Biomedical subjects

K Sakata

Publications and source records attributed to K Sakata.

570 records · Page 32Linked to original sources

PubMedDate not supplied

Dosimetry of radiation scattered to thyroid gland from prophylactic cranial irradiation for childhood leukemia.

Dosimetry of radiation scattered to the thyroid gland was performed in 17 children (9 boys, 8 girls) who were treated for acute lymphoblastic leukemia and received cranial irradiation for prophylaxis against central nervous system leukemia at a median age of 4 years and 2 months (range, 1 year and 1 month to 14 years). The absorbed dose to the thyroid gland in these children ranged from 0.7% to 7.3% of the dose delivered to the cranium. Thus the total dose to the thyroid gland ranged from 0.13 to 1.32 Gy by the end of the entire course of cranial irradiation. Doses tended to be larger in younger children, but the radiation source also had a large influence on the dose to the thyroid gland; that is, the absorbed dose to the thyroid gland with delivery by linear accelerator was smaller than that by cobalt irradiation. Long-term survivors treated with cranial irradiation for acute leukemia during childhood should be followed for the possible development of thyroid diseases, including malignant tumors, for a long period.

Adolescent↗

PubMedDate not supplied

Telomerase activity in gliomas with the use of non-radioisotopic and semi-quantitative procedure for terminal repeat amplification protocol.

To study the role of telomerase in the pathogenesis of different grades and subtype of gliomas, telomerase activity in 31 gliomas was assessed with the use of non-radioisotopic and semi-quantitative procedures for the terminal repeat amplification protocol in this study. Among the samples were 17 glioblastoma multiformes (GBMs); 4 anaplastic astrocytomas (AAs); 5 astrocytomas (ASs); 1 ependymoblastoma (EPB); 2 ependymomas (EPs); 1 oligodendroglioma (OG) and 1 medulloblastoma (MB). Postive telomerase activity was detected in 9 of 17 GBMs (53%), 1 of 4 AAs (25%), 1 of 5 ASs (20%), 1 of 1 EPB (100%), and in positive controls, T 98G and KE-1. Weakly positive activity was detected in 2 of 3 AAs (66%) and 2 of 5 ASs (40%). No telomerase activity was detected in 8 of 17 GBMs (47%), 1 of 4 AAs (25%), 2 of 5 AS (40%), 2 of 2 (100%) EPs, 1 of 1 OG (100%), 1 of 1 MB (100%) and normal brain tissue. We defined telomerase expression as positive and weakly positive cases. The percentage of telomerase activity expression in gliomas tended to correlate with tumour grade in spite of histopathology of tumours. These results indicated that the telomerase activity of gliomas may be used as a tumour marker and that the activation of telomerase should correlate with initiation and malignant progression of gliomas. In addition, non-radioisotopic and semi-quantitative procedure for the terminal repeat amplification protocol appears to be the most suitable to detect telomerase activity expression in small neurosurgical specimens.

Adult↗

PubMedDate not supplied

Clinical studies of immunohistochemical staining of DNA-dependent protein kinase in oropharyngeal and hypopharyngeal carcinomas.

PURPOSE: DNA-dependent protein kinase (DNA-PK), a serine/threonine kinase composed of p470 catalytic subunit (DNA-PKcs) and p85/p70 heterodimer (Ku antigen), is considered a critical enzyme in the repair of the DNA double-strand breaks (DSB) that are the major lethal lesions induced by ionizing radiation. We investigated the expression of DNA-PK subunits in human tumors. MATERIALS AND METHODS: We examined immunohistochemically the biopsy specimens of 44 patients with oropharyngeal carcinoma and 32 patients with hypopharyngeal carcinoma who had been treated with radiotherapy. RESULTS: Immunopositivity to Ku85 and DNA-PKcs was found in all patients. The staining of Ku85 and DNA-PKcs was nuclear, with none of the normal epithelial cells or malignant cells exhibiting cytoplasmic or membrane immunoreactivity. Normal epithelial cells were all stained intensely. In tumors, intense nuclear staining of DNA-PKcs was seen in 75 of 76 tumors, while that of Ku85 was seen in all 76 patients. The radiation responses of a primary tumor that was stained weakly with DNA-PKcs were excellent. CONCLUSION: Our results suggest the possibility of predicting the intrinsic radiosensitivity of human tumors in clinics able to perform immunohistochemical analysis of DNA-PK.

Aged↗

PubMedDate not supplied

Radiation therapy of intracranial germ cell tumors with radiosensitivity assessment.

Fifty patients with pineal and/or suprasellar tumors were treated in the Department of Radiology, University of Tokyo, from 1975 to 1988. Histological diagnosis was obtained in 28 cases, whereas 22 patients were irradiated without pathological verification. Of the 28 patients with histological diagnosis, 11 had germinomas, 13 non-germinoma germ cell tumors, including nine teratomas, two choriocarcinomas and two embryonal carcinomas, two pineocytomas and two pineoblastomas. The treatment protocol since 1981 has been that, after 20 Gy is given with a local irradiation field, if tumor regression is marked and germinoma is highly suspected, whole brain or whole CNS irradiation is performed subsequently; otherwise, surgical intervention is performed followed by systemic chemotherapy plus radiation therapy. The five-year survival rates of histologically proven germinomas, histologically proven non-germinoma germ cell tumors, and clinically suspected germinomas by means of the above-mentioned method as well as tumor marker status were 73%, 28%, and 83%, respectively. The overall five-year survival rate was 61.3%. A statistically significant difference was found between the survival rates for the 11 cases with histologically proven germinoma and the 13 cases with non-germinoma germ cell tumors, although there was no significant difference between the survival rates for the histologically proven germinomas and the clinically suspected germinomas. Therefore radiation therapy is an effective treatment method for the management of intracranial germ cell tumors.

Adolescent↗

PubMedDate not supplied

Radiation therapy of carcinoma of the oropharynx.

Forty consecutive cases of carcinoma of the oropharynx were treated by irradiation from 1973 through 1987. The overall five-year survival rate calculated by the Kaplan-Meier method was 21%. Data were also analyzed retrospectively to investigate the factors associated with prognosis. The following results were obtained. (1) The results of re-irradiation as salvage treatment were poor. (2) Irradiation to neck lymph node metastases was not particularly effective, especially under 50 Gy. (3) Stage T2(-4) primary tumors were difficult to control with irradiation of 50 Gy.

Adult↗

PubMedDate not supplied

Radiation therapy for primary non-Hodgkin's lymphoma of the head and neck in stages I and II.

From January 1975 through December 1986, 58 previously untreated patients with primary non-Hodgkin's lymphoma of the head and neck in stages I and II were treated at our department. Thirty-seven patients were classified as stage I and 21 as stage II. Complete local remission was obtained in all cases. The 5-year survival rates were 68% and 79% in stages I and II, respectively. The 5-year survival rates according to site of origin were as follows: Waldeyer's ring 77% and neck lymph node 63%. The 5-year survival rates according to the histological classification of the Working Formulation were 73% intermediate grade malignancy and 63% for high grade malignancy. Chemotherapy combined with radiotherapy was essential, especially for cases in stage II. The 5-year survival rate was 100% for patients with chemotherapy and 71% without chemotherapy. The relapse-free 5-year survival rate was 67% with chemotherapy and 36% without chemotherapy. Most first failures were due to the development of generalized disease and the 5-year survival rate after salvage was 44%.

Adolescent↗

PubMedDate not supplied

Carcinoma of the maxillary sinus: the role of radiotherapy.

From 1975 to 1986, 75 M0 patients with squamous cell carcinoma of the maxillary sinus were treated at the Department of Radiology, Tokyo University Hospital. The overall 5-year survival rate calculated with the Kaplan-Meier method was 24%. During the period of the study, the method of treatment used in our hospital changed. From 1975 to 1979 (the first period), the treatment of choice was low-dose irradiation and frequent necrotomy. From 1980 to 1982 (the second period), more extensive surgery was performed and 50 to 60 Gy of irradiation was given. The 5-year survival in the first period was 20%, that in the second 14%. From 1983 to 1986 (the third period), trimodal therapy (surgery + radiation + intra-arterial infusion) was introduced and 5-year survival was improved to 50%. Intra-arterial cisplatinum infusion and treatment planning using CT scans were especially useful in improving survival.

Adult↗

PubMedDate not supplied

An integrated radiotherapy treatment system and its clinical application.

A new total system for radiation therapy installed in our department consists of a linear accelerator unit with microcomputer-controlled multileaf collimators, along with a CT scanner installed in the same treatment room. Also included are a digitally controlled communal couch, a minicomputer, and a system of treatment planning devices. We have developed various kinds of external radiation treatment planning techniques (including dynamic ones) with this system on the basis of the concept of dose corresponding technique. A reference point setup method is needed to maintain a unified coordinate system through each step of the treatment procedure, and, as developed by us, permits a volume-oriented setup. This system has been evaluated for accuracy in a variety of clinical setups. A true three-dimensional dose calculation algorithm is required for treatment planning associated with multileaf collimator treatments in order to realize the potential accuracy of such a system.

Computer Simulation↗

PubMedDate not supplied

Evaluation of treatments for liver abscess: significance of intra-arterial antibiotic injection therapy.

Various treatments were performed in 14 patients with liver abscess, and their clinical effects were compared. The treatments were intra-arterial antibiotic infusion therapy (Group A, 4 patients), intra-arterial infusion therapy plus percutaneous drainage of the abscess (Group B, 4 patients), and intravenous antibiotics alone (Group C, 6 patients). The period from the beginning of treatment to negative conversion of CRP* (period until cure) was compared among the groups. Groups A and B had received intravenous antibiotics for a mean of 10 days and 16 days, respectively, but the treatment was ineffective. The mean period until cure from the beginning of intra-arterial infusion therapy was 36 days for Group A and 18 days for Group B. In Group C, the mean period until cure was 28 days. All patients recovered, and recurrence was observed in only one patient. Although liver abscess can be treated successfully in many patients by intravenous antibiotics alone, intra-arterial therapy is effective in those in whom intravenous therapy is not effective.

Adult↗

PubMedDate not supplied

A long-term investigation of transcatheter splenic arterial embolization for hypersplenism.

BACKGROUND/AIMS: This study investigated longterm changes in the parameters of blood and liver function tests following TSAE. PATIENTS AND MATERIALS: Twenty-five patients received transcatheter splenic arterial embolization (TSAE) as a treatment for hypersplenism, and their post- TSAE conditions were monitored for over a year. We evaluated changes in blood and liver function tests, and examined changes of platelet associated immunoglobulin G (PA-IgG), liver and spleen volumes and hemodynamics in order to consider the mechanism of liver function improvement following TSAE. RESULTS: In blood tests, platelet and WBC counts significantly increased one year after TSAE and this increased level continued up to the fifth year. In liver function tests, levels of serum total protein, albumin, total cholesterol, and results of the hepaplastin test significantly improved after the one year, and these levels remained even over one year. CONCLUSIONS: Results of this study indicated involvements of decreased platelet pool in the spleen and probable immunological mechanisms in association with PA-IgG in platelet count increase. Indocyanine green clearance (15') were improved in 5 of 8 patients (62.5%) after TSAE. These points may indicate an involvement of hemodynamic changes in the improvement of liver function parameters.

Blood Proteins↗

PubMedDate not supplied

Radiation therapy for patients with xeroderma pigmentosum.

Our experience reported here, as well as a review of the literature, suggests that radiation therapy can be used in the palliative treatment of XP-related malignancy. However, radiation therapy should be used with caution in XP patients with an anticipated prolonged life expectancy, because the late side effects of ionizing radiation in XP are not well known.

Adult↗

PubMedDate not supplied

Analysis of treatment results of hypopharyngeal cancer.

Sixty-three patients with squamous cell carcinoma of the hypopharynx were treated at the University of Tokyo between 1985 and 1993. Twelve patients were treated with surgery alone, 16 with preoperative irradiation, 26 with postoperative irradiation, and nine with irradiation alone. A tumor dose of 50 Gy (25 fractions/5 weeks) was used in postoperative irradiation, 40-60 Gy in preoperative irradiation, and 70 Gy in irradiation alone. When "number of indications," including, for example, partial pharyngectomy, positive or close (< or = 5 mm) margin, and extracapsular extension, was used for multivariate analysis in patients who underwent surgery, it proved to be the only significant prognostic factor for gross survival. Six of seven patients with a positive surgical margin or close margin who received postoperative irradiation had local recurrence. A tumor dose of 50 Gy (25 fractions/5 weeks) in postoperative irradiation is not enough. It is difficult to cure by irradiation metastases to the parapharyngeal lymph nodes large enough to be detected with CT. It is necessary to irradiate parapharyngeal lymph nodes prophylactically, but 50 Gy in postoperative irradiation may not be enough from our results. The same may be true for metastases to the paratracheal nodes, which lie close to the lower poles of the thyroid gland or within the superior mediastinum and are difficult to access through surgery. In the patients who were operated on, N stage and the number of lymph node metastases were significant for gross survival. When "number of indications" was used for analysis, "number of indications" proved to be the most significant prognostic factor for gross survival.

Carcinoma, Squamous Cell↗