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Biomedical subjects

K Takeda

Publications and source records attributed to K Takeda.

At least 703 records · Page 39Linked to original sources
PubMed1994

Changes in homeobox-containing gene expression during ectopic bone formation induced by bone morphogenetic protein.

Expression of homeobox genes in relation to ectopic bone formation induced by bone morphogenetic protein (BMP) was investigated. Oligonucleotide primers corresponding to highly conserved regions of Hox cluster and Msx genes were designed to detect homeobox sequences by means of the polymerase chain reaction (PCR). Nine rat homologues of Hox cluster genes and two Msx genes were discovered in the BMP-implanted tissue, at earlier stage and later cartilage and bone formation stage, respectively. The PCR study provided evidence of dynamic changes in BMP-induced homeobox gene expression.

Amino Acid Sequence↗
PubMed1994

Acute rejection of marrow grafts in mice. Dependence on and independence of functional TCR in the rejection process.

The question of how irradiated mice acutely reject marrow grafts has remained controversial, and evidence in support of T cell- and natural killer cell-mediated rejection mechanisms has been provided. Here we show in support of previous data that CB17 severe combined immunodeficiency mice acutely reject allogeneic marrow but the specificity of rejection cannot be mapped within the MHC. It is shown that a similar rejection specificity is also expressed in normal CB17 mice and that it is caused by CD3- or CD3+ effector cells that do not utilize TCR. In search of TCR-independent rejection mechanisms in other mouse strains, use is made of TCR transgenic mice expressing a defect in recognizing H-2Dd. It is shown that, although marrow graft rejection is impaired in these mice, pointing to participation of TCR in the rejection process, residual resistance does exist. This resistance maps to the MHC, cannot be shown to involve TCR, and appears to be expressed by NK1+ CD3+ cells. It is concluded that acute marrow graft rejection in normal mice can be mediated by both TCR-mediated and NK cell receptor-dependent effector mechanisms, depending on the particular mouse strains.

Acute Disease↗
PubMed1994

A pertussis toxin-insensitive calcium influx mediated by neuropeptide Y2 receptors in a human neuroblastoma cell line.

Stimulation of neuropeptide Y (NPY) Y2 receptors induced an intracellular free Ca2+ ([Ca2+]i) increase in a human neuroblastoma cell line, CHP-234. When NPY in a Ca(2+)-free solution was applied, this increase was abolished. Depolarization with high KCl evoked no response, suggesting that the responses were not mediated by voltage-gated Ca2+ channels. There was no evidence that the NPY response consisted of a capacitative Ca2+ entry sensitive to internal Ca2+ store levels. The [Ca2+]i elevation was diminished by Ni2+, a blocker of Ca2+ entry. Mn2+ induced a quench of the fura-2 fluorescence, which ceased promptly upon the removal of NPY, indicating that Ca2+ entry was linked tightly to receptor activation. Although thapsigargin- and ryanodine-sensitive Ca2+ stores were present, NPY-induced responses were not impaired by pretreatment with either drug. Furthermore, NPY had no effect on the thapsigargin-sensitive store. Pertussis toxin did not affect the NPY-stimulated [Ca2+]i increase, although it abolished the NPY-dependent inhibition of cAMP production. It is concluded that the Y2 receptors couple directly to receptor-operated Ca2+ channels without the involvement of intracellular Ca2+ stores. The results also indicate that Y2 receptors can activate both pertussis toxin-sensitive and -insensitive mechanisms in the same cell.

Calcium↗
PubMed1994

Structural studies on the chondroitinase ABC-resistant sulfated tetrasaccharides isolated from various chondroitin sulfate isomers.

Various commercially available chondroitin sulfates, including an A isomer from whale cartilage, C and D isomers from shark cartilage, and an E isomer from squid cartilage, were exhaustively digested with a commercial highly purified Proteus vulgaris chondroitinase ABC. Gel chromatography of all digests yielded a disaccharide and an oligosaccharide fraction which was resistant to the enzyme digestion and which accounts for 20-31 mol% of the produced total oligosaccharides. Variably sulfated tetrasaccharides were isolated from the oligosaccharide fraction of each chondroitin sulfate isomer by HPLC, then characterized chemically and enzymatically. One disulfated and three trisulfated components were also characterized by 500-MHz one- and two-dimensional 1H NMR spectroscopy. The structures of one tetrasulfated, four trisulfated, and five disulfated tetrasaccharides with the common core structure, alpha-L-delta 4,5HexpA-(1-->3)-beta-D-GalpNAc-(1-->4)-beta-D-GlcpA-(1-->3) -D-GalpNAc, were determined. All isolated tetrasaccharides were resistant to the highly purified enzyme, but susceptible to the conventional, commercial chondroitinase ABC. The former was also inactive towards alpha-L-delta 4,5HexpA-(1-->3)-beta-D-GalpNAc-(1-->4)-beta-D-GlcpA-(1-->3) -D-GalpNAc isolated from chondroitin, beta-D-GlcpA-(1-->3)-beta-D-GlcpNAc-(1-->4)-beta-D-GlcpA-(1- ->3)-D-GlcpNAc from hyaluronan, and alpha-L-delta 4,5HexpA-(1-->3)-beta-D-GalpNAc4SO3(-)-(1-->4)-alpha-L-Id opA-(1-->3)-D- GalpNAc4SO3- from dermatan sulfate. These results indicate that, unlike the conventional enzyme, highly purified chondroitinase ABC cannot degrade tetrasaccharides irrespective of their sulfation profiles. The enzymatic action is size-dependent.

Carbohydrate Sequence↗
PubMed1994

Chondroitinase ABC-resistant sulfated trisaccharides isolated from digests of chondroitin/dermatan sulfate chains.

Four kinds of sulfated trisaccharides resistant to chondroitinase ABC were isolated after chondroitinase B or ABC treatment of dermatan sulfate or various chondroitin sulfate isomers, respectively. Their composition was determined by chemical analysis and fast atom bombardment-mass spectrometry. Their structures were characterized by chondroitinase ACII digestion in conjunction with HPLC, and 500-MHz one- and two-dimensional 1H NMR spectroscopy. All the four trisaccharides have in common the core saccharide sequence, alpha-L-delta 4,5HexpA-(1-->3)-beta-D-GalpNAc-(1-->4)-D-GlcpA. A monosulfated component isolated from shark scapular cartilage chondroitin sulfate C or bovine aorta dermatan sulfate was elucidated as alpha-L-delta 4,5HexpA-(1-->3)-beta-D-GalpNAc6SO3(-)-(1-->4)-D-GlcpA or alpha-L-delta 4,5HexpA-(1-->3)-beta-D-GalpNAc4SO3(-)-(1-->4)-D-GlcpA , respectively. A disulfated component obtained from shark scapular cartilage chondroitin sulfate C or squid cartilage chondroitin sulfate E was identified as alpha-L-delta 4,5HexpA2SO3(-)-(1-->3)-beta-D-GalpNAc6SO3(-)-(1-->4)-D-G lcpA or alpha-L-delta 4,5HexpA-(1-->3)-beta-D-GalpNAc4SO3(-)6SO3(-)-(1-->4)- D-GlcpA, respectively. These trisaccharides are derived from the reducing termini of the parent polysaccharides. Some of the trisaccharides could be derived from the reducing termini exposed by the peeling reaction during the alkaline treatment while some others may represent the cleavage sites exposed by tissue endo-beta-D-glucuronidase(s), indicating the presence of such enzyme(s) which may release chondroitin/dermatan sulfate fragments from proteoglycans.

Animals↗
PubMed1994

Lymphotoxin lacks effects on 75-kDa receptors in cytotoxicity on U-937 cells.

We examined differences in cytotoxic activity between human lymphotoxin (LT) and tumor necrosis factor (TNF) as functions of their interaction with two types of TNF receptors, 55-kDa (p55R) and 75-kDa (p75R). Cytotoxic activity of LT was much lower than that of TNF on a human monocytic cell line, U-937, on which p75R was predominant. Monoclonal antibodies specific for p55R (htr-5 and htr-9) and p75R (utr-1) significantly diminished TNF cytotoxicity, whereas, utr-1 was only slightly inhibitory to LT cytotoxicity, and htr-5 reduced it significantly. TNF individual binding to p75R increased cytotoxic activity when p55R was occupied by htr-9 and a mutein of TNF which significantly lost affinity to p75R. However, LT binding to p75R did not increase. Scatchard analysis with [125I]LT and [125I]TNF showed that LT still had approximately half of the affinity to p75R and slightly less affinity to p55R than TNF. These results indicate slight cytotoxicity of LT compared to TNF, due to inability of LT to signal through p75R on U-937 cells without significant loss of affinity to p75R.

Humans↗
PubMed1994

Conformational stability of alpha-lactalbumin missing a peptide bond between Asp66 and Pro67.

The peptide bond between Asp66-Pro67 of alpha-lactalbumin was cleaved with formic acid (cleaved alpha-lactalbumin). Secondary structural changes of the cleaved alpha-lactalbumin, in which the two separated polypeptides were joined by disulfide bridges, were examined in solutions of sodium dodecyl sulfate (SDS), urea, and guanidine hydrochloride. The structural changes of the cleaved alpha-lactalbumin were compared with those of the intact protein. The relative proportions of secondary structures were determined by curve fitting of the circular dichroism. The cleaved alpha-lactalbumin contained 29% alpha-helical structure as against 34% for the intact protein. Some helices of the cleaved alpha-lactalbumin which had been disrupted by the cleavage appeared to be reformed upon the addition of SDS of very low concentration (0.5 mM). In the SDS solution, the helicities of both the intact and cleaved proteins increased, attaining 44% at 4 mM SDS. On the other hand, the helical structures of the cleaved alpha-lactalbumin began to be disrupted at low concentrations of guanidine hydrochloride and urea compared with that of the intact protein. However, no difference was observed in the thermal denaturations of the intact and cleaved proteins, except for the difference in the original helicities. The helicities of both proteins decreased with an increase of temperature up to 65 degrees C and recovered upon cooling.

Amino Acid Sequence↗
PubMed1994

Absence of p53 mutation in Japanese patients with malignant thyroid lymphoma.

Abnormalities of the gene encoding the sequence-specific DNA-binding protein, nuclear phosphorprotein p53, are among the most common genetic alterations observed in human cancers. A mutation of this tumor suppressor gene has been reported with a low prevalence in differentiated thyroid carcinomas, while the prevalence was high in undifferentiated thyroid carcinomas. We used denaturing gradient gel electrophoresis (DGGE) to probe for mutations of p53 gene in order to determine its role in the genesis of malignant thyroid lymphoma. Involvement of 27 samples had been proven by histopathologic examination of specimen obtained by open biopsy of the thyroid gland or from cervical lymph nodes. DNA was extracted from tissues embedded in paraffin blocks and exons 5-8 of p53 gene were examined for the presence of mutations by DGGE following amplification by PCR using GC-clamped primers. To confirm accuracy of the method, samples with known p53 mutations were included in the study. No mutations were detected in any of the amplified exons of malignant thyroid lymphoma samples. These results suggest that p53 mutations are not present or are uncommon in Japanese patients with malignant thyroid lymphomas. The role of p53 in this form of carcinogenesis cannot be fully excluded since we have not examined the occurrence of mutations in regions upstream of exon 5.

Aged↗
PubMed1994

Effects of prostaglandins E1 and E2 on cultured smooth muscle cells and strips of rat aorta.

Using patch-clamp and Indo-1AM techniques, we studied the effects of prostaglandins (PG) E1 and E2 on transmembrane ionic currents and cytosolic calcium concentration ([Ca2+]i) in cultured rat aortic smooth muscle cells (SMC) and on isotonic contraction-relaxation of strips of the rat thoracic aorta. In voltage-clamped at -70 mV single SMC PGE1 and PGE2 in concentration 100 nM evoked inward and outward currents. The inward current was unaffected by the Cl channel blocker DIDS (0.1 mM). The outward current was blocked by internal Cs+ and external Ba2+ and was likely due to increased Ca2+ activated K+ conductance. Application of PGE1 and PGE2 in the bath solution evoked relaxation of aortic strips in a concentration-dependent manner. In both cases indomethacin was ineffective. The rise in [Ca2]i evoked by PGEs was observed in single cells loaded with Indo-1AM. Whole-cell voltage-activated T- and L-type Ca2+ currents were reduced by both PGE1 and PGE2. The results obtained in this work indicate that in cultured rat aortic SMC PGE1 and PGE2 increase [Ca2+]i with subsequent activation of Ca(2+)-dependent K+ currents, block voltage-activated Ca2+ currents, and at the same time induce relaxation of aortic strips.

Alprostadil↗
PubMed1994

Effects of tretinoin tocoferil on gene expression of the extracellular matrix components in human dermal fibroblasts in vitro.

Recently, it has been reported that tretinoin tocoferil (TT), a synthesized ester-bond compound of all-trans-retinoic acid and alpha-tocopherol, accelerates the formation of granuloma and is effective in promoting experimental open skin wound healing. To investigate whether TT affects the gene expression of extracellular matrix components of human dermal fibroblasts, we measured the mRNA levels of various extracellular matrix components of fibroblasts incubated with TT using specific cDNA probes. The mRNA levels of elastin increased up to 30% of the controls and those of collagen III and VI up to 60%. The mRNA levels of collagen I and fibronectin remarkably increased up to 90% of the controls. These results suggest that the stimulatory effect of TT on the gene expression of many extracellular matrix components might be one of the mechanisms of its promotion of wound healing.

Actins↗
PubMed1994

Activation of fibroblast proliferation by Werner's syndrome fibroblast-conditioned medium.

The effects of Werner's syndrome (WS) fibroblast-conditioned medium on cell proliferation and collagen production of normal fibroblasts were studied using four WS fibroblast strains. The conditioned medium from the WS fibroblasts brought about activation of normal fibroblast proliferation, whereas, that from late passage normal fibroblasts and fibroblasts from aged donors' skin did not. Collagen and non-collagenous protein synthesis in normal fibroblasts were increased by the addition of conditioned medium from the WS fibroblasts, but the relative rates of collagen synthesis and non-collagenous protein synthesis were unaltered. These results suggest that activation of fibroblast proliferation by conditioned medium is one of the characteristics of WS fibroblasts.

Adult↗
PubMed1994

The anthocyanin responsible for purplish blue flower colour of Aconitum chinense.

The anthocyanin in the purplish blue flowers of Aconitum chinense was identified as delphinidin 3-rutinoside-7-O-(6-O-(4-(6-O-(4-hydroxybenzoyl)-beta-D-glucosyl)oxyb enzoyl- beta-D-glucoside), violdelphin by means of chromatography, FAB-MS including MS-MS, 1H and 13C NMR. The anthocyanin is stable in neutral or slightly acidic aqueous solution and the absorption spectra in the pH range of 4.0-6.2 exhibited three characteristic bands at 534, 569 and 620 nm, which are practically identical with those of purplish blue petals of A. chinense. Thus the purplish blue flower colour is manifested by intramolecular co-pigmentation of the anthocyanin.

Anthocyanins↗
PubMed1994

Physiological expression of the 2',5'-oligoadenylate synthetase gene in mouse intestine.

2',5'-Oligoadenylate synthetase (2-5A synthetase) is an enzyme induced by interferon (IFN) that is considered to play an important role in IFN action. The normal mouse, not treated exogenously with any IFN or IFN inducers, has been shown to have an enhanced level of 2-5A synthetase activity, which is distributed among several lymphoid tissues. In the present report, we investigated the expression of the 42-kD 2-5A synthetase mRNA in the organs of normal mice using RNA blot hybridization and reverse transcriptase polymerase chain reaction (RT-PCR). Among the organs tested, intestinal tissues had the highest levels of this mRNA. Furthermore, the 42-kD 2-5A synthetase mRNA was expressed in intestines from germ-free mice and fetuses. Immunoblotting analysis using a monoclonal antibody against the 42-kD 2-5A synthetase revealed that the 42-kD enzyme as well as a cross-reactive protein of 30 kD were produced in the organs of the normal mouse.

2',5'-Oligoadenylate Synthetase↗
PubMed1994

Downregulation of c-myc expression by tumor necrosis factor-alpha in combination with transforming growth factor-beta or interferon-gamma with concomitant inhibition of proliferation in human cell lines.

The modulation of cell growth by tumor necrosis factor-alpha (TNF-alpha), or TNF-alpha in combination with transforming growth factor-beta (TGF-beta) or interferon-gamma (IFN-gamma) was investigated. TNF-alpha inhibited the proliferation of U937 cells, a monocytic leukemic cell line, and of NA cells that were established from oral squamous cell carcinoma. TNF-alpha showed a cytolytic effect on NA cells in the presence of actinomycin D. TNF-alpha in combination with TGF-beta and TNF-alpha combined with INF-gamma synergistically inhibited the cell proliferation of U937 and NA cells, respectively. TNF-alpha dose-dependently reduced c-myc mRNA expression of U937 and NA cells within 1 h. The combination of TNF-alpha and TGF-beta in U937 cells and that of TNF-alpha and IFN-gamma in NA cells cooperatively reduced the expression of c-myc mRNA. TNF-alpha had little or no effect on the half-life of c-myc mRNA, indicating that c-myc mRNA expression was reduced at transcriptional level. Cycloheximide did not mediate the inhibition of c-myc gene expression, suggesting that the TNF-alpha action was independent of de novo protein synthesis. These data suggest that the reduction of c-myc gene at transcriptional level by TNF-alpha or TNF-alpha in combination with TGF-beta or IFN-gamma plays a primary role in the inhibition of cell growth at an early stage.

Cell Division↗
PubMed1994

Antihypertensive effects of 2-octynyladenosine (YT-146), a selective adenosine A2 receptor agonist, in Dahl salt-sensitive rats.

The antihypertensive effects of a novel adenosine A2 receptor agonist, 2-octynyl adenosine (YT-146), were evaluated in Dahl salt-sensitive rats. After rats were fed a high-salt (8% NaCl) diet for 2 or 3 weeks, they received oral YT-146 (0.1 or 1.0 mg/kg) or vehicle as a single dose (acute study) or once daily for 10 days (chronic study). In the acute study, tail-cuff blood pressure (BP) and pulse rate (PR) were measured before and 3, 6, and 24 h after administration, and blood samples were collected 3 h after administration. In the chronic study, BP and PR were measured 3 and 24 h after administration and urine was collected for 24 h on day 9. Blood samples were also collected 3 h after administration on day 10. BP was significantly lowered by 1.0 mg/kg of YT-146 in either the acute study (from 184 +/- 3 to 152 +/- 5 mm Hg, P < .01) or the chronic study (from 226 +/- 4 to 201 +/- 2 mm Hg, P < .01), while an increase in PR was not observed (acute study: from 382 +/- 8 to 366 +/- 3 beats/min; chronic study: from 420 +/- 8 to 411 +/- 8 beats/min). YT-146 had no effect on plasma renin activity (PRA), plasma aldosterone, vasopressin (ADH), and atrial natriuretic peptide (ANP) in the acute study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗