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R Aoki

Publications and source records attributed to R Aoki.

12 recordsLinked to original sources
PubMed1992

Effect of amphipathic peptides with different alpha-helical contents on liposome-fusion.

The peptide-induced fusion of neutral and acidic liposomes was studied in relation to the amphiphilicities evaluated by alpha-helical contents of peptides by means of a carboxyfluorescein leakage assay, light scattering, a membrane intermixing assay and electron microscopy. An amphipathic mother peptide, Ac-(Leu-Ala-Arg-Leu)3-NHCH3 (4(3], and its derivatives, [Pro6]4(3) (1), [Pro2,6]4(3) (2), and [Pro2,6,10]4(3) (3), which have very similar hydrophobic moments, caused a leakage of contents from small unilamellar vesicles composed of egg yolk phosphatidylcholine and egg yolk phosphatidic acid (3:1). The abilities of the peptides to induce the fusion of the acidic liposomes increased with increasing alpha-helical content: in acidic liposomes the helical contents were in the order of 4(3) greater than 1 greater than 2 greater than 3 (Lee et al. (1989) Chem. Lett., 599-602). Electron microscopic data showed that 1 caused a transformation of the small unilamellar vesicles (20-50 nm in diameter) to large ones (100-300 nm). Based on the fact that these peptides have very similar hydrophobic moments despite of decreasing in the mean residue hydrophobicities to some extent, it was concluded that the abilities of the peptides to induce the fusion of liposomes depend on the extent of amphiphilic conformation evaluated by alpha-helical contents of the peptides in the presence of liposomes. For neutral liposomes of egg yolk phosphatidylcholine, all the proline-containing peptides showed no fusogenic ability but weak leakage abilities, suggesting that the charge interaction between the basic peptides and acidic phospholipid is an important factor to induce the perturbation and fusion of the bilayer.

Amino Acid Sequence↗
PubMed1992

Role of corpus luteum function in embryo implantation.

The present study was undertaken to evaluate the role of corpus luteum function in the implantation process of cryopreserved embryos. Six patients with tubal infertility were studied, with a total of 27 fresh embryos being replaced following controlled ovarian hyperstimulation and in vitro fertilization. These embryo transfers failed to produce pregnancy. From the patients, 22 supernumerary embryos were cryopreserved and 10 viable frozen-thawed embryos were transferred in a subsequent natural cycle, resulting in 2 pregnancies. In 1 of the pregnancies, the serum concentrations of estradiol (E2) and progesterone (P4) in the midluteal phase were 29 pg/ml and 5.6 ng/ml, respectively. These values were considered to be below the physiological range. These data suggest that a pregnancy can be achieved in spite of low circulating E2 and P4 levels during the luteal phase, which are generally indicative of the luteal phase defect.

Adult↗
PubMed1992

[A case of adenosquamous carcinoma with unknown origin and with superior vena cava syndrome as the first symptom].

This report is concerning a case of adenosquamous carcinoma having unknown origin and showing SVC syndrome as the first symptom. A 44 year-old man was admitted to our hospital because of facial edema at the beginning of April 1990. He was diagnosed as having a mediastinal tumor of the SVC syndrome type. Resection of the SVC tumor and part of the pericardium was performed on June 20, 1990. The operation had extraordinary findings. Lymph nodes adhering to tumor invaded the adjacent right side of the trachea and were situated in a rosette-like form. Furthermore, a part of the tumor stemmed into the lumen of the superior vena cava causing complete obstruction. The pathological diagnosis of the SVC tumor was adenosquamous carcinoma, however, no clinical examinations could identify its original matrix. Mediastinal tumors of unknown origin are reported as about 1% of all mediastinal tumors, and are responsible for 0.68% of all carcinomas in the mediastinum. This was one experience of a rare case of mediastinal tumor having unknown origin and showing SVC syndrome as the first symptom.

Adenocarcinoma↗
PubMed1991

Ventilation-perfusion scintigram in diabetics.

We carried out ventilation and perfusion scintigraphies and pulmonary function tests in 20 diabetics under 50 years of age. 99mTc-MAA perfusion scintigrams showed evidence of minimal nonuniformity (MNU) in four cases (20%) and nonsegmental defect (NSD) in eight cases (40%). There was a ventilation defect in the single-breath image in one case (5%) and a delayed washout in three cases (15%) upon 133Xe ventilation scintigram. In the NSD group, the mean diffusing capacity value was abnormally low and the mean duration of the diabetes was long compared with other groups. The frequency of perfusion defects was higher than that of ventilation abnormalities; moreover, abnormal findings on ventilation scintigrams were very mild compared with those of perfusion defects. Perfusion defects correlated significantly with a decrease in diffusing capacity. These findings suggest that the disturbance in pulmonary arterial perfusion caused a decrease in diffusing capacity in diabetics.

Adult↗
PubMed1991

In vivo and in vitro studies in a patient with cyclical Cushing's disease showing some responsiveness to bromocriptine.

In vivo and in vitro studies were carried out in a 37-year old female with cyclical Cushing's disease. Preoperative studies revealed periodic secretions of urinary corticosteroids occurring with a cyclicity of 2-3 weeks. On transsphenoidal surgery, a microadenoma was visualized in the anteroinferior portion of the anterior pituitary. Gel filtration analyses of the adenoma and surrounding tissues revealed increased concentrations of beta-endorphin and an activated conversion of beta-lipotropin to beta-endorphin in the adenoma compared with the surrounding tissues. These findings were in agreement with the characteristics previously reported for corticotroph adenomas. However, unexpectedly, concentrations of ACTH and beta-lipotropin in the adenoma were only slightly higher than those in the surrounding tissues. Precise mechanisms underlying this unusual finding were elusive, but it may have been due to the periodic nature of her hypercortisolism. In addition, this patient was reproducibly responsive to bromocriptine (2.5 mg, per os) with a reduction of the plasma cortisol level. Although this may suggest an intermediate lobe subtype of Cushing's disease as proposed by Lamberts' group, our case did not have any other characteristic suggestive of this proposed variant. However, it is tempting to speculate that cyclical changes in the central dopaminergic tone may have been at least a partial trigger for the periodic hormonogenesis in this patient.

Adrenocorticotropic Hormone↗
PubMed1975

[Lymphokines].

Explore the source record for details and available documents.

Animals↗
PubMedDate not supplied

Swim-down separation of progressively motile sperm from poor quality human semen by the modified funnel procedure.

The simultaneous swimming up and down from identical semen specimens suggested that the separation efficiency of progressively motile sperm by the swim-down method was superior to that of the swim-up method. The swimming down was performed in a small plastic funnel, the bottom of which was plugged with a 2.5 ml disposable syringe. In this funnel, 2.0 ml of 70% Percoll was poured and then the sperm resuspension was overlaid. After 1 h, progressively motile sperm penetrating into the lower part of Percoll layer (1.6 ml) was collected in the syringe. The technical strategies to yield higher density of progressively motile sperm were found to be centrifugal concentration of the sperm from whole ejaculate prior to the swimming down, and subsequent re-centrifugation of the separated sperm after the swimming down. Oligo-asthenozoospermic semen (22 +/- 4.4 x 10(6) ml1, 5.5 +/- 4.4% motility, n = 8) was processed by the present method, yielding sperm qualities of 32 +/- 19 x 10(6) ml1, 74 +/- 14% in the final preparations. Overall improvement in fertility index (sperm density ml1 x motility % x 10(8)) reached 27-folds on average.

Cell Separation↗
PubMedDate not supplied

Intrauterine insemination with semen of oligozoospermic men: effectiveness of the continuous-step density gradient centrifugation technique.

There has been an argument as to whether the intrauterine insemination (IUI) substantially improves pregnancy rate in cases of oligoasthenozoospermia. The present study evaluates the efficiency of the IUI with the use of the life table analysis. The insemination was performed after washing and concentrating sperm using the continuous-step density gradient centrifugation reported in our previous papers. The number of IUI cycles studied was 222 (46 couples), in 13 cases of which pregnancy was established with a pregnancy rate of 28.3%. The cumulative probability of conception reached to 57% at the eleventh cycles of the IUI treatment. These results suggest that the potential efficiency of the IUI for the oligo-asthenozoospermic cases is high if the sperm is processed in a proper method.

Adult↗
PubMedDate not supplied

A simplified technique for freezing human sperm for AIH: cryosyringe/floating platform of liquid nitrogen vapor.

A cryosyringe and floating platform were developed to simplify the procedures for human sperm cryopreservation without sacrificing post-thaw sperm quality. The cryosyringe was developed as a vessel for cryopreservation and as a device for post-thaw insemination. A platform-like polystyrene foam board 3-cm in height was floated on the surface of liquid nitrogen in a polystyrene foam freezing container. The cryosyringe containing sperm/KS-II medium mixture was placed on it for 5 min, then it was dropped into the liquid nitrogen. Freezing velocity was -27 degrees C/min. Poor quality semen specimens (40 +/- 14 x 10(6)/ml, 18 +/- 2.6% motility, n = 9) were concentrated (87 +/- 46 x 10(6)/nl, 29 +/- 9.1%) previously and then cryopreserved in the cryosyringe or in a commercial tuberculin syringe under the conditions established in the present study. The post-thaw sperm motility of the specimens in the cryosyringe (18 +/- 7.4%) was significantly superior (p less than 0.05) to that in the commercial tuberculin syringe (13 +/- 5.3% motility).

Cryopreservation↗