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Biomedical subjects

I Hayashi

Publications and source records attributed to I Hayashi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Relationships among facial type, buccolingual molar inclination, and cortical bone thickness of the mandible.

The purpose of this study was to evaluate the relationships between different facial types, and both the buccolingual molar inclination and cortical bone thickness of the mandible. The material consisted of 31 dry skulls of modern Japanese males from the Museum of the University of Tokyo. They all demonstrated normal occlusion with minimal dental discrepancy, and without crossbite or facial asymmetry. The buccolingual inclination of the second molar (M2) in the long-faced subjects was significantly smaller than the same dimension in the average- and short-faced subjects. It was found that the teeth of long-faced subjects were more lingually inclined than those of the short-faced subjects. The cortical bone thickness of the first molar (M1) and M2 sections was thicker in short-faced subjects than in average- and long-faced subjects. The results of this study provide evidence that a significant, but complex relationship exists between structures of the mandibular body and facial types. The morphological features that relate to masticatory function and facial types are associated with the cortical bone thickness of the mandibular body, and the buccolingual inclination of the first and second molars.

Adolescent↗
PubMed2001

[Endogenous prostaglandins and angiogenesis].

Angiogenesis is a process involved in several physiological events including embryonic development, female reproductive cycle placentation and wound repair. It also plays a part in various pathological conditions such as tumor growth, diabetic retinopathy and rheumatoid arthritis. Angiogenesis is a very complex multistep process involving a variety of biologically active substances, among which are the prostaglandins (PGs), which can induce several growth factors and proliferation of endothelial cells in vitro and in vivo. Angiogenesis is reportedly enhanced by prostaglandins (PGs). We investigated whether or not COX-2 mediated angiogenesis in chronic and proliferate granuloma. In rat sponge implants, angiogenesis was gradually developed over a 14-day experimental period as granuloma formed. In sponge granuloma, mRNA of COX-1 was constitutively expressed, whereas that of COX-2 was increased with neovascularization in parallel with the increased expression of vascular endothelial growth factor (VEGF). bFGF-stimulated angiogenesis was inhibited by indomethacin or a selective COX-2 inhibitor, NS-398. These results suggested that endogenous PGs generated through COX-2 may enhance the neovascularization in sponge granuloma by increased expression of VEGF and that a COX-2 inhibitor would facilitate the management of conditions involving angiogenesis.

Animals↗
PubMed2001

Adenylate cyclase/protein kinase A signaling pathway enhances angiogenesis through induction of vascular endothelial growth factor in vivo.

We previously reported that endogenous prostaglandins (PGs) may increase cAMP facilitated angiogenesis through the induction of vascular endothelial growth factor (VEGF) in rat sponge implantation models. In the present experiment, we tested whether or not adenylate cyclase / protein kinase A (AC/PKA)-dependent VEGF induction enhanced angiogenesis in this model. Topical daily injections of 8-bromo-cAMP enhanced angiogenesis in a dose-dependent manner. Forskolin, an activator of AC, also facilitated angiogenesis as did amrinone, an inhibitor of phosphodiesterase. VEGF induction was confirmed by the increased levels in the fluids in the sponge matrix after topical injection of 8-bromo-cAMP. Immunohistochemical investigation further revealed the VEGF-expressed cells in the sponge granulation tissues to be fibroblasts, and the intensity of positive reactions was enhanced by 8-bromo-cAMP, forskolin and amrinone. Angiogenesis without topical injections of the above compounds was suppressed by SQ22,536, an inhibitor for AC, or H-89, an inhibitor for PKA, with concomitant reductions in VEGF levels. Daily topical injections of neutralizing antibody or anti-sense oligonucleotide against VEGF significantly suppressed angiogenesis. PGE2-induced angiogenesis was suppressed with SQ22,536 or H-89. These results suggested that AC/PKA-dependent induction of VEGF certainly enhanced angiogenesis and that pharmacological tools for controlling this signaling pathway may be able to facilitate the management of conditions involving angiogenesis.

Adenine↗
PubMed2001

Role of the renal kallikrein-kinin system in the development of salt-sensitive hypertension.

The role of the renal kallikrein-kinin system in the development of salt-sensitive hypertension was studied using mutant kininogen-deficient Brown-Norway Katholiek (BN-Ka) rats, which generate no kinin in their urine, and other hypertensive rat models. It was found that ingestion of a low sodium diet or infusion of NaCl in doses slightly above 0.15 M caused hypertension and sodium accumulation in erythrocytes and the cerebrospinal fluid of kininogen-deficient BN-Ka rats. Development of hypertension in the deoxycorticosterone-acetate-salt model was completely prevented by administration of a newly discovered inhibitor, ebelactone B, of carboxypeptidase Y-like exopeptidase (an urinary kininase). The urinary kallikrein excretion of spontaneously hypertensive rats was lower than that of Wistar Kyoto rats at 4 weeks of age and did not increase by administration of furosemide, a diuretic agent, although approximately 50% of the diuretic action of this agent was dependent upon the renal kallikrein-kinin system in normal rats. In conclusion, the renal kallikrein-kinin system works as a safety valve for excess sodium intake.

Animals↗
PubMed2001

Effects of oral administration of Echinacea purpurea (American herb) on incidence of spontaneous leukemia caused by recombinant leukemia viruses in AKR/J mice.

Four-week-old female AKR/J mice were given oral doses of powdered leaves from Echinacea purpurea three times weekly for 8 weeks (7.5 mg/mouse/week): controls received phosphate-buffered saline. Mean survival age of experimental AKR/J mice treated with the E. purpurea preparation was significantly prolonged and enlargement of thymic lymphoma in experimental mice was significantly suppressed compared with controls. In normal 3-week-old female AKR/J mice, mortality from thymic lymphoma was delayed markedly after injection into the thymus of cell-free extract of thymus from the experimental 28-week-old female AKR/J mice that received the oral E. purpurea preparation was injected directly into the thymus. Proliferation of endogenous recombinant murine leukemia viruses (MuLV) in the thymus was markedly inhibited after the first oral administration of the E. purpurea preparation as compared with untreated controls (final age, 28 weeks). Production of endogenous interferon (IFN)-gamma in AKR/J mice was also effectively augmented by the oral treatment with the E. purpurea preparation, however, the production of other cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-12 was minimal. These results suggest that this suppressive effects on spontaneously occurring leukemia caused by endogenous recombinant MuLV in female AKR/J mice may depend on enhancement of nonspecific immune or cellular immune systems (or of both) by the E. purpurea preparation.

Animals↗
PubMed2001

[Glycopeptides].

Glycopeptides(Vancomycin(VCM), Teicoplanin(TEIC)) are effective against Gram positive cocci(GPC) and mainly prescribing for Methicillin Resistant Staphylococcus aureus(MRSA) infection in Japan. Mode of actions are little bit difference between VCM and TEIC, for example the rate of protein binding, post antibiotic effect and half-life time. Effect of glycopeptide depend on the above MIC. To keep the effective serum concentrations of the drug, recommended the method of loading dose for TEIC and the method of continuous drip infusions for VCM. Also keep the effective serum concentrations shows to shorten the duration of treatment and to protect for development of resistant strains. Biofilm diseases caused by P. aeruginosa, MRSA and MRSE are treated by combination therapy with Fosfomycin(FOM). The most powerful intensive chemotherapy (FOM + Sulbactam/Cefoperazon + Glycopeptides) shows superior effects against multiple infections caused by P. aeruginosa and MRSA.

Anti-Bacterial Agents↗
PubMed2001

Coronary artery bypass grafting in patients with dialysis-dependent renal failure.

This study identified preoperative characteristics of dialysis patients undergoing coronary artery bypass grafting (CABG) and determined the early and long-term results. We retrospectively analyzed the data of 60 patients (mean age 60.8 +/- 7.6 years) with end-stage renal disease who underwent CABG between 1982 and 1999. Seventeen (28%) patients underwent CABG for unstable angina, and 9 (15%) patients required preoperative intraaortic balloon pumping. The incidence of congestive heart failure (18%) and diseased aorta (42%) was higher in the dialysis group. In-hospital mortality in the dialysis group was 13% (8/60). The estimated survival rate at 5 and 10 years in the dialysis patients was 55.6 +/- 8.8% and 31.8 +/- 11.6%, respectively. The cardiac event-free rate, excluding the in-hospital mortality, was 62.5 +/- 9.9% at 5 years. Although the early and long-term results of CABG in dialysis patients were inferior to those of nondialysis patients, CABG in dialysis-dependent patients allows the patients to continue their dialysis therapy and to improve their functional status.

Coronary Artery Bypass↗
PubMed2001

Right vagal nerve stimulation for coronary anastomosis without cardiopulmonary bypass: investigation in dogs.

BACKGROUND: The purpose of this study is to assess the potential of right vagal nerve stimulation for reducing the heart rate during coronary anastomosis without cardiopulmonary bypass. METHODS: Through the fourth left intercostal space, left internal thoracic artery grafts were sutured to the left anterior descending artery with the heart beating. In Group I (n=7), two dogs underwent right cervical vagal stimulation alone and five dogs underwent right cervical vagal stimulation during intravenous infusion of diltiazem or verapamil. In Group II (n=3), one dog underwent right thoracic vagal stimulation alone and two dogs underwent right thoracic vagal stimulation during intravenous infusion of diltiazem or verapamil. The thoracic vagal nerve was isolated endoscopically. The electrocardiogram and aortic pressure were monitored during interventions. RESULTS: In Group I, cervical vagal stimulation reduced the heart rate from 190 to 45 and 180 to 42 b/min. During intravenous infusion of diltiazem or verapamil, cervical vagal stimulation caused ventricular arrest. In Group II, thoracic vagal stimulation decreased the heart rate from 205 to 70 b/min, and stimulation during intravenous infusion of diltiazem caused ventricular arrest. CONCLUSIONS: Right vagal stimulation during intravenous infusion of diltiazem or verapamil has potential value as a technique for reducing the heart rate during coronary anastomosis without cardiopulmonary bypass.

Anastomosis, Surgical↗
PubMed2001

[Genome research and anticancer chemotherapy].

Worldwide research on the human genome is having a major impact on medical science and advanced medicine, although the detailed function and interaction of most genes remain unclear. The elucidation of human genome data makes it possible to take global views of biological processes and characteristics of cancer and individual drug response. This brings a number of new challenges such as genome based drug development and tailored cancer chemotherapy based on the individual genomic make-up. When a disease gene is identified, truly effective drugs targeting the genes can be developed. When biological characteristics such as polymorphism and gene expression profiles are closely related to drug response, an individually optimized drug therapy can be realized. cDNA microarray technology and new high-throughput single nucleotide polymorphism (SNP) screening offer great hope for such a global view by providing a systematic way to survey DNA and RNA variation. Evolutionary engineering techniques continue to be developed, which significantly promotes studies to understand molecular mechanisms causing diseases, novel disease genes, and genes related to drug response. Such progress in genome research and the functional analysis may revolutionize the anticancer chemotherapy world. The possible contribution of genome research to anticancer chemotherapy and problems of the day are reviewed herein.

Animals↗
PubMed2000

Both RadA and RadB are involved in homologous recombination in Pyrococcus furiosus.

RecA and Rad51 proteins are essential for homologous recombination in Bacteria and Eukarya, respectively. Homologous proteins, called RadA, have been described for Archaea. Here we present the characterization of two RecA/Rad51 family proteins, RadA and RadB, from Pyrococcus furiosus. The radA and radB genes were not induced by DNA damage resulting from exposure of the cells to gamma and UV irradiation and heat shock, suggesting that they might be constitutively expressed in this hyperthermophile. RadA had DNA-dependent ATPase, D-loop formation, and strand exchange activities. In contrast, RadB had a very weak ATPase activity that is not stimulated by DNA. This protein had a strong binding affinity for DNA, but little strand exchange activity could be detected. A direct interaction between RadA and RadB was detected by an immunoprecipitation assay. Moreover, RadB, but not RadA, coprecipitated with Hjc, a Holliday junction resolvase found in P. furiosus, in the absence of ATP. This interaction was suppressed in the presence of ATP. The Holliday junction cleavage activity of Hjc was inhibited by RadB in the absence, but not in the presence, of ATP. These results suggest that RadB has important roles in homologous recombination in Archaea and may regulate the cleavage reactions of the branch-structured DNA.

Adenosine Triphosphatases↗
PubMed2000

Chymase mediates mast cell-induced angiogenesis in hamster sponge granulomas.

We investigated the contribution of mast cell chymase in mast cell-dependent angiogenesis using the hamster sponge-implant model, where angiogenesis in the granulation tissue surrounding the subcutaneously implanted sponge was evaluated by measuring the hemoglobin content. Daily local injection of compound 48/80 (3-100 microg/site/day), a potent mast cell activator, induced formation of granulomas and angiogenesis in time- and dose-dependent manners. This angiogenic response was inhibited by chymase inhibitors including chymostatin (> or = 1 nmol/site/day), soybean trypsin inhibitor (SBTI; > or = 1.4 nmol/site/day) and lima bean trypsin inhibitor (LBTI; > or = 3.3 nmol/site/day), but not by a tryptase inhibitor like leupeptin (> or = 700 nmol/site/day). Although pyrilamine (> or = 2,580 nmol/site/day), a histamine H1 receptor antagonist, and protamine (300 microg/site/day) also inhibited angiogenesis, these effects were much less pronounced than those by chymase inhibitors. Furthermore, antigen-induced angiogenesis in hamsters pre-sensitized with ovalbumin was also inhibited by the chymase inhibitors by 60-70%. Our results suggest that chymase is a major mediator in mast cell-mediated angiogenesis.

Animals↗
PubMed2000

Whale high-molecular-weight and low-molecular-weight kininogens.

The expression of high-molecular-weight and low-molecular-weight kininogen mRNAs in the whale liver was examined by reverse transcription-polymerase chain reaction. The nucleotide sequences of the high-molecular-weight and low-molecular-weight kininogen cDNAs were analyzed and deduced to the amino acid sequences. The high-molecular-weight kininogen composed of 609 amino acid residues with 18 signal peptides possessed the consensus sequences of the cysteine protease inhibitor domains I and II, the bradykinin domain, the histidine-rich region, and the prekallikrein-binding region. Except for the histidine-rich region, the overall homologies with bovine, human, and rat high-molecular-weight kininogens were 81%, 76%, and 62%, respectively. The low-molecular-weight kininogen is composed of 408 amino acid residues. The nucleotide sequence down to C(1200) as well as the amino acid sequence till Ile(382) is identical to that of the high-molecular-weight kininogen. The remaining low-molecular-weight kininogen-specific carboxy-terminal portion possessed an amino acid sequence similar to that of the land mammals. The overall homologies with bovine, human, and rat low-molecular-weight kininogens were 82%, 79%, and 64%, respectively. The amino acid sequences of both whale high-molecular-weight and low-molecular-weight kininogens are most similar to those of the bovine among the land mammals analyzed so far. An incubation of dolphin/whale plasma with human plasma kallikrein, or with bovine trypsin, in the presence of carboxypeptidase inhibitors generated bradykinin antigen as well as the spasmogenic activity to the estrous rat uterus. The amount of bradykinin released by the latter enzyme was almost double of the former, indicating that the dolphin/whale plasma contained similar concentrations of low-molecular-weight and high-molecular-weight kininogens.

Amino Acid Sequence↗
PubMed2000

Chymase as a proangiogenic factor. A possible involvement of chymase-angiotensin-dependent pathway in the hamster sponge angiogenesis model.

We investigated the profound involvement of chymase, an alternative angiotensin II-generating enzyme, in angiogenesis using a hamster sponge implant model. In vivo transfection of human pro-chymase cDNA or a direct injection of purified chymase into the sponges implanted resulted in marked increment of hemoglobin contents in the sponge granuloma tissues, demonstrating that chymase has an ability to elicit angiogenesis and is a potent angiogenic factor. Daily injection of basic fibroblast growth factor into the sponges implanted also induced angiogenesis, which was suppressed by the treatment with chymostatin, an inhibitor of chymase, or TCV-116, an antagonist of angiotensin II (Ang II) type 1 receptor. Expression of chymase mRNA and production of Ang II in the granuloma tissues were enhanced by the stimulation with basic fibroblast growth factor. Chymase activity in the sponge granulomas increased in parallel with the rise in hemoglobin contents, and mast cells observed in the granuloma tissues were positively stained with anti-chymase antibody. Exogenous administration not only of Ang II but of angiotensin I (Ang I) directly into the sponges could enhance angiogenesis. Chymostatin inhibited the angiogenesis induced by Ang I but not Ang II, suggesting the presence of a chymase-like Ang II-generating activity in the sponge granulomas. Our results may suggest a potential ability of chymase to promote angiogenesis through the local chymase-dependent and angiotensin-converting enzyme-dependent Ang II generating system in pathophysiological angiogenesis.

Angiotensin I↗
PubMed2000

Is diabetes mellitus a major risk factor in coronary artery bypass grafting? The influence of internal thoracic artery grafting on late survival in diabetic patients.

OBJECTIVE: The presence of diabetes could possibly have an adverse influence on the late results of coronary artery bypass grafting (CABG). A retrospective observational risk-unadjusted estimation study was conducted to clarify the magnitude of this unfavorable influence of diabetes based on our experience at Juntendo University. METHODS: Between January 1984 and December 1995, 1,618 primary CABG operations were performed and 99.0% of these patients were followed up for a mean period of 81.2 months with a maximal follow-up of 14 years. Among the 1,610 patients who were successfully followed up, 523 patients (32.5%) were diabetic and this cohort was compared with 1,087 nondiabetic patients regarding the patient profiles, perioperative outcome, and the long-term outcome. RESULTS: Diabetic patients included a higher proportion of females, a greater preoperative presence of renal insufficiency, a higher rate of three vessel disease, and reception of a greater number of grafts (mean: 2.5 versus 2.4) and an internal thoracic artery graft (68% versus 58%). Hospital mortality was not significantly different (2.1% vs 1.0%: ns). An actuarial analysis revealed a significantly unfavorable long-term survival in the diabetic group (59.6%) at 14 years, compared with the nondiabetic group (73.4%), however diabetic patients with an internal thoracic artery graft had a favorable long-term survival (82.0%) at 13 years, and this finding was almost identical to that of nondiabetic patients with an internal thoracic artery graft (88.5%). CONCLUSION: We conclude that the presence of diabetes appears to be a major risk factor in patients undergoing CABG. However, diabetic patients with an internal thoracic artery graft had a survival almost identical to that of nondiabetic patients with an internal thoracic artery graft.

Coronary Artery Bypass↗
PubMed2000

Adeno-endocrine cell carcinoma of the gallbladder.

We encountered a rare case of adeno-endocrine cell carcinoma of the gallbladder in an 81-year-old woman. Imaging study revealed a common bile duct stone. Endoscopic sphincterotomy was performed, and the stone was extracted successfully. Thereafter, cholecystectomy was performed. A papillary tumor was found in the neck of the gallbladder. Histologically, the tumor consisted of two components, well differentiated adenocarcinoma and endocrine cell carcinoma. However, no clinical signs of tumor hormonal activity were observed. The tumor cells in the area of the endocrine cell carcinoma were small and round. Histochemical studies of these tumor cells were positive for chromogranin A and Grimelius silver impregnation. The tumor cells in the area of the adenocarcinoma were well differentiated adenocarcinoma and included goblet-type cells with a tubular structure or solid growth pattern. These adenocarcinoma cells stained positively for Alcian blue and periodic acid-Schiff, and both types of tumor cells stained positively for carbohydrate antigen and carcinoembryonic antigen. It was suggested that the histogenesis of the endocrine cell carcinoma of the gallbladder was closely related to that of the adenocarcinoma.

Adenocarcinoma↗