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K Nishitani

Publications and source records attributed to K Nishitani.

At least 19 recordsLinked to original sources
PubMed2001

Endoxyloglucan transferase is localized both in the cell plate and in the secretory pathway destined for the apoplast in tobacco cells.

Intracellular trafficking of enzymes responsible for constructing and modifying the cell wall architecture in plants is mostly unknown. To examine their translocation pathways, we employed an endoxyloglucan transferase (EXGT), a key enzyme responsible for forming and rearranging the cellulose/xyloglucan network of the cell wall. We traced its intracellular localization in suspension-cultured cells of tobacco bright yellow-2 by means of green fluorescent protein-fusion gene procedures as well as by indirect immunofluorescence. During interphase the protein was extensively secreted into the apoplast via the endoplasmic reticulum-Golgi apparatus network, whereas during cytokinesis, the protein was exclusively located in the phragmoplast and eventually transported to the cell plate. These results clearly indicate commitment of EXGT protein to the construction of both the cell plate and the cell wall. This study also visualized the process of phragmoplast development at a level of vesicle translocation in the living cell.

Amino Acid Sequence↗
PubMed2001

A comprehensive expression analysis of all members of a gene family encoding cell-wall enzymes allowed us to predict cis-regulatory regions involved in cell-wall construction in specific organs of Arabidopsis.

The Arabidopsis thaliana genome sequencing project has revealed that multigene families, such as those generated by genome duplications, are more abundant among plant genomes than among animal genomes. To gain insight into the evolutionary implications of the multigene families in higher plants, we examined the XTH gene family, a group of genes encoding xyloglucan endotransglucosylase/hydrolase, which are responsible for cell-wall construction in plants. Expression analysis of all members (33 genes) of this family, using quantitative real-time RT-PCR, revealed that most members exhibit distinct expression profiles in terms of tissue specificity and responses to hormonal signals, with some members exhibiting similar expression patterns. By comparing the flanking sequences of individual genes, we identified four sets of large-segment duplications and two sets of solitary gene duplications. In each set of gene duplicates, long nucleotide sequences, ranging from one to two hundred base pairs, are conserved. Furthermore, gene duplicates exhibit similar organ-specific expression profiles. These facts allowed us to predict putative cis-regulatory regions, particularly those responsible for cell-wall construction, and hence for morphogenesis, that are specific for certain organs or tissues in plants.

Arabidopsis↗
PubMed2000

Growth regulation mechanisms in higher plants under microgravity conditions - changes in cell wall metabolism.

During Space Shuttle STS-95 mission, we cultivated seedlings of rice (Oryza sativa L. cv. Koshihikari and cv. Tan-ginbozu) and Arabidopsis (Arabidopsis thaliana L. cv. Columbia and cv. etr1-1) for 68.5, 91.5, and 136 hr on board, and then analyzed changes in the nature of their cell walls, growth, and morphogenesis under microgravity conditions. In space, elongation growth of both rice coleoptiles and Arabidopsis hypocotyls was stimulated. Also, the increase in the cell wall extensibility, especially that in the irreversible extensibility, was observed for such materials. The analyses of the amounts, the structure, and the physicochemical properties of the cell wall constituents indicated that the decreases in levels and molecular masses of cell wall polysaccharides were induced under microgravity conditions, which appeared to contribute to the increase in the wall extensibility. The activity of certain wall enzymes responsible for the metabolic turnover of the wall polysaccharides was increased in space. By the space flight, we also confirmed the occurrence of automorphogenesis of both seedlings under microgravity conditions; rice coleoptiles showed an adaxial bending, whereas Arabidopsis hypocotyls elongated in random directions. Furthermore, it was shown that spontaneous curvatures of rice coleoptiles in space were brought about uneven modifications of cell wall properties between the convex and the concave sides.

Arabidopsis↗
PubMed1999

Agravitropic mutant for the study of hydrotropism in seedling roots.

Roots have been shown to respond to a moisture gradient by positive hydrotropism. Agravitropic mutant plants are useful for the study of the hydrotropism in roots because on Earth hydrotropism is obviously altered by the gravity response in the roots of normally gravitropic plants. The roots are able to sense water potential gradient as small as 0.5 MPa mm(-1). The root cap includes the sensing apparatus that causes a differential growth at the elongation region of roots. A gradient in apoplastic calcium and calcium influx through plasmamembrane in the root cap is somehow involved in the signal transduction mechanism in hydrotropism, which may cause a differential change in cell wall extensibility at the elongation region. We have isolated an endoxy loglucan transferase (EXGT) gene that is strongly expressed in pea roots and appears to be involved in the differential growth in hydrotropically responding roots. Thus, it is now possible to study hydrotropism in roots by comparing with or separate from gravitropism. These results also imply that microgravity conditions in space are useful for the study of hydrotropism and its interaction with gravitropism.

Calcium Channels↗
PubMed1999

Endoxyloglucan transferase cDNA isolated from pea roots and its fluctuating expression in hydrotropically responding roots.

We isolated an endoxyloglucan transferase cDNA (Ps-EXGT1) from the roots of an agravitropic pea mutant, ageotropum. The putative product of the cDNA was 34.1 kDa and consisted of 293 amino acid residues. The predicted amino acid sequence was 75.1-88.6% identical to those of EXGT genes in other plants. The Ps-EXGT1 cDNA was strongly expressed in elongating roots and stems but not in either mature stems or young leaves. In roots, the transcription level of Ps-EXGT1 was most abundant in the rapidly growing region. When root elongation was inhibited by a water stress, Ps-EXGT1 transcription was repressed. The roots curved hydrotropically due to differential growth of the cortical cells in the elongation zone when the root cap was exposed to a gradient of water potential; the length of the cells on the side of lower water potential was much longer than those on the side of higher water potential. The expression pattern of Ps-EXGT1 in the hydrotropically responding roots fluctuated between the side of the higher water potential and that of the lower water potential in the elongation zone. In other words, the accumulation of Ps-EXGT1 mRNA was much greater on the side of lower water potential than on that of higher potential just prior to the commencement of positive hydrotropism. When the roots started to curve slightly away from the side of higher water potential causing a rhythmic oscillatory movement [Takano et al. (1995) Planta 197: 410], there was more transcription of Ps-EXGT1 on the side of higher water potential. These results suggest that the transcription of Ps-EXGT1 is involved in cell growth and that this regulation of transcription plays a role in the differential growth of hydrotropically responding roots.

Amino Acid Sequence↗
PubMed1999

Expression of endoxyloglucan transferase genes in acaulis mutants of Arabidopsis.

A mutant of Arabidopsis with reduced internodal cell length, acaulis5 (acl5), has recently been shown to have reduced transcript levels of a gene for endoxyloglucan transferase, EXGT-A1 (Y. Hanzawa, T. Takahashi, Y. Komeda [1997] Plant J 12: 863-874). In the present study, we cloned genomic fragments of five members of the EXGT gene family, EXGT-A1, EXGT-A3, EXGT-A4, XTR2, and XTR3, and examined their expression in the wild type and in a series of acl mutants. In wild-type plants, the EXGT-A3 gene showed higher expression in lower internodes (internodes between nodes bearing axillary shoots) than in upper and young internodes, in which EXGT-A1 was highly expressed. EXGT-A4 was preferentially expressed in roots and XTR3 in siliques. The XTR2 gene was constitutively expressed. In acl1, acl3, and acl4 mutants, which have a severe defect in leaf expansion as well as in internode elongation, the EXGT-A1 gene showed reduced levels of expression before bolting of plants. In contrast, XTR3 was increased in these mutant seedlings. Reduction of EXGT-A1 expression was also detected after bolting of all acl mutants except acl2, whose growth defect is restricted to lower internodes. These results suggest the involvement of each EXGT in different aspects of organ development.

Arabidopsis↗
PubMed1999

Coronary artery stenosis evaluated by combined carotid and coronary angiography in patients undergoing carotid endarterectomy.

The relationship between coronary artery stenosis and the postoperative outcome was investigated in patients who underwent carotid endarterectomy (CEA). The benefit of combined carotid and coronary angiography was also evaluated. Combined carotid and coronary angiography was performed in 72 patients treated with CEA (mean age 64.0 years). Fourteen patients with a history of ischemic heart disease (IHD) had a higher Gensini score for coronary artery stenosis than patients with no history of IHD (37.9 +/- 36.8 vs. 7.9 +/- 12.5, p < 0.0001). However, 39.7% of patients with no history of IHD had a Gensini score exceeding 6. Patients with diabetes mellitus had a significantly higher Gensini score than nondiabetic patients. Eleven patients (15.3%) underwent percutaneous transluminal coronary angioplasty and three (4.2%) underwent coronary artery bypass grafting during the CEA perioperative period. None of the patients who underwent combined angiography showed signs of IHD during or after CEA (mean follow-up period 30 months). Combined angiography was not performed in 189 previous patients. Of these, two died of acute myocardial infarction in the postoperative period, 11 manifested nonfatal IHD, and 18 succumbed to IHD (mean follow-up period 8 years). Although patients with a history of IHD manifested more severe coronary artery stenosis than patients without such a history, the possibility of coronary artery stenosis must be considered in patients with no history of IHD, especially those with diabetes mellitus. Combined carotid and coronary angiography and careful management of coronary artery stenosis can be expected to decrease the mortality and morbidity in patients treated with CEA.

Adult↗
PubMed1998

Hyperperfusion syndrome following carotid endarterectomy: evaluation using diffusion-weighted magnetic resonance imaging--case report.

A 65-year-old female developed hyperperfusion syndrome following carotid endarterectomy for severe stenosis of the left internal carotid artery. Transcranial Doppler monitoring showed a sharp increase in flow velocity in the middle cerebral artery (MCA). Diffusion-weighted magnetic resonance (MR) imaging demonstrated diffuse hyperintensity in the region of the left MCA, which diminished markedly 9 days later. The abnormal hyperintensity decreased as the patient's symptoms improved, suggesting that diffusion-weighted MR imaging can be used for evaluating the course of hyperperfusion syndrome.

Aged↗
PubMed1998

[Effect of epidural pressure gradient on buprenorphine flux through the dural hole after combined spinal-epidural anesthesia--comparison between bolus injection and continuous infusion].

Combined spinal-epidural anesthesia is a useful technique. However, there has been no attempt to investigate the risk of epidural opioid, especially buprenorphine, flux through the dural hole. The purpose of this study was to compare the effect of epidural buprenorphine administered across the dura into subarachnoid space, between two different methods of administration; bolus injection (Group I) and continuous infusion (Group II). Sixty patients for transvaginal hysterectomy were divided into two groups. Group I received buprenorphine 0.1-0.2 mg with 0.25% bupivacaine, and Group II 0.4 mg with 0.25% bupivacaine 40 ml continuously (infusion rate was 1.7 ml.h-1). Pain relief was similar in both groups, but the total buprenorphine requirement was lower in Group I than in Group II. The incidence of nausea and vomiting was significantly higher in Group I than that in Group II, 73% and 16%, respectively. It indicates that the increase of nausea and vomiting is predominantly determined by a high rate of flux into subarachnoid space and only partly determined by blood concentrations. In contrast to continuous infusion, the drug movement through the dural hole may increase by bolus injection due to its higher pressure. We recommend careful injection of epidural buprenorphine such as by continuous infusion with low pressure after combined spinal-epidural anesthesia.

Adult↗
PubMed1998

[HELLP syndrome in triplet pregnancy complicated by DIC and transient diabetes insipidus].

A 29-year-old woman with a triplet pregnancy received emergency caesarean section in the 33rd week of pregnancy. She lost 2 babies, one of whom was a fetal death and the other a neonatal death. Three weeks before delivery, she was admitted to hospital suffering from vomiting, diarrhea and polyuria. There were no laboratory abnormalities such as a slightly elevated levels of liver enzymes, nor any clinical symptoms of preeclampsia. At the end of the operation, disseminated intravascular coagulation (DIC) occurred and HELLP syndrome was diagnosed. However, the hemoglobin level was in the normal range at this point. On the 2nd postoperative day, hemolytic anemia developed in spite of the resolution of other problems. We suggested that the hemolysis, which may have been caused by a latent hemoconcentration and a membrane disorder of the red cells, was an osmotic hemolysis. This case was unique for the following reasons; 1) a lack of symptoms of hypertension, proteinuria and edema, 2) complications due to diabetes insipidus, 3) postpartum severe hemolysis following latent hemoconcentration, and 4) slow progress of the condition after onset. Early detection of HELLP syndrome is difficult. It should be considered in the management of patients with unrecognizable hemoconcentration and nonspecific complications.

Adult↗
PubMed1997

The role of endoxyloglucan transferase in the organization of plant cell walls.

The plant cell wall plays a central role in morphogenesis as well as responsiveness to environmental signals. Xyloglucans are the principal component of the plant cell wall matrix and serve as cross-links between cellulose microfibrils to form the cellulose-xyloglucan framework. Endoxyloglucan transferase (EXGT), which was isolated and characterized in 1992, is an enzyme that mediates molecular grafting reaction between xyloglucan molecules. Structural studies on cDNAs encoding EXGT and its related proteins have disclosed the ubiquitous presence in the plant kingdom of a large multigene family of xyloglucan-related proteins (XRPs). Each XRP functions as either hydrolase or transferase acting on xyloglucans and is considered to be responsible for rearrangement of the cellulose-xyloglucan framework, the processes essential for the construction, modification, and degradation of plant cell walls. Different XRP genes exhibit potentially different expression profiles with respect to tissue specificity and responsiveness to hormonal and mechanical signals. The molecular approach to individual XRP genes will open a new path for exploring the controlling mechanisms by which the plant cell wall is constructed and reformed during plant growth and development.

Amino Acid Sequence↗
PubMed1997

[Management and long-term follow-up results in patients with carotid artery dissection].

The recognized incidence of extra- and intracranial carotid artery dissection has increased concomitantly with the progress and development of diagnostic methods. However, management for this condition is still controversial. We report in the present study the management and long-term follow-up results of 15 patients with carotid artery dissection. Mean age of the patients at onset was 47.8 years old, and male/female ratio was 12:3. Two patients were considered to be traumatic dissections and the other 13 patients were spontaneous dissections. Dissection occurred in 10 patients at the extracranial carotid artery, in 4 at the intracranial carotid artery and in 1 at the middle cerebral artery. Nine of 15 patients demonstrated hemiparesis and 5 complained of headache or facial pain. However, it was not possible to identify a characteristic symptom of dissection. Final diagnosis of dissection was made by cerebral angiography in all patients. Serial angiography was carried out in 10 of those, and 5 of the 10 patients showed some improvements of dissection in the cerebral angiogram. Treatment for those patients was selected according to the neurological and angiographical changes. Five patients were managed conservatively and 10 patients underwent surgical revascularization. During the follow-up period (mean 77.6 months), none of them showed any symptoms of reattack, and all but one, who died of heart failure 193 months after revascularization surgery, have lived independently. Although diagnosis of dissection was difficult because of the lack of characteristic symptom, serial angiography was a useful method for diagnosis and adequate management has led to a good clinical outcome.

Adolescent↗
PubMed1996

Effects of hypergravity on growth and cell wall properties of cress hypocotyls.

Elongation growth of etiolated hypocotyls of cress (Lepidium sativum L.) was suppressed when they were exposed to basipetal hypergravity at 35 x g and above. Acceleration at 135 x g caused a decrease in the mechanical extensibility and an increase in the minimum stress-relaxation time of the cell wall. Such changes in the mechanical properties of the cell wall were prominent in the lower regions of hypocotyls. The amounts of cell wall polysaccharides per unit length of hypocotyls increased under the hypergravity condition and, in particular, the increase in the amount of cellulose in the lower regions was conspicuous. Hypergravity did not influence the neutral sugar composition of either the pectin or the hemicellulose fraction. The amount of lignin was also increased by hypergravity treatment, although the level was low. The data suggest that hypergravity modifies the metabolism of cell wall components and thus makes the cell wall thick and rigid, thereby inhibiting elongation growth of cress hypocotyls. These changes may contribute to the plants' ability to sustain their structures against hypergravity.

Acceleration↗
PubMed1995

[On the antibacterial effect of hinokitiol against Staphylococcus aureus showing double zone phenomenon].

We studied the antibacterial effect of Hinokitiol against Staphylococcus aureus. As reference, we studied also the antibacterial effects of the oil and water from Thujopsis dolablata var. hondai Makino which contains Hinokitiol an important element of its antibacterial effect. Interestingly, Hinokitiol showed the double zone phenomenon, i.e., minimum inhibitory concentration of hinokitiol against MSSA was 15-125 micrograms/ml and against MSSA was 125 micrograms/ml. But when the concentration of Hinokitiol was diluted to 1.87-0.94 micrograms/ml, then the growth of MSSA was inhibited (Table 1 and Fig. 1). This phenomenon was observed the study on antibacterial effect using disk containing Hinokitiol (Fig/3). Similar phenomenon were observed also in the study using water from Thujopsis dolablata (Table 2 & Fig. 2). We deduce that Hinokitiol has a strong antibacterial effect against S. aureus. But this effect shows double zone effect. The antibacterial effect of Hinokitiol is more prominent against MRSA than MSSA.

Dose-Response Relationship, Drug↗
PubMed1995

[Usefulness of coronary angiography in patients undergoing carotid endarterectomy].

We evaluated 37 cases of coronary angiography in patients undergoing carotid endarterectomy (CEA). The severity of coronary stenosis was estimated by Gesini's scoring system. There was no correlation between the severity of carotid stenosis and that of coronary stenosis, but those patients who had a history of coronary artery disease, carotid bruit or intracranial artery stenoses presented significant severe coronary stenosis in most cases. Even in the patients who had no history of coronary artery disease (n = 26), 13 patients (50%) had stenotic lesions shown by coronary angiography. Eight patients required treatment for their coronary stenotic lesions: 5 were treated with percutaneous transluminal coronary angioplasty (PTCA) and 3 with coronary artery bypass grafting. Intraoperative occlusion tests monitored by EEG and SEP showed abnormal findings in 6 CEA operations. One of these patients received PTCA before CEA, and had a good clinical course during and after the CEA procedure. In conclusion, in patients undergoing CEA there is frequently concomitant coronary artery stenosis. We should thus assess the coronary artery lesion more precisely by coronary angiography, and should carry out prophylactic treatment for these lesions.

Aged↗