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Biomedical subjects

T Seki

Publications and source records attributed to T Seki.

839 records · Page 47Linked to original sources
PubMedDate not supplied

Modification of cerebrovascular CO2 reactivity by inhibition of dopamine beta-hydroxylase.

The influence of sympathetic nervous activity on cerebral circulation and cerebrovascular CO2 reactivity was investigated through inhibition of dopamine beta-hydroxylase (DBH). A PO2 electrode, a PCO2 electrode and a plate-type thermocouple-flowmeter were placed on the pial surface of the cat brain. Cerebrocortical PO2, PCO2, cerebrocortical blood flow and arterial blood pressure were continuously recorded before, during and after intracarotid infusion of 10 mg/kg of fusaric acid, a potent DBH inhibitor. The effects of 5% CO2 inhalation and hyperventilation were measured before and after the inhibition of DBH. Following the intracarotid infusion of fusaric acid, cerebrocortical PO2 and cerebrocortical blood flow increased significantly. After the inhibition of DBH, the degree of the increase in cerebrocortical PO2 during 5% CO2 inhalation was enhanced while the degree of the decrease in cerebrocortical PO2 during hyperventilation did not show any significant change. The cerebral vasodilatation caused by fusaric acid suggests that the sympathetic nervous system takes part in the resting tone of cerebral blood vessels. The increase in the cerebrovascular CO2 reactivity produced by the inhibition of DBH suggests that the sympathetic nervous system modifies cerebrovascular CO2 reactivity.

Animals↗
PubMedDate not supplied

Controlled release from a large capsule membrane corked with phosphatidylethanolamine bilayers: effect of temperature, pH and concentration of Ca2+ ions.

Permeations of a fluorescent probe entrapped in the inner aqueous phase of a large nylon capsule membrane corked with phosphatidylethanolamine bilayers were reversibly controlled by (i) the phase transition of bilayers, (ii) the ambient pH change, and (iii) the addition of Ca2+/EDTA from outside. Their signal-receptive permeation control could be reproduced repeatedly without damaging corking bilayers, in contrast to that of liposomal membranes.

Calcium↗
PubMedDate not supplied

Change of temperature in mouse tumour tissue immersed in a water bath at 44 degrees C.

We investigated the change in temperature in tumour and normal tissues of mice when immersed in a water bath at 44.0 degrees C as part of a series of studies of hyperthermia. The right hind legs of the mice bearing the experimental tumour sarcoma 180 were immersed in the water bath, and measurements were performed using the multi-thermocouple thermosensor from a radiofrequency (RF) generator every 24 sec with a precision of 0.1 degrees C. The temperature in all tumour tissues exceeded 43.0 degrees C only at 1 min 24 sec after immersion of the limbs. The rise in temperature then reached a plateau phase, and was maintained around 44.0 degrees C. However, we found that the temperature of the normal tissue was about 0.6 degrees C lower than that of the tumour tissue or the tissue around the tumour at the plateau phase.

Animals↗
PubMedDate not supplied

Usefulness of Lens culinaris agglutinin A-reactive fraction of alpha-fetoprotein (AFP-L3) as a marker of distant metastasis from hepatocellular carcinoma.

The objective of this study was to clarify the relationship between the serum level of the Lens culinaris agglutinin A-reactive fraction of alpha-fetoprotein (AFP-L3) and the clinical features including sex, age, Child's classification, virus markers, tumour size, tumour stage, distant metastasis, histopathologic findings, portal thrombus and outcome of hepatocellular carcinoma (HCC). We measured the AFP-L3 levels in 170 HCC cases at the time of diagnosis using lectin-affinity electrophoresis followed by antibody-affinity blotting. The patients were divided into two groups, those who were AFP-L3 positive (n=56; AFP-L3 >/=15% relative to the total alpha-fetoprotein (AFP) concentration) and those who were AFP-L3 negative (n=114; AFP-L3 <15%). Then we examined the association between the serum AFP-L3 level and the clinical features of HCC. No significant differences were found in age, sex, and virus markers between the AFP-L3-positive and -negative groups. However, patients in the positive group had worse liver function and larger tumours compared to the negative group. They also had more advanced cancer with poor tumour histology compared to the negative group. Distant metastasis was diagnosed significantly more often in the positive group than that in the negative group. There was no significant correlation between the AFP-L3 level and portal thrombus. Although the follow-up period was brief the prognosis for the positive group clearly was poor. These results suggest that AFP-L3 is a useful indicator of distant metastasis and a poor prognosis for HCC.

Adult↗
PubMedDate not supplied

Percutaneous injection of a low-concentration alkaline solution targeting hepatocellular carcinoma.

We developed a percutaneous low-concentration alkali injection therapy (PLAIT) targeting hepatocellular carcinoma (HCC), and compared the necrotic areas in the livers of rats that had received PLAIT [an alkaline solution of sodium hydroxide (NaOH)] with those that had received percutaneous ethanol injection therapy (PEIT) and percutaneous acetic acid injection therapy (PAIT). The necrotic area increased with increasing concentrations of NaOH solution. The survival rate of rats was 100% up to a concentration of 4 N; however, the rate dropped below 80% with concentrations over 5 N. Also, at a concentration of 2 N, the necrotic area increased with increasing quantities from 0.01 ml to 0.1 ml. PLAIT using 0.05 ml of 2 N NaOH was 1.56 times more effective than PEIT using 0.05 ml of 99.5% ethanol, and 63.33% less effective than PAIT using 0.05 ml of 50% acetic acid. However, the survival rate after PAIT was 50%, while that after PLAIT was 100%. Histopathological observation of normal rat livers after injection of 2 N NaOH at a volume of 0.05 ml showed that the tissue necrosis spread radially from the site immediately after injection by PLAIT, but necroses were not found in other organs. We conclude that PLAIT has promise as a new form of local therapy for HCC.

Animals↗
PubMedDate not supplied

Mechanism of growth-inhibitory effect of cisplatin on human pancreatic cancer cells and status of p53 gene.

Pancreatic cancer is a devastating malignant tumor in humans and the development of new modalities of treatment is needed. We studied the mechanism of the growth-inhibitory effect of cisplatin (CDDP) on human pancreatic cancer cells in connection with the status of the p53 gene and expression of the bcl-2 family. COLO-357 cells with wild-type p53 gene and T3M4, Panc-1 and AsPC-1 cells with mutant-p53 gene were used. Growth of these cells was inhibited by CDDP in a dose-dependent manner in both serum-deprived and serum-supplemented conditions. CDDP induced apoptosis of COLO-357 and T3M4 cells in the serum-supplemented condition, whereas necrosis of these cells was induced by CDDP at high concentrations in the serum-deprived condition. Although expression of bax mRNA and its protein product were enhanced, while bcl-2 protein was decreased by CDDP in COLO-357 cells, expression of mRNA of the bcl-2 family and protein product were not influenced by CDDP in T3M4 cells. Increased expression of bax and reduced expression of bcl-2 are involved in the growth-inhibitory effect of CDDP on pancreatic cancer cells with wild-type p53 gene.

Antineoplastic Agents↗
PubMedDate not supplied

MR imaging of the breast with Gd-DTPA enhancement: comparison with mammography and ultrasonography.

The accuracy of MR imaging with Gd-DTPA enhancement was compared with mammography and ultrasonography in 52 patients with clinically palpable benign and malignant breast masses (36 carcinomas, 2 malignant phyllodes tumors, 7 fibroadenomas, 7 cysts). On dynamic MR imaging, carcinomas and fibroadenomas were discriminated by their different dynamic enhancement profiles. In carcinomas, signal intensity increased rapidly, reaching a peak or plateau within 2 min after the injection of contrast medium. In fibroadenomas, signal intensity showed a much slower continuous increase without ceasing until about 8 min after injection. Malignant phyllodes tumors showed a dynamic enhancement profile identical to that of benign fibroadenomas. MR imaging correctly identified 84% of malignant tumors, 86% of fibroadenomas, and 100% of cysts, and was substantially more accurate in tissue characterization than mammography. The results of ultrasonography were highly similar to those of MR imaging. However, no single modality was infallible, and the three modalities were complementary rather than competitive. Considering the high cost and long examination time of MR imaging, mammography supplemented by ultrasonography seems to be the method of choice in the diagnosis of breast lesions. Nevertheless, MR imaging can add important information when the results of mammography and ultrasonography are insufficient or contradictory.

Adenofibroma↗
PubMedDate not supplied

Preoperative diagnosis of the follicular variant of papillary carcinoma of the thyroid: discrepancy between image and cytologic diagnoses.

Preoperative diagnosis of the follicular variant of thyroid papillary carcinoma has not been examined sufficiently. The preoperative diagnosis of six patients with the follicular variant was investigated retrospectively as compared with 46 cases of the common type of papillary carcinoma (papillary structure dominant type), four of follicular carcinoma, 27 of follicular adenoma, and 42 of adenomatous goiter. Cervical soft radiography of the disease exhibited calcification in three of six cases (50%), all of which showed coarse calcification not accompanied by minute type. 201Tl scintigraphy of the disease revealed that four of six cases (66.7%) showed abnormal accumulation in the delayed phase. Four cases had favorable washout and one (16.7%) unfavorable washout. On ultrasonography, one of six cases (16.7%) was diagnosed as papillary carcinoma, four as follicular adenoma, and one as adenomatous goiter. In fine-needle aspiration cytology, two of five cases were diagnosed as papillary carcinoma of class V, two as papillary carcinoma of class IV, and one as follicular tumor suspected of class IIIa. On the other hand, true positive diagnostic rates of the histological types of tumors other than follicular carcinoma by ultrasonography or fine-needle aspiration cytology were approximately 80% and relatively satisfactory. Fine-needle aspiration cytology was the most useful method of diagnosing the follicular variant of papillary carcinoma. It seems necessary to consider the possibility of the follicular variant in diagnosis when papillary carcinoma is suspected from fine-needle aspiration cytology by preoperative diagnosis, while imaging suggests follicular tumor.

Adenocarcinoma, Follicular↗
PubMedDate not supplied

Fast MR imaging of abdomen: application of the QD body coil and low refocusing flip angle.

The fast spin-echo (FSE) method as applied to abdominal imaging has undergone considerable technical and clinical study over the past several years. However, except in a limited number of institutions, this time-saving sequence has not replaced the conventional spin-echo (CSE) method. In particular, FSE is less frequently employed for examination of the liver because FSE and CSE images of hepatic tumors and normal hepatic tissues differ significantly in terms of contrast. The signal reduction effect of magnetization transfer contrast (MTC) is affected by the number of slice sections and by the specific absorption rate (SAR). We have employed a newly developed quadrature detection (QD) body coil to enhance the signal-to-noise ratio (S/N) and a low refocusing flip angle to suppress SAR and MTC effects. We have also evaluated the effectiveness of this new method by carrying out visual assessment of clinical images and quantitative measurements of signal intensity in these images. Several problems must be overcome before the FSE method is able to replace the CSE method in the clinical examination of the abdomen. The selection of sequences with a low refocusing flip angle combined with the use of the QD body coil promises to be one possible solution to these problems.

Abdomen↗
PubMedDate not supplied

A simple method for evaluating masticatory performance using a color-changeable chewing gum.

PURPOSE: This study investigated the usefulness of a newly developed color-changeable chewing gum for evaluating masticatory performance. MATERIALS AND METHODS: The color changes of the gum after chewing were measured using the L*a*b* color space defined by the Commission Internationale de l'Eclairage with a spectrophotometer. Numerical scores and a color scale were developed to easily evaluate color change. Numerical scores were assigned corresponding to the degree of color change, and a color scale was made by using the numerical scores. Four examiners graded the gum chewed by 18 fully dentate subjects by using the color scale. RESULTS: As the number of chews increased, the degree of color change increased significantly. The percentages of correct answers by examiners using the color scale method ranged from 67% to 83%. CONCLUSION: The results indicate that this simple method may be used to quantitatively evaluate masticatory performance and may be reliable enough to be used clinically.

Adult↗