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Biomedical subjects

H Aoki

Publications and source records attributed to H Aoki.

At least 289 records · Page 16Linked to original sources
PubMed1993

Mucosal folds in human eustachian tube: a hypothesis regarding functional localization in the tube.

Differences in the extent of mucosal folding in the superior versus the inferior half of the human eustachian tube (ET) lumen were studied by measuring, as it appeared in histologic cross section, the length of the mucosal margin in the pharyngeal portion, the midcartilaginous portion, the isthmus portion, and the osseous portion of each half of the ET in 16 normal ET temporal bone specimens from 16 individuals 12 to 70 years of age. The mucosal margin of the ET was significantly longer in the inferior half than in the superior half in all four portions (paired t test: pharyngeal portion t[15] = 3.59, p < .01; midcartilaginous portion t[15] = 3.52, p < .01; isthmus portion t[15] = 4.15, p < .01; osseous portion t[15] = 2.24, p < .05). These results indicate that the inferior half of the ET mucosa has more folds than the superior half, and that the surface area of the inferior half of the ET is larger than that of the superior half. This, together with the finding previously reported that secretory components of the ET such as glands and goblet cells are more richly distributed in the inferior (floor) portion than in the superior (roof) portion of the ET, may be related to the fact that the floor of the ET has an active role in clearance function. A hypothesis regarding localization of the ventilatory and clearance functions within the ET is proposed.

Adolescent↗
PubMed1993

Effects of cholesterol on the miscibility of synthetic glucosamine diesters in lipid bilayers and the entrapment of superoxide dismutase into the positively charged liposomes.

Methyl-D-glucosamine-3,6-dilauroyl, dimyristoyl, dipalmitoyl or distearoyl esters were synthesized as positively charged lipids. They were incorporated into phosphatidylcholine liposomal membranes and the entrapment of superoxide dismutase (SOD) into the liposomes was attempted. The efficiency of the SOD-entrapment into the positively charged multilamellar vesicles (MLVs), comprising egg yolk phosphatidylcholine and synthetic glucosamine diesters, was enhanced by the addition of cholesterol to the membranes. A differential scanning calorimetric study showed that the miscibility (solubility) of glucosamine diesters in phosphatidylcholine-bilayers increased on the addition of cholesterol to the membranes. Cholesterol assisted in the mixing of phosphatidylcholines with positively charged glucosamine diesters and increased the positive charges on the liposomal membranes. This was confirmed by incremental increases in the zeta-potential of liposomal membranes with an increase in the cholesterol content. Entrapment of SOD thus became more efficient due to the enhanced electrostatic attraction between the positively charged membranes and the negatively charged SOD, and/or the electrostatic repulsive interactions between positively charged membranes; the latter interactions induced a thickening of the water layer in MLVs.

Cholesterol↗
PubMed1993

Increased plasma endothelin concentrations in patients with acute heart failure after myocardial infarction.

We have investigated the relationship between plasma endothelin (ET) concentrations and several clinical characteristics in 31 patients with acute myocardial infarction (MI). ET levels were also measured in 10 age-matched healthy subjects, 9 patients with unstable angina, and 20 patients with chronic heart disease. In patients with MI, although no significant relationship was observed between plasma ET concentrations and measured hemodynamic parameters, plasma levels were higher in patients with pulmonary congestion than in those without this complication (1.61 +/- 0.29 vs 1.21 +/- 0.33 fmol/ml; p < 0.01). No significant difference in plasma ET levels was found between cardiac and peripheral sampling sites (pulmonary artery; 1.07 +/- 0.28, right atrium; 1.02 +/- 0.28, peripheral artery; 1.12 +/- 0.23, peripheral vein; 1.14 +/- 0.38 fmol/ml: N.S.), or among patients with uncomplicated MI, unstable angina (1.00 +/- 0.32 fmol/ml), and healthy subjects (1.01 +/- 0.29 fmol/ml). Increased level were observed in patients with decompensated heart failure due to chronic heart disease, but were not found in patients without pulmonary congestion (1.62 +/- 0.60 vs 1.11 +/- fmol/ml; p < 0.01). These observations suggest that plasma ET concentrations are elevated in the presence of congestive heart failure or severe ventricular depression, but are not persistently increased by myocardial ischemia per se.

Acute Disease↗
PubMed1993

Facial nerve near the external auditory meatus in man: computer reconstruction study--preliminary report.

The anatomy of the facial nerve relative to its intratemporal and extratemporal courses varies over time with developmental changes. Otologic and parotid surgery in infants and children demands detailed knowledge of the precise anatomy of the facial nerve with respect to the tympanic ring and external auditory canal. The authors analyzed this area using our three-dimensional (3-D) computer-aided reconstruction and measurement method studying the spatial relations of the facial nerve to the tympanic ring and stylomastoid foramen. Temporal bones from five normal individuals aged 36 gestational weeks, 3 months, 8 months, 4 years, and 17 years were retrieved from the temporal bone collection stored at the Elizabeth McCullough Knowles Otopathology Laboratory in Pittsburgh. Three-dimensional reconstruction of the facial nerve comparing the developmental anatomy across the various age groups provides the surgeon with the technical information necessary to address problems in this area.

Adolescent↗
PubMed1993

Effects of long-term infusion of synthetic atrial natriuretic factor on hemodynamics and water input-output balance in patients with acute myocardial infarction.

The administration of atrial natriuretic factor (ANF) increases coronary blood flow and decreases coronary vascular resistance. However, little is known about the feasibility and reliability of intravenous long-term infusion of ANF in patients with coronary heart disease. We therefore examined the effects on hemodynamic parameters and water input-output balance of 24-hour administration of synthetic ANF (ANF-[99-126]: 20-50 ng/kg/min) in 8 patients with acute myocardial infarction (6 men and 2 women; mean age 55 years). The ANF infusion significantly decreased pulmonary capillary wedge pressure to a maximum of greater than 50% 4 hours after infusion (from 16 +/- 2 to 7 +/- 2 mmHg; p < 0.01), and the effect was sustained throughout the 24-hour infusion without diuresis (mean water balance, + 25 +/- 12 ml/hr). This reduction was significantly correlated with the baseline value before infusion (r = -0.85, p < 0.01). The effect on pulmonary capillary wedge pressure was accompanied by small reductions (approximately 20%) in systemic blood pressure and cardiac index, without significant changes in systemic vascular resistance and heart rate. These results indicate that prolonged administration of low to medium doses of synthetic ANF causes potent and sustained left ventricular unloading without reflex, tachycardia and volume depletion, and may thus be safe and have potential benefits for patients with coronary heart disease.

Adult↗
PubMed1993

Prognostic implications of plasma levels of atrial natriuretic factor in patients with acute myocardial infarction.

Several neurohormonal factors have been proposed as markers of the severity of acute myocardial infarction (MI). To determine whether plasma concentrations of atrial natriuretic factor (ANF) might predict post-MI prognosis, we studied 130 patients with acute MI (97 males and 33 females, mean age 62 years). Within one-half to one day after admission, a blood sample was taken for estimation of circulating ANF. The mean follow-up period was 37 months, and the follow-up rate was 97%. Of the 130 patients, 28 died from cardiac causes during the follow-up period. Patients were classified into three groups according to plasma ANF levels (group 1, < 99 pg/ml; group 2, 100-199 pg/ml; group 3; > 200 pg/ml). The survival curves were constructed by the Kaplan-Meier method. There were significant differences in the cumulative survival rate among the three groups (group 1 > group 2 > group 3; p < 0.001). The baseline characteristics (age, atrial pressure, and cardiac index) were different among the groups, therefore these variables were analyzed by a Cox multiple regression model. Significant predictors of cardiac mortality were plasma ANF class (p < 0.002) and pulmonary capillary wedge pressure (p < 0.007). In conclusion, these observations demonstrated that stratification of acute MI patients by plasma ANF level is a useful non-invasive method for predicting prognosis and for identifying individuals at high risk of cardiac death.

Analysis of Variance↗
PubMed1993

[Treatment of sepsis by extracorporeal elimination of endotoxin using fiber-immobilized polymyxin B].

To remove endotoxin directly from the blood, an affinity adsorbent (PMX) has been developed. PMX is composed of a ligand of polymyxin B and a carrier of polystyrene fibers. We treated 16 patients, suffering from septic shock or multiple organ failure by PMX-F hemoperfusion. The pretreatment level of endotoxin decreased significantly from 80pg/ml to 21pg/ml on average 2 hours after the hemoperfusion. The hyperdynamic status in the cardiac index and the decreased systemic vascular resistance, which are characteristic to endotoxin shock, were normalized after the treatment. In septic shock patients with systolic pressure under 10mmHg, the systolic pressure increased significantly from pretreatment level. Nine of the sixteen patients remained alive for two weeks after the therapy, and seven out of the nine patients discharged alive. Hemoperfusion with PMX is likely to become an effective treatment for sepsis and septic shock.

Endotoxins↗
PubMed1993

Effect of exercise on strength and chemical composition of rat femur bone.

The effect of exercise on strength and chemical composition of rat femur bone was examined. Ten 5-week-old rats were forced to exercise on a treadmill with a running speed of 20 m/min at set time intervals for a 4-week period. Another 10 rats were kept idle as controls. After exercising, bending tests of the rat femur bones were carried out, and the content ratios of Sr to Ca, Sr/Ca, were measured by energy-dispersive fluorescent X-ray analysis and EPMA line analysis. The strength of the exercise group was greater than that of the control group. The ratio, Sr/Ca, of the exercise group showed a tendency to increase compared to that of the control group. It is clear that the chemical composition of bone varies with the degree of exercise, and that the bone becomes strengthened at the same time.

Animals↗
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↗