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Biomedical subjects

M Nishimura

Publications and source records attributed to M Nishimura.

At least 523 records · Page 29Linked to original sources
PubMed1997

Effects of feeding condition after birth on the sensitivity of neuromuscular transmission to d-tubocurarine in vitro in mice.

1. Effects of feeding condition from birth were examined on the sensitivity of neuromuscular transmission to d-tubocurarine (dTc) in vitro in male mice of the ddY strain. 2. Mice were trained to climb two separated cylindrical steel-wire tubes for feeding and drinking, respectively, from 16 days of age. Some mice were conventionally fed, from 99 days of age. Nerve-muscle preparations were made from the left phrenic nerve diaphragm muscle (DPH), the sciatic nerve soleus muscle (SOL), and the sciatic nerve extensor digitorum longus muscle (EDL) of 99-day-old and 155-day-old mice. The nerve trunk was electrically activated with trains of four pulses and tetanic pulses. 3. The sensitivity to the effects of dTc decreased in the order EDL, SOL, and DPH. This result held true in all mice tested. 4. This sensitivity was significantly potentiated by the compulsory movement. 5. The supersensitivity remained even when mice were conventionally fed after 99 days of age. 6. The compulsion rendered EDL antifatigable on tetanic stimulation. This property was also retained after a return to conventional feeding. 7. These results suggest that the effects of feeding condition from birth might remain on neuromuscular functions after termination of the conditioning.

Animals↗
PubMed1997

Effects of feeding conditions on sensitivity to tubocurarine of nerve-muscle preparations from the mouse.

1. The effects of feeding conditions on the sensitivity to the effect of tubocurarine (dTc) in vitro were compared among various nerve-muscle preparations from mice. The mice were fed under conditions that restricted or compelled their movement for 64 days and controls were fed conventionally. 2. The sensitivity to the effect of dTc differed considerably among preparations. It was much higher in the sciatic nerve-extensor digitorum longus muscle (EDL), moderately higher in the sciatic nerve-soleus muscle (SOL) and lower in the phrenic nerve-diaphragm (DPH) in control mice. 3. The order of the sensitivity was not altered by either type of conditioning. Constant restriction of movement or compelled movement did not modify the sensitivity of DPH to the effect of dTc in vitro. 4. Compulsion facilitated the sensitivity in both SOL and EDL. Restriction selectively increased the sensitivity of EDL. Both types of conditioning selectively and significantly reduced twitch development in EDL. 5. These results indicate that the sensitivity to dTc of neuromuscular transmission reflects constant states of motor activity.

Animals↗
PubMed1997

Optimization of a polarized photometric detector equipped with a split-type flow cell and its analytical application to oligo-saccharides.

A novel, non-modulated polarimeter called a polarized photometric detector (PPD) was previously described by the authors. The PPD enables the measurement of the optical rotation of chiral compounds as a change in absorbance by placing two linear polarizers on either side of a flow cell of a conventional photometric detector. The present study describes the optimization of the conditions of PPD for highly sensitive detection of saccharides. To maximize the light intensity, the light balancing filter and slit were removed from the detector (Shimadzu model SPD-10AV). These modifications resulted in an approximately 15-fold increase in the incident light intensity when the maximum current was applied to the lamp. When this intense light was transmitted through the polarizers, the signal intensity followed the theoretical equation for phase angles up to around 1 rad. If the energy of the transmitted light was less than 700 mV, however, the baseline noise was too great to determine the chiral analyte accurately. Setting the phase angle between two polarizers at 50 degrees and the detection wavelength at 400 nm provided the most suitable conditions. This detector was applicable for the determinations of oligosaccharides in foodstuffs separated by HPLC using gradient elution.

Flow Injection Analysis↗
PubMed1997

Morphological and morphometric features of the deformed cervical and caudal vertebrae in a new mutant knotty-tail (knt/knt) mouse.

Morphological and morphometric examinations were conducted on skeletons of knotty-tail (knt/knt) mouse, a new autosomal recessive mutant. The knt/knt mice have short and knotty tails. The number of caudal vertebrae is reduced and their deformed caudal vertebrae show no parallelism between the epiphyseal planes and no osseous fusions. Morphological changes, except for the caudal vertebrae, are confined to the neural arches of the axis in knt/knt mice. As for the tail anomaly, the knt gene seems to have the same action as the tk gene, but knt/knt mice differ from other strains with respect to cervical morphology. The morphometry of the caudal vertebrae revealed that knt/knt mice have a discontinuous and lower ratio of width to length after their 6th caudal vertebra. The morphometry also revealed that knt/knt mice have 1) broadened cervical vertebrae in the transverse direction, 2) thickened ventral lamina of the 6th cervical vertebra and 3) shortened and broadened ventral tuberculum of the atlas. From these results, the knt/knt mouse was considered to be a new pleomorphic mutant.

Animals↗
PubMed1997

cDNA cloning and differential gene expression of three catalases in pumpkin.

Three cDNA clones (cat1, cat2, cat3) for catalase (EC 1.11.1.6) were isolated from a cDNA library of pumpkin (Cucurbita sp.) cotyledons. In northern blotting using the cDNA-specific probe, the cat1 mRNA levels were high in seeds and early seedlings of pumpkin. The expression pattern of cat1 was similar to that of malate synthase, a characteristic enzyme of glyoxysomes. These data suggest that cat1 might encode a catalase associated with glyoxysomal functions. Furthermore, immunocytochemical analysis using cat1-specific anti-peptide antibody directly showed that cat1 encoding catalase is located in glyoxysomes. The cat2 mRNA was present at high levels in green cotyledons, mature leaf, stem and green hypocotyl of light-grown pumpkin plant, and correlated with chlorophyll content in the tissues. The tissue-specific expression of cat2 had a strong resemblance to that of glycolate oxidase, a characteristic enzyme of leaf peroxisomes. During germination of pumpkin seeds, cat2 mRNA levels increased in response to light, although the increase in cat2 mRNA by light was less than that of glycolate oxidase. cat3 mRNA was abundant in green cotyledons, etiolated cotyledons, green hypocotyl and root, but not in young leaf. cat3 mRNA expression was not dependent on light, but was constitutive in mature tissues. Interestingly, cat1 mRNA levels increased during senescence of pumpkin cotyledons, whereas cat2 and cat3 mRNAs disappeared during senescence, suggesting that cat1 encoding catalase may be involved in the senescence process. Thus, in pumpkin, three catalase genes are differentially regulated and may exhibit different functions.

Amino Acid Sequence↗
PubMed1997

Nitric oxide (NO) measurement accuracy.

BACKGROUND: Evaluation of the clinical utility of NO requires accurate assessment of inspired [NO]. Currently, chemiluminescence analyzers are the clinical standard for analysis; however, their performance in the clinical setting has not been systemically evaluated. METHODS: We evaluated the performance of four chemiluminescence analyzers (270B NOA, Sievers Instruments, Inc.; CLA 510S, Horiba Co., Ltd.; CLD 700 AL, Eco Physics Corp.; Model 42, Thermo Environmental Instruments Inc.) in simulated clinical settings. Transport delay and dynamic 95% response time were measured by the balloon in a glass chamber puncture technique. Fluctuating [NO] in a continuous flow of gas and [NO] during mechanical ventilation, where NO was premixed prior to entering the ventilator, were evaluated. RESULTS: Transport delay ranged from 1.02 +/- 0.02 to 24.36 +/- 2.47 s (p < 0.05) and the 95% response time ranged from 0.22 +/- 0.04 to 70.03 +/- 0.03 s (p < 0.05). Accurate analysis of [NO] in a continuous flow system was only possible with the most rapid response analyzer (270B NOA). All other analyzers under reported the maximum [NO] (p < 0.05) and over reported the minimum [NO] (p < 0.05). All analyzers accurately determined [NO] in the inspiratory limb of the ventilator circuit, but none accurately determined [NO] at the airway opening. CONCLUSIONS: Measurements of inhaled [NO] can vary greatly, dependent upon the performance characteristics of the analyzer and the location of NO analysis. All studies evaluating the clinical use of NO should fully describe the technical gas delivery methodology and the response time and transport delay of the chemiluminescence analyzer used.

Administration, Inhalation↗
PubMed1997

Voltage and pH dependent block of cloned N-type Ca2+ channels by amlodipine.

1. Two types of Ca2+ channel alpha1-subunits were co-expressed in Xenopus oocytes with the Ca2+ channel alpha2- and beta1-subunits. The Ba2+ current through the alpha1C alpha2beta and the alpha1B alpha2beta channels had electrophysiological and pharmacological properties of L- and N-type Ca2+ channels, respectively. 2. Amlodipine had a strong blocking action on both the L-type and N-type Ca2+ channels expressed in the oocyte. The potency of the amlodipine block on the N-type Ca2+ channel was comparable to that on the L-type Ca2+ channel. At -100 mV holding potential, the IC50 values for amlodipine block on the L-type and N-type Ca2+ channel were 2.4 and 5.8 microM, respectively. 3. The blocking action of amlodipine on the N-type Ca2+ channel was dependent on holding potential and extracellular pH, as has been observed with amlodipine block on the L-type Ca2+ channel. A depolarized holding potential and high pH enhanced the blocking action of amlodipine. 4. The time course of block development by amlodipine was similar for L-type and N-type Ca2+ channels. However, it was slower than the time course of block development by nifedipine for the L-type Ca2+ channel.

Amlodipine↗
PubMed1997

Existence of three regulatory regions each containing a highly conserved motif in the promoter of plastid-encoded RNA polymerase gene (rpoB).

The plastid gene rpoB encodes a plastid-specific, DNA-dependent RNA polymerase. A study of a barley mutant, albostrians, indicated that rpoB itself is transcribed by a nuclear-encoded RNA polymerase. However, the molecular nature of the nuclear-encoded RNA polymerase and mechanisms of the transcriptional regulation of rpoB expression have not been elucidated. Using an in vivo transient assay system for gene expression in plastids, the 5'-flanking region of rpoB from Arabidopsis thaliana in plastids of cultured BY-2 tobacco cells was analyzed. A series of deletion analyses of the 5'-flanking region indicated that there were two positive and one negative regulatory regions for rpoB expression. Comparison of the 5'-flanking sequences of rpoB among several plant species revealed the existence of three conserved motifs in these regions.

Arabidopsis↗
PubMed1997

Expression and activation of the vacuolar processing enzyme in Saccharomyces cerevisiae.

Vacuolar processing enzymes (VPEs) are cysteine proteinases responsible for maturation of various vacuolar proteins in plants. A larger precursor to VPE synthesized on rough endoplasmic reticulum is converted to an active enzyme in the vacuoles. In this study, a precursor to castor bean VPE was expressed in a pep4 strain of the yeast Saccharomyces cerevisiae to examine the mechanism of activation of VPE. Two VPE proteins of 59 and 46 kDa were detected in the vacuoles of the transformant. They were glycosylated in the yeast cells, although VPE is not glycosylated in plant cells in spite of the presence of two N-linked glycosylation sites. During the growth of the transformant, the level of the 59 kDa VPE increased slightly until a rapid decrease occurred after 9 h. By contrast, the 46 kDa VPE appeared simultaneously with the disappearance of the 59 kDa VPE. Vacuolar processing activity increased with the accumulation of the 46 kDa VPE, but not of the 59 kDa VPE. The specific activity of the 46 kDa VPE was at a similar level to that of VPE in plant cells. The 46 kDa VPE instead of proteinase A mediated the conversion of procarboxypeptidase Y to the mature form. This indicates that proteinase A responsible for maturation of yeast vacuolar proteins can be replaced functionally by plant VPE. These findings suggest that an inactive VPE precursor synthesized on the endoplasmic reticulum is transported to the vacuoles in the yeast cells and then processed to make an active VPE by self-catalytic proteolysis within the vacuoles.

Amino Acid Substitution↗
PubMed1997

Identification of HLA class II antigens as the targets of effector clones which may cause transfusion-associated graft-versus-host disease.

We established T cell clones, which were considered to be the possible cause of transfusion-associated graft-versus-host disease (TA-GVHD), from the peripheral blood lymphocytes (PBLs) of two patients. In both cases, several CD4+ cytotoxic T-cell (CTL) clones were established. In case I, the target antigen of the established CD4+ clones was a DRB1*0403-related antigen serologically typed as HLA DR4, which was one of the patient HLA antigens. In case II, the target of four out of five established CD4+ CTL was a DRB1*1302-related antigen. One CD4+ CTL clone showed cytotoxicity against cells carrying A*2402, B*4403, Cw*1403 and DPB1*0401. A monoclonal antibody (mAb) blocking study showed only anti-DP mAb inhibited the cytotoxicity of this clone. Thus, it might be considered that this clone recognizes HLA-DP with its binding peptides derived from either A*2402, B*4403, Cw*1403 or DRB1*1302. Our findings indicate that CD4+ CTLs may play important roles in the aetiology of TA-GVHD and that the antigens of patients recognized by donor-derived effector cells may not always recognize a single HLA antigen.

Aged↗
PubMed1997

Increased sensitivity of scid heterozygous mice to ionizing radiation.

In the present study, acute effects of ionizing radiation on animal survival, bone marrow cells and fibroblast cell lines of scid homozygous, scid heterozygous and wild-type mice with the same C.B-17 genetic background were examined. The sensitivities to ultraviolet light (UV) and various chemicals, bleomycin, mitomycin C, N-methyl-N'-nitro-N-nitrosoguanidine, methyl methanosulphonate, 5-fluorouracil, 6-mercaptopurine, 4-nitroquinoline 1-oxide and potassium bromate) were also investigated. In addition, micronucleus testing of whole-body irradiated mice was performed. Scid heterozygous mice were found to be less sensitive than the homozygotes but more sensitive to ionizing radiation than wild-type mice, not only in vivo but also for bone marrow cells in vitro, suggesting partial dominance under both conditions. In contrast, there were no differences in sensitivity to UV light and various chemicals, as compared with wild-type and scid heterozygous cell lines, either in vitro or in the micronucleus test.

Animals↗
PubMed1997

Campylobacter jejuni isolates from Japanese patients with Guillain-Barré syndrome.

Serologic evidence of recent Campylobacter jejuni infection was found in 92 (45%) of 205 Japanese patients with Guillain-Barré syndrome (GBS), and 49% of those 92 patients also had antibodies to GM1. Sixteen independent clinical isolates from GBS patients were serotyped: 12 belonged to Penner's heat-stable (HS) O serotype HS-19, 3 to HS-2, and 1 to HS-4. Of the patients whose C. jejuni isolates belonged to HS-19, 80% had elevated anti-GM1 antibodies. Although the correlation was significant between C. jejuni and GM1 antibody, anti-GM1 also was detected in 25% of patients without C. jejuni infection. Polymerase chain reaction-based restriction fragment length polymorphism analysis of an flaA gene showed that all HS-19 isolates, regardless of a GBS association, had an identical and distinguishable pattern, Cj-1, suggesting that HS-19:Cj-1 isolates are distinctive among C. jejuni isolates. Lectin typing showed that all GBS-associated HS-19 isolates contained terminal beta-N-acetylglucosamine residues on their cell surface, but HS-19 isolates from patients with enteritis did not.

Adolescent↗
PubMed1997

Identification of the Syrian hamster cardiomyopathy gene.

The BIO14.6 hamster is a widely used model for autosomal recessive cardiomyopathy. These animals die prematurely from progressive myocardial necrosis and heart failure. The primary genetic defect leading to the cardiomyopathy is still unknown. Recently, a genetic linkage map localized the cardiomyopathy locus on hamster chromosome 9qa2.1-b1, excluding several candidate genes. We now demonstrate that the cardiomyopathy results from a mutation in the delta-sarcoglycan gene that maps to the disease locus. This mutation was completely coincident with the disease in backcross and F2 pedigrees. This constitutes the first animal model identified for human sarcoglycan disorders.

Amino Acid Sequence↗
PubMed1997

Molecular features of the CAG repeats of spinocerebellar ataxia 6 (SCA6).

Spinocerebellar ataxia 6 (SCA6) is an autosomal dominant spinocerebellar degeneration caused by the expansion of the polymorphic CAG repeat in the human alpha1A voltage-dependent calcium channel subunit gene (CACNL1A4 gene). We have analyzed 60 SCA6 individuals from 39 independent SCA6 Japanese families and found that the CAG repeat length is inversely correlated with the age of onset (n = 58, r = -0.51, P < 0.0001). SCA6 chromosomes contained 21-30 repeat units, whereas normal chromosomes displayed 6-17 repeats. There was no overlap between the normal and affected CAG repeat number. The anticipation of the disease was observed clinically in all eight parent-child pairs that we examined; the mean age of onset was significantly lower (P = 0.0042) in children than in parents. However, a parent-child analysis showed the increase in the expansion of CAG repeats only in one pair and no diminution in any affected cases. This result suggests that factors other than CAG repeats may produce the clinical anticipation. A homozygotic case could not demonstrate an unequivocal gene dosage effect on the age of onset.

Adult↗
PubMed1997

A pumpkin 72-kDa membrane protein of precursor-accumulating vesicles has characteristics of a vacuolar sorting receptor.

Precursor-accumulating (PAC) vesicles were previously shown to mediate the transport of the precursor of a major storage protein (pro2S albumin) to protein-storage vacuoles in developing pumpkin cotyledons. In this study, we characterized two homologous proteins from PAC vesicles, a 72 kDa protein (PV72) and an 82 kDa protein (PV82). PV72 and PV82 showed an ability to bind to peptides derived from both an internal propeptide and a C-terminal peptide of pro2S albumin. PV72 was predicted to be a type I integral membrane protein with epidermal growth factor (EGF)-like motifs. These results suggest that PV72 and PV82 are potential sorting receptors for 2S albumin to protein-storage vacuoles.

2S Albumins, Plant↗
PubMed1997

A rapid increase in the level of binding protein (BiP) is accompanied by synthesis and degradation of storage proteins in pumpkin cotyledons.

The binding protein (BiP) has been implicated in cotranslational folding of nascent polypeptides, and in the recognition and disposal of aberrant polypeptides. To elucidate the involvement of BiP in the biosynthesis of vacuolar proteins, we have characterized the protein in pumpkin cotyledons during seed maturation and seedling growth. Isolated microsomes from maturing pumpkin cotyledons contained a significant amount of BiP, protein-disulfide isomerase and calreticulin. We have purified a 70-kDa protein; sequences of the N-terminus and internal fragments of this protein exhibited a high identity to the sequence of soybean. Immunoblot analysis with specific antibodies raised against the purified BiP showed that the amount of BiP in a cotyledon increased markedly at the middle stages and then decreased. The increase was accompanied by the synthesis of storage proteins and the development of the endoplasmic reticulum in the cotyledons at the middle stage of seed maturation. Most of these storage proteins degraded dramatically between 2 and 5 days after seed germination, and the degradation was also accompanied by a rapid increase in the level of BiP. Subcellular fractionation of the 4-day-old cotyledons showed a high accumulation of BiP in the endoplasmic reticulum. It is possible that BiP might be involved in the synthesis of seed storage proteins during maturation and in the synthesis of hydrolytic enzymes responsible for the degradation of the storage proteins during seed germination.

Amino Acid Sequence↗
PubMed1997

Heterologous expression and subcellular localization of pumpkin seed tonoplast intrinsic proteins (TIP) in yeast cells.

Two tonoplast intrinsic proteins (TIP) of pumpkin seeds, pMP23 and MP28, were expressed in yeast cells under control of the GAL1 promoter, and the subcellular localization of the proteins was analyzed. The pMP23 and MP28 stably accumulated in the yeast vacuolar membrane when the proteins were expressed in the proteinase A-deficient strain (pep4), which lacks the activities of vacuolar proteases. However, pMP23 and MP28 did not accumulate in the wild-type strain; the expressed pMP23 and MP28 were degraded in a proteinase A-dependent manner. These results indicate that pMP23 and MP28 are transported to the vacuolar membrane when expressed in yeast.

Cloning, Molecular↗