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Biomedical subjects

K Ono

Publications and source records attributed to K Ono.

At least 109 records · Page 6Linked to original sources
PubMed2001

Angiotensin II induces inward currents in subfornical organ neurones of rats.

The action of angiotensin II on subfornical organ (SFO) neurones was studied using whole-cell current and voltage-clamp recordings in rat slice preparations. In the current-clamp mode, membrane depolarization in response to angiotensin II was accompanied by an increased frequency of action potentials and an increased membrane conductance. In the voltage-clamp mode, angiotensin II elicited inward currents in a dose-dependent manner. The net angiotensin II-induced inward currents were voltage-independent, with a mean reversal potential of -29.8 +/- 6.2 mV. Amplitudes of the angiotensin II-induced inward currents were decreased during perfusion with a low sodium medium. The angiotensin II-induced inward currents were blocked by the AT1 antagonist losartan, and were partially blocked by the AT2 antagonist PD-123319. Neurones which were sensitive to angiotensin II were found in the peripheral region of the SFO, whereas neurones in the central region were less sensitive to angiotensin II. These results suggest that angiotensin II induces inward currents, with opening of nonselective cation channels through mainly AT1 receptors in a subpopulation of SFO neurones of rats.

Angiotensin II↗
PubMed2001

cDNA cloning of the chicken branched-chain alpha-keto acid dehydrogenase complex. Chicken-specific residues of the acyltransferase affect the overall activity and the interaction with the dehydrogenase.

Branched-chain alpha-keto acid dehydrogenase complex is a macromolecule comprising three catalytic components: a dehydrogenase (E1) with alpha(2)beta(2) structure, an acyltransferase (E2) and a dihydrolipoamide dehydrogenase (E3). In the mammalian complex, the E2 component with 24 identical subunits forms a structural core, to which multiple copies of E1 and E3 bind noncovalently. We isolated cDNA clones encoding E1 alpha, E1 beta and E2 subunits from a chicken-liver cDNA library and performed nucleotide sequencing. Amino-acid sequences deduced from the nucleotide sequences revealed that chicken E1 alpha and E1 beta chains had substantially homologous sequences with the corresponding mammalian polypeptides, except for the N-terminus. Chicken E2 conserved three functional domains, a lipoyl-bearing domain, an E1/E3 binding domain and an inner-core domain, but contrasted strongly with mammalian E2 in respect of containing 11 additional residues in two interdomain linkers: nine sequential residues in one linker and two residues in the other. Replacement of many residues was also observed in the chicken linkers. When E2 activity for catalyzing the overall reaction was measured by activity reconstitution in combination with E1 and E3, chicken E2 was markedly less effective than mammalian E2. The capability of chicken E2 for binding E1 was also reduced when determined by the binding assay using sucrose density gradient centrifugation. Chicken E1 was functionally as well as structurally indistinguishable from mammalian E1. Thus the reduced catalytic activity of chicken E2 must arise from its reduced E1-binding capacity, which results from the characteristic structure of interdomain linkers in chicken E2.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed2001

Successful primary reinforced repair of esophageal perforation using a pedicled omental graft through a transhiatal approach.

Esophageal perforation is potentially lethal if untreated. We report a case of distal esophageal perforation probably caused by swallowing a fish bone. The patient initially received conservative treatment 4 days after the esophageal injury. The treatment was promptly changed from conservative to operative treatment owing to rapid manifestation of suppurative mediastinitis followed by peritonitis. The patient successfully underwent primary repair of the perforation buttressed with a pedicled omental graft pulled up through the esophageal hiatus following a laparotomy. We discuss the validity of this method of transhiatal approach without thoracotomy for primary repair of distal esophageal perforation.

Aged↗
PubMed2001

LST-2, a human liver-specific organic anion transporter, determines methotrexate sensitivity in gastrointestinal cancers.

BACKGROUND & AIMS: One approach to the development of targeted cancer chemotherapy exploits increased uptake of the agent into neoplastic cells. In this scenario, higher concentrations of the agent in cancer cells are responsible for differential killing, whereas the low concentration in normal human cells decreases side effects. The aim of this study was to isolate an organic anion transporter that is weak in normal cells, but abundantly expressed in cancer cells, to deliver the anticancer drugs to the cells. METHODS: A human liver complementary DNA (cDNA) library was screened with liver-specific transporter (LST)-1 cDNA as a probe. Northern blot analyses were performed using the isolated cDNA (termed LST-2). An LST-2-specific antibody was raised, and immunohistochemical analyses including immunoelectron microscopy were performed. Xenopus oocyte expression system was used for functional analysis. We also established a permanent cell line that consistently expresses LST-2 to examine the relationship between methotrexate uptake and sensitivity. RESULTS: The isolated cDNA, LST-2, has 79.7% of overall homology with human LST-1. LST-2 exclusively expressed in the liver under normal conditions and its immunoreactivity was highest at the basolateral membrane of the hepatocytes around the central vein. Although its weak expression in the liver, LST-2 is abundantly expressed in the gastric, colon, and pancreatic cancers. On the other hand, the LST-1 was only detected in a hepatic cell line. LST-2 transports methotrexate in a saturable and dose-dependent manner. Furthermore, introduction of the LST-2 gene into mammalian cells potentiates sensitivity to methotrexate. CONCLUSIONS: LST-2 is one of the prime candidate molecules for determining methotrexate sensitivity and may be a good target to deliver anticancer drugs to the gastrointestinal cancers.

Amino Acid Sequence↗
PubMed2001

Laparoscopic adhesiolysis for recurrent small bowel obstruction: long-term follow-up.

BACKGROUND: Recurrent small bowel obstruction caused by postoperative adhesions has traditionally been treated by conventional laparotomy, but laparoscopic management of acute small bowel obstruction has been reported. The aim of this study was to assess the long-term efficacy and clinical outcome of laparoscopic adhesiolysis for recurrent small bowel obstruction. METHODS: After conservative treatment, elective laparoscopic treatment was attempted in 17 patients hospitalized for recurrent small bowel obstruction after abdominal or pelvic surgery. RESULTS: Postoperative adhesions were identified laparoscopically in all patients. Laparoscopic treatment was possible in 14 patients (82.4%). Conversion to laparotomy was required for 3 patients (17.6%) because of intestinal perforation (n = 1) or a convoluted mass of adherent bowel (n = 2). Long-term follow-up was possible in 16 patients. Two recurrences of small bowel obstructions were noted over a mean follow-up period of 61.7 months. CONCLUSIONS: Laparoscopic adhesiolysis is a safe and effective treatment for recurrent small bowel obstruction. Conversion to laparotomy should be considered in patients with dense adhesions.

Feasibility Studies↗
PubMed2001

Experimental evaluation of photocrosslinkable chitosan as a biologic adhesive with surgical applications.

BACKGROUND: In various surgical cases, effective tissue adhesives are required for both hemostasis (eg, intraoperative bleeding) and air sealing (eg, thoracic surgery). We have designed a chitosan molecule (Az-CH-LA) that can be photocrosslinked by ultraviolet (UV) light irradiation, thereby forming a hydrogel. The purpose of this work was to evaluate the effectiveness and safety of the photocrosslinkable chitosan hydrogel as an adhesive with surgical applications. METHODS: The sealing ability of the chitosan hydrogel, determined as a bursting pressure, was assessed with removed thoracic aorta, trachea, and lung of farm pigs and in a rabbit model. The carotid artery and lung of rabbits were punctured with a needle, and the chitosan hydrogel was applied to, respectively, stop the bleeding and the air leakage. In vivo chitosan degradability and biologic responses were histologically assessed in animal models. RESULTS: The bursting pressure of chitosan hydrogel (30 mg/mL) and fibrin glue, respectively, was 225 +/- 25 mm Hg (mean +/- SD) and 80 +/- 20 mm Hg in the thoracic aorta; 77 +/- 29 mm Hg and 48 +/- 21 mm Hg in the trachea; and in the lung, 51 +/- 11 mm Hg (chitosan hydrogel), 62 +/- 4 mm Hg (fibrin glue, rubbing method), and 12 +/- 2 mm Hg (fibrin glue, layer method). The sealing ability of the chitosan hydrogel was stronger than that of fibrin glue. All rabbits with a carotid artery (n = 8) or lung (n = 8) that was punctured with a needle and then sealed with chitosan hydrogel survived the 1-month observation period without any bleeding or air leakage from the puncture sites. Histologic examinations demonstrated that 30 days after application, a fraction of the chitosan hydrogel was phagocytosed by macrophages, had partially degraded, and had induced the formation of fibrous tissues around the hydrogel. CONCLUSIONS: A newly developed photocrosslinkable chitosan has demonstrated strong sealing ability and a great potential for use as an adhesive in surgical operations.

Animals↗
PubMed2001

Enhancement of oxidative damage to cultured cells and Caenorhabditis elegans by mitochondrial electron transport inhibitors.

The mechanisms that lead to mitochondrial damage under oxidative stress conditions were examined in primary and cultured cells as well as in the nematode Caenorhabditis elegans (C. elegans) treated simultaneously with electron transport inhibitors and oxygen gas. Oxygen loading enhanced the damage of PC 12 cells by thenoyltrifluoroacetone (TTFA, a complex II inhibitor), but did not by rotenone (a complex I inhibitor), antimycin (a complex III inhibitor), and sodium azide (a complex IV inhibitor). In primary hepatocytes, the enhancement was observed with the addition of sodium azide and rotenone, but not by TTFA or antimycin. In the nematode, only rotenone and TTFA enhanced the sensitivity under hyperoxia. These results demonstrate that highly specific inhibitors of electron transport can induce oxygen hypersensitivity in cell levels such as PC 12 cells and primary hepatocytes, and animal level of C. elegans. In addition the cell damage is different dependent on cell type and organism.

Animals↗
PubMed2001

Are contents of Rubisco, soluble protein and nitrogen in flag leaves of rice controlled by the same genetics?

Genetic relations among the contents of Rubisco, soluble protein and total leaf nitrogen (N) in leaves of rice (Oryza sativa L.) were studied by quantitative trait loci (QTL) analysis with a population of backcross inbred lines (BILs) of japonica Nipponbarexindica Kasalath. The ratio of Rubisco to total leaf N in leaves is the main target in improving photosynthetic N-use efficiency in plants. QTLs controlling Rubisco content were not detected near QTLs for total leaf N content. These results indicate that contents of Rubisco and total leaf N are controlled by different genetics. QTLs that controlled the ratio of Rubisco to total leaf N (CORNs) were detected. These results suggest that some mechanism(s) may be involved in determining this ratio, while the contents of Rubisco and total leaf N are controlled in other ways. In elite BILs, the ratios of Rubisco to total leaf N were higher than those of both parents. These results suggest a good possibility of improving N-use efficiency by CORNs in cultivated rice. A QTL controlling Rubisco content was mapped near a QTL for soluble protein content on chromosome 8 at 5 d after heading and on chromosome 9 at 25 d. In each chromosome region, the peaks of both QTLs overlapped accurately, giving a high possibility of pleiotropic effects by the same genes. Different QTLs controlling soluble protein or Rubisco were detected from those detected at 5 d or 25 d after heading. This suggests that these traits are genetically controlled depending on the growth stages of leaves.

Chromosome Mapping↗
PubMed2001

Budding of fowlpox and pigeonpox viruses at the surface of infected cells.

Chick embryo fibroblasts and chorioallantoic membranes infected with fowlpox virus (FWPV) or pigeonpox virus (PPV) were examined by transmission and scanning electron microscopy. Immature virus particles were observed in finely granular areas, i.e. virus factories, of the cytoplasm. These particles had various forms depending on their stages of development. Many tubular structures were also seen in these regions. Mature virus particles with ellipsoidal or brick-shaped forms enclosing electron-dense cores were detected throughout the cytoplasm. Notably, there was a high frequency of virus budding at the cell surface, but only occasional virus wrapping in the cytoplasm. Another remarkable feature of the infected cells was accumulation of many virions just beneath the plasma membrane, indicating that this phenomenon is closely related to virus budding. Based on the observed frequency of budding, this mechanism seems to be the predominant way for FWPV and PPV to exit the cell.

Animals↗
PubMed2001

Protamine-modified DDAB lipid vesicles promote gene transfer in the presence of serum.

Cationic lipid vesicle-mediated gene transfer has become common for in vitro gene delivery. However, the transfection efficiency is often impaired by serum. DDAB (dimethyldioctadecyl ammonium bromide) lipid vesicle-mediated gene transfer, which we previously reported, has the same problem. To overcome this obstacle, we here report a novel transfection vehicle using protamine-modified DDAB lipid vesicles. While free protamine was simply added to the DNA/lipid complex in the previous study, in the present method the protamine is chemically conjugated to stearic acid and incorporated into DDAB lipid vesicles. Gene transfer was not significantly inhibited in 10% serum-containing medium by this method for the transfection of cultured cells. Protamine-modified DDAB lipid vesicles also enhanced virus transduction efficiency in the presence of serum using a replication-defective retroviral vector. Furthermore, the vesicles allowed efficient gene transfer for avian embryos in vivo. These results indicate that the method is useful for the production of transgenic animals and gene therapy.

3T3 Cells↗
PubMed2001

High level expression of C4-specific NADP-malic enzyme in leaves and impairment of photoautotrophic growth in a C3 plant, rice.

The chloroplastic NADP-malic enzyme (NADP-ME) is a key enzyme of the C4 photosynthesis pathway in NADP-ME type C4 plants such as maize. To express the chloroplastic NADP-ME in leaves of a C3 plant, rice, full-length cDNAs encoding the rice C3-specific isoform and the maize C4-specific isoform of the enzyme were expressed under the control of the rice CAB: promoter. Transformants carrying the rice cDNA showed the NADP-ME activities in the leaves less than several-fold that of non-transformants, while those carrying the maize cDNA showed activities up to 30-fold that of non-transformants or about 60% of the NADP-ME activity of maize leaves. These results indicate that expression of the rice C3-specific NADP-ME is suppressed at co- and/or post-transcriptional levels by some regulation mechanisms intrinsic to rice, while that of the foreign C4-specific isoform can escape from such suppression. The accumulation of the maize C4-specific NADP-ME led to bleaching of leaf color and growth hindrance in rice plants under natural light. These deteriorative effects resulted from enhanced photoinhibition of photosynthesis due to an increase in the level of NADPH inside the chloroplast by the action of the maize enzyme.

Gene Expression↗
PubMed2001

Antisense expression of a rice sucrose transporter OsSUT1 in rice (Oryza sativa L.).

We analyzed the function of a rice sucrose transporter, OsSUT1, by using antisense rice. There was no difference between antisense and wild-type plants in carbohydrate content and photosynthetic ability of the flag leaves in the vegetative growth stage, suggesting that OsSUT1 may not play an important role in carbon metabolism, at least in these materials.

Base Sequence↗
PubMed2001

Analysis and comparison of reflex times and electromyograms of cervical muscles under impact loading using surface and fine-wire electroces.

Myoelectric signals [electromyograms (EMGs)] can be collected using either surface or fine-wire electrodes. Application of the latter results in higher-frequency contents of EMG. In the field of impact biomechanics, surface electrodes are more often utilized than fine-wire ones. However, the removal of motion artefacts from EMG recorded under transient loads requires application of high-pass filters with relatively high cutoff frequencies, which may eliminate a significant part of the surface EMG power spectra. Therefore, in the current study, both surface and fine-wire electrodes were utilized to record the EMG of cervical muscles under conditions simulating a rear-end car collision at low speed. The results indicated that application of high-pass filtering at 50 Hz can be necessary to remove motion artefacts from the EMG collected under such conditions. Such filtering resulted in a higher decrease in amplitude of the surface EMG than that of the fine-wire one. However, the reflex times obtained here were not significantly affected by the type of the electrodes utilized to collect EMG.

Artifacts↗
PubMed2001

Evaluation of the potential of p-boronophenylalaninol as a boron carrier in boron neutron capture therapy, referring to the effect on intratumor quiescent cells.

C57BL mice bearing EL4 tumors and C3H / He mice bearing SCC VII tumors received 5-bromo-2'-deoxyuridine (BrdU) continuously for 5 days via implanted mini-osmotic pumps to label all proliferating (P) cells. Three hours after oral administration of l-p-boronophenylalanine-(10)B (BPA), or 30 min after intraperitoneal injection of sodium borocaptate-(10)B (BSH) or l-p-boronophenylalaninol (BPA-ol), a newly developed (10)B-containing alpha-amino alcohol, the tumors were irradiated with thermal neutron beams. For the combination with mild temperature hyperthermia (MTH) and / or tirapazamine (TPZ), the tumors were heated at 40 degrees C for 30 min immediately before neutron exposure, and TPZ was intraperitoneally injected 30 min before irradiation. The tumors were then excised, minced and trypsinized. The tumor cell suspensions thus obtained were incubated with cytochalasin-B (a cytokinesis blocker), and the micronucleus (MN) frequency in cells without BrdU labeling ( = quiescent (Q) cells) was determined using immunofluorescence staining for BrdU. Meanwhile, 6 h after irradiation, tumor cell suspensions obtained in the same manner were used for determining the apoptosis frequency in Q cells. The MN and apoptosis frequency in total (P + Q) tumor cells were determined from tumors that were not pretreated with BrdU. Without TPZ or MTH, BPA-ol increased both frequencies most markedly, especially for total cells. However, as with BPA, the sensitivity difference between total and Q cells was much larger than with BSH. On combined treatment with both MTH and TPZ, this sensitivity difference was markedly reduced, similarly to when BPA was used. MTH increased the (10)B uptake of all (10)B-compounds into both tumor cells. BPA-ol has good potential as a (10)B-carrier in neutron capture therapy, especially when combined with both MTH and TPZ.

Administration, Oral↗
PubMed2001

[Isolation and incidence of Cryptosporidium and Giardia from river water].

A study was conducted during the period from July to October in 1999, surface water samples were collected from 13 rivers in Hyogo Prefecture serving as tap water sources and examined for Cryptosporidium oocysts and Giardia cysts using the immunomagnetic separation method. In 9 (69%) of the 13 rivers, Cryptosporidium oocyst was detected. Giardia cyst was detected in 5 (38%) of the 13 rivers. The Cryptosporidium oocyst positive rate was comparable to that of fecal bacteriological indicators, which was also examined and detected in 10 (77%) of 13 rivers. Water samples were collected at 69 points in the 13 rivers. Cryptosporidium parvum oocyst was detected at 38 (55%) of the 69 points, demonstrating widely spread contamination. Comparing 3 areas which were divided on the basis of agricultural circumstance as well as geographical locating, the Cryptosporidium positive rate varied widely according to the area, ranging from 37% to 100%. To elucidate the reason for these differences, the relationship between positive rate and the species and number of livestock animals raised in each respective region was investigated. The results showed a strong correlation (r = 0.91) between the number of raised cattle and contamination with the rate of Cryptosporidium in each area. Furthermore, genetic analysis by PCR-restriction fragment length polymophism method revealed that C. parvum oocyst detected in the rivers studied was the bovine type, probably indicating that the oocyst was excreted from the cattle in the river basins. The degree of contamination with Cryptosporidium in river water was comparable to that of fecal bacteriological indicators, suggesting the possibility that fecal bacteriological indicators examination might be used as a criterion of Cryptosporidium contamination.

Animals↗
PubMed2001

Contamination of river water by Cryptosporidium parvum oocysts in western Japan.

In Japan, only a few rivers have been inspected for Cryptosporidium parvum contamination, and the methods used had low sensitivity. In 1998 and 1999, we used a method with higher sensitivity to examine all large rivers used as sources of water supply in one prefecture (which we divided into four areas) in western Japan for Cryptosporidium oocysts. One sample was collected at each of 156 sites along 18 rivers, and samples were tested for Cryptosporidium oocysts by immunomagnetic separation. Samples were classified as being obtained on an island with livestock and fishing industries, a densely populated urban area, a western region including farming villages, or a still more rural northern area with agriculture and fishing. Restriction fragment length polymorphism analysis was used for identification of the C. parvum found as the bovine or human type. C. parvum was detected in at least one sample from 13 of the 18 rivers and in 47% (74 of 156) of the samples. One-third to all of the samples from each area contained C. parvum oocysts. The number of C. parvum oocysts per 20 liters of river water varied in the same pattern as the number of cattle kept in the four kinds of areas (as determined by the Mantel extension test). Oocysts isolated were of the bovine type; the C. parvum detected in rivers probably came from cattle kept in that valley. As we had expected, when tested with a more sensitive method, river water in western Japan was found to be greatly contaminated with C. parvum oocysts, as reported in other countries.

Animals↗
PubMed2001

Resistance to tumor necrosis factor-induced cell death mediated by PMCA4 deficiency.

We used retrovirus insertion-mediated random mutagenesis to generate tumor necrosis factor (TNF)-resistant lines from L929 cells. Using this approach, we discovered that the plasma membrane calcium ATPase 4 (PMCA4) is required for TNF-induced cell death in L929 cells. Under basal conditions, PMCA4-deficient (PMCA(mut)) cells have a normal phenotype. However, stimulation with TNF induces an abnormal increase in the intracellular calcium concentration ([Ca(2+)](i)). The substantially elevated [Ca(2+)](i) caused resistance to TNF-induced cell death. We found that an increase in the total volume of acidic compartments (VAC), mainly constituted by lysosomes, is a common event in cell death caused by a variety of agonists. The increased [Ca(2+)](i) in PMCA(mut) cells promoted lysosome exocytosis, which, at least in part, accounted for the inhibition of TNF-induced increase in VAC and cell death. Promoting lysosome exocytosis by calcium inhibited TNF-induced cell death in wild-type L929 cells, while inhibition of lysosome exocytosis or increase of VAC by sucrose restored the sensitivity of PMCA(mut) cells to TNF-induced cell death. Thus, increase of the volume of acidic compartment is a part of the cell death process, and the antideath effect of calcium is mediated, at least in part, by inhibition of the TNF-induced increase in VAC.

Animals↗