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Biomedical subjects

M Okamoto

Publications and source records attributed to M Okamoto.

At least 433 records · Page 24Linked to original sources
PubMed1997

[Circadian chemotherapy in cancer patients].

Continuous infusion of 5-FU at night was performed for four patients: three had liver metastasis (one with gastric cancer and two with rectal cancer) and one had local recurrence of rectal cancer. The chemotherapy schedule was 400 mg/m2/day 5-FU intraarterial or intravenous infusion from 6:00 p.m. to 6:00 a.m. for five days repeated every 3 weeks. There were one complete response, two partial responses and one with no change. It is expected that the chemotherapy of 5-FU at night will result in a high efficacy and lower toxicity.

Adult↗
PubMed1997

Toward a virtual-labo-system for metabolic engineering: development of biochemical engineering system analyzing tool-kit (BEST-KIT).

BEST-KIT is an efficient and user-friendly "biochemical engineering system analyzing tool-kit" integrated the following key modules: 1) mathematical modeling and editing of reaction-scheme, 2) automatic derivation of differential equations, 3) numerical calculation, 4) nonlinear optimization, 5) visualization, 6) retrieve the information on reaction mechanism and kinetic parameters from data-base of metabolic pathways. The users of this simulator are assumed to be unfamiliar with computer technology and with computer programming. The integrated interface (UNIX version) is based on Xlib, XToolkit and OSF/Motif Widget.

Biochemistry↗
PubMed1996

Effect of transfected interleukin-6 in non-tumorigenic and tumorigenic rat urothelial cell lines.

It has been suggested that interleukin (IL)-6 plays a significant role in bladder carcinomas. We conducted the present experiment to determine whether over-expressed IL-6 enhanced the tumorigenicity of a weakly tumorigenic rat bladder carcinoma, and whether it was sufficient to induce a tumorigenic phenotype in a non-tumorigenic, anchorage-dependent rat urothelial cell line, MYP3. P3M6-10 and P3M6-12 (anchorage-independent but non-tumorigenic) and MYP3T6 (anchorage-independent and tumorigenic) were isolated from MYP3 after treatment with MNU in vitro. None of these clones produced IL-6. The cells were transfected with an expression vector containing human IL-6 cDNA. The transfectants secreted a large amount of IL-6. In MYP3T6, over-expression of IL-6 enhanced tumorigenicity markedly in nude mice, as evidenced by acceleration of the growth rate in vivo as well as of anchorage-dependent and -independent growth. In P3M6-10 and P3M6-12, the introduced IL-6 cDNA markedly enhanced their growth potential, both on a plastic surface and in soft agar, but did not induce a tumorigenic potential. In MYP3, introduced IL-6 weakly enhanced their growth on a plastic surface, but caused neither tumorigenesis in nude mice nor colony formation in soft agar. Expression of gp130, an IL-6 signal transducer, was increased in IL-6-expressing clones, especially in the P3M6-10 and MYP3T6. We conclude that acquisition of the ability to synthesize endogenous IL-6 markedly accelerates the growth rate of weakly tumorigenic rat urothelial cells, but is not sufficient to induce a tumorigenic phenotype in non-tumorigenic cells.

Animals↗
PubMed1996

Fish testicular 11beta-hydroxylase: cDNA cloning and mRNA expression during spermatogenesis.

We isolated and characterized a cDNA encoding testicular 11beta-hydroxylase, cytochrome P450(11beta) from the Japanese eel (Anguilla japonica) testis. The cDNA contains an open reading frame that encodes a protein of 511 amino acids. The predicted amino acid sequence shares 38-48% homology with those of adrenal P450(11beta) from mammals and frog. Transient expression in COS 1 cells confirmed that the protein encoded by this cDNA had P450(11beta) activity. Northern blotting revealed a single 1.8 kb long transcript of P450(11beta). This transcript was not found in immature eel testes prior to an injection with human chorionic gonadotropin (hCG), but it was present in eel testes after hCG injection.

Amino Acid Sequence↗
PubMed1996

Transformation in vitro of a nontumorigenic rat urothelial cell line by hydrogen peroxide.

Chronic infection/inflammation of the urinary tract is a significant risk factor for the development of bladder cancer. The present study examined the hypothesis that hydrogen peroxide (H202) and cytokines released during inflammation are involved in the enhancement of bladder carcinogenesis. Using growth in soft agar and tumorigenicity in athymic nude mice as indices of transformation, we examined the effect of H202 and cytokines on the enhancement of N-methyl-N-nitrosourea (MNU)-initiated transformation of MYP3 cells, an anchorage-dependent nontumorigenic rat bladder epithelial cell line. MYP3 cells pretreated with or without MNU were exposed to H202 (0.001 to 0.1 mM) daily for 1 week in monolayer culture and were then tested for growth in soft agar. A marked increase in colony numbers was observed in the cells that were MNU-initiated and exposed to H202 (P < 0.01). Furthermore, H202 exposure alone at 0.01 mM or 0.1 mM caused colony formation in soft agar. The transformants induced by MNU plus H202 or H202 alone formed high-grade transitional cell carcinomas when injected into nude mice. The growth of these transformants was stimulated by several cytokines (interleukin 1alpha, interleukin 6, and tumor necrosis factor-alpha) better than the parental cells both on a plastic surface and in soft agar. Our results indicate that H202 causes genetic change(s) to induce tumorigenic conversion in urothelial cells and that the transformants are stimulated to grow because of their selective response to several cytokines. We suggest that these mechanisms may be involved in the in vivo carcinogenesis associated with chronic urinary tract infection.

Animals↗
PubMed1996

Geranylgeraniol causes a decrease in levels of calreticulin and tyrosine phosphorylation of a 36-kDa protein prior to the appearance of apoptotic features in HL-60 cells.

It was demonstrated recently that geranylgeraniol (GGO) has potent apoptosis-inducing activity in various lines of tumor cells, including HL-60 cells. In the present study, we found that GGO markedly inhibited the expression of a calcium-binding protein, calreticulin, prior to the induction of apoptosis in HL-60 cells. Furthermore, we also observed a significant decrease in the tyrosine phosphorylation of a 36-kDa protein that is a major tyrosine-phosphorylated protein in HL-60 cells. These findings suggest that decreases in levels of calreticulin and in the tyrosine phosphorylation of the 36-kDa protein might be associated with the induction of apoptosis by GGO in HL-60 cells.

Amino Acid Sequence↗
PubMed1996

Human group II phospholipase A2 in normal and diseased intervertebral discs.

We measured calcium-dependent phospholipase A2 (PLA2) activity and immunoreactive group II PLA2 levels of 54 normal discs obtained from cadavers and 73 disc samples surgically obtained from patients with spinal disorders, including intervertebral disc herniations, spondylosis, and spondylolisthesis. Both cadaveric and surgical disc specimens contained about two-fold greater PLA2 activity than the ileal mucosa, one of the richest sources of group II PLA2. Discs of middle-aged cases had significantly higher activity than those of younger and elder cases. In cadaveric normal discs, calcium-dependent PLA2 activity was significantly higher in females than in males. Annulus fibrosus and nucleus pulposus contained the same PLA2 levels. In diseased disc, herniated fragments that had extruded or protruded out of the discs possessed lower activity than other parts of discs in the intervertebral space. Immunoreactive group II PLA2 levels of intervertebral discs closely correlated with PLA2 enzymatic activity. We purified a PLA2 from human intervertebral disc to homogeneity to further identify the isozymic nature of discal PLA2. Its NH2-terminal amino acid sequences and molecular weight were identical to those of human group II PLA2. Immunohistochemical analysis using a monoclonal anti-group II PLA2 antibody showed that in both annulus fibrosus and nucleus pulposus chondrocytes contained intense group II PLA2 immunoreactivity in their cytoplasm, and that the matrix contained no substantial immunoreactivity. These results suggest that group II PLA2 in chondrocytes has important physiological roles in discal ordinary metabolism, maintaining discal homeostasis.

Adolescent↗
PubMed1996

Effect of endogenous hypergastrinemia on carcinogenesis in the rat esophagus.

We surgically prepared a hypergastrinemia model in rats and studied the effects of hypergastrinemia on chemically induced carcinogenesis in the esophagus. Operations were performed on 5-week-old male Donryu rats as follows: (1) truncal vagotomy plus pyloroplasty (group V), (2) segmental gastrectomy plus pyloroplasty (group G), (3) antrectomy (group A), and (4) no operation (group C) as a control. From the age of 6 weeks, the animals were given 0.003% N-methyl- N-amylnitrosamine (MAN) solution as drinking water for 8 weeks. After 20 weeks of MAN administration, the animals were bled and killed. The average serum gastrin levels in groups V and G were significantly higher than those groups C or A. There were significant differences between C and V in the incidence of carcinoma, and between V and A in the incidence of carcinoma including severe dysplasia. The incidence of histologically identified lesions per animal was determined, and significant differences were observed between C and both V and G in the incidence of carcinoma including severe dysplasia. Furthermore, we also detected gastrin receptors in the esophageal lesions produced by the oral administration of MAN to rats. The results of the present study suggest that endogenous hypergastrinemia has a positive influence on chemically induced carcinogenesis in the rat esophagus.

Animals↗
PubMed1996

Insulin-induced activation of phosphoinositide 3-kinase in Fao cells.

Phosphoinositide 3-kinase (PI3-kinase) plays a crucial role in insulin signal transduction. We studied the molecular mechanism of the insulin-induced activation of PI3-kinase in rat hepatoma Fao cells using an antibody against the 110-kDa catalytic subunit (p110) and two against the 85-kDa regulatory subunit (p85 alpha). PI3-kinase activity increased 1.6-fold in anti-p85 immunoprecipitates after insulin stimulation, whereas it did not increase when cell lysates were first immunoprecipitated with anti-phosphotyrosine or anti-insulin receptor substrate-1 (IRS-1), then with anti-p85, suggesting that the PI3-kinase which associates with tyrosyl phosphoproteins including IRS-1 is responsible for the increase in kinase activity. The activated PI3-kinase molecules constituted 4-6% of the total PI3-kinase, and their specific activity was 11-14 times higher than that of the basal state. Anti-p110 recognized the catalytically active form of p110, and immunoprecipitated p110 only after exposure to insulin. Hence, the epitope of anti-p110, P200-C215, seems to be included in the portion of p110, the conformation of which is changed by insulin stimulation. We conclude that, in response to insulin stimulation, only a small fraction of p85 in the PI3-kinase pool associates with tyrosyl phosphoproteins including IRS-1, and that the specific activity of p110 is increased presumably through a conformational change including the P200-C215 region.

Animals↗
PubMed1996

Pancreaticobiliary maljunction-associated pancreatitis: an experimental study on the activation of pancreatic phospholipase A2.

Congenital dilatation of the bile duct (CDBD), or choledochalcyst, is often complicated by recurrent pancreatitis. Reflux of pancreatic juice into the bile duct through pancreaticobiliary maljunction (PBM), an anomaly commonly associated with CDBD, and ensuing activation of pancreatic enzymes could be involved in the pathophysiologic mechanism of recurrent pancreatitis. A study was undertaken to follow the time course of the activity of phospholipase A2 (PLA2) in animal models of PBM. The assay procedures for PLA2 were evaluated, as were the conditions for separating the active enzyme from its inactive proenzyme (pro-PLA2) by immunoblotting. A rat model was designed according to Block's method with some modifications. The kinetics of prophospholipase A2 (proPLA2) activation in bile was examined by measuring PLA2 activity and by immunoblotting using anti-rat pancreatic enzyme antibody after separating PLA2 from its zymogen under nonreducing conditions. Experimental animals were divided into three groups: group 1 (PBM group) in which bile and pancreatic juice were mixed with occlusion of the papilla; group 2, in which the papilla and hepatic hillus were occluded without mixing the two juices; and group 3, in which simple laparotomy was done. In group 1 animals, pro-PLA2 in bile was activated to its active form. In group 2 animals, where proPLA2 was predominant, there was only slight elevation of PLA2 activity in bile. In group 1 an immunohistologic study demonstrated localization of PLA2 around necrotic foci in the pancreatic parenchyma. These results suggest the involvement of activated PLA2 in the pathogenesis of choledochal cystassociated pancreatitis.

Animals↗
PubMed1996

Flexibacter japonensis sp. nov., a new species that produces a novel inhibitor of human leukocyte elastase isolated from soil.

This strain 758 of a new member of Flexibacter species isolated from a soil is a Gram-negative, nonflagellated, gliding, long rod or filamentous. The GC contents of the deoxyribonucleic acid of this strain is 49.8 mol %GC. The isolate can be distinguished from other Flexibacter species on the basis of physiological and biochemical properties and DNA relatedness data. Therefore, we propose a new species, Flexibacter japonensis, for this strain. The strain 758 is deposited to the Japan Collection of Microorganisms as JCM 9735.

Bacteroidetes↗
PubMed1996

Complete inhibition of viral breakthrough by combination of MKC-442 with AZT during a long-term culture of HIV-1 infected cells.

We have investigated viral breakthrough during a long-term culture of HIV-1-infected cells with the non-nucleoside reverse transcriptase inhibitors (NNRTIs) 6-benzyl-1-ethoxymethyl-5-isopropyluracil (MKC-442), nevirapine and loviride (alpha-APA). When the compounds were examined for their inhibitory effects on HIV-1 (HE strain) replication in MT-4 cells on day 4 after virus infection, the 50% effective concentrations (EC50) of MKC-442, nevirapine and loviride were 9.4, 98 and 21 nM, respectively. After a 48-day culture period, MKC-442, nevirapine and loviride completely inhibited viral breakthrough at concentrations of 1, 5 and 1 microM, respectively. These concentrations were 50-100-fold higher than their EC50 values. When the cells were treated with either MKC-442 (0.04 and 0.2 microM), nevirapine (0.2 and 1 microM) or loviride (0.04 and 0.2 microM) in combination with AZT (0.005 microM), only the combination of 0.2 microM MKC-442 with 0.005 microM AZT could completely inhibit the breakthrough of HIV-1 after a 68-day culture period. Polymerase chain reaction (PCR) analysis revealed that no proviral DNA was detected in the cells treated with this combination. Except for two combinations (0.04 microM MKC-442 + 0.005 microM AZT and 0.04 microM loviride + 0.005 microM AZT), all of the viruses isolated during combination treatments had various amino acid mutations in their reverse transcriptase (RT). These results indicate that the combination treatment with a relatively high dose of MKC-442 and a low dose of AZT may have potential to suppress the emergence of drug resistance during a long-term treatment in vivo and should be further pursued in HIV-1-infected patients.

Acetamides↗
PubMed1996

Production of recombinant SERA proteins of Plasmodium falciparum in Escherichia coli by using synthetic genes.

We expressed two regions of the serine repeat antigen (SERA) protein of Plasmodium falciparum in Escherichia coli by synthesizing the genes with a changed codon usage. One of the synthetic gene sequences encodes amino acid residues 17-382 (SE47') and the other encodes amino acid residues 586-802 (SE50A). The products produced by the synthetic gene sequences in E. coli accounted for 15-30% of the total bacterial protein. Antisera against both the purified gene products prepared in rats inhibited malaria parasite growth in vitro. The anti-SE47' serum was significantly more inhibitory than the anti-SE50A serum. The described methods provide a large scale preparation of recombinant antigens for improving and producing malaria vaccine.

Amino Acid Sequence↗
PubMed1996

Effect of transcranial Doppler intensity on successful recording in Japanese patients.

The major limitation of transcranial Doppler sonography (TCD) is the failure to obtain data for all patients. The purpose of this study was to determine in detail the effect of increasing ultrasonic acoustic intensity on the rate of successful recording of intracranial blood velocity signals. The study was performed in 239 Japanese patients using a 2-MHz range-gated, pulsed-wave TCD. The middle cerebral artery flow signals were recorded at 76, 152, 228, 304, 380, 456 and 532 mW/cm2 and the results analyzed by age, gender and intensity. The rate of successful recording showed significant increase with the ultrasonic intensity in both genders (45.7% at 76 mW/cm2 vs. 81.1% at 532 mW/cm2 in males and 29.5% vs. 60.7% in females). However, recording was only successful in 54% of aged (50-89 gamma) female patients at the highest ultrasonic intensity used. It should be possible to significantly increase TCD usefulness in an aging Japanese population by further increasing TCD acoustic intensity within safety limitation.

Adult↗
PubMed1996

Trimming a tether: a simple way to prevent complications related to tethered ureteral stents.

PURPOSE: A method to prevent complications related to a tethered ureteral stent was assessed. MATERIALS AND METHODS: In 17 male patients tethers were trimmed just short of the meatus after insertion of a ureteral stent. At stent removal a rigid cystoscope was inserted into the anterior urethra, and the edge of the tether was grasped with foreign body forceps. RESULTS: Only 1 patient required removal of the tether due to severe urethral discomfort. Pain at cystoscopy for removal of the ureteral stent was minimal. CONCLUSIONS: This method is useful for improving the quality of life during the catheterization period without decreasing effectiveness of a conventional ureteral stent with a tether.

Adult↗
PubMed1996

Lengthening of the forearm by callus distraction.

Ten patients aged 3 to 13 years (mean, 9 years and 7 months) underwent forearm lengthening by callotasis. The indications for lengthening were shortening and/or deformity of the forearm due to exostosis of the distal ulna in five cases, enchondroma of the distal ulna in one, growth disturbance after fracture of the distal radius in one, radial club hand in one, congenital amputation of the forearm in one and congenital dislocation of the radial head in one. Four had lengthening of the ulna, one of the radius and five of both the radius and the ulna. The average lengthening achieved was 30 mm. Complications encountered were pin track discharge in three cases, callus fracture in five, delayed consolidation of the callus in one and no callus formation in one. Review after 1 to 7 years follow-up (with a mean of 4 years and 9 months) showed satisfactory improvement in appearance and function especially in patients who had tumorous conditions or traumatic epiphyseal arrest.

Adolescent↗