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Biomedical subjects

H Aoki

Publications and source records attributed to H Aoki.

At least 19 recordsLinked to original sources
PubMed1992

The asparaginyl-tRNA synthetase gene encodes one of the complementing factors for thermosensitive translation in the Escherichia coli mutant strain, N4316.

Escherichia coli strain N4316 is a mutant that exhibits temperature-sensitive growth at 43 degrees C and temperature-sensitive translation in vivo and in vitro. Extracts of the mutant produce an aberrant pattern of translation products of MS2 bacteriophage RNA. Previous work has shown that a protein, called 'rescue', isolated from the parental strain partly corrects the defective translation in vitro. Here we report the purification to homogeneity of a second factor from ribosomal eluates of the wild-type parental strain; the purified protein is a homodimer of 54 kDa. The partial sequence of the second protein was determined, and a recombinant plasmid was isolated based on its ability to complement the temperature-sensitive growth phenotype of the mutant at the non-permissive temperatures. The cloned gene was sequenced, mapped to the 20.9-min region of the E. coli chromosome and shown to code for a 466-amino-acid protein with a molecular mass of 52 kDa. Analysis of the DNA sequence and the correspondence to that of the partial protein sequence has identified the complementing factor as asparaginyl-tRNA synthetase. Marker rescue experiments indicate that the asnS mutation in N4316 resides within the motif 2 domain of the synthetase. A potential role of this synthetase in restoring normal protein synthesis with respect to ribosomal frameshifting, read-through of nonsense codons and protein copy number is discussed.

Amino Acid Sequence↗
PubMed1992

Detection of bcl-2 protein and bcl-2 messenger RNA in normal and neoplastic lymphoid tissues by immunohistochemistry and in situ hybridization.

bcl-2 protein has been detected in surgical specimens and cultured permanent cell lines of non-Hodgkin's lymphomas and leukemias using enzyme immunohistochemistry and immunofluorescence with anti-bcl-2 monoclonal antibodies. Of 40 surgical specimens, bcl-2 protein was expressed in 50% of B-cell and 41% of T-cell lymphomas, both with and without the bcl-2 gene rearrangement. In investigations of 38 hematopoietic cell lines, bcl-2 protein was detected not only in lymphoid cell lines but also in myeloid cell lines. In situ hybridization and immunohistochemical analysis of reactive lymph nodes showed that lymphocytes in mantle zones and paracortical areas expressed bcl-2 protein consistent with the messenger RNA distribution and that germinal center cells showed abundant bcl-2 transcript, despite the absence of detectable bcl-2 protein. These results suggest that bcl-2 protein is broadly expressed in various hematopoietic neoplasms not restricted in t(14; 18) lymphomas and that germinal center cells may be involved in some arrest of bcl-2 protein expression at the posttranscriptional level.

Blotting, Northern↗
PubMed1992

Endothelin-1 inhibits and enhances contraction of porcine coronary arterial strips with an intact endothelium.

Using front-surface fluorometry and fura-2-loaded porcine coronary arterial strips with an intact endothelium, changes in cytosolic Ca2+ concentrations ([Ca2+]i) and tension of smooth muscle were simultaneously monitored in an attempt to determine the vasoactive properties of endothelin-1 (ET-1). ET-1 in low concentrations (0.1-1nM) caused a significant transient decrease in [Ca2+]i and tension of the strips precontracted with 10(-7) M U-46619. The maximal decreases in [Ca2+]i and tension were obtained with 0.6nM ET-1. In higher concentrations (1nM-100nM), there was no reduction in [Ca2+]i or tension; the contraction induced by U-46619 was potentiated. The decreases in [Ca2+]i and tension induced by ET-1 were inhibited by the mechanical removal of the endothelium or by pretreatment with NG-nitro-L-arginine and were slightly attenuated by indomethacin. Thus, ET-1 in low concentrations can induce endothelium-dependent transient relaxations accompanied by transient reductions of [Ca2+]i in isolated porcine coronary arteries. This effect is mainly mediated by the release of endothelium-derived relaxing factor.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1992

The role of GTP binding proteins in ischemic brain damage: autoradiographic and histopathological study.

Cerebral ischemia produces perturbation of signal transduction systems in neurons. In order to estimate the contribution of guanine nucleotide-binding protein (G-protein) to hippocampal neuronal death, the effect of pertussis toxin (PTX) on the CA1 pyramidal cell damage after transient forebrain ischemia in rats was examined. PTX was administered 3 days before 20 min of transient forebrain ischemia. PTX injection into the CA1 subfield failed to alter the number of ischemic-damaged CA1 pyramidal cells. In contrast, ventricular PTX injection exacerbated CA1 pyramidal cell damage. We also studied postischemic alteration of GTP binding sites in the hippocampal formation using quantitative in vitro autoradiography. Autoradiographic imaging demonstrated predominant distribution of GTP binding sites in synaptic areas in the hippocampus. No significant change of GTP binding activity was observed in the hippocampus until 2 days after recirculation. Seven days after ischemia, when the CA1 pyramidal cells were depleted, the GTP binding sites of the strata oriens and radiatum in the CA1 subfield had reduced by 32% and 31%, respectively. In contrast, GTP binding in the CA3 subfield and the dentate gyrus remained unaltered throughout the reperfusion period. These results suggest that the amount of G-proteins as estimated by GTP binding remained unaltered in the hippocampus during the early recirculation period, when the CA1 pyramidal cells were morphologically intact, and that signal transduction pathways mediated by Gi and Go do not play a major role in delayed death of the CA1 pyramidal cells.

Animals↗
PubMed1992

Human helper T cell lines established by coculture of normal human cord leukocytes with an HTLV-II-infected rabbit leukocyte cell line (Ra-IIA).

Three helper T cell lines, designated CR-IIA (CR-IIA-1, CR-IIA-2, and CR-IIA-3), were established by coculturing normal human cord leukocytes with a lethally irradiated HTLV-II (human T-lymphotropic virus type II)-infected rabbit leukocyte cell line (Ra-IIA). CR-IIA had a normal human karyotype and expressed the surface markers CD3(+), CD4(+), CD8(-), CD19(-), CD25(+) and HLA-DR(+), confirming their helper T cell nature. CR-IIA cells were all free of Epstein-Barr virus nuclear antigen and were immunoreactive with serum samples from HTLV-I- or HTLV-II-infected patients and with anti-HTLV-I, p19 or p24 antibody. The provirus genome of HTLV-II was detected in these cell lines by the polymerase chain reaction combined with a digoxigenin-enzyme-linked immunosorbent assay. Electron microscopy of CR-IIA-1 cells revealed a few immature type C virus particles. These results suggest that HTLV-II was transmitted from the infected rabbit leukocyte cell line to human cord helper T lymphocytes with the development of immortalized HTLV-II-producing T cell lines.

Animals↗
PubMed1992

Effects of antacids, ferrous sulfate, and ranitidine on absorption of DR-3355 in humans.

This study examined the effects of widely used antacids (aluminum hydroxide, magnesium oxide, and calcium carbonate), ferrous sulfate, and ranitidine on the absorption of a fluorinated quinolone, (-)-(S)-9-fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro- 7H- pyrido-[1,2,3,-de][1,4]benzoxazine-6-carboxylic acid hemihydrate (DR-3355), in healthy male volunteers enrolled in three separate randomized crossover studies. Study 1 used 100-mg doses of DR-3355 and concurrent doses of aluminum hydroxide (1 g) or magnesium oxide (500 mg), while study 2 used DR-3355 (100 mg) and concurrent ferrous sulfate (160 mg) or calcium carbonate (1 g). Study 3 used DR-3355 (100 mg) and concurrent ranitidine (150 mg). Each study included control doses of DR-3355 (100 mg) alone. When aluminum hydroxide, ferrous sulfate, and magnesium oxide were coadministered with DR-3355, the relative bioavailability of DR-3355 was decreased to 56, 81, and 78%, respectively, of that for DR-3355 (100 mg) alone. Urinary excretion of DR-3355 was also significantly decreased by coadministration of these drugs. Thus, the magnitude of the decrease in the area under the concentration-time curve for DR-3355 varied among antacids, and the ranking of their inhibitory effects correlated with previously reported rankings of stability constants for chelate formation. DR-3355 bioavailability was not influenced by the concurrent administration of calcium carbonate and ranitidine, indicating that changes in gastric pH do not affect DR-3355 absorption.

Adult↗
PubMed1992

Plasma atrial natriuretic factor in patients with acute myocardial infarction.

To examine whether atrial natriuretic factor (ANF) is secreted adequately in the early phase of myocardial infarction, plasma ANF concentration and clinical parameters, including hemodynamic variables, were studied in 118 patients with acute myocardial infarction (AMI). The patients were divided into 2 subgroups according to the absence (group A, n = 41) or presence (group B, n = 77) of a history of valvular heart disease, previous myocardial infarction, hypertension, or renal failure. Although no significant difference in atrial pressure after the infarction was found between the 2 groups, the plasma ANF level was significantly lower in group A than in group B (76 +/- 6 vs. 185 +/- 26 pg/ml; mean +/- SEM, p < 0.01). Plasma ANF was correlated with pulmonary capillary wedge pressure in group B (r = 0.54, p < 0.001), whereas no relationship with hemodynamic parameters was observed in group A. In 56 of the 118 patients (group A, n = 18; group B, n = 38), the pulmonary arterial plasma level was significantly higher in group A (p < 0.05), whereas the difference was not significant in group B. Seven of the 8 expired cases among these 56 patients had peripheral plasma ANF levels of more than 150 pg/ml, which were higher than those in pulmonary arterial plasma. These observations suggest firstly that the plasma level of ANF is lower in patients with a new onset of myocardial infarction compared to those with a history of cardiac or renal diseases, and secondly that stimulated ANF release originates not only from the right side of the heart, but also from additional site(s), particularly in patients with chronic ventricle overload and a poor prognosis.

Atrial Function, Right↗
PubMed1992

[Amino acid metabolism in surgical stress].

Amino acid metabolism under surgical stress, injury or infection was reviewed from the literature. The glucose-alanine cycle in coupling with branched chain amino acids (BCAA) metabolism plays a central role for gluconeogenesis, in such a catabolic state. Glutamine is as important as alanine for sparing glucose and furthermore for intestinal repair. Changes in plasma amino acid concentration and clearance following hepatectomy are described, and effects of BCAA solution are evaluated. It was suggested that BCAA improved the Fischer ratio by increasing, not only plasma BCAA level, but also AAA clearance.

Alanine↗
PubMed1992

Intramedullary spinal cord metastasis from lung cancer presenting with paraparesis: an autopsied case.

A 75-year-old male presented with paraparesis and pain in the thighs, which progressed rapidly. Five days later, he was unable to stand or to void urine. A lung cancer was found in the right upper lobe. A spinal cord metastasis from the lung cancer was suspected from the neurologic and pulmonary findings. After 2 weeks, motor dysfunction and a total sensory deficit were observed below the lumbar region, and the patient developed pneumonia, which resulted in death. Autopsy showed an extensive intramedullary metastasis at the third lumbar segment of the spinal cord. Histology revealed poorly differentiated adenocarcinoma of the lung.

Adenocarcinoma↗
PubMed1992

[Decision analysis in therapeutic strategies for small bowel obstructions].

Clinical decision analysis was applied in therapeutic decision-making regarding small bowel obstructions. For strangulation obstruction, the three strategies of immediate surgery, observation of clinical course, and decision according to ultrasonographic findings were analyzed. When mortality rate, morbidity rate, or duration of hospital stay was used as the utility value, decision on the basis of ultrasonographic findings was selected as the most effective strategy, while the strategy of immediate surgery was selected when the rate of intestinal necrosis was used as the utility value. For adhesive obstructions, the three strategies of immediate surgery, conservative treatment with long tube decompression, and long tube decompression with enteroclysis (infusion contrast radiography) were analyzed. The strategy of enteroclysis was selected when morbidity rate and duration of hospital stay were used as utility values, while immediate surgery was selected when recurrence rate of adhesive obstruction was used as the utility value. For obstruction caused by intraabdominal recurrent cancer, operative treatment and conservative treatment were analyzed. The strategy of surgery was selected when rate of obstruction resolved and number of months of survival were used as utility values. Clinical decision analysis is valuable in quantitatively assessing individual variables affecting therapeutic decision-making.

Decision Support Techniques↗
PubMed1992

[Perioperative renal functions in patients with chronic renal disease].

Renal function was studied in patients with compensated renal failure and in those with slight renal disorder during and after operations focusing on several aggravating factors. After perioperative episodes of hypovolemia, bleeding and shock, the levels of urine beta 2 microglobulin and FENa were elevated, showing the abnormal renal tubule functions. Elevation of NAG and the decrease of Ccr were observed, showing the organic damage on the renal tubular cell and the influence on GFR. These aggravating factors should be eliminated to prevent the irreversible renal changes.

Acetylglucosaminidase↗
PubMed1992

[Three cases of perioperative brain infarction].

In recent years, the number of elderly patients who require operation has been increasing. We experienced three patients with perioperative brain infarction, occurring respectively, during the preoperative period, just after operation, and three days after operation. All three patients had more than one of the common risk factors for cerebrovascular accidents, including hypertension, advanced age, hyperfibrinogenemia, diabetes mellitus, and past history of cerebrovascular accident. On the basis of our experience with these three patients, we suggest the following: (1) Waiting period of elective surgery should be reconsidered in some cases with a past history of stroke. (2) Some high-risk patients may benefit from anticoagulative or antiaggregative drugs (e.g. low-molecular dextran or prostaglandin E1) to prevent brain ischemia. (3) Abrupt control of hypertension or diabetes mellitus status undoubtedly adversely affects the patient's general condition; and (4) A practical monitoring system to detect regional brain ischemia during operation under general anesthesia should be developed.

Aged↗
PubMed1992

[A new method for preoperative evaluation of platelet aggregation: Part I].

Newly introduced antiplatelet drugs such as ticlopidine or cilostazol are often administered to preoperative patients. However, how to evaluate the effect of these drugs on anesthetic management remains unsettled. The platelet aggregation test was performed on 20 operative patients, and the aggregation patterns are classified into five categories. The platelet aggregation is almost unchanged in some patients, and slightly depressed in others. The new classification of platelet aggregation patterns that we introduced for preoperative evaluation seems to be a good indicator of platelet function in patients medicated with antiplatelet drugs.

Humans↗
PubMed1992

[A new preoperative evaluation of platelet aggregation--Part II].

With the new platelet function test which we reported in the first paper, the platelet aggregation was evaluated in 50 patients, and the comparison with the results of bleeding time was made in 20 cases. There was no statistical correlation between the bleeding time and the platelet aggregation. The bleeding time has been considered as an indicator of platelet function and is included in a preoperative check list. However, its result depends on the amount of platelets and the endothelial factor, and the reliability of bleeding time on platelet function is considered small, especially in patients medicated with antiplatelet drugs. For such patients, the platelet aggregation test is essential. The present study demonstrated that the patient belonging to grade-1 were resistant to hemostasis during the operation. Taking into the surgical and anesthetic depression on the platelet function into consideration, the patients below grade-2 are risky for the surgery.

Adult↗
PubMed1991

Endothelin induces the Ca(2+)-transient in endothelial cells in situ.

Using front-surface fluorometry of fura-2 and valvular strips of the pig aorta, we recorded changes in the cytosolic Ca2+ concentration, [Ca2+]i, of endothelial cells in situ, quantitatively, and investigated the effects of endothelin-1 and -3 on these endothelial cells. Both endothelin-1 and -3 elevated [Ca2+]i of a peak (the first phase) and sustained type. This first phase is considered to be due to a release of Ca2+ from intracellular storage sites. The sustained phase depended on extracellular Ca2+ and is considered to be due to an influx of Ca2+ through the plasma membrane. At equimolar concentrations, the peak elevations of [Ca2+]i induced by endothelin-1 were much higher than those induced by endothelin-3. We suggest that, in endothelial cells in situ, endothelin-1 mobilizes stored Ca2+ and may activate Ca(2+)-sensitive pathways, including the release of prostacyclin and endothelium-derived relaxing factors, more potently than does endothelin-3.

Animals↗