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E Sakai

Publications and source records attributed to E Sakai.

At least 37 records · Page 2Linked to original sources
PubMed1999

The Ig heavy chain intronic enhancer core region is necessary and sufficient to promote efficient class switch recombination.

The intronic IgH enhancer E(mu), which consists of the core enhancer (cE(mu) flanked by 5' and 3' matrix attachment regions (MAR), has been implicated in the control of IgH locus recombination and transcription. Both cE(mu) and the MAR are required to enhance transcription of an IgH transgene. To elucidate the regulatory functions of cE(mu) versus its associated MAR in IgH class switch recombination (CSR), we have assayed ES cell lines which have targeted deletions of these elements, both individually and in combination, by the Rag-2-deficient blastocyst complementation method. Mutant B cells from chimeric mice were activated in culture and the influence of the mutations on CSR was assessed by analysis of B cell hybridomas. We find that the cE(mu) is necessary and sufficient for providing the functions of E(mu) required for efficient CSR at the IgH locus. However, the 5' and 3' MAR sequences, as well as the known I(mu) transcription start sites and the bulk of I(mu) coding sequences, were dispensable for the process.

Animals↗
PubMed1999

Force-induced rapid changes in cell fate at midpalatal suture cartilage of growing rats.

The application of expansional force induces replacement of the cartilaginous tissue with bone at the midpalatal suture of growing rats. We examined the early cellular events evoked by force by analyzing the expression of proliferating cell nuclear antigen (PCNA), an operational marker of cell proliferation, and of several bone matrix proteins. A rectangular orthodontic appliance was set between the right and left upper molars of four-week-old rats, with 50 g of initial expansional force. Two days after application of the force, the pre-existing cartilage was separated laterally. Mesenchymal cells with stretched shapes were arranged parallel to the expansional force and filled the center of the suture. Only a few of these stretched cells exhibited nuclear accumulation of PCNA. In contrast, many polygonal mesenchymal cells distributed along the inner lateral side of the cartilaginous tissue exhibited strong immunoreactivity for PCNA. Localization of alkaline phosphatase activity overlapped into this proliferating cell zone. Nascent extracellular matrix under the proliferating cells was positive for osteocalcin, indicating commencement of active bone formation. These findings indicated that, among mesenchymal cells subjected to expansional forces, only cells located on the inner side of the cartilaginous tissue proliferate and differentiate into osteoblasts. In agreement with rapid bone growth progression, apoptosis was also observed in the zone of proliferating cells, as measured by TdT-mediated dUTP-biotin nick end labeling (TUNEL) assays.

Animals↗
PubMed1999

Effects of a novel cardioprotective drug, JTV-519, on membrane currents of guinea pig ventricular myocytes.

We investigated effects of a novel cardioprotective drug, JTV-519 (4-[3-(4-benzylpiperidin-1-yl)propionyl]-7-methoxy-2,3,4,5-tetrahy dro-1,4-benzothiazepine monohydrochloride) on membrane currents of guinea pig ventricular myocytes by whole-cell voltage and current clamp methods. The fast Na+ current (iNa) was activated by ramp pulses from various holding potentials of -90, -80 or -60 mV to 10 mV with various intervals. At 0.2 Hz, JTV-519 inhibited iNa in a concentration-dependent manner with an IC50 of approximately 1.2 and 2 microM at the holding potential of -60 and -90 mM, respectively, implicating a voltage-dependent block. Increasing the pulse frequency from 1 to 2 or 3.3 Hz in the presence of 1 microM JTV-519 shortened the time-course and increased the level of iNa block, indicating a frequency-dependent block. The time-course of iNa blocking by JTV-519 was slower than that of lidocaine and similar to that of quinidine. Ca2+ current (iCa) and the inwardly rectifying K+ current (iK1) were also inhibited by JTV-519. JTV-519 decreased the duration and the height of the plateau of the action potential. We conclude that JTV-519 has frequency- and voltage-dependent blocking effects on iNa as well as inhibition of iCa and iK1.

Action Potentials↗
PubMed1998

Genomic structure and chromosomal mapping of the human and mouse hippocalcin genes.

In an attempt to elucidate the possible relationship of hippocalcin to neurological disorders, we isolated and analyzed the human and mouse hippocalcin genes. The human and mouse hippocalcin genes contain three exons and two introns, and span approximately 7 and 8kb, respectively. The exon/intron splice junctions of the human and mouse genes are all situated in exactly the same position and are not consistently placed with respect to the coding regions of the tandemly repeated EF-hand motifs. The amino acid sequences of human and mouse hippocalcins deduced from the genes are 100% identical. Within the 2-kb 3'-flanking sequences of the human and mouse genes, one conserved polyadenylation signal was identified at positions 762 and 823bp downstream from TAG, respectively. Within the 2.6-kb 5'-flanking sequences of the human and mouse genes, neither a canonical 'TATA' box nor a 'CAAT' box was found. Southern blot analysis of the human and mouse genomic DNAs demonstrated that the positive bands coincide exactly with those expected from the sequence of the cloned genes, indicating that the human and mouse hippocalcin genes are present as a single-copy gene. Fluorescence in-situ hybridization revealed that the human hippocalcin gene is located at chromosome 1 p34.2-35 and the mouse hippocalcin gene at chromosome 4 D2-D3.

Animals↗
PubMed1998

Isolation of two human cDNAs, HLP3 and HLP4, homologous to the neuron-specific calcium-binding protein genes.

We have cloned and sequenced two types of human cDNA, HLP3 and HLP4, encoding a protein of 191 amino acid residues with four EF-hand calcium-binding motifs. The HLP3 and HLP4 proteins are homologous to the neuron-specific calcium-binding proteins and are likely human counterparts of the neural visinin-like protein(NVP) 1 and NVP2 identified in the rat brain (Kajimoto et al. 1993), displaying 98% and 99% amino acid identities with these sequences, respectively. The human HLP3 and 4 mRNAs are detected only in the brain and found at high amount in the cerebral cortex and cerebellum by Northern blot analysis.

Amino Acid Sequence↗
PubMed1997

Flow sensing in mycelial fungi.

Hyphae of a variety of mycelial fungi were shown to reorient their direction of growth to grow upstream in a continuous flowing current of liquid medium. Among those tested fungi, Aspergillus niger hyphae was most polarized towards the upstream. Hyphae of A. niger which had been attached to poly-L-lysine coated plates on the base of a continuous-culture flow cell were exposed to a current of medium of flow rates in the range of 0-6400 microns s-1 for 1-4 h. Hyphal tips quickly reoriented towards the upstream of the flowing medium and became aligned parallel to the flow axis as they grew larger. At flow rates above 1600 microns s-1, however, the percentage of polarization of hyphae reached a constant level. With other fungi, germ tube emergence was not polarized but hyphae and branches grew towards the upstream. There was no detectable difference in the pH and oxygen concentration of the flowing medium between inlet and outlet of the flow cell. This result suggests that hyphae of mycelial fungi sense transient flow of liquid medium over their surface and reorient their direction to grow upstream.

Aspergillus niger↗
PubMed1997

Technetium-99m methoxyisobutylisonitrile single-photon emission tomography in hepatocellular carcinoma.

Nine lesions in eight patients with hepatocellular carcinoma (HCC) were studied using single-photon emission tomography (SPET) and technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) to evaluate the pattern of uptake of 99mTc-MIBI in the lesions and the relation between the uptake pattern and the histopathology of HCC. All the lesions were diagnosed as HCC by percutaneous needle biopsy. Four of the nine lesions showed positive uptake of 99mTc-MIBI, while the other five showed negative uptake. All of the lesions which showed positive uptake were of the compact type. Of the five lesions that showed negative uptake, four were of the trabecular type while one was of the compact type. These results suggest that the patterns of 99mTc-MIBI accumulation in HCC are divided into positive and negative types and that these uptake patterns are associated with the tissue structure of HCC.

Aged↗
PubMed1997

Genomic organization and alternative splicing of human PACE4 (SPC4), kexin-like processing endoprotease.

PACE4 (paired basic amino acid cleaving enzyme) is a member of a family of the mammalian kexin-like proprotein convertases containing a subtilisin-like catalytic domain. Previously we reported seven isoform mRNAs of PACE4 that vary in size and 3'-coding sequence [A. Tsuji et al. (1994) Biochem. Biophys. Res. Commun. 200, 943-950; K. Mori et al. (1997) J. Biochem. 121, 941-948]. To determine the origin of these isoforms, the entire human PACE4 gene has been isolated as a set of overlapping genomic DNA fragments, and analyzed by restriction enzyme digestion and nucleotide sequence determination. The human PACE4 gene spans at least 250 kb and is distributed over 25 exons that range in size from 39 to 1,422 base pairs. Human PACE4 gene is the largest kexin-like proprotein convertase gene reported to date. The most striking feature of its genomic structure is the size of the introns and the number of exons, although the general organization of signal peptide, propeptide, and catalytic domains, which are conserved in this family, is very similar to that reported for other kexin-like protease genes. The structural analysis of PACE4 genomic DNA indicates that multiple PACE4 transcripts are produced as a consequence of alternative RNA splicing events, including exon skipping, and differences in the usage of the inner 5'-splicing donor and polyadenylation sites. A major transcriptional start site was detected 314 bp upstream from the ATG translational start site by primer extension analysis. Sequence analysis of the 5'-flanking region revealed that PACE4 gene lacks TATA and CCAAT boxes in the proximal upstream region of the start site, although potential binding sites for several transcription factors including SP1, AP1, AP2, PEA3, Ets-1, GHF (growth hormone factor)-1, CREB (cyclic AMP response element binding protein), and basic helix-loop-helix proteins, were present. An unusual sequence of six tandem repeats of a nonadecamer (GGCCTGGGGGTTCACCTGC) containing an E box is found in the 5'-flanking region. These results suggest that PACE4 is not a constitutive gene product and its expression is regulated by various transcription factors.

Alternative Splicing↗
PubMed1996

Age-related and dexamethasone-induced changes in cathepsins E and D in rat thymic and splenic cells.

Age-related and dexamethasone (DEX)-induced changes in the cellular levels, distributions, and molecular forms of two distinct intracellular aspartic proteinases, cathepsin E (CE) and cathepsin D (CD), were investigated in rat thymus and spleen by immunohistochemical and quantitative analyses. In the thymus, CE was predominantly restricted to thymocytes and macrophage-like cells, whereas CD was associated mainly with the stromal cells. The increased thymic CE level observed in young rats up to 8 weeks of age was markedly decreased in aged rats (78-80 weeks of age), in accordance with the involution of the thymus, while there was little difference in the thymic CD level between young and aged rats. Subcutaneous administration of DEX also caused a marked decrease of the thymic CE level in response to the depletion of thymocytes. In contrast, a great accumulation of CD occurred in the thymic stromal cells after DEX treatment. Immunoblotting analyses revealed that CE in thymocytes isolated from young rats consisted predominantly of a 46-kDa proform which was greatly converted into a 42-kDa mature form in DEX-treated thymocytes. This conversion, however, was scarcely observed during the normal aging process. In the spleen, CE was also abundant in macrophage-like cells and lymphocytes and its level was not significantly changed between young and aged rats. However, DEX treatment caused a marked decrease of the splenic CE and CD levels in accordance with the depletion of the white pulp. Among the lymphoid cell types examined, splenic B cells were the most abundant in CE. The CE level in thymocytes and splenic T-cells was more than twice that in circulating lymphocytes. We concluded that CE is related to the process of activation-induced lymphocyte depletion.

Aging↗
PubMed1994

Immune response and in vivo distribution of the virus in chickens inoculated with the cell-associated vaccine of attenuated infectious laryngotracheitis (ILT) virus.

Chickens inoculated with the cell-associated (CA) vaccine acquired higher protective immunity to ILT. In chickens vaccinated with CA or cell-free (CF) vaccine, respectively, virus-neutralizing and IgG- and IgM-ELISA antibodies were detected in the serum, but no antibody was detected in the tracheal washes of the vaccinated chickens. More apparent antibody response was seen in chickens vaccinated with the CA vaccine than with the CF vaccine. The antibody titers did not correlate closely with the protection against challenge with ILT virus. After subcutaneous injection of either CA or CF vaccine, ILT virus was isolated from the liver, spleen, thymus, lungs and other organs of the chickens from 1 to 6 days after injection, and there was no correlation of the isolation rate for the CA-vaccinated and the CF-vaccinated chickens.

Animals↗
PubMed1994

[Reduction in cellular immunity in diabetics receiving coronary artery bypass grafting].

We studied the changes in peripheral lymphocyte subsets, mitogen responsiveness, natural killer (NK) cell activity, and interleukin-2 (IL-2) production in patients with or without diabetes receiving coronary artery bypass surgery. Group I (GI): 9 diabetic patients comprising three on oral diabetics during therapy, two on insulin therapy, and four on alimentary therapy. Group II (GII): 12 non-diabetic patients (borderline diabetics excluded). age, amount of blood transfusion, number of grafts, aortic cross-clamp time (ACC), cardio-pulmonary bypass time (CPB), and operative time (OP) did not significantly differ between the groups. Lymphocyte subsets were measured using monoclonal antibodies and IL-2 production was measured by radio-immuno assay using IL-2 labeled with I125. All variables were measured the day before, the day after, 3 days after and 7 days after the operation. The number of lymphocytes and their subsets (CD3+, CD+, CD8+, 4/8 ratio, IL-2R+) did not significantly differ between the groups, but in GI patients, the number of OKIa1 positive lymphocytes were significantly lower than in GII the day before and 7 days after the operation. II-2 production on the day after the operation was significantly (p < 0.05) reduced from the preoperative level in both groups. On 3 days, there was a significant difference (p < 0.05) between the two groups: IL-2 production in GI (3.1 +/- 2.6 U) was remarkably lower than in GII (6.6 +/- 4.0 U). IL-2 production in GII was significantly correlated to the number of CD4 positive lymphocytes, but this was not true in GI. Mitogen responsiveness to stimulation with PHA was not significantly different between the groups. NK cell activity on the first postoperative day was significantly reduced (p < 0.01) in the both groups, but there was no difference between the groups. The % change in IL-2 production (%IL-2) in GII on 3 days after the operation was significantly correlated to the amount of blood transfusion (r = -0.7, p = 0.0077) but that in GI was not. %IL-2 was not significantly correlated to ACC, CPB, OP, or age in both groups. This study clearly showed that diabetics who underwent coronary artery bypass surgery suffered depression of cellular immunity, in particular, IL-2 production, which might be a key factor in cellular immunity. It showed a decrease in helper T lymphocyte function after surgery, implying postoperative immunodeficiency in diabetics.

Aged↗
PubMed1994

[A successful surgical treatment for type IA cor triatriatum with an unroofed coronary sinus].

The combination of type IA cor triatriatum (Lucas-Schmidt's classification) and unroofed coronary sinus is very rare in congenital heart diseases. We have presented the first successful surgical treatment for an infant who had this combination. The patient was 10-month-old infant who admitted with cardiac murmur and short stature. Echocardiography revealed that an abnormal septum in the left atrium and dilated coronary sinus. Under cardiopulmonary bypass she underwent surgical treatment which consisted of a resection of the intra-left-atrial diaphragma, closure of ASD with an equine pericardial patch. During operation, unroofed coronary sinus (partially unroofed terminal portion of the coronary sinus) was revealed. Her postoperative course was uneventful.

Cor Triatriatum↗
PubMed1994

[Angiomyolipoma].

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Angiomyolipoma↗