Search PubMed⌕ Search

Biomedical subjects

H Hayashi

Publications and source records attributed to H Hayashi.

At least 181 records · Page 10Linked to original sources
PubMed2001

Enhancement of nitrifying biofilm formation using selected EPS produced by heterotrophic bacteria.

The possibility of enhancing nitrifying biofilm formation rate with the aid of selected EPS produced by heterotrophic bacteria was investigated. When EPS production characteristics were examined for four kinds of heterotrophs isolated from a domestic wastewater treatment reactor, two strains obtained from biofilms (B1, B2) exhibited a higher polysaccharide production rate than those from suspended flocs (A1, A2). Among EPS components, the concentration of uronic acids gave a good correlation with flocculation ability, which suggests that acidic polysaccharides play a major role in bioaggregate formation. Addition of 1 g/L D-glucuronic acid as an EPS substitute enhanced the homocoagulation rate of autotrophic Nitrosomonas europaea and altered its zeta potential from ñ30.4 mV to +4.3 mV, which indicates a possibility that particular EPS components produced by heterotrophs are utilized as neutralising reagents for nitrifying biofilm formation. Moreover, when heterotrophic isolates with Nitrobacter winogradskyi were cultured in batch with fabric supports, biofilm formed on the substratum. These experimental results suggest the application of selected EPS for enhancing nitrifying biofilm formation.

Bacteria↗
PubMed2001

Inhibitory action of gemfibrozil on cholesterol absorption in rat intestine.

This study was designed to determine whether gemfibrozil inhibits intestinal lipid absorption. Male Sprague-Dawley rats received an oral dose of 30 mg gemfibrozil/kg body weight for 14 days. Mesenteric lymph cannulation was performed, and a lipid infusion containing 40 micromol/h (35.4 mg/h) of radiolabeled triolein and 2.74 micromol/h (1.06 mg/h) of radiolabeled cholesterol with the addition of 1 mg/h of gemfibrozil was infused intraduodenally at a rate of 3 ml/h for 8 h. The lymph was collected, and the radioactivity levels of the lumen and gut mucosa were measured after the infusion. Lymph cholesterol transport was depressed in gemfibrozil-treated rats, in terms of mass measurements as well as radioactivity in a lesser degree. More radioactive cholesterol remained in the proximal portion of the intestinal lumen and mucosa in the treated rats than in the control rats. More radioactive triglycerides also remained in the proximal intestinal lumen of treated rats, although no difference in lymphatic triglyceride transport was observed between the groups. A significant portion of the radioactive cholesterol remained in the lumen in the gemfibrozil-treated rats. Gemfibrozil increased biliary cholesterol excretion. Thus, this study shows that gemfibrozil inhibits cholesterol absorption in rat intestine.

Animals↗
PubMed2001

Body iron stores and iron restoration rate in Japanese patients with chronic hepatitis C as measured during therapeutic iron removal revealed neither increased body iron stores nor effects of C282Y and H63D mutations on iron indices.

Information on the level of iron stores in chronic hepatitis C is clinically important because its reduction is technically simple and therapeutically effective. This study was performed to measure the levels of iron stores from the total amounts of hemoglobin removed during iron reduction therapy. The C282Y and H63D mutations of HFE gene were analyzed in 94 patients. All of the patients were negative for C282Y mutation. One patient was homozygous, and 4 patients were heterozygous for H63D mutation. The body iron stores and iron restoration rate were measured in 59 patients in serial courses of iron reduction therapy. Mean values of body iron stores in the two groups with and without H63D mutation were 890 and 606 mg, while those of iron restoration rate were 1.85 and 1.52 mg/day, respectively. None of the indices of iron metabolism were different from the reference values measured similarly in healthy subjects, suggesting that the iron deposition in chronic hepatitis C is limited to the liver, probably due to changes in the iron distribution in tissues.

Female↗
PubMed2001

Importance of glycolytically derived ATP for Na+ loading via Na+/H+ exchange during metabolic inhibition in guinea pig ventricular myocytes.

The increase in the intracellular Na+ concentration ([Na+](i)) during myocardial ischaemia is crucial for ischaemia/reperfusion cell injury, and the cardiac subtype of the Na+/H+ exchanger (NHE-1) has been shown to be a major pathway for Na(+) loading. While the importance of glycolytically derived ATP for the optimal functioning of membrane transporters and channels has been suggested, whether NHE-1 is actually activated during myocardial ischaemia remains controversial. Here we examined whether the activity of NHE-1 is predominantly dependent on intracellular ATP generated by glycolysis, and whether the additional inhibition of glycolysis can affect the increase in ([Na+](i)) during the inhibition of oxidative phosphorylation in intact guinea pig ventricular myocytes. The selective inhibition of glycolysis by 2-deoxyglucose prevented the recovery of intracellular pH and the transient increase in ([Na+](i)) following intracellular acidosis induced by a NH(4)Cl pre-pulse. During severe metabolic inhibition (SMI; induced by amobarbital and carbonyl cyanide m-chlorophenylhydrazone in a glucose-free perfusate), most myocytes changed from rod-shaped to contracted forms by approximately 15 min. ([Na+](i)) increased linearly until rigor contracture occurred, but after rigor contracture the rate of increase was blunted. The increase in ([Na+](i)) during SMI was suppressed significantly by an inhibitor of NHE-1, hexamethylene amiloride. The increase in the intracellular Mg(2+) concentration, which can reciprocally indicate depletion of intracellular ATP, was small during the initial 10 min of SMI, but became larger from just a few minutes before rigor contracture. In the presence of 2-deoxyglucose, the time to rigor during SMI was shortened, but the increase in ([Na+](i)) before rigor contracture was not significant, and was much less than that in the absence of 2-deoxyglucose. It is concluded that ATP generated by glycolysis is essential to activate NHE-1, and that the dependence of NHE-1 on glycolysis might affect the increase in ([Na+](i)) observed during myocardial ischaemia.

Adenosine Triphosphate↗
PubMed2001

[Result of surgical treatment to early stage peripheral non-small cell lung cancer].

In the lung cancer, the announcement of the definition, the clinical behavior and the treatment result of the central early stage lung cancer, especially in situ lung cancer, have been seen. However, the definition and a clinicopathological concept of the peripheral lung cancer are still uncertain. The so-called small lung cancer of the tumor diameter 20 mm or less are peripheral lung adenocarcinoma. These patients' prognosis is excellent better, in contradiction to the prognosis of the patients with positive for pleural involvement or vessels invasion is worse. We studied the clinicopathological features, the Noguchi's classification, and prognosis of the 101 patients with small lung adenocarcinoma which were performed the operation, and refere about the selection of the operation method including the VATS and the limited operation.

Adult↗
PubMed2001

[Adenomatoid tumor of testicular tunica albuginea: a case report].

Adenomatoid tumors are uncommon neoplasms of the paratesticular tissues. We report a case of an adenomatoid tumor of the testicular tunica albuginea. A 54-year-old man presented with a painless right intrascrotal mass. Serum levels of HCG-beta and AFP were within normal limits. Scrotal ultrasonography showed an oval-shaped low echoic lesion located on the surface of the testis. The patient underwent right partial orchiectomy. Histological examination revealed adenomatoid tumor of the tunica alubuginea testis. Adenomatoid tumors of the testicular tunica alubuginea are rare. Examination of tumor markers, ultrasound studies and diagnoses of frozen sections can prevent needless orchiectomy.

Adenomatoid Tumor↗
PubMed2001

Validation of salmonellosis and shigellosis diagnostic test kits at a provincial hospital in Thailand.

Rapid Diagnosis of salmonellosis and shigellosis was performed using six different diagnostic test kits which recently have been made available commercially. They were Salmo-Dot, Typhi-Dot, Shigel Dot A, B, C, and D test kits for detection of Salmonella spp., group D salmonellae, and groups A, B, C, and D Shigella spp., respectively. The principle of all test kits is a membrane (dot) ELISA using specific monoclonal antibodies to the respective pathogens as the detection reagents. The present study was designed to validate the accuracy of the test kits, at a laboratory in a provincial hospital in Thailand, in comparison with the conventional bacterial culture method alone or with the combined results of the culture and the Western blot analysis (WB) for detecting the respective bacterial lipopolysacchharides (LPS) in specimens. Five hundred rectal swab samples of patients with diarrhea who seeked treatment at the hospital, were evaluated. The diagnostic accuracy of the Salmo-Dot was 91.0% when compared with the conventional bacterial culture method alone but was 100.0% in comparison with the combined results of the culture and the WB. The Typhi-Dot and the Shigel-Dot A, B, C, and D showed 100%, 99.2%, 95.0%, 94.0% and 96.4%, respectively when compared with the culture alone and all were 100% in comparison with the combination of the results of the bacterial culture and the WB. The Shigel-Dot A revealed antigen of type 1 Shigella dysenteriae in several specimens in which the bacteria could not be recovered by the culture method. This difference is important as type 1 Shigella dysenteriae have high epidemic potential and often cause severe morbidity. Unawareness of their presence by the conventional culture may have great impact on disease surveillance for public health. The pathogen detection using the six diagnostic test kits is sensitive, specific, rapid, and relatively simple and less expensive. Several specimens can be tested at the same time without much increase in turn around time. Moreover, these kits produce no contaminated waste as compared with the bacterial culture method. The test kits should be used for rapid screening of specimens of patients with diarrhea especially in areas where culture facilities are inadequate.

Diagnosis, Differential↗
PubMed2001

[Intraperitoneal cisplatin chemotherapy for ovarian cancer].

It is well known that the 5-year survival rate of advanced ovarian cancer patients greatly improved after the appearance of cisplatin. Recently, paclitaxel has been reported to be effective in the treatment of cisplatin-resistant ovarian cancer. However, control of intraperitoneal lesions is still the biggest problem in this treatment, and attention is focused on the development of effective approaches. Intraperitoneal chemotherapy is considered to be a mode of administration expected to have a direct effect on ovarian cancer by penetrating the tumor and an indirect effect via blood vessels. We examined the outcome and adverse drug reactions in 102 ovarian cancer patients who underwent repeated intraperitoneal administration of cisplatin in our hospital between April 1987 and April 1999. We confirmed that this method may greatly improve the five-year survival rate compared to intravenous administration.

Adenocarcinoma↗
PubMed2000

The substrate activation process in the catalytic reaction of Escherichia coli aromatic amino acid aminotransferase.

Aromatic amino acid aminotransferase is active toward both aromatic and dicarboxylic amino acids, and the mechanism for this dual substrate recognition has been an issue in the enzymology of this enzyme. Here we show that, in the reactions with aromatic and dicarboxylic ligands, the pK(a) of the Schiff base formed between the coenzyme pyridoxal 5'-phosphate and Lys258 or the substrate increases successively from 6.6 in the unliganded enzyme to approximately 8.8 in the Michaelis complex and to >10.5 in the external Schiff base complex. Mutations of Arg292 and Arg386 to Leu, which mimic neutralization of the positive charges of the two arginine residues by the ligand carboxylate groups, increased the Schiff base pK(a) by 0.1 and 0.7 unit, respectively. In contrast to these moderate effects of the Arg mutations, the cleavage of the Lys258 side chain of the Schiff base, which was brought about by preparing a mutant enzyme in which Lys258 was changed to Ala and the Schiff base was reconstituted with methylamine, produced the Schiff base pK(a) value of 10.2, that being 3.6 units higher than that of the wild-type enzyme. The observation indicates that the Schiff base pK(a) in the enzyme is lowered by the torsion around the C4-C4' axis of the Schiff base and suggests that the pK(a) is mainly controlled by changing the torsion angle during the course of catalysis. This mechanism, first observed for the reaction of aspartate aminotransferase with aspartate [Hayashi, H., Mizuguchi, H., and Kagamiyama, H. (1998) Biochemistry 37, 15076-15085], does not require the electrostatic contribution from the omega-carboxylate group of the substrate, and can explain why in aromatic amino acid aminotransferase the aromatic substrates can increase the Schiff base pK(a) during catalysis to the same extent as the dicarboxylic substrates. This is the first example in which the torsion pK(a) coupling of the pyridoxal 5'-phosphate Schiff base has been demonstrated in pyridoxal enzymes other than aspartate aminotransferase, and suggests the generality of the mechanism in the catalysis of aminotransferases related to aspartate aminotransferase.

Bacterial Proteins↗
PubMed2000

Nuclear localization of yeast Nfs1p is required for cell survival.

Saccharomyces cerevisiae Nfs1p is mainly found in the mitochondrial matrix and has been shown to participate in iron-sulfur cluster assembly. We show here that Nfs1p contains a potential nuclear localization signal, RRRPR, in its mature part. When this sequence was mutated to RRGSR, the mutant protein could not restore cell growth under chromosomal NFS1-depleted conditions. However, this mutation did not affect the function of Nfs1p in biogenesis of mitochondrial iron-sulfur proteins. The growth defect of the mutant was complemented by simultaneous expression of the mature Nfs1p, which contains the intact nuclear localization signal but lacks its mitochondrial-targeting presequence. These results suggest that a fraction of Nfs1p is localized in the nucleus and is essential for cell viability.

Amino Acid Sequence↗
PubMed2000

Chloroplast development in Arabidopsis thaliana requires the nuclear-encoded transcription factor sigma B.

Development of plastids into chloroplasts, the organelles of photosynthesis, is triggered by light. However, little is known of the factors involved in the complex coordination of light-induced plastid gene expression, which must be directed by both nuclear and plastid genomes. We have isolated an Arabidopsis mutant, abc1, with impaired chloroplast development, which results in a pale green leaf phenotype. The mutated nuclear gene encodes a sigma factor, SigB, presumably for the eubacterial-like plastid RNA polymerase. Our results provide direct evidence that a nuclear-derived prokaryotic-like SigB protein, plays a critical role in the coordination of the two genomes for chloroplast development.

Arabidopsis↗
PubMed2000

cDNA cloning and characterization of vascular apoptosis-inducing protein 1.

Hemorrhagic snake venom induces apoptosis in vascular endothelial cells (VEC). In previous reports, we described the purification from crude venom of Crotalus atrox of two vascular apoptosis-inducing proteins (VAP1 and VAP2) that specifically induce apoptosis in vascular endothelial cells. We report here the cDNA cloning and characterization of VAP1. VAP1 cDNA encoded a protein with 610 amino acid residues. The amino acid sequence predicted from the cDNA indicated that VAP1 belongs to the metalloprotease/disintegrin family and that it is a multidomain polypeptide with a proprotein domain, a metalloprotease domain, a disintegrin-like domain, and a cysteine-rich domain. In the disintegrin-like domain, the sequence DECD replaces the RGD sequence that has frequently been found in such domains. We demonstrated that VAP1 has Zn(2+)-dependent metalloprotease activity and degrades fibrinogen. After incubation in the presence of either EDTA or EGTA, VAP1 was hardly able to degrade fibrinogen and to induce apoptosis in VEC. Our results indicated that VAP1 is a new type of snake venom metalloprotease/disintegrin and suggest that the metalloprotease activity of VAP1 might be involved in the induction of apoptosis by VAP1 in VEC.

Amino Acid Sequence↗
PubMed2000

Serum p53 antibody is a useful tumor marker in superficial esophageal squamous cell carcinoma.

BACKGROUND: Patients with superficial (mucosal or submucosal) esophageal carcinoma (SEC) have significantly better survival rates than patients with advanced carcinoma. Some patients with advanced esophageal carcinoma have been reported to test positive for serum p53 antibodies (Abs). Because very few patients with superficial carcinoma have been examined, the aim of this study was to evaluate the clinical significance of serum p53-Abs in patients with superficial esophageal squamous cell carcinoma (SESCC). METHODS: Thirty-five consecutive patients with SESCC were studied for serum p53-Abs by enzyme-linked immunoabsorbent assay before and after treatment. The clinicopathologic features of p53 seropositive and p53 negative patients were compared. The relation between the presence of serum p53-Abs and p53 immunoreactivity of the resected specimens was examined. Three tumor markers (squamous cell carcinoma antigen [SCC-Ag], CYFRA21-1, and carcinoembryonic antigen [CEA]) were assessed to compare their sensitivities with serum p53-Abs. RESULTS: Fourteen of 35 patients (40%) were p53 seropositive. Relatively few patients tested positive for the other tumor markers: CEA, 11.4%; SCC-Ag, 14.3%; CYFRA21-1, 5.7%. There were no significant correlations between clinicopathologic features and p53 seropositivity except for tumor location. A strong correlation between p53 immunostaining and the presence of serum p53-Abs was observed (P = 0.003). Of the 14 patients with seropositive results, 12 turned seronegative after resection, and the other 2 experienced disease recurrence. CONCLUSIONS: Surveillance of serum p53-Abs is superior to the three tumor markers for detecting SESCC. This serum marker is also useful for the detection of p53 protein overexpression and for the monitoring of residual tumor cells.

Aged↗
PubMed2000

Synthesis and PKC isozyme surrogate binding of indothiolactam-V, a new thioamide analogue of tumor promoting indolactam-V.

To investigate the role of the amide group of (-)-indolactam-V (1) on PKC binding, we synthesized (-)-indothiolactam-V (2), a new thioamide analogue of 1, by microbial conversion using Streptomyces blastmyceticum. Compounds 2 and 1 showed similar binding affinities to conventional PKCs but 2 had lower affinities to novel PKCs, suggesting that novel PKCs recognize amide modifications more effectively than conventional PKCs.

Binding, Competitive↗
PubMed2000

AMP-Activated protein kinase is activated by the stimulations of G(q)-coupled receptors.

The AMP-activated protein kinase (AMPK) functions as a metabolic sensor that monitors cellular AMP and ATP levels. Platelet-activating factor (PAF) activates endogeneous AMPKalpha1 in Chinese hamster ovary cells expressing the PAF receptor coupled with both G(i) and G(q), but its activity was not inhibited after treatment with islet-activating protein. Norepinephrine and bradykinin also activated AMPKalpha1 in cells expressing the G(q)-coupled alpha(1b)-adrenergic receptor and bradykinin receptor, respectively. Stimulations of the G(i)-coupled alpha(2A)-adrenergic receptor, fMet-Leu-Phe receptor, prostaglandin EP3alpha receptor, and G(s)-coupled beta(2)-adrenergic receptor did not activate AMPKalpha1. AMPKalpha1 thus is activated specifically by stimulation of G(q)-coupled receptors. G(q)-coupled receptors transmit the signal for GLUT4 translocation and glucose uptake through an insulin-independent pathway. However, direct activation of AMPKalpha1 with treatment of 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside did not trigger GLUT4 translocation nor stimulate glucose uptake in our cells. Thus, activation of AMPKalpha1 via G(q) is not sufficient to trigger GLUT4 translocation or stimulate glucose uptake.

AMP-Activated Protein Kinases↗