapride (0.5 mg/kg, iv) were determined by a multiple strain gauge method on Postoperative Days 2,4,7,14,21, and 28. Compared to the control, immediately transplanted grafts and those preserved for 24 hr developed delayed reappearance of migrating myoelectric complexes (MMC), hypercontractile activity, and reduced response to bethanechol and cisapride administration. Animals in the preservation group developed more abnormal fasting motility after transplantation, but responses to bethanechol and cisapride stimulation were not markedly different from those of the immediate group. The reappearance of MMC occurred 3 weeks postoperatively in the preservation group compared to 2 days in the immediate group. The results of our study indicate that intestinal dysmotility is augmented in prolonged-preservation grafts compared to those with brief preservation. The dysmotility was transient and normalized 3 to 4 weeks after surgery. Preservation and reperfusion injury to the neuromuscular system of intestinal grafts are reversible and are attenuated by simple hypothermia.

Animals↗