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Biomedical subjects

R Suzuki

Publications and source records attributed to R Suzuki.

At least 397 records · Page 22Linked to original sources
PubMed1995

Electrophysiological effects of Ro 22-9194, a new antiarrhythmic agent, on guinea-pig ventricular cells.

1. Cardiac effects of Ro 22-9194 were examined in papillary muscles and single ventricular myocytes isolated from guinea-pigs and compared with those of moricizine. 2. In papillary muscles, both Ro 22-9194 (> or = 10 microM) and moricizine (> or = 1 microM) caused a significant dose-dependent decrease in the maximum upstroke velocity (Vmax) and a shortening of the action potential duration. 3. In the presence of either drug, trains of stimuli at rates > or = 0.2 Hz led to an exponential decline in Vmax. This use-dependent block was enhanced at higher stimulation frequencies. A time constant (tau R) for Vmax recovery from the use-dependent block was 9.3 s for Ro 22-9194 and 26.4 s for moricizine. 4. The curves relating membrane potential and Vmax in single myocytes were shifted by Ro 22-9194 (30 microM) or by moricizine (3 microM) in a hyperpolarizing direction by 8.4 mV and 8.0 mV respectively. 5. In myocytes treated with Ro 22-9194 (30 microM), a 10 ms conditioning clamp to 0 mV caused a significant decrease in Vmax of the subsequent test action potential; further prolongation of the clamp pulse duration resulted in a modest enhancement of the Vmax inhibition. In the presence of moricizine (3 microM), a similar conditioning clamp > 200 ms caused a significant Vmax reduction; the longer the clamp pulse duration, the greater the Vmax reduction. 6. Ro 22-9194 > or = 30 microM caused a slight decrease of calcium inward current (ICa) of myocytes without affecting the delayed rectifier potassium current (IK). 7. These findings suggest that the primary electrophysiological effect of Ro 22-9194 as an antiarrhythmicagent is, like moricizine, a use- and voltage-dependent inhibition of sodium channels. From the onset and offset kinetics of the use-dependent block, Ro 22-9194 belongs to the intermediate kinetic Class I drugs, while moricizine is a slow kinetic drug. From the state-dependence of sodium channel block, Ro 22-9194 may belong to activated channel blockers, while moricizine belongs to inactivated channel blockers.

Action Potentials↗
PubMed1995

Cerebral blood flow: measurement with xenon-enhanced dynamic helical CT.

PURPOSE: To improve CT number reproducibility in helical CT, a newly developed controlled-orbit helical scan mechanism was applied. The authors developed a method for volumetric measurement of cerebral blood flow (CBF) with dynamic helical computed tomography (CT) after inhalation of xenon gas. MATERIALS AND METHODS: In three subjects (two healthy men aged 22 and 38 years and a 7-year-old girl with moyamoya disease), six helical scans were obtained during 6-minute xenon inhalation, and CT scans with 41 sections in 2-mm increments were reconstructed from each scan. Conventional CBF calculation was then applied to the CT images. RESULTS: CBF maps of 40 sections for each subject of sufficient diagnostic quality were obtained with a 39-cGy radiation dose. The spatial resolution was 2.5 line pairs per centimeter. CONCLUSION: This volumetric CBF mapping method is applicable in clinical practice because of the short examination time and acceptable radiation dose.

Adult↗
PubMed1995

Selective induction of cell death in cancer cells by gallic acid.

Gallic acid (3,4,5-trihydroxybenzoic acid) is a naturally occurring plant phenol obtained by the hydrolysis of tannins and is know to show some pharmacological activities. In screening anti-cancer agents in traditional Chinese medicines, gallic acid was found to show cytotoxicity against all cancer cells that we examined in this study (IC50s: 4.8-13.2 micrograms/ml). Gallic acid was found to show cytotoxicity against primary cultured rat hepatocytes and macrophages, and lesser cytotoxicity against fibroblasts and endothelial cells. Cell death in dRLh-84 cells occurred within 6h after gallic acid treatment at a concentration of more than 20 micrograms/ml. A study of structurally related compounds suggested that the cytotoxicity shown by gallic acid was not a common feature in phenolic compounds, but was a fairly specific characteristic of gallic acid. That is, three adjacent phenolic hydroxyl groups of gallic acid were responsible for the cytotoxicity, and the carboxyl group was not responsible, but seemed to be implicated in distinguishing between normal cells and cancer cells.

Animals↗
PubMed1995

Prosthodontic abutment in four patients with unilateral cleft lip and palate.

An examination of the relation between the number of teeth used as the abutment of a fixed prosthesis and the increase of the functional loading capacity of the upper jaw was conducted in four male patients with unilateral cleft lip and palate (age range, 19 to 21 years). This was measured at the maximum biting force at each two teeth adjacent to the cleft under various splint extension conditions and compared with that in the nonsplint condition. In all subjects, the maximum biting force under every splinted condition was significantly increased compared with the nonsplint condition. The increase was proportional to the number of teeth included in the splinting. Results indicated that two teeth should be used in each segment in the abutment of the splint across the cleft in order to increase the functional loading capability of the upper jaw comparable to that of the lower jaw. The results also indicated that inclusion of more than two teeth has no further advantageous effect on the functional loading capability.

Adult↗
PubMed1995

[Effect of dosing schedule on efficacy of corticosteroid inhalation in chronic asthma].

A randomized study was conducted for 4 weeks to evaluate the effect of twice daily inhalation of beclomethasone dipropionate (BDP) inhalation (group A) as compared to four times a day inhalation (group B) in chronic asthma. Patients were randomly allocated to receive BDP at a dosage of eight puffs twice daily (800 micrograms/day, group A) or four puffs four times daily (800 micrograms/day, group B). Forty four patients entered the study but eleven were excluded because of their insufficient records or unfitness to eligibility criteria. There was no significant difference in patients' characteristics such as types, and severity of diseases between the two groups. Daily keeping of symptom scores, twice daily measurement of morning and night peak expiratory flow (PEF) and checking of the drug consumption were performed throughout the study. There was no significant difference in the mean %PEF either at 2 and 4 weeks at the study between the two groups. Symptom scores, asthmatic scores, bronchial hyperresponsiveness, pulmonary function tests (FVC, FEV1, FEV1%) and serum cortisol levels also showed no significant difference between the two groups. These results indicate that twice daily inhalation of BDP (800 micrograms/day) for four weeks caused the same effects on the patients with chronic bronchial asthma as 4 times daily inhalation did. Therefore, twice daily inhalation therapy with BDP is recommended for chronic bronchial asthma patients.

Administration, Inhalation↗
PubMed1995

Ionic basis of the chronotropic effect of acetylcholine on the rabbit sinoatrial node.

OBJECTIVE: The aim was to study the ionic basis of the chronotropic effects of bath applied acetylcholine and vagal stimulation on the rabbit sinoatrial node. METHODS: The chronotropic effect of bath applied acetylcholine was measured in single cells and small multicellular preparations from the rabbit sinoatrial node and the chronotropic effect of postganglionic vagal stimulation was measured in the intact sinoatrial node. The roles of the hyperpolarisation activated current, i(f), the acetylcholine activated potassium current, iK,ACh, and the L-type calcium current, iCa, were investigated by blocking the currents with 1-2 mM Cs+ or 10(-6) M UL-FS49, 0.2-1.0 mM Ba2+, and 6 x 10(-6) M nifedipine, respectively. RESULTS: Under control conditions, small multicellular preparations were approximately two orders of magnitude less sensitive to bath applied acetylcholine than single cells. However, after block of acetylcholinesterase by eserine in small multicellular preparations the sensitivities of the two types of preparation were approximately the same. Block of i(f) either had no discernible effect or increased the chronotropic effect of bath applied acetylcholine on single cells or small multicellular preparations, whereas partial block of iK,ACh reduced it substantially. Similarly, block of i(f) did not suppress the initial slowing of spontaneous action potentials by vagal stimulation, whereas partial block of iK,ACh reduced it. The hyperpolarisation of the arrested sinoatrial node in response to vagal stimulation was also substantially reduced by block of iK,ACh. Partial block of iCa caused large decreases in the action potential amplitude and maximum diastolic potential, but little decrease in the rate of spontaneous action potentials, and therefore did not mimic the effect of acetylcholine. CONCLUSIONS: The chronotropic effects of bath applied acetylcholine and vagal stimulation are not principally the result of a suppression of i(f) or iCa, whereas the activation of iK,ACh may play an important role.

Acetylcholine↗
PubMed1995

Vascular reserve in chronic cerebral ischemia measured by the acetazolamide challenge test: comparison with positron emission tomography.

PURPOSE: To determine the value of the acetazolamide challenge test with stable xenon-enhanced CT (Xe CT) for making therapeutic decisions in patients with chronic cerebrovascular disease. METHODS: We compared the Xe CT-measured acetazolamide response with various measures obtained by positron emission tomography. We performed both a positron emission tomographic scan and a Xe CT study in 11 patients with chronic cerebral ischemic diseases within a 1-week interval. An increase of cerebral blood flow after injection of acetazolamide was expressed as delta AT. Regional cerebral blood flow, cerebral oxygen metabolism, oxygen extraction fraction, and cerebral blood volume were measured with oxygen-15-labeled gases by positron emission tomography. RESULTS: In low-cerebral blood flow regions, decreased delta AT was accompanied by a significant elevation of oxygen extraction fraction and cerebral blood volume, compared with oxygen extraction fraction and cerebral blood volume in regions of normal delta AT. Plotting of regional data indicated that delta was significantly dependent on oxygen extraction fraction and cerebral blood volume. The area of decreased vascular reserve determined by the Xe CT image corresponded to the area of "misery perfusion" determined by positron emission tomography. CONCLUSION: The acetazolamide challenge test with Xe CT may offer an alternative to positron-emission tomography in detecting lesions with elevated oxygen extraction fraction and cerebral blood volume (misery perfusion) that result from chronic hemodynamic stress.

Acetazolamide↗
PubMed1995

[Two cases of squamous cell carcinoma of the ureter].

Herein, we report two cases of squamous cell carcinoma of the ureter. The first case was in a 56-year-old-male. Total cystectomy and ileal conduit were performed because of bladder tumor suspected to be accompanied by carcinoma in situ and atrophic urinary bladder induced by chronic cystitis in December, 1993. Pathological examination revealed transitional cell carcinoma (TCC) > squamous cell carcinoma (SCC), G2 > G1, INF beta, pT1, 1y1, v1. He complained of back pain under medical observation in December, 1994. Left hydronephrosis was found and antegrade pyelography showed leakage from the left pelvic ureteral junction. Urinary cytology revealed class V and suggested TCC. He received left nephroureterectomy, and pathohistological examination of resected specimen revealed SCC, INF gamma, pT3, pRo, pLx, pVx, pNo, pMo. CABO chemotherapy (cisplatin, methotrexate, bleomycin, vincristine) was performed postoperatively. The second case was in a 61-year-old female. She complained of macrohematuria in the course of observation of pyelonephritis. Drip infusion pyelography showed right hydronephrosis and retrograde ureterogram revealed stenosis of the right lower ureter. Urinary cytology revealed class V. Nephroureterectomy and bladder cuff were performed. The tumor was histologically diagnosed as SCC > TCC, INF beta, pT3, pRo, pLo, pVo, pNo, pMo. Postoperatively, CABO chemotherapy was performed. So far, no recurrence has been observed. Fifty five cases of squamous cell carcinoma of ureter were collected from the Japanese literatures including our cases.

Carcinoma, Squamous Cell↗
PubMed1995

[A case report of prostate cancer with Paneth cell-like change].

We report one case of Paneth cell-like change of prostate cancer. An 81-year-old male reported to our hospital with the chief complaint of urinary retention. The serum concentration of prostate specific antigen, 168 ng/ml, was high, and digital examination was performed. Because we suspected prostate cancer, needle biopsy of the prostate was performed. Histological examination revealed moderately-poorly differentiated adenocarcinoma. Computed tomography revealed no invasion to the prostatic wall and no metastasis to the lymph node. 99mTc-HMDP revealed no bone metastasis. We chose intravenous hormonotherapy (fosfestrol 500 mg/day, 20 days), but urinary retention did not improve. Therefore, we performed transurethral prostatectomy to improve the symptoms. Histological examination of the removed specimen revealed moderately differentiated adenocarcinoma with Paneth cell-like change. Immunochemical and histochemical stains were positive for Grimelius, serotonin and prostatic acid phosphatase and negative for periodic acid-Schiff reaction, lysozyme, neuron specific enolase, prostate specific antigen, alpha-1-antitrypsin and IgA.

Adenocarcinoma↗
PubMed1994

Molecular analysis of T cell receptor V beta chain to detect leukemia cell clonality in patients by adaptor ligation-mediated polymerase chain reaction.

We have developed a simple and rapid method to analyze the clonality of leukemia cells. After three rounds of amplification by adaptor-ligation polymerase chain reaction (PCR), the cDNA is cut with AluI, HaeIII, RsaI, and Sau3AI, and analyzed by polyacrylamide gel electrophoresis. The size of the restriction fragments is compared to that of the published restriction fragments size each TCR-beta subfamily V region. The sensitivity of adaptor-ligation PCR restriction enzyme analysis (AL-PCR-REA) was 10(-4) MOLT-4 T-ALL cell population in the normal peripheral blood lymphocytes (PBL). Application of AL-PCR-REA to PBL and bone marrow (BM) cells from eight clinical leukemia samples indicated that a detection sensitivity was rather low, but revealed the clonality of all eight clinical samples. This AL-PCR-REA method can detect clonality without the need for either radioisotopes or sequencing procedures.

Base Sequence↗
PubMed1994

Processing of E1 and E2 glycoproteins of hepatitis C virus expressed in mammalian and insect cells.

Processing of the envelope glycoproteins (E1 and E2) of hepatitis C virus (HCV) was investigated by using cDNA clones covering the structural and part of the nonstructural (NS) protein regions. The cDNA clones expressed in mammalian and insect cells were immunoprecipitated by serum of a hepatitis C patient and by monoclonal and polyclonal antibodies raised against the recombinant proteins expressed in insect cells or Escherichia coli. The E2 protein expressed in both insect and mammalian cells was a glycoprotein of 60 kDa (gp60) and removal of the sugar residues by N-glycanase yielded 38- and 40-kDa proteins. Pulse-chase experiments revealed that efficient expression and processing of the envelope proteins required coexpression with the flanking core and NS2 proteins. Not only E1 and E2 proteins but also NS2 and NS3 proteins were coprecipitated by anti-E1 or anti-E2 monoclonal antibody in the cells infected with the recombinant baculovirus expressing structural and NS proteins (NS2 and NS3), while only the NS3 protein was precipitated by anti-NS3 antibody. The association of E1 and E2 proteins was not influenced by the presence of a reducing agent and was still observed in the cells coinfected with the deletion mutants lacking both internal and C-terminal hydrophobic regions of each protein. Furthermore, the truncated forms of the E1 and E2 proteins were secreted into the culture supernatant and some of them were still associated with each other.

Animals↗
PubMed1994

Antioxidant, gallic acid, induces apoptosis in HL-60RG cells.

Gallic acid, a naturally occurring plant phenol with antioxidative activity, was found to induce cell death in promyelocytic leukemia HL-60RG cells, although many antioxidants are well known to protect the cell from oxidative stress. Morphological and biochemical studies indicated that the gallic acid-induced cell death is apoptosis. Flow cytometric analysis revealed that the apoptosis was not triggered at a specific phase of the cell cycle and that 2 h exposure of gallic acid to HL-60RG cells was enough to induce apoptosis. The inhibitory assay suggested that gallic acid-induced cell death was mediated by reactive oxygen species such as hydrogen peroxide, superoxide anion in addition to Ca2+ ion, calmodulin-dependent enzymes. Structure-activity analysis suggests that gallic acid induces apoptosis in HL-60RG cells, depending on its distinctive feature derived from the structure but not on its antioxidative activity.

Animals↗
PubMed1994

Establishment and characterization of nurse cell-like clones from human skin. Nurse cell-like clones can stimulate autologous mixed lymphocyte reaction.

We have established nurse cell-like clones from long-term cultures of the human skin. These human skin nurse cell (HSNC)-like clones were type I collagen+, type IV collagen-, vimentin+, cytokeratin-, CD44+, CD54+, and weakly positive for VCAM-1, and easily identified by the pseudoemperipolesis that allowed T lymphocytes to migrate beneath the HSNCs. HSNCs and various T cell lines formed a typical complex in the hanging drop culture system. The majority of human and murine T cells, and some of the tumor cell lines other than T cells, including B lymphoma and myeloblastoma cells, migrated beneath the HSNC clones. HSNC clones produced various cytokines, including IL-6, IL-7, IL-8, IL-9, granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF), macrophage CSF (CSF-1), TGF-beta 1, and c-kit ligand, but could not produce IL-1 alpha, IL-1 beta, IL-2, IL-3, IL-4, TNF-alpha, or TNF-beta. These characteristics were similar to those of nurse cells established from the murine thymus. Furthermore, IFN-gamma-pretreated HSNC clones that expressed MHC class II Ags induced autologous mixed lymphocyte reaction (AMLR) in autologous PBMCs to proliferate and exhibit the cytotoxicity against altered autologous cells and various tumor cells. These results suggest that HSNCs play an important role in the immunoregulation at skin tissues.

Animals↗
PubMed1994

Analysis of the population of human T cell receptor gamma and delta chain variable region subfamilies by reverse dot blot hybridization.

We have developed a simple method to analyze the population of T cell receptor (TCR) gamma and delta chain variable (V) region subfamilies by the application of reverse dot blot hybridization, which was originally developed for the analysis of human HLA-DR polymorphism. The four oligonucleotides corresponding to each TCR-gamma V region subfamily and the six oligonucleotides to each TCR-delta V region gene were synthesized, and tailed with dTTP. The cDNA was amplified by ligation-mediated PCR in the presence of biotinylated deoxynucleotides. Hybridization between immobilized specific oligoprobes and biotinylated target DNA was nonradioactively detected by a reaction using alkaline phosphatase. The population of the V region subfamilies of TCR-gamma and -delta in PBL analyzed by reverse dot blot hybridization described here showed good correlations with the result of colony hybridization.

Base Sequence↗
PubMed1994

Transmission of maternal blood cells to the fetus during pregnancy: detection in mouse neonatal spleen by immunofluorescence flow cytometry and polymerase chain reaction.

Mouse embryos were transferred to allogeneic pseudopregnant foster mothers and the cells of the resultant neonates were analyzed for the expression of maternal major histocompatibility complex (MHC) antigens to elucidate maternal cell transmission to the fetus during pregnancy. Expression of maternal-type MHC antigens was detected in the spleen but not in the liver or thymus of the neonates in analyses by immunofluorescence flow cytometry and polymerase chain reaction. These findings provide evidence, on the molecular basis, that maternal blood cells are transmitted to the fetus through the placenta.

Animals↗
PubMed1994

Stimulation of in vitro hematopoiesis by a murine fetal hepatocyte clone through cell-cell contact.

We have previously shown that a fetal liver-derived epithelial cell clone, FHC-4D2, could support hematopoiesis in vitro through its colony-stimulating factor (CSF) activities in a short-term culture. In this study, since FHC-4D2 cells were found capable of maintaining hematopoietic progenitors in the coculture for a long time, we examined how FHC-4D2 could exert hematopoietic supporting activity in a long-term culture by coculturing adult bone marrow (BM) cells or fetal liver (FL) cells on a monolayer of FHC-4D2 cells. This clone could maintain the colony-forming unit of granulocytes and macrophages (CFU-GM) of BM for > or = 12 weeks under the coculture condition, but the fibroblastic cell clone from the fetal liver, FHC-4A3, could not support the survival of CFU-GM, even for 1 week. In addition to BM CFU-GM, the FHC-4D2 clone also supported the survival of FL CFU-GM, burst-forming unit of erythroid cells (BFUe), and colony-forming unit of mixed progenitors (CFU-Mix) for longer than 4 weeks. When BM cells were separated by a membrane filter from the FHC-4D2 cells in the coculture, the comparable number of CFU-GM was maintained at day 3, but virtually no hematopoietic progenitors were detected at the end of the first week. CFU-GM were present in both nonadherent and adherent cells to the FHC-4D2 cells at day 3 of the coculture, but at day 7, the adherent population contained greater number of CFU-GM. CFU-GM derived from the adherent cells formed larger colonies and contained more bipotential CFU-GM than the nonadherent population. When BM cells from mice given 5-fluorouracil were cocultured with FHC-4D2 cells under the limiting dilution condition, interleukin-3 (IL-3)-responsive CFU-GM were induced from immature hematopoietic progenitor cells that were otherwise unresponsive to IL-3. From these data we conclude that the FHC-4D2 clone could generate and maintain IL-3-responsive hematopoietic progenitors via close contact and that, in the fetal liver, the contact between hepatocytes and hematopoietic cells may be critically important in inducing the differentiation of resting, IL-3-unresponsive immature hematopoietic cells into CFU-GM (progenitors responsive to IL-3) and in triggering the self-renewal of CFU-GM.

Animals↗