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Y Imai

Publications and source records attributed to Y Imai.

At least 595 records · Page 33Linked to original sources
PubMed1995

[Tumor-rejection antigens expressed on human squamous cell carcinoma].

Squamous cell carcinoma (SCC) is one of the most common cancers in human. SCC, particularly, esophageal and lung SCC are relatively resistant to currently available regimens of chemotherapy or radiation therapy. Therefore, development of a specific immunotherapy using tumor specific cytotoxic T lymphocytes (CTL) would be important to offer other treatment modalities. However, generation of HLA class I-restricted CTL recognizing SCC has been rarely reported. We established the HLA A2601-restricted CTL cell line recognizing a peptide antigen expressed on SCC. This CD4- CD8+ cytotoxic T lymphocyte (KE-4 CTL) cell line was established in a patient with esophageal cancer. The KE-4 CTL recognized a peptide antigen on esohageal and lung SCC in an HLA A2601-restricted manner as evaluated by cytotoxity against a panel of tumor cells, transfection experiments with HLA A2601 cDNA, and reconstitution with eleted peptides. None of normal cells tested was lysed by this CTL. These results suggest the exstence of HLA A2601-restricted CTL precursors recognizing a peptide antigen on SCC in a patient with esophageal cancer.

Antigens, Neoplasm↗
PubMed1995

[A modified Damus-Kaye-Stansel anastomosis for restrictive bulvoventricular foramen developed 5 years after Fontan procedure].

An one-year old girl, who had pulmonary artery (PA) banding and balloon atrioseptostomy done in the newborn period, underwent modified Fontan procedure on an emergency basis without cardiac catheterization, because of right heart failure. Echocardiogram showed no subaortic stenosis at Fontan procedure. Five years later, subaortic stenosis was documented with a 65 mmHg of ventricular-aortic pressure gradient at catheterization. A modified Damus-Kaye- Stansel (D-K-S) procedure was successfully performed using an end-to-end anastomosis of the distal aorta and a common stump, consisting of previously suture-closed main PA stump and the proximal aorta. At postoperative catheterization, the pulmonary valve was functioning well at LV outlet portion without regurgitation and stenosis. Significant subaortic stenosis may develop after Fontan procedure in patients with morphological narrowing without demonstrable pressure gradient. Such patients should have surgical intervention to the narrowing at the time of Fontan procedure. The modified D-K-S procedure can be an effective procedure to relieve subaortic stenosis after Fontan procedure.

Anastomosis, Surgical↗
PubMed1995

Increased gain in baroreceptor-heart rate reflex in patients with primary aldosteronism.

OBJECTIVE: Reduced baroreflex sensitivity has been reported in several kinds of human hypertension. However, the nature of the baroreceptor-heart rate reflex in hypertension due to excess mineralocorticoid has never been fully explored. PATIENTS AND METHODS: Thirty patients with primary aldosteronism, 60 patients with essential hypertension (World Health organization stages I or II) and 45 normotensive subjects were enrolled. The groups did not differ in mean age. Blood pressure was similar between patients with primary aldosteronism and those with essential hypertension. Blood pressure (Finapres) and the RR interval (ECG) were monitored continuously at rest. The closed loop gain between systolic blood pressure and RR interval variabilities was used to measure the sensitivity of the baroreceptor-heart rate reflex. RESULTS: Baroreflex sensitivity in the group with primary aldosteronism was significantly greater than in the essential hypertensive group, but did not differ significantly between the group with aldosteronism and the normotensive group. Three to four weeks after removal of an adrenal adenoma (n = 25), both systolic and diastolic blood pressure were decreased significantly in the aldosteronism group but were still higher than in the normotensive group. The baroreflex sensitivity was reduced by about 40% after adrenalectomy compared to pre-operative values. The decrease in the baroreflex gain following adrenalectomy was correlated negatively with the decrease in systolic blood pressure (r = -4.00, P=0.05). CONCLUSION: These results demonstrate that hypertension due to excess mineralocorticoids is characterized by an increase in the gain of the baroreceptor-heart rate reflex. The reduction in baroreflex gain following adrenalectomy may delay the normalization of blood pressure.

Adolescent↗
PubMed1994

Isolation and characterization of krp, a dibasic endopeptidase required for cell viability in the fission yeast Schizosaccharomyces pombe.

The activation of pro-hormones and many precursor proteins involves cleavage by endopeptidases belonging to the subtilisin-like family of enzymes. Here we describe the isolation and characterization of the first member of this family from the fission yeast Schizosaccharomyces pombe. The enzyme, which has been named krp for KEX2-related protease, is a type I membrane-bound endopeptidase that cleaves substrates after pairs of dibasic residues. It appears to be synthesized as a pre-pro-protein that is likely to undergo processing following translocation into the endoplasmic reticulum. Processing has been characterized in a cell-free translation/translocation system prepared from Xenopus eggs. Krp is N-glycosylated on all five of its potential sites and both the pre-sequence and the pro-sequence are quickly removed following translocation, the latter probably by autocatalytic cleavage. The inhibitor profile of krp broadly reflects the known properties of the eukaryotic subtilisin proteases, while its pH and Ca2+ dependence are consistent with it being active within the secretory pathway. One of its physiological substrates is likely to be the pheromone precursor pro-P-factor, which it is shown to process in an in vitro system, but identification of other substrates is complicated because, unlike other members of this family, krp is essential for cell viability.

Amino Acid Sequence↗
PubMed1994

Fusidic acid suppresses nitric oxide toxicity in pancreatic islet cells.

Earlier preclinical and clinical trials indicate that fusidic acid, a triterpenoid compound originally described as an antimicrobial drug may protect islet beta cells from destruction in type I (insulin-dependent) diabetes mellitus. Since nitric oxide appears to be an important mediator of inflammatory islet cell death we analyzed whether fusidic acid interferes with nitric oxide production or action. We report here that fusidic acid dose-dependently inhibits lysis of isolated islet cells by activated macrophages, a process mediated by nitric oxide. In the presence of 100 microM fusidic acid macrophage-mediated islet cell lysis was reduced from 52.5 to 1.7% (P < 0.001). Fusidic acid only slightly affected macrophage function and did not inhibit the release of nitric oxide. We therefore tested whether fusidic acid suppresses nitric oxide toxicity in target cells. Isolated islet cells were exposed to the nitric oxide donor nitroprusside which led to DNA strand breaks and plasma membrane lysis. DNA strand breaks were reduced from 54.6 to 34.9% (P < 0.001) in the presence of 100 microM fusidic acid and cell lysis was reduced from 60.1 to 27.5% with 100 microM (P < 0.001). In the presence of 500 microM fusidic acid DNA strand breaks and cell lysis were reduced further to 27.1 and 10.7%, respectively (P < 0.001). No protection by fusidic acid was observed when cells were exposed to oxygen radicals or the alkylating beta cell toxin streptozotocin. The suppression of nitric oxide toxicity by fusidic acid was not due to its known inhibitory action on protein biosynthesis and thus represents a hitherto unknown activity of this drug.

Animals↗
PubMed1994

TGF beta 1 suppresses EGF-induced increase in nuclear type 1 protein phosphatase activity at the G1/S transition of hepatocyte proliferation.

Nuclear type 1 protein phosphatase (PP1) activity in primary culture of EGF-stimulated hepatocytes was significantly and transiently increased at the G1/S transition, being about 2.5-fold, while that in non-stimulated hepatocytes showed almost no change. On the other hand, non-nuclear PP1 activity was gradually increased until the G1/S transition, but the activity showed no difference between EGF-stimulated and non-stimulated hepatocytes. Under growth-inhibited conditions in the presence of TGF beta 1, the increase in nuclear PP1 activity was completely suppressed, whereas non-nuclear PP1 activity was little affected. Such close correlation between nuclear PP1 activity and growth factor-induced positive or negative growth signaling strongly suggests an involvement of PP1 in progression from G1 to S phase of hepatocytes. On Western immunoblotting using antisera for PP1 alpha, PP1 gamma 1, and PP1 delta, no isoform showed any change in amount under these conditions. Mechanism(s) of growth-associated alterations in nuclear PP1 activity is discussed.

Animals↗
PubMed1994

Measurement of contribution from intracellular cysteine to sulfate in phosphoadenosine phosphosulfate in rat ovarian granulosa cells.

Synthesis of the large dermatan sulfate (DS) proteoglycan by rat ovarian granulosa cells was studied using metabolic radiolabel precursors in culture media with varying concentrations of environmental sulfate (20-800 microM) and cysteine (130 and 650 microM). Experiments using [3H]glucosamine and [35S]sulfate showed that the average size of the DS chains and the rate of DS proteoglycan synthesis were independent of the sulfate and cysteine concentrations in the medium. Experiments with [35S]cysteine were then used to determine the contribution that metabolic conversion of cysteine sulfur to sulfate makes to the 3'-phosphoadenosine 5'-phosphosulfate (PAPS) pool which provides the substrate for sulfoester formation in DS synthesis. When 35S in cysteine is metabolized into [35S]PAPS, the specific activity is reduced from that of the [35S]cysteine pool, by dilution with other sulfur sources such as extracellular sulfate, and this dilution factor directly reflects the contribution of cysteine to the PAPS pool. The decreases of 35S specific activity were measured under various sulfate-depleted and cysteine-supplemented conditions by comparing the specific activity of [35S]sulfate ester in the DS chains with that of [35S]cysteine residues in the core protein of the DS proteoglycan. The contribution of sulfur in cysteine to the intracellular PAPS pool was 0.03% in culture medium with normal sulfate (800 microM). Depleted environmental sulfate (20 microM) and increased cysteine supply (650 microM) only increased the sulfur contribution from cysteine to PAPS up to 0.74 and 1.5%, respectively, even though the DS chains were greatly undersulfated (55 and 82% of the control value). Thus, the source of sulfur in the intracellular pool of PAPS was mainly derived from environmental sulfate, and the contribution from cysteine was minimal in these cells.

Animals↗
PubMed1994

Improvement of a d-biotin-hyperproducing recombinant strain of Serratia marcescens.

We previously reported that a recombinant strain, SB412(pLGM304), was constructed from acidomycin-resistant mutants of Serratia marcescens and produced 200 mg of d-biotin per liter of a medium containing sucrose and urea (Sakurai et al., 1993a, b). In the present work, we intended to improve the d-biotin production. Both ethionine and S-2-aminoethylcysteine resistances were added to the host strain SB412, producing d-biotin at 20 mg l-1, and a resultant strain, ETA23, producing it at 33 mg l-1, was obtained. Cells of ETA23 did not maintain pLGM304 stably after greater than 30 generations under non-selective culture conditions. A new recombinant plasmid, pLGM304P, was constructed so as to be composed of pLGM304 and the parB locus, a plasmid-stabilizing element. ETA23 stably maintained pLGM304P after 50 generations under non-selective culture conditions. ETA23(pLGM304) produced 250 mg l-1 of d-biotin in a shaking flask under batch culture conditions and 500 mg l-1 in a jar fermentor under fed-batch culture conditions.

Biotin↗
PubMed1994

Comparison of heme environment at the putative distal region of P-450s utilizing their external and internal nitrogenous ligand bound forms.

Thr-303 to Lys-mutated P-450 2E1, as well as Thr-301 to Lys-mutated P-450 2C2, had absorption spectra characteristic of a nitrogenous ligand-bound form of P-450, such as the pyridine complex of P-450 2E1; (i) in the ferric state, the red-shifted Soret band, compared with the typical low-spin type spectrum of P-450, and the more intense beta band than the alpha band and (ii) in the ferrous state, two Soret peaks at around 447 and 422 nm, the relative intensities of which depended on pH, indicating the existence of two interconvertible states. The equilibrium between the two states of the mutated P-450 2E1 appeared to be shifted toward the 422 nm state, compared with the mutated P-450 2C2. The corresponding mutant of P-450 2C14 had similar spectral properties to those of both mutated P-450s except that the shorter of the two Soret bands of its ferrous form was relatively broad and appeared at 418 nm. These findings suggest that the epsilon-amino-nitrogen of the Lys of the mutated P-450s is located in the appropriate position to occupy the sixth coordination position with the heme iron and spatial differences exist in the essentially conserved structure of the distal heme domain among the three ferrous Lys-mutated P-450s.

Base Sequence↗
PubMed1994

cDNA cloning of an orphan opiate receptor gene family member and its splice variant.

Radioligand binding and cDNA homology studies have suggested the existence of opiate receptors distinct from the recently-cloned mu, delta and kappa receptors. XOR1S, a rat brain cDNA whose predicted translation product displays 67-72% homology with those encoded by mu 1, delta 1 and kappa 1 opiate receptor cDNAs, was constructed from two partial cDNAs identified through cDNA homology approaches. A longer XOR1L variant of this cDNA was also identified by polymerase chain reaction studies using genomic DNA and cDNA from brain and peripheral tissues. XOR1 mRNA is most highly expressed in hypothalamus. COS cell expression of both clones confers neither robust binding of opiate ligands nor reproducible opiate inhibition of forskolin-stimulated adenylate cyclase. These studies identify an orphan clone that helps to define features of the opiate receptor gene family, including apparent differential splicing and expression in peripheral tissues.

Adolescent↗
PubMed1994

Protection of thyroid cancer cells by complement-regulatory factors.

BACKGROUND: Clinical and experimental studies have suggested that complement activation may play a role in tumor cytotoxicity. Little information is available concerning the presence of complement activation and the localization of complement-regulatory factors in cells or tissues of malignant tumors. The aim of the present study was to examine, using immunohistochemistry and immunoelectron microscopy, whether the complement system is activated in tissues of thyroid carcinoma and whether thyroid carcinoma cells are protected from cell lysis by in situ complement activation. METHODS: Fresh tissues were obtained by thyroidectomy from 15 patients with papillary carcinomas, 7 with follicular carcinomas, and 5 with follicular adenomas. In addition, five specimens of histologically normal thyroid tissue and five specimens of chronically inflamed tissue adjacent to thyroid neoplasms were studied. Immunohistochemical and immunoelectron microscopic localization of complement components, C3d and C5b-9, and the complement-regulatory factors, such as s-protein, decay-accelerating factor (CD55), membrane cofactor protein (CD46), complement receptor types 1 (CD35) and 2 (CD21), and protectin (CD59), were examined in these tissues. RESULTS: The staining patterns of C3d, C5b-9, and s-protein were positive and homogeneous in the nonneoplastic and most neoplastic thyroid tissues. Immunoelectron microscopy showed these antigens were localized mainly on the subepithelial and vascular basement membranes and attached to the cell surface of thyroid follicular cells. Decay-accelerating factor (CD55) was present homogeneously on the basement membranes, on the basal cell border of the thyroid follicular cells, and often on the luminal surface of carcinoma cells. Both membrane cofactor protein (CD46) and protectin (CD59) were expressed strongly on the cell surface of almost all benign and malignant thyroid follicular cells. Membrane cofactor protein was expressed on both the basal and lateral membrane, showing cell-to-cell interaction, but rarely on the luminal surface, whereas protectin was expressed strongly on the luminal surface and often on the basal cell border but rarely on the lateral membrane. Neither complement receptor type 1 (CD35) nor complement receptor type 2 (CD21) was expressed on any thyroid follicular cells. CONCLUSIONS: The present study confirmed the presence of complement activation with subsequent deposition of C3d and C5b-9 complexes in thyroid carcinomas. It also indicated that thyroid carcinoma cells are protected from cell lysis because of complement activation in multiple phases by complete coverage of the entire cell membrane surface with complement-regulatory factors. These findings were similar to those found in nonneoplastic thyroid follicular cells.

Adenoma↗
PubMed1994

Quantitative measurement of carbohydrate binding activity of mouse macrophage lectin.

A simple ELISA assay measuring lectin activity of a mouse macrophage galactose/N-acetylgalactosamine-specific C-type lectin (MMGL) was developed. The binding of galactosylated poly-lysine (termed a ligand) to the immobilized soluble form of MMGL (rML) was measured quantitatively. Consistent with the characteristics of MMGL, the binding was calcium dependent and inhibited by galactose and N-acetylgalactosamine. An antiserum against rML inhibited the ligand binding, demonstrating the usefulness of this method for the screening of blocking antibodies. Using this assay, we found a significant interaction between MMGL and carrageenans, a group of sulfated polygalactans. The inhibitory effect of carrageenans was not attributable to a nonspecific interaction because other types of sulfated polysaccharides, such as glycosaminoglycans and fucoidin, did not interfere with the ligand binding. The relevance of the present finding to the biological activities of carrageenans is discussed.

Acetylgalactosamine↗
PubMed1994

Neurotrophic effects of annexin V on cultured neurons from embryonic rat brain.

Recombinant human annexin V showed survival promoting activity in embryonic rat neocortical and mesencephalic neurons in vitro. The neurotrophic effect was observed from a relatively low dose and in a dose-dependent manner. The neurotrophic activity of annexin V was completely blocked by anti-annexin V antibody. Northern blot analysis demonstrated that annexin V mRNA is expressed in non-neuronal cells in the CNS. These results suggest that annexin V plays certain roles in the CNS as a paracrine-type neurotrophic factor.

Amino Acid Sequence↗
PubMed1994

Expression of the alpha 2-macroglobulin-encoding gene in rat brain and cultured astrocytes.

The alpha 2-macroglobulin (alpha 2M), a protease inhibitor, is a major acute-phase protein in rats, and is produced in the liver during acute inflammation. Recently, it has been demonstrated that alpha 2M is also produced by cultured astrocytes from newborn rat brain and has neurite-promoting activity. Here, we found that the expression of the alpha 2M gene was significantly enhanced in the brain following intraperitoneal injection of the neurotoxicant, kainic acid (KA), suggesting that alpha 2M acts as an acute-phase protein in the brain, as in the case of the liver, and may be involved in neural repair processes. Expression of alpha 2M in cultured astrocytes was shown to be stimulated by interleukin-6 (IL-6) and/or leukemia inhibitory factor (LIF) in the presence of glucocorticoid. The amount of mRNAs for IL-6 and LIF increased in the brain of KA-injected rats prior to alpha 2M induction. These results strongly suggested that IL-6 and LIF are involved in alpha 2M induction in the brain, as in the case of the liver. Analysis of the cis-acting element(s) and the trans-acting factor(s) suggested that the regulatory mechanism for alpha 2M expression in astrocytes was similar to that in inflamed liver.

Animals↗
PubMed1994

Platelet-activating factor antagonist TCV-309 attenuates the induction of the cytokine network in experimental endotoxemia in chimpanzees.

Platelet-activating factor (PAF) has been postulated to play a role in the pathogenesis of sepsis. Additionally, in vitro studies have revealed tight interactions between PAF and the cytokine network, and PAF is considered to be an important stimulator of neutrophil functions. To assess the intermediate role of PAF in the induction of cytokines and neutrophil degranulation in endotoxemia in vivo, 12 healthy adult chimpanzees were i.v. injected with a bolus dose of Escherichia coli endotoxin (4 ng/kg); four animals received endotoxin alone, whereas the other chimpanzees were infused with the specific and potent PAF antagonist TCV-309 (bolus of 100 micrograms/kg, followed by either 100 micrograms/kg/h (n = 4) or 500 micrograms/kg/h (n = 4) for 5 h). At both doses TCV-309 significantly inhibited the endotoxin-induced rise in cytokine levels. Peak TNF concentrations after injection of endotoxin alone were 366 +/- 96 pg/ml, vs 105 +/- 47 and 115 +/- 56 pg/ml after administration of endotoxin together with the lower or higher dose of TCV-309, respectively (p < 0.05). TCV-309 also reduced the appearance of soluble TNFRs. Maximal levels of the type I soluble TNFR were diminished from 2.53 +/- 0.27 ng/ml (endotoxin alone) to 1.69 +/- 0.36 ng/ml (high dose TCV-309; p < 0.05); peak values of the type II soluble TNFR were diminished from 8.62 +/- 1.19 ng/ml to 5.76 +/- 0.92 ng/ml (p < 0.05). Furthermore, TCV-309 attenuated the endotoxin-induced release of IL-6 (160 +/- 82 pg/ml after endotoxin alone, vs 63 +/- 30 pg/ml in the low dose TCV-309 group (p < 0.05) and 65 +/- 29 pg/ml in the high dose group (p = 0.07) as well as that of IL-8 (279 +/- 168, vs 71 +/- 15 and 46 +/- 17 pg/ml, respectively; both p < 0.05). TCV-309 tended to reduce the endotoxin-provoked rise in serum IL-1R antagonist levels. In contrast, TCV-309 did not affect the neutrophilic leukocytosis elicited by endotoxin, nor did it inhibit endotoxin-induced neutrophil degranulation, as monitored by the plasma levels of elastase-alpha 1-antitrypsin complexes. We conclude that PAF plays a role, either directly or indirectly, in the stimulation of the cytokine network and in the shedding of soluble TNFR in endotoxemia. PAF does not seem to be an important intermediate factor in endotoxin-induced neutrophilia or neutrophil degranulation.

Animals↗
PubMed1994

The fission yeast mating pheromone P-factor: its molecular structure, gene structure, and ability to induce gene expression and G1 arrest in the mating partner.

Schizosaccharomyces pombe h+ cells secrete a diffusable mating pheromone called P-factor. Here we show that the map2 gene, a defect of which confers h(+)-specific sterility, encodes the precursor of P-factor. We purified P-factor from cells overexpressing map2 and determined its amino acid sequence. P-factor is a peptide of 23 residues, with the sequence Thr-Tyr-Ala-Asp-Phe-Leu-Arg-Ala-Tyr-Gln-Ser- Trp-Asn-Thr-Phe-Val-Asn-Pro-Asp-Arg-Pro-Asn-Leu. A synthetic peptide of this sequence gave the same specific activity and chromatographic profile as the purified P-factor, suggesting that P-factor is unmodified. h- cells starved for nutrition showed a morphological response to P-factor. Transcription of the sxa2 gene, which encodes a protease thought to degrade P-factor, was activated in these cells. The cry1 null mutant, which lacks adenylyl cyclase and has little intracellular cAMP, was susceptible to P-factor even in the presence of nutrients. Combination of the cyr1 and sxa2 mutations enhanced this susceptibility. P-factor induced not only responses toward mating but also arrest of the cell cycle at the G1 phase in h- cyr1 sxa2 cells. This proves that the S. pombe mating pheromone has the ability to arrest cell cycle progression, which has previously been obscured by the usual requirement for mating of nutritional starvation and subsequent growth arrest.

Amino Acid Sequence↗
PubMed1994

Glial conditioned medium alters the expression of amyloid precursor protein in SH-SY5Y neuroblastoma cells.

The effect of conditioned medium from astroglia or microglia cultures on the mRNA expression of amyloid precursor protein (APP) in SH-SY5Y human neuroblastoma cells was examined. When incubated with conditioned medium of glial cells, SH-SY5Y cells expressed a larger amount of APP mRNA than the control cells. Reverse transcription followed by the polymerase chain reaction showed marked induction of expression of APP isoforms containing a Kunitz-type protease inhibitor domain. Our results suggest that glial cells may contribute to the regulation of expression of APP in neurons.

Amyloid beta-Protein Precursor↗