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Biomedical subjects

I Yamada

Publications and source records attributed to I Yamada.

At least 127 records · Page 7Linked to original sources
PubMed1992

Moyamoya disease: diagnosis with three-dimensional time-of-flight MR angiography.

Twelve patients with moyamoya disease were studied with three-dimensional time-of-flight magnetic resonance (MR) angiography, and the findings were compared with results obtained with conventional arteriography. Of a total of 24 supraclinoid internal carotid arteries studied, 21 arteries (88%) were accurately evaluated with MR angiography and in three arteries the extent of occlusive disease was overestimated. Of a total of 72 large branch basal cerebral vessels, including the bilateral anterior, middle, and posterior cerebral arteries, 61 arteries (85%) were accurately evaluated with MR angiography and in 11 arteries the extent of occlusive disease was overestimated. While conventional arteriography showed basal cerebral moyamoya vessels in all 24 hemispheres, MR angiography showed moyamoya vessels in 20 of these. Of a total of 28 large leptomeningeal and transdural collateral vessels, 18 were identified with MR angiography. In the one surgical collateral vessel evaluated, MR angiography successfully showed its patency. MR angiography may have value in following disease progression and, perhaps, in evaluation of surgical bypass patency.

Adolescent↗
PubMed1992

Powder coating mixture of a novel anxiolytic, Y-23684: dissolution characteristics and bioavailability.

A powder coating mixture was investigated with a view toward improving the dissolution property of the anxiolytic 2-(4-chlorophenyl)-5,6-dihydro-[1]benzo-thiepino-[5,4-c]-pyrida zin-3(2H)-one 7-oxide (1), which was barely water soluble. The powder coating mixture in various ratios of 1 and cornstarch was prepared in an automated mortar. Among these mixtures, at the optimum ratio of 1 and cornstarch (2:1, 67% drug content), the powder coating mixture gave a maximized effect for solubilizing 1 on the bases of stability and solubility. Conventional granules were made from the 67% powder coating mixture. The granules showed an excellent absorption profile in beagle dogs. The mechanism of the solubilizing effect resulting from a pharmaceutical process was also discussed.

Animals↗
PubMed1992

Bioavailability study of commercial sustained-release preparations of diclofenac sodium in gastrointestinal physiology regulated-dogs.

The gastrointestinal (GI) physiology of beagle dogs was regulated with a combined-treatment of intramuscular pentagastrin (10 micrograms/kg x 2) and intravenous atropine sulfate (0.02 mg/kg x 1). Here, the gastric acidity, the gastric emptying time and the small intestinal transit time in the regulated-dogs were respectively around pH 2, 0.7h and 4h, approximating those in healthy humans. The superiority of the regulated-dogs over the intact dogs was confirmed in comparative bioavailability studies by using two classes of commercial preparations. Both the conventional tablet and the sustained-release capsule of diclofenac sodium exhibited simple and similar average plasma concentration-time curves of free diclofenac in the intact dogs, while the latter preparation is reported to reveal a bimodal plasma curve of the drug in healthy humans. The regulated-dogs, however, permitted a bimodal average plasma pattern of the drug for the capsules due to an approximation of the GI physiology between humans and these classes of the dogs. The combined-treatment of beagle dogs with pentagastrin and atropine sulfate seems to supply a useful animal model in predicting the absorption characteristics of the sustained-release preparations and poor water-soluble drugs.

Animals↗
PubMed1992

Pulmonary artery disease in Takayasu's arteritis: angiographic findings.

One hundred sixteen arteriographic examinations in 98 patients with Takayasu's arteritis were studied retrospectively to evaluate the extent of aortic and pulmonary disease. Stenosis was the most frequent finding in the aorta and its branches, but occlusion, dilatation, and aneurysms were also seen. Adventitial vascular structures, consistent with dilated vasa vasorum, were observed in five patients (5%) and systemic artery-pulmonary artery communication was seen in six (6%). Twenty-one (70%) of 30 patients who had pulmonary arteriography were shown to have pulmonary artery involvement. Upper lobe pulmonary arterial branches showed abnormalities most frequently; segmental branches, followed by subsegmental branches, were most often involved. The frequency of abnormal findings on pulmonary arteriograms correlated with the number of involved brachiocephalic vessels. Stenotic lesions in the aorta and its branches progressed in five (45%) of 11 patients, and those in the pulmonary artery progressed in one (33%) of three cases. Takayasu's arteritis characteristically involves the systemic and pulmonary arteries, and the extent of arteritis in the major branches of the aortic arch appears to correlate with pulmonary arterial involvement. Both thoracic and abdominal aortographic studies and pulmonary arteriography are necessary to properly diagnose the extent of the disease, and angiography should be repeated for appropriate patient follow-up.

Adolescent↗
PubMed1991

The killing effect of 4-S-cysteaminylphenol, a newly synthesised melanin precursor, on B16 melanoma cell lines.

We have examined the killing effect of 4-S-cysteaminylphenol (4-S-CAP), a newly synthesised melanin precursor, on B16 melanoma cell lines possessing different melanin-producing activities and found it to be particularly effective in heavily melanised melanoma cells, but less so in moderately melanised melanoma cells, and having no effect on amelanotic melanoma cells and nonmelanoma cells. Thus, it was found that the killing effect of 4-S-CAP is highly dependent upon the synthesis of melanin and tyrosinase in melanoma cells, suggesting that 4-S-CAP may become toxic to melanoma cells only after oxidation by tyrosinase. The killing activity of 4-S-CAP also was found to be associated with a profound inhibition of the thymidine incorporation in pigmented melanoma cells, as compared to the uridine and leucine incorporation. Further, the inhibition of DNA synthesis was most pronounced in heavily melanised melanoma cells, less so in moderately melanised melanoma cells, and not seen in amelanotic melanoma cells. As a possible mechanism that might account for this action, it may be that 4-S-CAP is oxidised by tyrosinase to the o-quinone form via the catechol derivative and that some of the quinones then conjugate with sulfhydryl enzymes including DNA polymerase, thus exerting a killing activity for pigmented melanoma cells. Thus, 4-S-CAP appears to provide a new, effective cytotoxic agent for rational chemotherapy of malignant melanomas.

Animals↗
PubMed1991

CT findings in primary osteosarcoma of the jaw.

Findings of computed tomography (CT) in five patients with osteosarcoma of the jaw are presented. CT played an important role in the assessment of the tumour extent before the planning of treatment for both primary and recurrent jaw osteosarcoma. Plain CT was capable of demonstrating subtle bony change (cortical reaction and calcification) and medullary tumour extension without interference from other superimposed bones. Tumour vasculature was well represented by thin-slice CT scan with intravenous bolus injection of contrast medium. We emphasize the importance of preoperative CT scanning from both a radiological and surgical point of view when confronted with a tumour of the maxilla or mandible.

Adult↗
PubMed1991

Several cation transporters and volume regulation in high-K dog red blood cells.

Normal dog red blood cells lack the Na-K pump, and their cation composition is low K and high Na (LK). Recently, a dog was found with red blood cells containing high K and low Na concentrations (HK) due to the existence of the Na-K pump. In the present study, cation transport and volume regulation in HK cells were compared with those of LK cells. HK cells showed not only Rb influx through a Na-K pump, but also Rb influx through a Cl-dependent K transporter. The Rb influx rate through the Na-K pump was 0.65-1.44 mmol.l cells-1.h-1 in Cl and 1.75-2.24 mmol.l cells-1.h-1 in NO3, in HK cells, but only trace activities are found in LK cells. In HK cells, the Rb influx rate through Cl-dependent K transport was 0.36-0.96 mmol.l cells-1.h-1, and it was enhanced in swollen cells but vanished in shrunken cells. In LK cells, the transport was evident only in swollen cells. The original volume of swollen HK cells was restored by water extrusion promoted by Cl-dependent transport. The Na-Ca exchange transporter, which works as a volume regulator in LK cells, functioned in HK cells only when they were loaded with Na. Hence, the exchange transporter is latent in HK cells under physiological conditions. Moreover, the exchange transporter could restore the cell volume in swollen and Na-loaded HK cells. However, the volume in HK cells was still larger than that in LK cells, while the Na-Ca exchange transporter was working.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

CT features in second cancers of the maxillary sinus.

Five patients with a second maxillary cancer (squamous cell carcinoma), which developed 6 to 17 years after initial treatment for the first cancer on the opposite side, were compared with 21 control cases with a primary cancer on the basis of computed tomography (CT) findings. Generally, the second cancer was found at an earlier stage. The specific CT findings of early sinus carcinoma were uneven soft tissue distribution in the antrum and tumor permeation with bone fragments remaining at the original tumor site. These findings may be helpful for distinguishing this cancer from benign chronic sinusitis and/or other malignant sinus disease. The pterygoid process, medial bony wall, and ethmoid sinus had a tendency to be spared in most of the 5 patients with second maxillary cancer compared to the 21 control cases.

Aged↗
PubMed1990

The effect of L-dopa on the potentiation of radiation damage to human melanoma cells.

Since L-dopa (L-3,4-dihydroxyphenylalanine) has been shown to possess a selective toxicity for melanoma cells both in vitro and in vivo, we have examined the combined effect of L-dopa and radiation on human melanoma cells. It was found that the combined use of L-dopa potentiated the radiation cytotoxicity to HMV-I human melanoma cells, compared with the response seen in non-melanoma HeLa S3 cells. In HMV-I cells during their exponential phase, L-dopa decreased the shoulder width of the radiation survival curve significantly. In addition, L-dopa significantly inhibited the repair of potentially lethal damage (PLD) in HMV-I cells during their plateau phase. When the distributions of the G1, S, and G2-M cells were measured 24 h after combined L-dopa and radiation treatment, there was significant increase in the accumulation of cells in the G2-M phase of the cell cycle, compared to cells that received either L-dopa or radiation treatment only.

Cell Cycle↗
PubMed1990

Measurement of gastric pH during digestion of a solid meal in dogs.

The behavior of gastric pH during digestion of a solid meal in beagle dogs was determined by use of an ion-selective field effect transistor pH sensor. The pH in the stomach was 3.9 +/- 0.4 (mean +/- S.D., n = 6) at 0.5 h after meals. It was maintained at a mildly acidic (about pH 3) level for long periods.

Animals↗
PubMed1990

Comparative pharmacokinetics of sulpiride and N-[(1-butyl-2-pyrrolidinyl)methyl]-2-methyl-5-sulfamoyl-2,3- dihydrobenzofuran-7-carboxamide hydrochloride, a new lipophilic substituted benzamide in rats.

The pharmacokinetics of a new lipophilic substituted benzamide N-[(1-butyl-2-pyrrolidinyl)methyl]-2-methyl-5-sulfamoyl-2,3- dihydrobenzofuran-7-carboxamide hydrochloride (1) and sulpiride in both plasma and brain were investigated in rats. The octanol-water partition coefficients of the base of 1(2) and sulpiride were 6.3 and 0.2, respectively. The eliminations of 2 from plasma and brain were similar to those of sulpiride. The systemic bioavailabilities of 1 and sulpiride after oral administration of 200 mg/kg were 60.9 +/- 10.9 and 18.2 +/- 6.4%, respectively. The brain concentrations of 2 were about 2-3 times higher than those of sulpiride until 4 h after oral administration of 100 mg/kg. The brain/plasma ratios of 2 were about 2 times higher than those of sulpiride. These results indicate that the penetration of 2 through the gastrointestinal membrane and/or the blood-brain barrier are higher than those of sulpiride.

Animals↗
PubMed1990

Gastric acidity-dependent bioavailability of commercial sustained release preparations of indomethacin, evaluated by gastric acidity-controlled beagle dogs.

The relationship between gastric acidity and the bioavailability of two kinds of sustained-release indomethacin (IM) formulations was investigated in gastric acidity-controlled beagle dogs, and compared with that of rapid-release IM formulations. All test dosage forms were more rapidly dissolved in simulated intestinal fluid than in simulated gastric fluid. Gastric acidity did not affect the bioavailability of IM from the rapid-release formulation. However, the bioavailability of IM from the two kinds of sustained-release formulations were markedly influenced by gastric acidity. The rates of IM bioavailability from both of the sustained-release formulations were faster under low acidity conditions than under high acidity conditions (p less than 0.01). In addition, Tmax and mean residence time (MRT) were approximately the same for the rapid-release and sustained-release formulations under low acidity conditions. These results suggest that the IM sustained-release formulations showed a rapid-release profile under low acidity conditions.

Animals↗
PubMed1990

[Application of gastric acidity-controlled beagle dog to bioavailability study of cinnarizine].

The relationship between gastric acidity and bioavailability of a weakly basic drug, cinnarizine (CN) was investigated in the gastric acidity-controlled beagle dogs. The dissolution of CN from capsules was very fast at pH 1.2 but it decreased with an increase in pH. The capsules containing CN were orally administered to the beagle dogs of the following three groups: 1) the dogs whose gastric acidity were not controlled; 2) the dogs whose gastric acidity were controlled to high levels (less than pH 2) with pentagastrin; 3) the dogs whose gastric acidity were controlled to low levels (more than pH 6) with omeprazole. The peak plasma concentration (Cmax) and the area under the plasma concentration-time curve (AUC0-8h) of CN were most variable in the first group. On the other hand, the variations of these parameters were small in the second and third groups. The Cmax and AUC0-8h of CN in the high acidity group were about 20 times larger than those in the low acidity group (p less than 0.01). The bioavailability of CN was markedly influenced by the gastric acidity. This finding was similar to that in human subjects. The gastric acidity-controlled beagle dogs are useful animal models to evaluate the bioavailability of weakly basic drugs such as CN, exhibiting pH-dependent dissolution behavior.

Animals↗
PubMed1990

[Ten cases of an apocrine carcinoma of the breast and a review of cases in the Japanese literature].

To encounter an apocrine carcinoma of the breast is very rare. We have experienced, however, 10 cases of an apocrine carcinoma (0.65%) among 1541 primary breast carcinoma cases. The mean age of the patients was 58.1 years, and the tumor size on palpation ranged from 1.1 to 6.0 cm (mean 3.5 cm). A lymph node metastasis was seen in 5 cases. While one patient determined as being in stage III b of the disease died of the cancer approximately 5 months after surgery, all of other patients are still alive. The prognosis of this type of disease appears to be better than that of a common invasive ductal carcinoma. Thirty-four cases of an apocrine carcinoma have been found in the Japanese literature, this number including our 10 cases. Discussed are the clinicopathological features and the histogenesis of this type of cancer.

Adenocarcinoma↗
PubMed1989

[Mass screening for breast cancer in Gunma prefecture--the results for 8 years and future problems].

In Gunma prefecture, mass screening for both breast and thyroid cancer at the same time was conducted between April 1980 and March 1988 with the cooperation of the Gunma Cancer Society. In this paper, the results of mass screening for breast cancer and further problems are reported and discussed. The total number of subjects during these eight years was 191, 603 on the first screening with physical examination alone. Of these, 18,208 (9.5%) examinees were required to attend the second examination. Breast cancer was detected in 159 cases. The detection rate was 0.08% among total subjects. Also thyroid cancer was detected in 244 (0.13%). The detection rate for breast cancer was approximately twice as high at the initial screening (0.11%) than at the subsequent periodic screening (0.06%). Patients with breast cancer detected by mass screening showed an earlier stage and a better prognosis compared with those of our ordinary outpatients. The 8-year disease-free survival rate in mass screening and in outpatient cases was 94.9% and 83.2%, respectively, but there was no significant difference between the two groups. Interval breast cancer was also found in 19 cases (Tis; 1, Stage I; 8 and Stage II; 10) and 5 patients had nodal metastases. This mass screening program is a useful means for early discovery and early treatment of breast cancer. Hereafter, we should intend to increase the number of initial examinees and women aged 60 and over. Also it is important to make and train physicians for such screening, and to educate women about the practice of breast self-examination.

Adult↗