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Biomedical subjects

H Akagi

Publications and source records attributed to H Akagi.

At least 73 records · Page 4Linked to original sources
PubMed1996

A codominant DNA marker closely linked to the rice nuclear restorer gene, RF-1, identified with inter-SSR fingerprinting.

A new molecular marker (OSRRf) closely linked to the nuclear restorer gene (Rf-1) for fertility in rice has been found. The Rf-1 gene is essential for hybrid rice seed production. A PCR-fingerprinting technique using simple sequence repeats (SSRs) was applied to compare two near-isogenic lines with (MTC-10R) or without (MTC-10A) the Rf-1 gene. Of 76 inter-SSR primers tested, only one primer, (AG)8YC, generated polymorphisms. The tetranucleotide repeats generating polymorphisms were found within each amplicon. the genetic distance between OSRRf and Rf-1 was 3.7 +/- 1.1 cM. As in the case of a codominant marker, this marker will be applied not only to breeding both restorer lines and maintainer lines, but also to the purity management of hybrid rice seeds.

Aldehyde Dehydrogenase↗
PubMed1996

[Sedation with flunitarazepam at magnetic resonance imaging in the elderly patients with dementia].

Magnetic resonance imaging (MRI) of the brain is useful in diagnosing senile dementia, but to avoid the creation of artifacts the patient should be kept immobile. We studied the effects of pretreatment with flunitrazepam, a sleep inducer of the benzodiazepine class, as a sedative prior to imaging. The subjects consisted of 108 patients with senile dementia admitted to the Dementia Ward of Kyoto Higashiyama Geriatric Hospital. Their ages ranged from 64-95 years (mean, 81) and the mean body weights of the 76 women and 32 men were 36 and 47 kg, respectively. Immediately before undergoing MRI the patients were given a slow intravenous injection of flunitrazepam (2 mg/ml diluted in 19 ml of saline). Immediately before the patients fell asleep, administration was discontinued and the dose was noted: mean 0.008 mg/kg. In all patients sleep induction and sedation were achieved. No adverse reactions such as apnea were observed. The flunitrazepam dose in our study was much lower than that in previous reports on adults. As body weights of the elderly are also lower than those of younger adults, the optimum dose of flunitrazepam for the elderly may be much lower. Intravenous flunitrazepam may be a useful and safe premedication for MRI in elderly patients with dementia. To avoid serious adverse reactions the dose should be minimized by: 1) determining body weight before MRI, 2) administering diluted flunitrazepam, and 3) discontinuing the drug before the patient falls asleep.

Aged↗
PubMed1995

Mercury and methylmercury in fish and human hair from the Tapajós river basin, Brazil.

Mercury is being released in the Amazon in an abusive way due to goldmining activities. The Tapajós river basin was the first to be intensively exploited in the modern Amazon gold rush. Fish and hair samples as the best indicators of human methylmercury contamination were investigated in the main cities and villages along the Tapajós river basin. The upper basin has typical fish fauna with much larger carnivorous fish with higher mercury levels reaching an average value of 0.69 microgram.g-1 wet wt. in 43 fish. This was accompanied by high levels in hair of the human population living in the same area. The maximum hair value reach 151 micrograms.g-1 dry wt. with two villages presenting an average value close to 25 micrograms.g-1 dry wt. An analytical laboratory intercalibration exercise was performed between Japanese and Brazilian laboratories for total mercury analysis. Critical fish, areas, and more exposed human groups are identified.

Animals↗
PubMed1995

High-frequency inter-parental recombination between mitochondrial genomes of rice cybrids.

Analyzing more than 100 independent rice cybrids, we found evidence for inter-molecular recombination between parental mitochondrial genomes occurring at high frequency soon after protoplast fusion. The structure of the region around the atp6 gene showed extensive polymorphism among Indica (MTC-5A), Japonica (Nipponbare), and wild abortive (IR58024A) mitochondrial genomes. Recombination between the mitochondrial genomes of IR58024A and MTC-5A around the atp6 gene was detected by Southern-blot analysis of cybrid plants. Such recombinant mitochondrial molecules were also cloned from IR58024A/Nipponbare cybrid callus. PCR analysis around the atp6 gene demonstrated that inter-parental recombination occurs in practically all cybrid calli within 2 weeks after protoplast fusion. At this point, parental and recombinant mitochondrial genomes co-existed within the callus. Over the course of further cultivation, however, mitochondrial genome diversity decreased as parental and/or recombinant genomes segregated out.

Base Sequence↗
PubMed1995

Distribution patterns of mRNAs encoding glycine receptor channels in the developing rat spinal cord.

The developmental changes in the expression of mRNAs encoding the alpha 1 and alpha 2 subunits of inhibitory glycine receptors in the spinal cord of fetal and postnatal rats were examined by in situ hybridization. During embryonic periods (E11-18), the mantle zone was scarce in the alpha 1 mRNA, but the germinal zone (matrix layer) at E11-14 expressed higher levels of the message. At postnatal day 0 (P0), the alpha 1 signals became manifested throughout the gray matter of the spinal cord. The intensities of the signals were increased to reach a maximal level at P21. By contrast, the spinal tissues at P0 exhibited the highest levels of alpha 2 mRNA, which decreased with the postnatal development. In P50 rats, the alpha 2 mRNA was barely expressed in the ventral horn, but a significant number of grains could still be detectable in a population of cells in the dorsal horn. During postnatal development from P0 to P10, the spinal tissues were rich in the alpha 1 and alpha 2 mRNAs, both of which were detected in the presumed motoneurons. The coexistence of the two subunits in single neurons might correlate with the modification of the glycine receptor function during the development of the spinal cord.

Age Factors↗
PubMed1995

Hemolysis and heat generation in six different types of centrifugal blood pumps.

What the most causative factor affecting hemolysis is still controversial. To resolve this problem, we investigated the relationship between hemolysis and heat generation in six types of centrifugal blood pumps (Bio-Pump, Delphin, Capiox, Nikkiso, Isoflow, and Toyobo). The analyzed parameters were index of hemolysis in fresh goat blood, pumping performance, and heat generation in a thermally isolated mock circuit. These parameters were analyzed at a flow rate of 5 L/min by changing the pressure head (100 mm Hg and 500 mm Hg). At 500 mm Hg of pressure head, the Bio-Pump needed the highest rotation number and showed the highest hemolytic rate and heat generation. The index of hemolysis is well correlated to heat generation (r2 = 0.721). Heat may originate from the motor by conduction, hydraulic energy loss, and mechanical friction between the shaft and seal. We strongly suspect that hemolysis was caused by a factor such as mechanical friction which generates heat locally.

Animals↗
PubMed1995

TOC-39, a novel parenteral broad-spectrum cephalosporin with excellent activity against methicillin-resistant Staphylococcus aureus.

TOC-39, a new parenteral cephalosporin, is a hydroxyimino-type cephem antibiotic with vinylthio-pyridyl moiety at the 3 position. TOC-39 was evaluated for antibacterial activity against various clinically isolated strains. TOC-39 had excellent activity, stronger than that of methicillin, oxacillin, the cephalosporins tested, imipenem, gentamicin, minocycline, tobramycin, ofloxacin, and ciprofloxacin against methicillin-resistant Staphylococcus aureus (MRSA) and had an MIC comparable to that of vancomycin (the MICs of TOC-39 and vancomycin for 90% of the strains tested were 3.13 and 1.56 micrograms/ml, respectively). Against Enterococcus faecalis strains, which are resistant to cephalosporins, TOC-39 was twice as active as ampicillin. Against methicillin-susceptible S. aureus, coagulase-negative Staphylococcus spp., and Streptococcus pneumoniae, TOC-39 was twice as active as or more active than cefotiam, ceftazidime, flomoxef, and cefpirome. Against Streptococcus pyogenes, TOC-39 was superior to cefotiam, ceftazidime, and flomoxef and was similar to cefpirome. In addition, the activity of TOC-39 was equal to or greater than that of cefotiam, ceftazidime, flomoxef, and cefpirome against Haemophilus influenzae, Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, and Morganella morganii. In terms of bactericidal effect against MRSA, TOC-39 was superior to vancomycin. No mutant resistant to TOC-39 or vancomycin was obtained from susceptible MRSA strains. In murine systemic infection models, TOC-39 showed potent activity against S. aureus and E. coli. Against highly MRSA, the activity of TOC-39 was comparable to that of vancomycin.

Animals↗
PubMed1995

Blood microvascular organization of the nasal-associated lymphoid tissue of the guinea pig: a scanning electron microscopic study of corrosion casts.

It has previously been confirmed that the guinea pig has aggregations of 10-20 lymphoid follicles at the junction of the nasal cavity and the nasopharyngeal duct. The vascular architecture of this nasal-associated lymphoid tissue (NALT) was studied by the corrosion cast/scanning electron microscope method. The NALT was supplied by branches of the inferior nasal artery. These afferent arterial branches gave off arterioles to the follicles and the interfollicular regions, where the arterioles ramified into capillaries. Some of these arterioles reached the subepithelial region to form a single-layer dense capillary network. The subepithelial capillaries gathered into short collecting venules, which in turn drained into high endothelial venules (HEV) in the interfollicular region. The HEV, which also receives tributaries from the follicular and interfollicular capillary plexuses, descended in the interfollicular regions and finally flowed into the efferent veins at the bottom of the NALT. Indentations impressed by high endothelial cells (HEC) were prominent on the surface of the HEV casts, and their frequency was larger in the upper course or segments than in the lower. This suggests that the incidence of HEC in the upper segments is higher than in the lower segments, and these findings are consistent with the hypothesis that some substances which are taken up into the subepithelial capillaries and transported to the venules induce differentiation and maintain of HEVs.

Animals↗
PubMed1995

[Arsenic (As)].

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Arsenic↗
PubMed1995

[Mercury].

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Humans↗
PubMed1994

A unique sequence located downstream from the rice mitochondrial atp6 may cause male sterility.

Asymmetric cell-fusion of the japonica cultivar of Oryza sativa (rice) with cytoplasmic-male-sterile (CMS) plants bearing cytoplasm derived from Chinsurah Boro II, resulted in two classes of cytoplasmic hybrids (cybrids), fertile and CMS. Southern-blot analysis of the mitochondrial DNA (mtDNA) indicates recombination events around a number of genes; however, the appearance of the CMS character is tightly correlated to reorganization around the atp6 gene, suggesting recombination downstream from the atp6 gene is involved in CMS. The nucleotide sequence downstream from atp6 contains a pseudogene which was probably created by recombination of the mitochondrial genome. Sense and antisense transcripts of the downstream region of atp6 were found in CMS- and restored CMS (fertile)-lines, but not in the normal (fertile) line. In the CMS line, several antisense transcripts of the atp6 gene were also found. However, in the restored line which contains a nuclear-encoded gene, Rf-1, the levels of these transcripts were lower than in the CMS line. These results suggest abnormal transcripts of the atp6 gene produced in the antisense direction may be involved in CMS, and that products of the nuclear-encoded restorer gene may reduce abnormal transcription in this region of the mitochondrial genome.

Base Sequence↗
PubMed1994

Down-regulation of glycine receptor channels by protein kinase C in Xenopus oocytes injected with synthetic RNA.

Interaction of protein kinase C (PKC) with glycine receptor channels was examined using Xenopus oocytes expressing homomeric alpha 1 glycine channels. 4 beta-Phorbol 12-myristate 13-acetate (4 beta-PMA), an activator of PKC, reduced the response to glycine; this effect was inhibited in the presence of staurosporine, a PKC inhibitor. By contrast, 4 alpha-PMA, a poor PKC stimulant, did not affect the glycine currents. Thus, the PKC system is involved in negative-regulation of the glycine receptor channels. The results obtained from experiments with mutant receptors suggest that phosphorylation of the intracellular serine residue at 419 may relate to modification of the channel function.

Alkaloids↗
PubMed1994

A flow visualization study of the NCVC centrifugal blood pump.

A compact centrifugal pump, NCVC-1, has an open-type impeller with 6 curved vanes, and it is characterized by no shaft and no seal. A tunnel is placed in the center of the impeller-rotor assembly to irrigate the back space behind the rotor. To evaluate the flow, we performed 3 visualization methods: tracer, oil film, and injection streak line method. The flow, observed by the tracer method in NCVC-1, indicated little turbulence along vanes. A volute chamber proved effective to reduce vortex formation in the outlet. Oil film pattern revealed no flow separation on vanes at 5 L/min. Washout flow behind the rotor is essential to prevent thrombus formation and was shown as inward spiral flow without any stagnation. These data suggested that a combination of visualization techniques was useful to analyze various flow conditions, and the NCVC-1 has excellent flow characteristics with little turbulence and little flow stagnation, which must be beneficial to low hemolysis and high antithrombogenicity.

Heart-Assist Devices↗