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S Kitajima

Publications and source records attributed to S Kitajima.

At least 127 records · Page 7Linked to original sources
PubMed1993

The effects of ATP and alpha,beta-methylene-ATP on cytosolic Ca2+ level and force in rat isolated aorta.

1. The effects of a non-selective P2-receptor agonist ATP and a selective P2x-receptor agonist alpha,beta-methylene-ATP on intracellular free Ca2+ level ([Ca2+]i) and force were examined in rat isolated aorta without endothelium. 2. Both ATP (1-1000 microM) and alpha,beta-methylene-ATP (0.1-100 microM) induced transient increase followed by small sustained increase in [Ca2+]i in a concentration-dependent manner. Compared with the force induced by a high concentration of KCl, the force induced by alpha,beta-methylene-ATP was smaller and that induced by ATP was much smaller at a given [Ca2+]i. 3. An L-type Ca2+ channel blocker, verapamil (10 microM), completely inhibited the high K(+)-stimulated [Ca2+]i and force. Verapamil partially inhibited the transient and sustained increases in [Ca2+]i induced by 10 microM alpha,beta-methylene-ATP and the sustained increase but not the transient increase induced by 1 mM ATP. 4. In the absence of extracellular Ca2+ (with 0.5 mM EGTA) 1 mM ATP caused transient increase in [Ca2+]i while 10 microM alpha,beta-methylene-ATP was ineffective 5. ATP, but not alpha,beta-methylene-ATP, increased the tissue adenosine 3':5'-cyclic monophosphate (cyclic AMP) level. 6. These data suggest that ATP and alpha,beta-methylene-ATP increase [Ca2+]i by an activation of both L-type and non-L-type Ca2+ channels. In addition, ATP, but not alpha,beta-methylene-ATP, increases [Ca2+]i by a release of Ca2+ from an intracellular Ca2+ store. Possible reasons are discussed as to why the increase in [Ca2+]i due to ATP and alpha,beta-methylene-ATP resulted in only a small contraction.

Adenosine Triphosphate↗
PubMed1993

[Changes and present status of a Japanese National Leprosarium--analysis of smear positive rate and relapse in Hoshizuka-Keiaien between 1972-1991].

Change of clinical features of leprosy in a Japanese National Leprosarium Hoshizuka-Keiaien during 20 years (1972-91) was studied by analyzing clinical records. (1) Skin slit smear positive rate among lepromatous and borderline cases once increased from 16.3% (1972) to 28.8% (1981) and then declined to 3% (1991). (2) Relapse was 4.25 cases per annum among 817 patients (0.52% per annum). Relapse of lepromatous leprosy (0.42% per annum) is decreasing, and borderline or neuritic relapse (0.12% per annum) of previously lepromatous cases is the major feature in recent years. (3) In lepromatous relapse cases, it took 3.5 years in average to become smear negative again, but this duration is shortening in recently relapsed cases. (4) Number of erythema nodosum leprosum is remarkably decreased, but iridocyclitis is still observed. (5) 85% of inpatients in 1991 are classified as clinical cure (Japanese criteria 1989). By the advance of chemotherapy and aging of the inpatients (average age: 68 years), geriatric diseases, instead of leprosy, are becoming major problems in Japanese National Leprosaria.

Aged↗
PubMed1992

Origin of brain 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet.

The present study established that 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet common to mammalian brain originates from an alternative splicing. Peptides specific to the predicted larger translation product were synthesized and antisera against these peptides were prepared. Immunostaining of SDS/PAGE blots showed that the antisera react with the larger protein, but not with the smaller protein, of 2',3'-cyclic-nucleotide 3'-phosphodiesterase doublet in all mammals studied.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1992

Characterization of cDNA for the large subunit of the transcription initiation factor TFIIF.

At least six chromatographically resolvable general transcription factors may participate in accurate initiation by RNA polymerase II in HeLa cell-derived systems. TFIIF (also termed FC, RAP30/74 and beta/gamma) can bind directly to RNA polymerase II in solution and decrease the affinity of RNA polymerase II for nonspecific DNA. From studies on the kinetics of transcription initiation, on the composition of transcription initiation complexes fractionated by acrylamide gel electrophoresis, and on template competition experiments, TFIIF is known to act at an intermediate stage in initiation complex formation. It acts after TFIID firmly associates with DNA, but coincidentally with or immediately after RNA polymerase II binding to DNA, and before the recruitment of factor TFIIE. TFIIF may or may not have DNA helicase activity. The small subunit (RAP30) of TFIIF has been cloned and shows some amino-acid sequence homology to bacterial sigma factors. We have partially sequenced the RAP74 protein from purified HeLa cells, cloned its complementary DNA and shown that its translation product can interact with RAP30 in vitro as well as in vivo. The cDNA predicts an amino-acid sequence that lacks obvious DNA or RNA helicase motifs. It has regions rich in charged amino acids, including segments containing a higher content of acidic amino acids than are found in strong transcriptional activators such as VP16.

Amino Acid Sequence↗
PubMed1992

Activation of microtubule-associated protein kinase in PC12D cells in response to both fibroblast growth factor and epidermal growth factor and concomitant stimulation of the outgrowth of neurites.

When PC12D cells, a subline of PC12 cells, were cultured with nerve growth factor (NGF), outgrowth of neurites was promoted even when RNA synthesis was blocked. This property of PC12D cells may enable us to resolve the mechanism of the outgrowth of neurites that is induced in a transcription-independent manner. The outgrowth of neurites from PC12D cells was also stimulated in response to fibroblast growth factor (FGF) and was slightly stimulated in response to epidermal growth factor (EGF). The brief exposure of intact PC12D cells not only to NGF but also to FGF or to EGF stimulated a protein kinase activity in extracts of such cells that catalyzed phosphorylation of microtubule-associated protein 1 (MAP-1) and MAP-2 in vitro. Similar dose-response relationships for the effects of NGF and of FGF on the activation of the kinase and on the outgrowth of neurites were observed. The effects of combinations of NGF and GFG or EGF were not additive in terms of either the outgrowth of neurites or the increase in the kinase activity. Treatment of cells with phorbol 12-myristate 13-acetate (PMA) also stimulated the kinase activity that phosphorylated MAPs in vitro. However, the level of the enzymatic activity that resulted from the combined treatment of cells with PMA and NGF was additive, as is the case with dibutyryl cyclic AMP and NGF. These findings suggest that NGF, FGF, and EGF may stimulate the activity of the same MAP kinase.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Effects of pH on vascular smooth muscle contraction].

Effects of pH on vascular smooth muscle contractility were reviewed. Basic effect of acidosis seems to be the inhibition of K channels and L-type Ca channels. Inhibition of K channels results in a membrane depolarization, opening of L-type Ca channels, increase in Ca influx and muscle contraction. Inhibition of Ca channels results in an opposit effect. Thus, the effect of acidosis is determined by the relative potency of these two contradictory effects. This may be the reason why acidosis induces contraction in polarized muscle whereas it slightly inhibits contraction in depolarized muscle. In addition, measurements of cytosolic Ca level simultaneously with muscle tension suggest that acidosis increases Ca sensitivity of contractile elements, and this effect also helps acidosis to induce contraction in vascular smooth muscle.

Animals↗
PubMed1991

Calmodulin and calbindin localization in retina from six vertebrate species.

Calmodulin is abundant in the central nervous system, including the retina. However, the localization of calmodulin in the retina has not been described in detail. We therefore decided to investigate calmodulin localization in retinae from six vertebrate species, by using immunohistochemical labeling with four different rabbit polyclonal antibodies against calmodulin. The localization of calbindin-D28k, another calcium-binding protein already well described in retina, was compared. We found that calmodulin distribution is more highly conserved among species, contrasting with calbindin variability. The most striking result emerging is that calmodulin could not be detected in photoreceptors although other layers are intensely calmodulin-immunoreactive, casting doubt about a direct role of calmodulin in phototransduction. Horizontal cells are weakly calmodulin-immunoreactive, bipolar cells are calmodulin-immunoreactive except in turtle retina, numerous amacrine and ganglion cells are labeled in all species, and the fiber layer is always labeled. These data demonstrate that, while the calmodulin distribution in retina is similar among vertebrate species, selective differences in localization can be detected not only among the same cell types in different species but also among different cell types in the same species. The results showing differences in calmodulin immunoreactivity among cell types also provide further evidence that calmodulin expression in eukaryotes is not constitutive, in the sense that not every cell expresses similar levels of calmodulin.

Animals↗
PubMed1991

Biological behavior of cloned cells of human malignant fibrous histiocytoma in vivo and in vitro.

A human malignant fibrous histiocytoma cell line was established in vitro. Cells showed a wide variety of morphologies, although the karyotype study showed that the tumor was monoclonal in origin because of the presence of unique marker chromosomes in 100% of the cells examined (50 of 50). Cells were cloned according to their characteristic morphologies and biological behavior in culture. The cloned cells were sparse spindle, packed spindle, epithelioid, and lymphoid. In colonies, sparse spindle cells grew separately from each other without cell to cell contact but produced a cartwheel pattern at confluency. Packed spindle cells grew in a tightly packed fashion and produced a storiform pattern at confluency. Epithelioid cells were spindle shaped as individuals but became epithelioid when in contact with each other and produced many multinucleated giant cells at confluency. Lymphoid cells were spindle shaped as individuals but became spherical at confluency. When tumors were grown in nude mice after transplantation of these cloned cells, the histology was shown to be unrelated to morphology in culture and was epithelioid (histiocytic), as was the original tumor. These results show that (a) a single cell derived from malignant fibrous histiocytoma cells exhibits a wide range of phenotypical expression in vitro, (b) cells have their own morphological and biological characteristics in vitro, which (c) however, are easily influenced by environmental factors and (d) which are unstable and even interchangeable. These characteristics may contribute to the endless variety of cellular forms and growth patterns of malignant fibrous histiocytomas in humans.

Animals↗
PubMed1991

Construction and characterization of a NotI-BsuE linking library from the human X chromosome.

We describe the construction and characterization of methylation-resistant sequence-tagged NotI linking clones specific for the X chromosome, referred to as NotI-BsuE linking clones. The approach consists of methylating the X-chromosome-specific cloned DNA with BsuE methylase (M. BsuE), an enzyme that methylates the first C residue in the CGCG sequence, followed by selection of the methylation-resistant NotI sites by insertion of a kanamycin-resistance gene in the clones cleavable by NotI. The frequent occurrence of NotI sites in CpG islands is expected to cause methylation of a large number of NotI sites with BsuE methylase, thereby rendering them resistant to NotI cleavage. Thus, the combination of M. BsuE and NotI yields less frequent cutting than the NotI alone. We have isolated, partially sequenced, and characterized 113 NotI-BsuE linking clones, and mapped 50 clones to various regions along the chromosome.

Base Sequence↗
PubMed1991

Inhibition of transcription by mammalian ribonucleic acid polymerase II: effects of diethylstilbestrol and its analogues.

We examined the effects of diethylstilbestrol (1), Z,Z-dienestrol (2), E,E-dienestrol (3), indenestrol A (4), indenestrol B (5) and estradiol (6) on the activity of in vitro accurate transcription from adenovirus 2 major late promoter by mammalian ribonucleic acid (RNA) polymerase II using partially purified transcription factors from HeLa cell nuclear extract as well as on RNA polymerase II activity assayed for random incorporation of ribonucleotides. 1, 2, and 3 inhibited both activities, whereas 4 and 5 were inhibitory only in the transcription activity at concentrations higher than 10 micrograms/ml. However 6 had no effects on both activities.

Adenoviridae↗
PubMed1991

[An effect of priming task repetition on memory processes in an epileptic with amnesia].

The purpose of this paper is to investigate memory processes in an epileptic with amnesia. Selective impairment of memory in organic amnesia has been reported in some clinical observations. They also demonstrated that organic amnesia can retain some aspects of learning experience, despite their inability to recollect them. We investigated an effect of priming task repetition on memory processes in a female with organic amnesia aged 28 (probable encephalitic patient) and eight control college students aged 20-26. In this paper, her memory processes were analyzed, using the same picture priming task, carried twelve times during the period of seven months. We used semantic priming paradigm. Three types of prime-target pair were used: identical, semantically related and unrelated. After a prime picture, a target picture appeared on the CRT display. She was asked to name each target as rapidly and accurately as possible. We analysed reaction time (RT) in naming the picture targets, error rate, and verbal reports of the priming task in the pre- and post-examination interview. In the first examination, priming effect was observed in her RT as in the controls'. This suggests that she retained some amount of semantic memory, and the structure of her semantic memory closely resembled that in the controls. Naming RT reduced and error rate decreased with repetition of the examination. This suggests that she acquired picture naming skill during early few examinations. However it was difficult for her to recognize and recollect the picture stimuli in this period. Further, she did not show any episodic memory of the examinations. There was dissociation between improved RT performance and poor verbal reports during early few examinations. When the same priming task was repeated in early few examinations, the priming effect became weaker in her RT. In the controls, on the contrary, the priming effect remained during the whole task repetition. Semantic strategy was apparently used in the controls, but not in the amnesic patient. She apparently used strategy of non-semantic association between the prime and target. In the last few examinations, her naming RT delayed and the priming effect was observed again as in the first examination. She seemed to use semantic strategy. In addition to this priming effect, she re-collected a few pictures and showed some episodic memory of the examination.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1990

A heteromeric transcription factor required for mammalian RNA polymerase II.

A general transcription factor, FC, essential for specific initiation of in vitro transcription by mammalian RNA polymerase II was identified and a procedure developed to purify it to near homogeneity from HeLa cell nuclei. Purified FC is composed of two polypeptides of apparent molecular masses 80 kDa and 30 kDa, on SDS-PAGE, and has a native size of 280 kDa estimated by gel filtration column. Both polypeptides were shown to be essential for reconstituting in vitro transcription activity. Biochemical analysis showed that the 80 kDa and 30 kDa components were present in a 1:1 molar ratio. FC was also demonstrated to interact directly or indirectly with purified RNA polymerase II. Similarities between FC and transcription factors reported by others from human, rat or Drosophila cells are discussed.

Chromatography, High Pressure Liquid↗
PubMed1990

Changes in levels of microtubule-associated proteins in relation to the outgrowth of neurites from PC12D cells, a forskolin- and nerve growth factor-responsive subline of PC12 pheochromocytoma cells.

Immunoblotting analysis and immunofluorescence studies of proteins that react with MAP1- and MAP2-specific antibodies in PC12 rat pheochromocytoma cells were carried out. When cells of the PC12D subline of PC12 cells, which rapidly extend neurites in response to NGF or drugs that elevate intracellular levels of cyclic AMP, were examined, they were found to contain a relatively higher level of MAP1 or of a MAP1-like protein than conventional PC12 cells. Immunoblotting study showed that levels of MAP1 and MAP2 or of MAP1 or MAP2-like proteins increased in PC12D cells, but not in conventional PC12 cells, in response to forskolin. Immunofluorescence studies also revealed increases in levels of MAP1 and MAP2 or of MAP1 or MAP2-like proteins in conjunction with the outgrowth of neurites from the cells. These results support the hypothesis that the induction of MAPs may be one of the first steps required for outgrowth of neurites from PC12 cells. Furthermore, PC12D cells may contain a sufficiently high level of MAP1 or MAP1-like protein to permit the extension of neurites in the absence of the lag period normally required by PC12 cells. The MAP1 or a MAP1-like protein was localized in the cell soma and neurites. An increase of MAP2-specific immunoreactivity in perikarya was observed in the differentiated cells. After immunostaining with a monoclonal antibody that reacted with phosphorylated MAP1, intense fluorescence was seen in the growth cones of neurites. This observation supports the hypothesis that the phosphorylation of MAP1 or of a MAP1-like protein may play a regulatory role in the formation of neurites in growth cones.

Adrenal Gland Neoplasms↗
PubMed1990

Purification of two transcription factors required for initiation by mammalian RNA polymerase II.

We have purified two general transcription factors (FA and FE) necessary for specific transcription by mammalian RNA polymerase II to near homogeneity. Both activities are associated with peptides of approximately 33 kDa. FA and FE do not replace one another and show different kinetics of action in a sarkosyl block assay. In particular, FE participated in a rapid reaction after the formation of an initial complex with the other transcription factors. Furthermore, FE can associate with purified calf thymus RNA polymerase II.

Animals↗
PubMed1990

A nerve growth factor-dependent protein kinase that phosphorylates microtubule-associated proteins in vitro: possible involvement of its activity in the outgrowth of neurites from PC12 cells.

We have established a subline of PC12 cells (PC12D) that extend neurites very quickly in response not only to nerve growth factor (NGF) but also to cyclic AMP (cAMP) in the same way as primed PC12 cells (NGF-pretreated cells). When phosphorylation of brain microtubule proteins by extracts of these cells was monitored, two distinct kinase activities were found to be increased [from three-to eightfold in terms of phosphorylation of microtubule-associated protein (MAP) 2] by a brief exposure of cells to NGF or to dibutyryl cAMP (dbcAMP). The effect of the combined stimulation with both NGF and dbcAMP was additive in terms of the phosphorylation of MAP2. The apparent molecular mass of the kinase activated by dbcAMP was 40 kDa, and this kinase appears to be cAMP-dependent protein kinase. The molecular mass of the kinase activated by NGF was 50 kDa. The latter was activated to a measurable extent after 5 min of exposure of cells to NGF: it required Mg2+ for activity but not Mn2+ or Ca2+. This kinase appears to be distinct from previously reported kinases in PC12 cells, and it has been designated as NGF-dependent MAP kinase, although its physiological substrates are not known at present. An inhibitor of protein kinases, K-252a, selectively inhibited the outgrowth of neurites from PC12D cells in response to NGF but not to dbcAMP. When this inhibitor was added to the incubation medium of cells exposed simultaneously to NGF or dbcAMP, the increase in activity of the NGF-dependent MAP kinase was selectively abolished.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Gland Neoplasms↗