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Biomedical subjects

T Aoki

Publications and source records attributed to T Aoki.

At least 379 records · Page 21Linked to original sources
PubMed1998

DNA sequencing of the gene encoding Salmonella typhimurium-derived T-cell inhibitor (STI) and characterization of the gene product, cloned STI.

In a previous study, we found a novel protein which inhibited T-cell responsiveness to interleukin-2 (IL-2) in Salmonella typhimurium and called it S. typhimurium-derived T-cell inhibitor (STI). In this study, we analyzed the DNA sequence of the gene encoding STI. The STI gene was cloned into a plasmid vector, pUC118, and expressed in Escherichia coli JM109. Like native STI, the cloned STI inhibited IL-2-dependent CTLL-2 cell growth. Furthermore, this growth inhibition involved down-regulation of IL-2 receptor expression. These results indicate that the cloned STI expressed in E. coli was identical to native STI. Sequencing revealed that the STI gene contained an open reading frame of 2298 base pairs encoding a precursor form of 765 amino acid residues (molecular mass 83605) that is processed into a mature form of 745 amino acid residues with molecular mass 81 548. Homology analysis revealed that its amino acid sequence was highly homologous with that of the beta-glucosidase of E. coli K-12. We designated the gene encoding STI sti.

Amino Acid Sequence↗
PubMed1998

A new internal ribosomal entry site 5' boundary is required for poliovirus translation initiation in a mouse system.

Four mutants of the virulent Mahoney strain of poliovirus were generated by introducing mutations in nucleotides (nt) 128 to 134 of the genome, a region that contains a part of the stem-loop II (SLII) structure located within the internal ribosomal entry site (IRES; nt 120 to 590) (K. Shiroki, T. Ishii, T. Aoki, Y. Ota, W.-X. Yang, T. Komatsu, Y. Ami, M. Arita, S. Abe, S. Hashizume, and A. Nomoto, J. Virol. 71:1-8, 1997). These mutants (SLII mutants) replicated well in human HeLa cells but not in mouse TgSVA cells that had been established from the kidney of a poliovirus-sensitive transgenic mouse. Their neurovirulence in mice was also greatly attenuated compared to that of the parental virus. The poor replication activity of the SLII mutants in TgSVA cells appeared to be attributable to reduced activity of the IRES. Two and three naturally occurring revertants that replicated well in TgSVA cells were isolated from mutants SLII-1 and SLII-5, respectively. The revertants recovered IRES activity in a cell-free translation system from TgSVA cells and returned to a neurovirulent phenotype like that of the Mahoney strain in mice. Two of the revertant sites that affected the phenotype were identified as being at nt 107 and within a region from nt 120 to 161. A mutation at nt 107, specifically a change from uridine to adenine, was observed in all the revertant genomes and exerted a significant effect on the revertant phenotype. Exhibition of the full revertant phenotype required mutations in both regions. These results suggested that nt 107 of poliovirus RNA is involved in structures required for the IRES activity in mouse cells.

Animals↗
PubMed1998

Differential contribution of various adhesion molecules to leukocyte kinetics in pulmonary microvessels of hyperoxia-exposed rat lungs.

To elucidate the differential role of various adhesion molecules in distorting leukocyte behavior in the microvasculature of hyperoxia-exposed rat lungs, we investigated fluorescein-labeled leukocyte and erythrocyte kinetics in isolated lungs taken from the animals exposed to 90% O2 for 48 h under conditions in which endothelial intercellular adhesion molecule-1 (ICAM-1) and P-selectin were inhibited by appropriate monoclonal antibodies (1A29 for ICAM-1 and ARP2-4 for P-selectin), while leukocyte L-selectin was restrained with fucoidin. Measurements of blood cell kinetics were made by a confocal laser luminescence microscope coupled with a high-speed video camera. In addition, we histologically examined leukocyte accumulation within the alveolar septa and ICAM-1 as well as P-selectin expressions in the lung. We found that P-selectin expression was sparsely enhanced only in arterioles, whereas ICAM-1 was significantly induced in both venules and capillaries. Firm adhesion of leukocytes was not identified in arterioles and venules, whereas leukocyte rolling was evident in both the vessels. Arteriolar rolling was regulated via a P-selectin- and ICAM-1-independent but L-selectin-dependent mechanism, whereas venular rolling was mediated via a P-selectin-independent but ICAM-1- and L-selectin-dependent pathway. Leukocyte sequestration within capillaries was augmented by an ICAM-1-related mechanism. These findings may suggest that, in hyperoxia-exposed lungs, induction of adhesion molecules and their obstacles to leukocyte behavior are qualitatively different among arterioles, venules, and capillaries.

Animals↗
PubMed1998

Airway hyperresponsiveness to methacholine in mutant mice deficient in endothelin-1.

Endothelin-1 (ET-1) has recently been reported to have a potential pathophysiologic role in bronchial asthma. In the current study, we hypothesized whether ET-1 and a gene encoding ET-1 might be involved in airway hyperresponsiveness (AHR), which is a major feature of bronchial asthma. To test this hypothesis, we investigated airway responsiveness in ET-1(+/-) heterozygous knockout mice, which genetically produce lower levels of ET-1, and in ET-1(+/+) wild-type mice. Airway responsiveness was assessed through the concentration of an agonist required to double lung resistance (EC200 RL). Unexpectedly, airway responsiveness to methacholine was markedly enhanced in ET-1(+/-) heterozygous mice as compared with ET-1(+/+) wild-type mice (EC200 RL: 1.8 +/- 0.1 versus 21.6 +/- 5.6 mg/ml, p < 0.002). Pretreatment with the nitric oxide (NO) synthase inhibitor Ng-monomethyl-L-arginine (L-NMMA) significantly enhanced methacholine responsiveness in ET-1(+/+) wild-type mice, but not in ET-1(+/-) heterozygous mice. Meanwhile, there was no difference between ET-1(+/-) heterozygous mice and the wild-type mice in airway responsiveness to 5-hydroxytryptamine (5-HT). In sensitized mice, no significant differences in responsiveness to antigen were observed between the two groups. These findings suggest that the gene encoding ET-1 may be potentially involved in the etiology of airway hyperreactivity, and that the decrease in ET-1 concentration is associated with AHR to methacholine. In mice, ET-1 as well as NO may have a significant role in the homeostasis of airway physiology.

Airway Resistance↗
PubMed1998

Impaired hypoxic vasoconstriction in intraacinar microvasculature in hyperoxia-exposed rat lungs.

To assess the effects of exposure of the lung to hyperoxic conditions on reactivity of pulmonary microcirculation to hypoxic stimulation, we measured hypoxia-elicited overall pulmonary pressor changes (HPV) and microvascular diameter changes in intraacinar arterioles, venules, and capillaries in isolated perfused rat lungs exposed to a hyperoxic environment (90% O2). To estimate the importance of vasoactive prostaglandins and nitric oxide (NO) for HPV modification, we examined the roles of constitutive and inducible forms of cyclooxygenase (COX-1 and COX-2) and those of NO synthase (eNOS and iNOS). Indomethacin was used for inhibiting both COX-1 and COX-2, while NS-398 was used as a selective inhibitor of COX-2. Both eNOS and iNOS were suppressed by L-NAME, whereas iNOS alone was inhibited by aminoguanidine. Microvascular diameter was measured with a real-time confocal laser scanning luminescence microscope. We found that (1) exposure to hyperoxia caused overall HPV and arteriolar constriction to be attenuated; (2) the blunted HPV was restored by L-NAME but not by aminoguanidine, indomethacin, or NS-398; and (3) arteriolar constriction was improved by either L-NAME, aminoguanidine, or indomethacin but only slightly by NS-398. In conclusion, attenuation of overall HPV in hyperoxia-exposed lungs is explicable mainly by excessive NO generated via eNOS, while impaired arteriolar constriction is caused by NO yielded by eNOS and iNOS as well as by vasodilating prostaglandin(s) produced by COX-1.

Animals↗
PubMed1998

Do adhesion molecules importantly regulate leukocyte kinetics within intraacinar microvessels of the lung?

Precise assessment of blood cell kinetics in the pulmonary microcirculation is extremely difficult because pulmonary microvascular architecture contains arterioles, venules and capillaries in an exceedingly intricate and densely convoluted fashion. Conventional epiluminescence microscopy may not be suitable for investigation of blood cell kinetic in the pulmonary microcirculation, in which arterioles, venules and capillary networks are not located in the same plane. To overcome these impediments, we recently developed a real-time confocal laser luminescence microscope with a high-speed analysis component having the capacity to yield confocal-images of rapidly moving cells at a rate of 1,000 frames/sec and at sufficiently high magnification. In the current review, we will first introduce the details of our newly developed observation system constructed with a view to estimation of blood cell dynamics in the intraacinar microcirculation of the lung. Applying this novel method to isolated perfused rat lungs, we will secondly address the issue of whether or not leukocyte-endothelium interactions in the pulmonary microcirculation qualitatively differ from those serving in the systemic microcirculation. We will particularly shed light on possible roles of endothelial ICAM-1, endothelial P-selectin and leukocyte L-selectin in distorting leukocyte kinetics in the intraacinar microvessels under a variety of diseased conditions, including prolonged exposure to a hyperoxic environment inducing a significant upregulation of ICAM-1 as well as P-selectin on the pulmonary microvascular endothelium, and stimulation of leukocytes by an IL-8 analog causing downregulation of leukocyte L-selectin but inverse upregulation of CD18-related integrins.

Animals↗
PubMed1998

Decline in plasma retinol in unconjugated hyperbilirubinemia treated with bilirubin adsorption using an anion-exchange resin.

When an anion-exchange resin column (Plasorba BR-350) was used for the treatment of unconjugated hyperbilirubinemia, we found an unexpected decrease in plasma retinol (vitamin A) concentrations in a patient with type I Crigler-Najjar syndrome. The purpose of our study was to investigate the mechanism of this decrease in plasma retinol. When the patient's serum bilirubin exceeded the bilirubin binding capacity of 14.7 mumol bilirubin/g serum albumin (i.e., 720 mumol/L of bilirubin), abrupt deterioration of the patient's neurologic status (suppression in his gait and speech) occurred, so the need to apply plasmapheresis to reduce the unconjugated bilirubin was indicated. Blood was drawn from the radial artery at a flow rate of 160 mL/min and pumped into a membrane plasma separator at a rate of 40 mL/min. The plasma was passed through the bilirubin adsorbent column and returned to the venous blood line of the plasma separator. Plasma samples were taken at the inlet and outlet of the bilirubin adsorbent column before and after treatment. The concentration of unconjugated bilirubin in plasma was effectively reduced by the perfusion, but plasma retinol was coincidentally decreased by the perfusion to vitamin A deficiency levels. The patient's plasma retinol was 2,127 nmol/L at the beginning of therapy and decreased to 1,492 nmol/L after repeated adsorption treatments. As the amounts of decrease in retinol (912 +/- 123 nmol/L) after the perfusion were almost equal to those in retinol-binding protein (1,010 +/- 192 nmol/L), retinol may have been removed as a form of holo retinol-binding protein. Decreases in retinol and retinol-binding protein levels were also observed in low-density lipoprotein (LDL) apheresis with a dextran sulfate column (i.e., a cation-exchange resin column). In the patient with Crigler-Najjar syndrome, retinol taken dietarily was removed by plasmapheresis. However, the patient manifested no clinical symptoms associated with vitamin A deficiency, since his liver storage of retinol could supply the loss caused by plasmapheresis treatment. We should measure plasma retinol concentrations to evaluate the loss of retinol during plasmapheresis treatment coupled with an anion-exchange resin column.

Adolescent↗
PubMed1998

Preparation and characterization of micellar calcium phosphate-casein phosphopeptide complex.

Micellar calcium phosphate (MCP) in bovine milk was separated as the complex with casein phosphopeptide (CPP) by the following procedures. Rennet curd obtained from skim milk was suspended in water, the pH was adjusted to 4.6, and the suspension was centrifuged at 1,000 x g. CPP was separated from the precipitated casein by tryptic hydrolysis and ethanol precipitation. The supernatant, which contained calcium and inorganic phosphate liberated from casein micelles by acidification, and CPP were mixed; the pH was adjusted to 6.7; and then the solution was lyophilized. From 1 L of skim milk, 3.16 g of the MCP-CPP complex was obtained. The dried MCP-CPP complex was easily dissolved in water and contained 12.7% calcium, 0.3% magnesium, 3.4% inorganic phosphorous, and 2.2% organic phosphorous. No crystal structure of hydroxyapatite was shown in the MCP-CPP complex by the X-ray diffraction analysis, although the pattern of NaCl crystal was observed. The X-ray diffraction pattern of commercial whey mineral, which was prepared by precipitation at alkaline pH from rennet whey, was similar to that of hydroxyapatite. It was confirmed by high-performance gel chromatographic analysis that the form of calcium phosphate in the MCP-CPP complex was similar to that of casein micelles. The MCP-CPP complex was also separated from commercial rennet casein. The method for the separation of MCP-CPP complex described above can be applied to the large-scale preparation.

Animals↗
PubMed1998

Langerhans cells in the human oviduct mucosa.

Langerhans cells (LCs) are the predominant antigen-presenting cells in epithelial tissues. They have been known to be present in the vagina and uterine cervix. In the present study, localization of LCs in the oviduct was investigated by electron microscopy and immunohistochemistry using an anti-CD1a (CD; cluster of differentiation) antibody. Although the cell density was variable, CD1a-positive LCs were detected in the oviduct epithelium. Their occurrence was most common in women at the age of 40 to 59. LCs extended cell processes along the base of the epithelium and were ultrastructurally characterized by rod-shaped Birbeck granules and a well-developed Golgi apparatus. LCs, together with lymphocytes and macrophages, are considered to engage in the mucosal immune system of the oviduct.

Adult↗
PubMed1998

[Feasibility of limited surgery for small peripheral lung cancer].

We investigated the pathologic factors of small (< or = 20 mm in diameter) peripheral non-small-cell lung cancer lesions and postoperative course of the patients with these lesions to evaluate feasibility of limited surgery for small peripheral lung cancer. From 1982 to 1997, 114 patients underwent resection for small (< or = 20 mm in diameter) peripheral non-small-cell lung cancer. The histologic type was adenocarcinoma in 92 and squamous cell carcinoma in 22. Lobectomy was performed in 111, pneumonectomy in two and segmentectomy in one patient. The systematic mediastinal dissection was carried out in all patients. In 33 patients with tumors 12 mm in diameter or smaller, there were no one with lymph-node metastasis or pulmonary metastasis. Likewise, all patients were survived without relapse. In conclusion, curative resection may be possible without mediastinal dissection or with lesser lung resection (segmentectomy or partial resection), when the tumor diameter is less than 10 mm, for small peripheral non-small-cell lung cancer.

Adenocarcinoma↗
PubMed1998

[Aortic stop flow and hypoxic perfusion chemotherapy for unresectable gallbladder cancer].

We performed the aortic stop flow and hypoxic perfusion chemotherapy for unresectable gallbladder cancer under general anesthesia and made the perfusion only in the abdominal cavity by clamping the abdominal aorta and inferior vena cava near the site of diaphragma. Although temporary hypertension occurred just after clamping the aorta, no severe problem could be seen during operation. After surgery the patient had no abnormalities such as liver or kidney dysfunction, and tumor markers gradually came to decrease. Furthermore, the effectiveness of this therapy is greatly anticipated for the unresectable abdominal cancer, evaluating the selection of anti-cancer drugs and their administration dosage etc.

Anesthesia, General↗
PubMed1998

[The effects of midazolam on the memory of pain].

The purpose of this study was to evaluate the effects of low dose midazolam (MZ) on memories of spinal puncture. The low doses of MZ were administered to 70 patients (ASA 1-2), of whom 37 patients were premedicated with atropine sulfate 0.5 mg and pethidine hydrochloride i.m. (group P), and 33 patients received no premedication (group N). Double blind randomized trials were conducted with the doses of MZ (0, 0.03, 0.06 mg.kg-1), and MZ was administered i.v. to the patients just prior to spinal puncture. Subjective evaluation of pain was performed with pain score (PS) on postoperative phase, and objective evaluation of pain was performed with the reaction of spinal puncture. Short term memory was impaired mainly after administration of MZ. However, subjective memory of pain almost disappeared, but objective evaluation was not so good. We conclude that MZ induces impairment to recall of pain. However, it might maintain the response to the pain.

Adjuvants, Anesthesia↗
PubMed1998

Occult intestinal bleeding imaged by technetium-99m-HSA-D radionuclide angiography: a case report.

Radionuclide angiography (RNA) with 99mTc-diethylenetriamine pentaacetic acid human serum albumin (99mTc-HSA-D) is a sensitive screening method for diagnosing systemic perfusion abnormalities. Sometimes the results produce unexpected information. This information is helpful when considering the clinical perfusion pathophysiology. Recently, we were able to detect an intestinal bleeding lesion clearly for a patient by using RNA.

Aged↗
PubMed1998

Structure and expression of activin genes in rainbow trout.

Activins are dimeric members of the transforming growth factor-beta (TGF-beta) superfamily. By using the polymerase chain reaction (PCR), we have cloned and sequenced activin beta A and beta B genes encoding the mature region of the peptides from the rainbow trout genomic DNA. Two forms of beta A and a single form of beta B-subunits were found. There is high identity with mammalian counterparts; the two rainbow trout beta A-subunits have more than 75% nucleotide sequence identity with the human beta A-subunit, and the beta B-subunit had 82% sequence identity with the human beta B-subunit. Expression of rainbow trout activin genes was examined by reverse transcription-PCR (RT-PCR). The major expression tissue of rainbow trout activin was ovary and brain at the messenger RNA level, and the major expression subunit of rainbow trout activin was the beta B subunit.

Activins↗
PubMed1998

[Experimental study on 5-FU intraperitoneal injection for liver metastasis].

The 5-FU concentrations in peripheral blood and portal blood were determined in rats after 5-FU injection via three routes. Rats were given 1 ml of 5-FU (250 mg/kg) via the subphrenic, Douglas or intravenous routes. From comparison of 5-FU concentrations between the intravenous injection group and the intraperitoneal group (subphrenic injection group + Douglas injection group), the intraperitoneal group had a lower concentration than the intravenous one in peripheral blood. The intraperitoneal group showed a higher concentration than the intravenous one in portal blood. The intraperitoneal group was divided into two groups, a subphrenic injection group and a Douglas injection group. Though there was no significant difference between the 2 groups in the 5-FU concentrations in portal blood, the 5-FU concentration of peripheral blood in subphrenic injection group was significantly higher than in the Douglas injection group. It was conceivable that the subphrenic injection group had another absorption route from the abdominal cavity to the peripheral blood. Accordingly, the intraperitoneal injection of the agent may be useful therapy for liver metastasis. However, due care must be given to the injection lesion in the abdominal cavity, the concentration and volume of the agent.

Animals↗
PubMed1998

Detection of K-ras gene mutations in plasma DNA of patients with pancreatic adenocarcinoma: correlation with clinicopathological features.

We investigated the presence of K-ras gene mutation in plasma DNA and assessed its clinical value in patients with pancreatic adenocarcinoma. Mutations in codon 12 of the K-ras gene were examined by mutant allele-specific amplification method using DNA extracted from surgical specimens and plasma samples of 21 patients with pancreatic adenocarcinoma. K-ras gene mutation was detected in 15 of 21 (71%) primary tumors. In 9 of 15 (60%) patients with K-ras gene mutation-positive tumors, an identical mutation was detected in the plasma DNA. None of four patients with chronic pancreatitis or five healthy subjects had such mutations in plasma DNA. Tumors positive for K-ras gene mutation in plasma DNA were significantly larger (P = 0.04) and less likely to result in a curative cure after surgical resection (P = 0.09) than those negative for the mutation. Other clinicopathological features, including age, sex, histological type, mode of invasion, and metastasis, did not correlate with K-ras gene mutations in plasma DNA. Treatment resulted in disappearance of K-ras gene mutations in plasma DNA in six of nine (67%) patients. Three patients with a persistently positive K-ras gene mutation in pre- and post-treatment plasma samples were likely to show early recurrence or have a progressive disease. Our findings suggest that K-ras gene mutation can be detected in plasma DNA of patients with pancreatic adenocarcinoma. Detection of K-ras mutations in plasma may be clinically useful for evaluating tumor burden and efficacy of treatment.

Adenocarcinoma↗
PubMed1998

Molecular cloning of a novel interferon regulatory factor in Japanese flounder, Paralichthys olivaceus.

A complementary DNA library was constructed in lambda ZAP II using messenger RNA from the leukocytes of some heterocloned Japanese flounder, Paralichthys olivaceus, that had been artificially infected with Hirame rhabdovirus (HRV). A cloned flounder interferon regulatory factor (designated fIRF) cDNA was found to be 1746 bp in length, with an open reading frame of 297 amino acids. The overall amino acid sequence of fIRF had approximately 40% identity with the previously reported avian and mammalian IRF-1s and IRF-2s. The fIRF sequence was most similar to that recorded for the chicken IRF-1. Amino acid sequence identities between the DNA-binding domain of the fIRF and that of both chicken IRF-1 and chicken IRF-2 were 72.3%. The DNA-binding domain of fIRF contained the repeated tryptophan motif that is characteristic of members of the IRF family. The mRNA of fIRF was detected in various tissues by reverse transcription-polymerase chain reaction (RT-PCR). The fIRF was transcribed mainly in the intestine, ovary, muscle, liver, heart and spleen, while it was minimally transcribed in the brain and kidney. When Japanese flounder were injected with HRV, the relative expression of fIRF mRNA was found to increase and peak 3 days after injection. The quantities of the fIRF mRNA increased to levels that were 7.5-fold higher than those of noninjected fish. In addition, when Japanese flounder were injected with Edwardsiella tarda, the expression of fIRF mRNA showed increases 2, 3, and 4 days after injection. The quantities of the fIRF mRNA on those days represented approximately 6-, 15-, and 14-fold increases, respectively, over the levels in noninjected fish.

Amino Acid Sequence↗