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Biomedical subjects

N Yamada

Publications and source records attributed to N Yamada.

At least 703 records · Page 39Linked to original sources
PubMed1989

Serial assessment of myocardial infarction by using gated MR imaging and Gd-DTPA.

In order to assess the usefulness of Gd-DTPA in the evaluation of myocardial infarction, 17 patients were examined with gated MR imaging. Scans were made by using a spin-echo pulse sequence before and after IV administration of 0.15 mmol/kg of Gd-DTPA. The images were made at four intervals (average of 5, 12, 30, and 90 days) after the onset of the infarction. Gd-DTPA uptake at the infarcted area was graded as marked, moderate, or no increase in signal intensity by visual inspection. At these four time intervals, an area of increased signal intensity in the infarcted myocardium was detected on T1-weighted images after administration of Gd-DTPA in 14 (82%) of 17 cases, 16 (94%) of 17 cases, six (38%) of 16 cases, and three (21%) of 14 cases, respectively. Markedly increased signal intensity in infarcted areas was shown on T1-weighted images with Gd-DTPA at 5 and 12 days. The ratio of gadolinium uptake in the infarcted area to that in normal myocardium also was evaluated. At 5 and 12 days, the mean increase in signal intensity in the infarcted area was significantly higher than that in a normal area, but not at 30 and 90 days. Increased signal intensity also was apparent on T2-weighted images without Gd-DTPA at 5 and 12 days; however, the use of late echo reduced the signal-to-noise ratio, leading to image degradation. Uptake of Gd-DTPA was a positive marker in acute myocardial infarction, but no significant uptake of Gd-DTPA occurred in chronic myocardial infarction.

Contrast Media↗
PubMed1989

Cine MR imaging in mitral regurgitation: comparison with color Doppler flow imaging.

Cine MR imaging is a new technique that combines short repetition times, limited flip angles, gradient-refocused echoes, and cardiac gating. This procedure was performed in 20 patients in whom mitral regurgitation was shown on left ventriculography, and the results were compared with those of color Doppler flow mapping. In all cases, mitral regurgitation on cine MR imaging was depicted as an area of decreased signal intensity within the left atrium. The extent and severity of the regurgitant jet as seen by the two techniques were classified visually as 4+ (severe), 3+ (moderate), 2+ (mild), and 1+ (minimal). The results of the two methods were the same in 14 (70%) of the 20 patients. In five patients the results differed by one grade and in one patient by two grades. In addition, the maximal intrusion distance and area of the regurgitant jet divided by the area of the left atrium as determined by the two methods were compared. The correlation coefficients between the two methods in regard to the length and area of mitral regurgitation were .74 and .71, respectively. These data suggest that the accuracy of cine MR imaging in assessing the severity of mitral regurgitation is comparable to that of color Doppler flow imaging.

Adult↗
PubMed1989

Improvement of reduced coronary vasodilatory response during reactive hyperemia by diltiazem.

This study was performed to reconfirm transiently-reduced vasodilatory responses of the coronary artery in the reactive hyperemic period, and also to study whether an increase in calcium influx into the coronary smooth muscle accounts for the reduced coronary vasodilatory responses. Blood flow in the circumflex coronary artery was measured with an electromagnetic flow transducer in anesthetized open-chest dogs. Two successive occlusions for 3 to 7 s performed in pairs with a brief interval were accompanied by decreasing reactive hyperemia: the maximum reduction of reactive hyperemia appeared when the occlusion period was around 5 s with a 5-s interval. Around 5 s after the release of occlusion, excess arterial inflow almost equaled the blood flow debt incurred during the first occlusion. Pretreatment with diltiazem (150 micrograms/kg), a calcium entry blocker, significantly attenuated the reduction of coronary vasodilatory responses, but glyceryl trinitrate (nitroglycerin) did not affect the phenomenon of coronary reactivity. The results suggest that excess accumulation of calcium in the smooth muscle of small coronary arteries occurred during an early period of post-occlusion hyperemia, which resulted in a reduced vasodilatory reactivity of the vessels to the second ischemic stimulus.

Animals↗
PubMed1989

[Efficacy of UFT in advanced gastric carcinoma under comparative study of MMC + UFT and MMC + tegafur therapies].

Antitumor effect of MMC + UFT(A) and MMC + tegafur(B) therapies for advanced gastric carcinoma was compared from February 1985 to March 1988. UFT and tegafur were orally given at dose of 400 mg/m2 daily, and MMC was intravenously administered at dose of 6-8 mg/m2 every two weeks. The following results were obtained. 1. Twenty-nine cases entered in this study were divided into A or B therapies at random. All cases entered were eligible. Fourteen of 29 cases were randomized into A therapy and 15 cases into B therapy. One case treated with B was evaluated as incomplete. 2. There were no differences in the characteristics of patients between A and B therapies. 3. Among 29 eligible cases, a partial response was obtained in 3 out of 14 cases (21.4%) treated with A and in 3 out of 15 cases (20.0%) treated with B. Among 28 cases evaluated completely, a partial response was obtained in 3 out of 14 cases (21.4%) treated with each A and B. 4. Response rate with every ps or for every lesion did not differ between A and B therapies. 5. Median survival day treated with A and B therapies was 223 and 181 days, respectively. The survival curve did not differ significantly between the two therapies. 6. The frequency of adverse reactions within eight weeks after beginning the therapy was 64.2 and 73.3% with A and B therapies, respectively. From the results mentioned, it was concluded that the antitumor effect of UFT was not superior to that of tegafur for advanced gastric carcinoma.

Adult↗
PubMed1989

Effect of beraprost sodium on peripheral circulatory disturbances induced by various stimuli.

Effects of beraprost sodium (sodium(+/-)-(1R*,2R*,3aS*,8bS*)-2,3,3a,8b-tetrahydro-2-hydr oxy-1- [(E)-(3S*)-3-hydroxy-4-methyl-octen-6-ynyl]-1H-cyclopenta[b] benzofuran- 5-butyrate, TRK-100), a stable prostacyclin analogue, on the peripheral circulatory disturbances induced by various vasoconstrictive stimuli were studied. Orally administered beraprost sodium (10, 30 micrograms/kg) caused increase in skin blood flow in anesthetized rats and rise in skin temperature in conscious rats. Intravenously administered beraprost sodium (0.01-0.3 microgram/kg) reduced the recovery time of decreased pulse pressure by topical cooling of the leg in anesthetized rats. In conscious rabbits, intravenous infusion of beraprost sodium (10 micrograms/kg/min) inhibited the fluctuation of ear artery diameter, and dilated the ear artery and vein, resulting in a rise in the ear temperature. In anesthetized dogs, intravenously administered beraprost sodium (0.313-5 micrograms/kg) caused decrease in femoral blood flow and muscle blood flow in the hindlimb, however, it caused increase in skin blood flow at the hind leg instep. Furthermore, intra-arterially administered beraprost sodium (0.1-0.3 microgram/kg/min) under stimulation of lumbar sympathetic nerve caused increase in femoral artery blood flow and selective increase in the skin blood flow without affecting muscle blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Alprostadil↗
PubMed1989

Cell wall formation in regenerating protoplasts of Schizosaccharomyces pombe: study by high resolution, low voltage scanning electron microscopy.

The ultrastructure of regenerating cell wall in Schizosaccharomyces pombe protoplasts was studied with a high resolution, low voltage scanning electron microscope (LVSEM). In contrast to the transmission electron microscopy, the LVSEM images give three-dimensional information on the cell wall regeneration in yeast protoplasts. We found that, after only a few minutes of incubation, the protoplasts began to show protuberances in a unipolar manner, and a fibrilar network was formed asymmetrically which covered the whole surface of the protoplasts after 5 hr. The network consisted of microfibrils about 8 to 10 nm wide, forming flat and wavy bundles of various widths and lengths, up to about 200 nm wide and 1 micron long, mainly made of yeast glucan. Free ends of microfibrils were seldom found. Interfibrillar spaces were progressively filled with granular particles and finally the complete cell wall was formed after 12 hr. The fibrillar network was destroyed by the digestion with beta (1----3)-glucanase. When protoplasts were regenerating in the presence of aculeacin A, the fibrillar networks were not formed, resulting in incomplete cell wall formation. These observations suggest that beta-glucan is the main component of the microfibrils and that it plays an important role in the formation of the cell wall in S. pombe.

Antifungal Agents↗
PubMed1989

[The occurrence of tyrosine hydroxylase-immunoreactive neurons in a parietal lobe ganglioglioma].

A parietal lobe ganglioglioma in a 61-year-old male was investigated ultrastructurally and immunohistochemically, using antiserum against tyrosine hydroxylase (TH), a rate-limiting enzyme of the catecholamine (CA)-synthesizing pathway. On light microscopy, the tumor was composed mainly of neuronal and astrocytic cells. The neuronal cells had typical round vesicular nuclei with prominent nucleoli and showed abundant cytoplasm with variable amounts of Nissl bodies. Bi-nucleated neuronal cells were occasionally found. The astrocytic cells had eosinophilic cytoplasm of variable shapes and hyperchromatic small nuclei. Electron microscopy revealed numerous dense core vesicles (DCVs) in the neuronal cytoplasm and processes. Immunohistochemically, TH-immunoreactive neuronal cells were found sporadically in the tumor tissue. They were often binucleated or multinucleated. The presence of TH-immunoreactive neuronal cells in the present case is of interest in considering the origin of neuronal cells in ganglioglioma. Some investigators have considered that they may arise from the ectopic autonomic neuronal cell nests in view of the presence of DCVs. However, Gasper et al. have recently demonstrated the presence of TH-immunoreactive neurons in the normal human cerebral cortex. Therefore, it may also be possible to consider that TH-immunoreactive neuronal cells in this tumor originated from a certain dysgenetic focus containing such TH-immunoreactive neurons in the developmental stage.

Brain Neoplasms↗
PubMed1989

Synthesis of novel nucleosides.

A new spironucleoside structural type and two new bicyclic nucleoside structural types were synthesized from the reaction of ribose nitrile oxide with dimethyl acetylenedicarboxylate. Next, a synthetic method for novel meso-ionic nucleoside structual type is presented.

Nucleosides↗
PubMed1989

[Magnetic resonance imaging of cerebrovascular disorders; cerebral infarction].

Patients with cerebral infarction and with suspicion of cerebral infarction were studied with magnetic resonance imaging (MRI) and correlative CT scans. MRI was more sensitive than CT for detecting cerebral infarction, and T2-weighted spin echo pulse sequence was most sensitive in the diagnosis of cerebral infarction except some lacunar infarctions and some cortical and subcortical infarctions. MRI using Gd-DTPA was more sensitive than contrast CT for detecting fresh infarcted areas, especially in the cases with multiple cerebral infarcted areas and cortical and subcortical infarcted areas, and many offer some informations in evaluating the state of circulation.

Adult↗
PubMed1989

Effect of beraprost sodium (TRK-100) on acetic acid-induced skin ulcer.

Effect of beraprost sodium (TRK-100), a stable PGI2 analog, on experimentally induced skin ulcer was studied in rats. An experimental skin ulcer was developed by intradermal injection of acetic acid. Injection of glacial acetic acid to the skin in the left hind leg instep of rats resulted in the necrosis of the skin, and a skin ulcer developed in 3 days. The ulcer area reached its peak on the 5th day, and recovered to its control level within 4 weeks. The effects of TRK-100 and indomethacin on the ulcer were tested. TRK-100 showed suppressive effects on the development of the ulcer. A dose of 30 micrograms/kg (p.o.) accelerated healing of the ulcer when scored macroscopically on the 9th or 15th day. At a dose of 100 micrograms/kg (p.o.), it reduced the development of the ulcer and accelerated healing with statistical significance from the 5th day and thereafter. Indomethacin also reduced the development of the ulcer and accelerated healing with statistical significance from the 7th day and thereafter. These results suggest TRK-100 may be effective on the inhibition of the development and accelerated the healing of the skin ulcer formed in various pathological states.

Acetates↗
PubMed1989

[Preoperative localization of supernumerary and ectopic parathyroid glands in patients with secondary hyperparathyroidism].

The undetectable supernumerary and ectopic parathyroid glands have a high risk of persistent and recurrent hyperparathyroidism, especially in the patients with secondary hyperparathyroidism. Preoperative image diagnosis, CT scan, echogram and 201T1C1 scintigram were very useful for detecting supernumerary and ectopic parathyroid glands in our 132 patients who underwent parathyroidectomy for secondary hyperparathyroidism. Among these methods the scintigraphy showed the highest detection rate of the glands in the thymic tongue and in the upper mediastinum. CT scan showed the best detection rate of the glands located in the thyroid gland and those located between the thyroid gland and trachea. The echography was useful in detecting the glands in the thyroid gland, but could not offer easy visualization those located in the mediastinum. Even the ectopic parathyroid glands, weighing more than 500 mg were identifiable at about 90% when all the methods were applied routinely. In our experience, four patients had a supernumerary gland which was detected by the preoperative image diagnostic procedures at the initial surgery. One patient had a supernumerary gland in the mediastinum which was detected by image diagnosis after the initial operation and was removed at reoperation.

Adult↗
PubMed1989

Composition of very-low-density lipoproteins in non-insulin-dependent diabetes mellitus.

We studied the characteristics of very-low-density lipoproteins (VLDLs) composition in patients with non-insulin-dependent diabetes mellitus. VLDLs were isolated from 28 diabetics and 33 nondiabetics with a wide range of plasma lipid concentrations, so we could compare VLDL composition between the two groups at similar lipid concentrations. The mean cholesterol and triglyceride concentrations in plasma of diabetic subjects were 2170 (SD 570) and 2510 (SD 2230) mg/L, respectively, and 2230 (SD 560) and 2210 (SD 1830) mg/L in nondiabetics. Diabetic subjects showed positive correlations between plasma triglyceride concentrations and either preprandial blood glucose or glycated hemoglobin values (P less than 0.02 and less than 0.01, respectively). Concentrations of triglycerides, cholesterol, and apolipoproteins (apo) B, CII, CIII, and E in VLDL were not significantly different between diabetics and nondiabetics. At comparable triglyceride concentrations, the chemical compositions of the VLDL in the two groups were still very similar. Dividing the concentration of each component by the VLDL-apo B concentrations yielded similar contents of each component per unit of VLDL for the two groups. We conclude that the composition of VLDLs in diabetics is much the same as that in nondiabetics at comparable concentrations of triglycerides in plasma.

Adult↗