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Biomedical subjects

Y Okuda

Publications and source records attributed to Y Okuda.

At least 235 records · Page 13Linked to original sources
PubMed1995

Transient nephrogenic diabetes insipidus accompanied by possible psychogenic polydipsia.

A 50-year-old Japanese man had been suffering from polydipsia and polyuria for 2 months without any other specific symptoms. His daily urinary output reached 5 liters. On admission, no abnormalities of the kidneys, heart, thyroid, adrenals, pituitary or hypothalamus were detected by laboratory tests and MRI of the head. Pure psychogenic polydipsia was ruled out because his urine volume did not decrease sufficiently with 18 h of water deprivation and the subsequent injection of aqueous vasopressin. Plasma arginine vasopressin (AVP) levels against plasma osmolality remained within the normal range during the test. These results indicated that diabetes insipidus in this case was caused by renal insensitivity to AVP. The symptoms disappeared spontaneously, and marked improvement was observed in a second water deprivation test 1 month later, although the maximum urine concentration was still subnormal. The combination of both latent insufficiency of AVP secretion and impairment of the renal countercurrent system induced by psychogenic polydipsia was speculated as a possible mechanism for the transient nephrogenic diabetes insipidus in this case.

Arginine Vasopressin↗
PubMed1995

Efficacy of Ibudilast on lower limb circulation of diabetic patients with minimally impaired baseline flow: a study using color Doppler ultrasonography and laser Doppler flowmetry.

Ibudilast is a prostacyclin-mediated vasodilator and antiplatelet agent. The hemodynamic effects of ibudilast were evaluated in 41 patients with non-insulin-dependent diabetes mellitus by means of two-dimensional Doppler ultrasonography and laser Doppler blood flowmetry. Before and one hour after oral administration of ibudilast (10 mg), or elastase (1800 U) as a control, the cross-sectional area (CSA) of the dorsal pedis artery, its blood flow index (BFI), and dermal microcirculatory blood volume (MBV) were measured. In the ibudilast group, all of the parameters (CSA, BFI, and MBV) significantly increased as compared with the elastase group. These data suggest that ibudilast is effective in ameliorating diabetic macroangiopathy and microangiopathy of the lower limbs.

Administration, Oral↗
PubMed1995

Effects of repeated doses of compound E for 4 and 9 weeks on the male reproductive organs.

Results of two toxicity studies of Compound E, which is an anticancer drug, on male reproductive organs and fertility by oral repeated dosing at dose levels of 12.5, 25 and 50 mg/kg/day for 4 and 9 weeks in rats were compared. After repeated dosing, the male fertility was studied by mating with untreated female animals. At the dose of 50 mg/kg/day in the 4-week study, Compound E significantly decreased testes weight and number of epididymal sperm, caused histopathological changes in the testis and epididymis characterized by decreased germ cells, but did not affect fertility. The dose of 25 mg/kg/day in the 9-week study caused reduction in epididymal weight and number of epididymal sperm and histopathological changes in the testis. The dose of 50 mg/kg/day in the 9-week study was lethal and caused more prominent toxic effects in the reproductive organs and loss of fertility. The present studies suggest that the order of sensitivity of parameters on male reproductive organs is as follows; histopathological examination = organ weight > number of sperm in epididymis > pregnancy index> copulation index. Further, 4-weeks repeated dosing is of sufficient duration to predict adverse effects of test compounds.

Animals↗
PubMed1995

[The plasma concentration measurement of local anesthetics, thiobarbiturates and mexiletine by HPLC with automatic pre-treatment system].

The concentrations of lidocaine, its metabolites (MEGX, GX), mepivacaine, bupivacaine, thiamylal, thiopental and mexiletine in plasma have been determined by HPLC method with automatic pre-treatment system. The drugs carried by pre-treatment mobile phase are trapped by hydrophobic interaction on the pre-treatment column (4 mm i.d. x 30 mm L., tetramethylolmethanetriacrylate resin packing). As sending analytical mobile phase which was conditioned with 0.1 M sodium phosphate buffer (pH 2.1) and acetonitrile by switching the flow changeover valve, the absorped drugs were eluted quickly and introduced to the analytical column (6 mm i.d x 150 mm L., octadecylsilan chemical bond sillica packing). On this column, the drugs were separated and analyzed, then measured by a UV spectrophotmetric detector. The time of switching valve, the wave length of detector for measurement and the buffer/acetonitrile ratio of analytical mobile phase were specific for the drugs, respectively. And high recovery and reproducibility were obtained for using auto-injector, so it has been possible to determine the concentrations of drugs in plasma with absolute calibration curves.

Anesthetics, Intravenous↗
PubMed1995

[Pneumocystis carinii pneumonia associated with low dose methotrexate treatment for malignant rheumatoid arthritis].

Low dose pulse methotrexate (MTX) has become a widely used therapy for rheumatoid arthritis (RA) because of its good response rate profile. With the increased use of MTX, reports of opportunistic infections associated with MTX therapy have appeared. Fourteen cases of pneumocystis carinii (PC) pneumonia in patients receiving low dose MTX have been previously reported. Yet, no case of PC pneumonia associated with low dose MTX has so far been reported in Japan. We report the first case in Japan of PC pneumonia occurring in a patient with rheumatoid vasculitis who was receiving low dose MTX. A 70-year old woman with 13 year history of RA presented with 3-day history of rapidly aggravating dyspnea, dry cough and fever. She had been receiving MTX 7.5 mg/week for 2.5 months because of her vasculitis symptoms. She had also been receiving prednisolone 7.5 mg/day which had been successfully tapered from an initial dose of 15 mg/day. At the time of her presentation with respiratory symptoms, all of her vasculitis symptoms had been alleviated. A chest radiograph revealed diffuse interstitial shadowing bilaterally and bilateral hilar and right lower lung field infiltrates. Her arterial blood gas showed severe hypoxemia (PaO2 27.7 torr). Polymerase chain reaction assay of bronchoalveolar lavage fluid showed PC. Although the patient required ventilatory support for 9 days, she was successfully treated with trimethoprime-sulphamethoxazole and methylprednisolone pulse therapy. Eight months later, the patient was well with no evidence of vasculitis or respiratory symptoms.

Aged↗
PubMed1995

Water jet angioplasty--an experimental study.

The usefulness and safety of water jet angioplasty was studied in vitro, using agar phantom and autopsied aorta, and in vivo in acute and chronic arterial occlusions in mongrel dogs. At an injection rate of 1.0 ml/s, the water jet produced erosion of the agar surface when the distance between the catheter and the agar was 1 mm. With an injection rate of 1.5 ml/s, erosion was produced at a distance of 15 mm from the catheter tip. When the water jet was directed at an arterial wall, intimal ablation and ruptured elastic fibers were found histopathologically. A smaller angle between the vascular wall and the catheter was associated with less vascular damage. In vivo, water jet angioplasty was effective against acute obstructions, but not against chronic obstructions. These results suggest that water jet angioplasty may be effective against arterial obstruction due to acute thrombus.

Agar↗
PubMed1995

[Influence of stellate ganglion block on respiratory system].

The purpose of this study was to investigate the influence of a stellate ganglion block (SGB) or stellate ganglion electrical stimulation (SGES) on pulmonary resistance, on blood flows of the bronchial, pulmonary and common carotid arteries, and on arterial blood gases. Thirteen mongrel dogs were divided into two groups; a SGB group (n = 8) and a SGES group (n = 5). Anesthesia was induced with pentobarbital 25 mg.kg-1 and the animals were mechanically ventilated to maintain constant PaO2 (90-100 mmHg) and PaCO2 (35-40 mmHg). After a thoracotomy, the SGB with 0.5% mepivacaine 1.5 ml was performed, or the SGES was performed at a strength of 12 volts, and at a frequency of 50 Hz, applied for 30 min. In the SGB group, pulmonary resistance after the block did not significantly differ from the control. No significant change occurred in blood flows of the bronchial and pulmonary arteries, but the common carotid artery flow increased significantly after the SGB. Arterial blood gases did not change significantly after the SGB. In the SGES group, pulmonary resistance after the stimulation did not significantly differ from the pre-value. However, blood flows of the bronchial, pulmonary and common carotid arteries decreased significantly after the SGES. Arterial blood gases did not change significantly after the SGES. These results suggest that the SGB may not influence the respiratory system under normal conditions.

Animals↗
PubMed1995

[Physical properties of Strecker stents].

Strecker stent is a balloon-expandable metallic stent that is made of knitted tantalum wire mesh in order to Maintain flexibility. Therefore, the prosthesis is well suited to irregular and tortuous tube organs. We performed several physical experiments using 8 mm and 6 mm diameter stents made of 0.1 mm diameter wire filament. The bearing power of the 8 mm diameter stent against the circumferential compression pressure was divided into two groups, that is, 77-100% and under 66% of expansile rate. The capacity bearing the circumferential compression pressure of the latter group was greater than that of the former. Further, the bearing power of the 6 mm diameter stent was greater than that of the 56% expansile rate of the 8 mm diameter stent. The smaller the expansile rate of the stent, the smaller the minimum radius of curvature within the limits of the stent's plastic. To evaluate the suitability of the stent in clinical use, we made two projections on the inner surface of rubber tubes, and the stents were placed into the rubber tubes at different expansile rates. We evaluated the degree of contact of the stents against the rubber wall by taking soft X-ray photographs. The stents showed good suitability under the condition of incomplete expansion. For the above reasons, we concluded that, from the view-point of bearing power, the stent should be placed in the full expansile state. From the viewpoint of contact against the vessel wall, the stent should be placed in the incomplete expansile state.

Physical Phenomena↗
PubMed1995

[Sleep apnea syndrome in rheumatoid arthritis (RA) patients complicated with cervical and temporomandibular lesions].

All-night polysomnographic studies were performed on ten patients (all female) with rheumatoid arthritis complicated with temporomandibular joint destruction and cervical lesions. The mean age of these subjects was 67.5 yrs, ranging from 48-81 yr. They all had some morphologic abnormalities of cervical spines and/or temporomandibular joints. Sleep study revealed that all of them had sleep apnea; five of them were of obstructive type (obstructive group) while the remaining showed central type of sleep apnea (central group) predominantly. There were no statistically significant differences of the levels of apnea index, mean-nadir SO2 and the lowest SO2 between the obstructive group and the central group. No detectable differences of cephalographic measurements and MRI findings existed between the two groups either. In one patient, nasal-CPAP converted central apnea to normal breathing dramatically. Our observations indicate that the cause of central apnea in RA patients with temporomandibular lesions is collapse of upper airway, inducing inhibitory inputs from the mechanoreceptors in that region.

Aged↗
PubMed1995

[Parathyroid selective venous sampling].

It is important to localize the site of abnormal parathyroid glands in treatment of primary hyperparathyroidism. Selective venous sampling with parathyroid hormone assay is one of the methods for localization of adenoma or hyperplasia in primary hyperparathyroidism. Since Reitz first described it in 1969, it has been improved during the last two decades and there is a high sensitivity (70-80%). Especially in those cases, localization is unknown in imaging methods, the first operation fails or the patients has previously been explored in the neck, venous sampling becomes a very useful method. How to perform, indication, performance, strengths and weakness of selective venous sampling is described here.

Blood Specimen Collection↗
PubMed1995

[Percutaneous placement of intraluminal stent-graft for aortic dissection: experimental study].

Highly porous fabric vascular grafts fabricated of ultrafine polyester fibers (UFPF-graft; porosity, 7,000 ml, 9,000 ml, 11,000 ml at 120 mmHg) were attached between two Gianturco stents connected with two stainless steel struts. UFPF-grafts with two Gianturco stents were placed into the aortas of six adult mongrel dogs without firm contact with the luminal surface. From two days to four months after placement, all the UFPF-grafts were completely sealed with fresh thrombus or neointima. Within two months, complete endothelialization was observed on both surfaces of the neointima. In three dogs, aortic dissections were created experimentally. Then an UFPF-graft (porosity, 9,000 ml) with two Gianturco stents was placed at the site of entry of the dissection, followed by additional Gianturco stents to expand the UFPF-graft. X-ray angiography showed that the entries were closed immediately after placement, and false lumens disappeared within one hour after placement. These results indicated that the method has the possibility of treating aortic dissection with complete sealing of the fabric by the neointima.

Aortic Dissection↗
PubMed1995

[Surgical treatment of syringomyelia].

Eighty cases of surgically treated syringomyelia were retrospectively reviewed. The cases were classified into following 4 types, type 1: syringomyelia with Chiari malformation (54 cases), type 2: syringomyelia with basal arachnoiditis (15 cases), type 3: syringomyelia with an obstruction of the foramen Magendie (1 case), and type 4: syringomyelia with spinal arachnoiditis (14 cases). Foramen magnum decompression (FMD) was performed in patients with type 1, in type 2 fourth ventricle-subarachnoid shunt was additionally performed. Gardner's operation was performed in patients with type 3. Syrinx-peritoneal shunt was performed in patients with type 4. Surgical procedures for syringomyelia which we selected were thought to be appropriate, based on postoperative syrinx collapse rate in MRI. However, postoperative clinical course was much different in each type of syringomyelia after the collapse of syrinx had been equally achieved. Neurological disorders were stopped in deterioration after surgery in all cases of type 1. However, motor weakness was still deteriorated in half cases of type 2, and in 60% of type 4. When clinical severity of the patients with type 1 and 2, based on the distribution of dissociated sensory loss and motor weakness, were classified into 5 grades. The rate of improvement of patient's symptoms and signs was higher in the lower grades. We concluded that a surgical treatment for syringomyelia was essentially a preventive one, therefore it should be done in early stage of disorders.

Arachnoiditis↗
PubMed1995

A pilot/introducer needle for central vein cannulation.

A kit for safe and easy insertion of a central vein cannula was devised. A small gauge (22 gauge) metal pilot needle was equipped with a Y-shaped hub which had a side-port to accept a small gauge (0.46 mm) Seldinger guide wire. Once the needle reached the vein, guidewire was threaded in through the side-port. There was no need to remove the pilot needle and no need to repeat vein puncture with a larger-bore needle. Three puncture methods were used with the kit: (1) the central approach via the internal jugular vein, (2) the supraclavicular approach via the junction of the internal jugular vein and subclavian vein, and (3) the infraclavicular approach via the subclavian vein. Each method was used on 20 patients, for total of 60 patients, with a high success rate. Less than 3 minutes were required from puncture to catheter insertion. No serious complications were encountered.

Catheterization, Central Venous↗
PubMed1994

[Brain development during the first year of life: quantitative assessment with ADC imaging].

Brain development during the first year of life was assessed quantitatively using apparent diffusion coefficient (ADC) images constructed from diffusion-weighted MR image data. The imaging plane was coronal at the section of the pons. The cerebral peduncle, internal capsule, corona radiata, superior longitudinal fasciculus and thalamus were selected for evaluation of their ADC values. A diffusion sensitive gradient was added in the anteroposterior direction. Thus the orientation of nerve fibers in the cerebral peduncle, internal capsule and corona radiata was perpendicular to it, and that in the superior longitudinal fasciculus was parallel to it. In neonates, the cerebral peduncle and internal capsule, having been moderately myelinated at birth, showed the slowest diffusion. The corona radiata and superior longitudinal fasciculus, having been unmyelinated at birth, showed the fastest diffusion. The thalamus had intermediate diffusion. These neonatal diffusions tended to be promptly restricted within the first five months, followed by additional slight restriction thereafter. ADC values in the first year were significantly reduced in all regions compared with those in the neonatal period, particularly in the corona radiata and thalamus. This study showed that ADC analysis can estimate normal brain development in detail and might be useful for investigating various neonatal brain diseases.

Brain↗