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Biomedical subjects

M Ooi

Publications and source records attributed to M Ooi.

12 recordsLinked to original sources
PubMed2001

Very-long-period seismic signals and caldera formation at Miyake Island, Japan.

Over a period of roughly 40 days, starting on 8 July 2000, a caldera structure 1.7 kilometers in diameter developed by means of gradual depression and expansion of the summit crater at Miyake Island, Japan. At the same time, very-long-period (VLP) seismic signals were observed once or twice a day. Source mechanism analyses of the VLP signals show that the moment tensor solutions are smooth step functions over a time scale of 50 seconds, with dominant volumetric change components. We developed a model to explain the caldera and the VLP signals, in which a vertical piston of solid materials in the conduit is intermittently sucked into the magma chamber by lateral magma outflow. This model offers potential for making quantitative estimations of the characteristic physical properties of magma systems.

Journal Article↗
PubMed2001

Carbon-carbon bond formation by electrophilic addition at the central carbon of the mu-eta(3)-allenyl/propargyl ligand on the Pd-Pd bond.

The mu-eta(3)-allenyl/propargyldipalladium complexes were synthesized by the reaction of the corresponding eta(1)-allenyl- or eta(1)-propargylpalladium complexes with Pd(2)(dba)(3). The X-ray diffraction analysis indicates that the dinuclear complex has a unique structure, in which two palladium, three carbon, two phosphorus, and one halogen atoms are in the same plane. These dinuclear complexes react with electrophiles, such as HCl or AcCl, at the central carbon of the mu-eta(3)-allenyl/propargyl ligand to give the mu-eta(3)-vinylcarbenedipalladium complexes. Intramolecular reaction proceeded smoothly to give cyclization products quantitatively. Addition of a catalytic amount of a palladium(0) complex dramatically accelerated the carbon-carbon bond formation. The MO calculations on the mu-eta(3)-allenyl/propargyl complexes indicated that the reaction proceeds via orbital control.

Journal Article↗
PubMed2000

Whisker growth of l-menthol in coexistence with various excipients.

The purpose of the present study was to clarify the mechanism for l-menthol whisker growth. l-Menthol was mixed with an excipient, and the interaction was examined by IR measurement, thermal analysis and powder X-ray diffraction. Then we examined the involvement of the capillary condensation using the pore size distribution measurement. By mixing l-menthol with an excipient with whisker growth, the hydroxyl group stretching band of l-menthol was shifted to the higher wavenumber in the IR spectrum, the melting point and heat of fusion of l-menthol became lower in the thermal analysis, and the diffraction intensity of l-menthol became lower in the powder X-ray diffraction. The excipients with whisker growth showed the tendency to have the meso-pore involved in the capillary condensation in the pore size distribution measurement. From the above results, the whisker growth mechanism is considered as follows. When l-menthol was mixed with an excipient with whisker growth, the crystallinity of l-menthol was lowered and the vapor pressure was increased by the interaction mainly consisting of the hydrogen bond. The generated l-menthol vapor entered meso-pore, the saturated vapor pressure was lowered by the capillary condensation, and the nucleation occurred. The vapor was further supplied, generating the growth of whisker.

Crystallization↗
PubMed1997

High dose rate endobronchial brachytherapy using a new applicator.

BACKGROUND AND PURPOSE: To obtain adequate spatial dose distribution for endobronchial brachytherapy, we applied reference dose points according to the bronchial diameter. For this purpose, we devised a new applicator of which the source transfer tube is contained in the center of the lumen for high dose rate (HDR) brachytherapy. MATERIALS AND METHODS: Thirty-nine patients with endobronchial cancer underwent endobronchial brachytherapy using an HDR afterloading machine with an Ir-192 source. In the nine patients treated with curative intent, treatment consisted of external beam radiotherapy with 40-60 Gy for 4-6 weeks and endobronchial brachytherapy with three fractions of 6 Gy. The 30 patients treated with palliative intent received one fraction of 10 Gy with or without external beam irradiation. The reference dose points were prescribed according to bronchial diameter, which was measured by the applicator's radiopaque wing expansion reflecting the bronchial caliber. RESULTS: The new applicator could be placed at the intended site in 37 lesions. Of 12 lesions which were treated with curative intent, eight (67%) disappeared after brachytherapy. The overall survival at 3 years of all patients and of the patients treated with curative intent was 22 and 64%, respectively. CONCLUSIONS: The source should be positioned in the center of the lumen; this technique is helpful in reducing side-effects caused by inhomogeneous dose distribution of endobronchial brachytherapy.

Adult↗
PubMed1996

[Endobronchial brachytherapy with high dose rate 192Ir afterloading technique using a new applicator].

Recently, high dose rate endobronchial brachytherapy has been carried out for the treatment of lung cancer. We devised a new applicator for Ir-192 high dose rate brachytherapy that can position the source in the center of the bronchial lumen, and tried to set up reference points according to bronchial diameter, for optimal dose distribution. Treatment consisted of external beam radiotherapy (40-60 Gy in 4-6 weeks) and endobronchial brachytherapy (6 Gy x 3 fractions for curative intent, 10 Gy x 1 fraction for palliative intent). Reference dose points were 3, 5, 7 and 10 mm from the center of the source according to bronchial diameter. We treated 19 patients with endobronchial brachytherapy and used the new applicator in 13 of them. We could place the applicator in all 13 patients, and no remarkable side effects were observed during the observation period. Our newly designed applicator will help to reduce radiation side effects caused by irradiation overdose due to adherence of the source to the bronchial wall. The reference point should be set according to bronchial diameter not only for curative intent but also palliative intent.

Brachytherapy↗
PubMed1996

A study of lipid profile before and after coronary artery bypass grafting.

This study was undertaken to establish the variability in the levels of total cholesterol (TC), total triglyceride (TG), low-density lipoprotein (LDL) cholesterol, and high-density lipoprotein (HDL) cholesterol before and after coronary artery bypass graft (CABG) surgery, in order to determine postoperatively when an accurate assessment can be made of the lipid status. During a prospective study over 4 months, fasting venous samples were taken pre- and postoperatively on day 5, and in the 4th, 8th and 12th weeks. Ninety-six patients admitted to the cardiothoracic and cardiac wards for CABG were recruited to the study. The mean preoperative levels were: TC 5.94 (+/- 0.1 mmol/l), LDL cholesterol 4.02 (+/- 0.09mmol/l) and HDL cholesterol 1.00 (+/- 0.03mmol/l). These were significantly different (p < 0.01) from the levels on the 5th postoperative day when the mean level of TC was 4.14 (+/- 0.084mmol/l), LDL cholesterol was 2.45 (+/- 0.07mmol/l) and HDL cholesterol was 0.74 (+/- 0.03mmol/l). By the 4th postoperative week, mean TC (5.73 +/- 0.13mmol/l), LDL cholesterol (3.79 +/- 0.14mmol/l) and HDL cholesterol (1.03 +/- 0.04mmol/l) did not vary significantly from the mean preoperative values. There was no significant difference in the mean TG levels pre- and postoperatively. The mean TC, LDL cholesterol and HDL cholesterol rise to preoperative levels by the 4th week after CABG. Thus, an accurate assessment of patients' lipid status can be made from this period. An earlier postoperative assessment may be falsely reassuring.

Adult↗
PubMed1995

Adult-onset Still's disease with submassive hepatic necrosis.

We present a 74-year old woman who was hospitalized because of typical spiking fever, evanescent rash, polyarthralgia, lymphadenopathy, and marked elevation of serum transaminases and lactate dehydrogenase (LDH) due to adult-onset Still's disease (AOSD) with submassive hepatic necrosis. All of the symptoms and abnormal laboratory findings were dramatically improved after treatment with prednisolone. The clinical course of this patient indicates that AOSD with severe hepatic necrosis can successfully be treated with early administration of corticosteroid, although it remains unknown whether the disease can remain in remission with no or minimal treatment.

Aged↗
PubMed1993

[Embolization of the internal maxillary artery for severe epistaxis--including an experience of the approach from the superficial temporal artery].

Six cases of severe epistaxis were treated with the super-selective intraarterial embolization of the internal maxillary artery. Tens of fragments of Gelfoam were delivered into the distal internal maxillary artery and, additionally, embolized by several pieces of the coils. In a case with cerebral infraction, catheter was inserted via the superficial temporal artery. There were no complications due to these procedures in all cases of this study. It is considered that therapeutic intraarterial embolization of the internal maxillary artery is an effective therapy for severe epistaxis and the superficial temporal artery approach is useful for selected cases.

Aged↗
PubMed1991

Double aortic arch associated with coarctation of both limbs: a case report.

A case of double aortic arch with coarctation of both limbs is described. The patient, a thirteen-year-old girl, demonstrated only the symptoms of coarctation and had no intracardiac anomalies. Discrete coarctation of bilateral limbs distal to the subclavian artery was shown by aortography. Although either double aortic arch or coarctation of the aorta is not so rare, the combination of these two anomalies is quite unusual. This is the third case in the world literature.

Abnormalities, Multiple↗