Biomedical subjects

K Miyasaka

Publications and source records attributed to K Miyasaka.

At least 55 records · Page 3Linked to original sources

PubMed2000

Effects of systemic injection of interleukin-1beta on gastric vagal afferent activity in rats lacking type A cholecystokinin receptors.

We have shown that systemic administration of interleukin-1beta (IL-1beta) excites gastric vagal afferent activity in part via stimulation of type A cholecystokinin (CCK-A) receptors in rats. The present study was undertaken to determine whether the response of the gastric vagal afferent nerve to systemic IL-1beta is altered in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, which lack CCK-A receptors. The response was compared with that of the control strain, Long-Evans Tokushima Otsuka (LETO) rats. All animals were anesthetized with pentobarbital and artificially ventilated. Intravenous administration of 4 microg/kg of IL-1beta increased gastric vagal afferent activity in both LETO and OLETF rats, whereas a smaller dose of 2 microg/kg of IL-1beta increased activity only in the OLETF rats. The present results demonstrate that the response of the gastric vagal afferent activity in CCK-A receptor deficient OLETF rats was more sensitive to intravenous administration of IL-1beta than was in control LETO rats.

Animals↗

PubMed2000

Respiratory failure in postpneumonectomy syndrome complicated by thoracic lordoscoliosis: treatment with prosthetic implants, partial vertebrectomies, and spinal fusion.

STUDY DESIGN: This study investigated the case of a 17-year-old girl with postpneumonectomy syndrome, complicated by a thoracic lordoscoliosis, who was successfully treated with prosthetic implants, partial vertebrectomies, and anteroposterior spinal fusion. OBJECTIVE: To report a unique case and describe the authors' method of treatment. SUMMARY OF BACKGROUND DATA: Postpneumonectomy syndrome is an uncommon complication of pneumonectomy. Many case reports describe successful treatment with insertion of prosthetic implants into the empty hemithorax to shift the mediastinum to its original position. Thoracic lordoscoliosis reportedly has contributed to pulmonary compromise, but no cases have shown its occurrence in the setting of postpneumonectomy syndrome. METHODS: The patient was observed at the National Children's Hospital in Tokyo, referred to Children's Hospital in Los Angeles, California for surgical correction, and followed in Tokyo for the next year. RESULTS: Two prosthetic implants with an injection port for further expansion were positioned in the right hemithorax to restore the mediastinum to its normal position. Anterior discectomies, partial vertebrectomies, and fusion of T5-T10 was performed concurrently. Then 5 days later, posterior spinal fusion of T1-T12 with instrumentation and bone graft were performed to correct the thoracic lordoscoliosis and increase the chest cavity space. At 1 month after the surgery, the patient was extubated after being ventilator dependent for 5 months. At the time of operation, the girl was ventilator dependent and nonambulatory, but 1 year later could participate in all activities of daily living without any oxygen supplementation. CONCLUSIONS: Postpneumonectomy syndrome can be treated successfully with prosthetic implants to restore the normal position of the mediastinum. Thoracic lordoscoliosis can complicate the syndrome and may be corrected to help restore normal pulmonary function.

Adolescent↗

PubMed2000

High-speed magnetic resonance imaging for four-dimensional treatment planning of conformal radiotherapy of moving body tumors.

PURPOSE: High-speed magnetic resonance imaging (MRI) was applied to the determination of the planning target volume (PTV) of moving hepatobiliary tumors. METHODS AND MATERIALS: Three moving tumors, including two metastatic hepatic tumors and one bile duct tumor, were examined using high-speed MRI and reference fiducial markers before external radiotherapy. Patients were examined for 30 seconds under conditions of normal breathing during the examination. The coordinates of the center of the tumor contours were shown on sagittal and coronal images displayed on the monitor. RESULTS: The maximum length of movement was 10.6 +/- 7.0 mm in a craniocaudal direction; 5.2 +/- 1.8 mm in a lateral direction; and 4.6 +/- 1.6 mm in a ventrodorsal direction. When the PTV was determined using MRI at exhalation phase with a 10-mm safety margin, clinical target volume (CTV) was not covered in 19% of all images in the 3 patients. With MRI at inhalation phase with a 10-mm safety margin, CTV was not covered in 36% of all images. CONCLUSION: Four-dimensional treatment planning using high speed MRI, and integrating time and spatial information, has the potential to determine the planning target volume of moving body tumors more precisely than does conventional CT planning.

Bile Duct Neoplasms↗

PubMed2000

Four-dimensional treatment planning and fluoroscopic real-time tumor tracking radiotherapy for moving tumor.

PURPOSE: To achieve precise three-dimensional (3D) conformal radiotherapy for mobile tumors, a new radiotherapy system and its treatment planning system were developed and used for clinical practice. METHODS AND MATERIALS: We developed a linear accelerator synchronized with a fluoroscopic real-time tumor tracking system by which 3D coordinates of a 2.0-mm gold marker in the tumor can be determined every 0.03 second. The 3D relationships between the marker and the tumor at different respiratory phases are evaluated using CT image at each respiratory phase, whereby the optimum phase can be selected to synchronize with irradiation (4D treatment planning). The linac is triggered to irradiate the tumor only when the marker is located within the region of the planned coordinates relative to the isocenter. RESULTS: The coordinates of the marker were detected with an accuracy of +/- 1 mm during radiotherapy in the phantom experiment. The time delay between recognition of the marker position and the start or stop of megavoltage X-ray irradiation was 0.03 second. Fourteen patients with various tumors were treated by conformal radiotherapy with a "tight" planning target volume (PTV) margin. They were surviving without relapse or complications with a median follow-up of 6 months. CONCLUSION: Fluoroscopic real-time tumor tracking radiotherapy following 4D treatment planning was developed and shown to be feasible to improve the accuracy of the radiotherapy for mobile tumors.

Computer Systems↗

PubMed2000

Skull-base invasion of nasopharyngeal carcinoma: magnetic resonance imaging findings and therapeutic implications.

PURPOSE: To evaluate the value of skull-base abnormality on MRI for predicting local recurrence in nasopharyngeal carcinoma. MATERIALS AND METHODS: Between November 1988 and February 1997, 48 patients with NPC were examined with both MRI (1.5 T) and CT prior to radiation therapy. T classification (1987 UICC) based on physical examination and CT findings were T1 in 3 cases, T2 in 22, T3 in 9, and T4 in 14. On MRI, low-intensity tissue with Gd enhancement in the marrow of the skull was considered to be a suspicious finding of skull-base invasion. CT simulation was performed in all patients. The total dose to the primary tumor was 60-75 Gy (mean, 67 Gy). The mean follow-up period was 42 months. RESULTS: All 14 T4 patients had abnormal tissue in the marrow of the skull base on MRI. Thirty-eight percent (13 of 34) of T1-3 patients were suspected to have skull-base invasion based on MRI (0% for T1, 27% [6 of 22] for T2, and 78% [7 of 9] for T3). The 5-year local control rate was significantly different between T1-3 and T4 tumors (97% vs. 69%, p < 0.025) but was not different by the presence of the MRI abnormality in the skull base. CONCLUSION: Skull-base invasion suspected solely by MRI does not relate to local recurrence provided that careful treatment planning is performed with the aid of MRI and CT simulator.

Bone Marrow Examination↗

PubMed2000

Impact of respiratory movement on the computed tomographic images of small lung tumors in three-dimensional (3D) radiotherapy.

PURPOSE: Three-dimensional (3D) treatment planning has often been performed while patients breathe freely, under the assumption that the computed tomography (CT) images represent the average position of the tumor. We investigated the impact of respiratory movement on the free-breathing CT images of small lung tumors using sequential CT scanning at the same table position. METHODS: Using a preparatory free-breathing CT scan, the patient's couch was fixed at the position where each tumor showed its maximum diameter on image. For 16 tumors, over 20 sequential CT images were taken every 2 s, with a 1-s acquisition time occurring during free breathing. For each tumor, the distance between the surface of the CT table and the posterior border of the tumor was measured to determine whether the edge of the tumor was sufficiently included in the planning target volume (PTV) during normal breathing. RESULTS: In the sequential CT scanning, the tumor itself was not visible in the examination slice in 21% (75/357) of cases. There were statistically significant differences between lower lobe tumors (39.4%, 71/180) and upper lobe tumors (0%, 0/89) (p < 0.01) and between lower lobe tumors and middle lobe tumor (8.9%, 4/45) (p < 0.01) in the incidence of the disappearance of the tumor from the image. The mean difference between the maximum and minimum distances between the surface of the CT table and the posterior border of the tumor was 6.4 mm (range 2.1-24.4). CONCLUSION: Three-dimensional treatment planning for lung carcinoma would significantly underdose many lesions, especially those in the lower lobe. The excess "safety margin" might call into question any additional benefit of 3D treatment. More work is required to determine how to control respiratory movement.

Adolescent↗

PubMed2000

Radiographic analysis of lumbar motion in relation to lumbosacral stability. Investigation of moderate and maximum motion.

STUDY DESIGN: This in vivo study was performed to examine active lumbar motion without any support. OBJECTIVES: To establish the behavior of segmental flexibility according to the degree of whole lumbar motion and to clarify the correlation between bony characteristics of the lumbosacral junction and stability in the segment. SUMMARY OF BACKGROUND DATA: In previous studies, the full mobility of the lumbar segments has been investigated. The details of motion commonly seen with the activities of daily living have not been clarified. It has been reported that the iliolumbar ligaments have an influence on lumbosacral stability and that the relative thickness of the transverse process of L5 could indicate the functional strength of the iliolumbar ligaments. However, the effects of the iliolumbar ligaments on the lumbosacral range of motion have not been studied in vivo. METHODS: Ninety adults, aged 20-39 years, were requested to perform motion commonly associated with activities of daily living, defined as moderate motions of the lumbar spine. The subjects then were asked to perform maximal motion of the lumbar spine. The segmental ranges of motion, segmental flexion, and extension at every level of the lumbar spine were calculated by using functional radiographs. The correlation between the relative thickness of the transverse process of L5 and the motion seen at the lumbosacral junction was also determined. RESULTS: The greatest segmental range of motion was found at L2-L3 in moderate motion and at L4-L5 in maximal motion. It shifted gradually from the upper to lower lumbar levels with the increase in total lumbar motion. With an increase in lumbar spine motion, maximum segmental flexion shifted from L2-L3 to L3-L4, then to L4-L5. Segmental extension changed only at L5-S1, increasing with total lumbar spine motion. There was an inverse statistical correlation between lumbosacral motion and relative thickness of the L5 transverse process. CONCLUSIONS: The greatest segmental flexibility induced by the moderate lumbar motion, usually seen with the activities of daily living, occurred more in the upper segments of the lumbar spine, especially in flexion. Further, the iliolumbar ligaments regulate lumbosacral motion especially flexion.

Activities of Daily Living↗

PubMed2000

Lymphatic lipid transport is not impaired in ageing rat intestine.

Lymphatic lipid transport in the intestine of adult and ageing rats was compared. Adult (8-10 months old) and old (24-26 months old) male Wistar rats were cannulated into the mesenteric lymph under ethrane anesthesia. On the following day, lipid emulsion containing 35.4 mg/h of olive oil was infused intraduodenally for 7 h and lymph collected hourly was assayed for triglyceride and apolipoprotein A-IV (apo A-IV). The results showed there was no difference in lymphatic lipid and apo A-IV transport between adult and old rats. Since apo A-IV synthesis in the enterocytes is linked to the intracellular assembly of lipoprotein, it is likely that in addition to lymphatic transport, production of chylomicrons is not impaired in ageing rats.

Aging↗

PubMed2000

Gene structure of human cholecystokinin (CCK) type-A receptor: body fat content is related to CCK type-A receptor gene promoter polymorphism.

The transcriptional start site of the human cholecystokinin (CCK)-A receptor gene was determined by the Capsite Hunting method. Two sequence changes were detected, a G to T change in nucleotide -128, and an A to G change in nucleotide -81. The homozygote (T/T, G/G) was detected in 25 of 1296 individuals (1.9%) in the cohort study. This polymorphism showed a significantly higher percent body fat and higher levels of serum insulin and leptin, compared with wild type and heterozygotes. Our study provided the possibility that polymorphism in the promoter region of the CCK-A receptor gene may be one of genetic factors affecting fat deposition.

Adipose Tissue↗

PubMed2000

Color Doppler sonographic findings in splenic hamartoma.

We present the gray-scale and color Doppler sonographic findings in a case of a splenic hamartoma in a 40-year-old man. Gray-scale sonograms showed a 2 x 2 cm, hypoechoic splenic mass that was homogeneous without evidence of cystic change or calcification. Color Doppler sonograms showed multiple radial blood-flow signals inside the mass, and spectral analysis confirmed arterial and venous flow. Arteriograms showed multiple small, hypervascular masses with fine tumor vessels and tumor stains within the spleen. Histologic analysis following a splenectomy showed dilated vessels and congestion consistent with the color Doppler sonographic findings.

Adult↗

PubMed2000

Elucidation of accuracy in calibration of MR signal intensity based on transmission amplitude method.

To calibrate magnetic resonance (MR) signal intensity that depends on radio frequency (RF) coil loading, the transmission amplitude (TRA) for the excitation in the transmit-receive RF coil has been used as a good index in the so-called TRA method. As this TRA method needs neither an internal reference nor an additional external reference for the calibration, its accuracy is free from reference measurements. This study elucidated the calibration accuracy of MR signal intensities based on the TRA method. A cylindrical gel phantom was used for accuracy measurements with a 1.5-T MRI unit with conventional T1 imaging as a simple pulse sequence for various loading conditions. The brain parenchyma of eight healthy volunteers also showed calibrated MR signal deviations. The error of the phantom calibration measurements was 2.18% (S.D.%). The background noise intensity of images was theoretically derived to correlate with the impedance mismatching of the RF coil, which is inevitable for fixed tuning, even for automatic tuning that is not always exact. Taking into account this noise intensity, the calibration method was modified to reduce its error to 1.50%. The standard deviations of the calibrated values in the thalamus and frontal white matter were 2.9 and 3.8%, respectively. We suggest that the modified TRA method is a practical and reliable technique to obtain clinical numeric evidence.

Brain↗

PubMed2000

Wavelet compression on detection of brain lesions with magnetic resonance imaging.

The purpose of this report is to assess clinically acceptable compression ratios on the detection of brain lesions at magnetic resonance imaging (MRI). Four consecutive T2-weighted and the corresponding T1-weighted images obtained in 20 patients were studied for 109 anatomic sites including 50 with lesions and 59 without lesions. The images were obtained on a 1.5-T MR unit with a pixel size of 0.9 to 1.2 x 0.47 mm and a section thickness of 5 mm. The image data were compressed by wavelet-based algorithm at ratios of 20:1, 40:1, and 60:1. Three radiologists reviewed these images on an interactive workstation and rated the presence or absence of a lesion with a 50 point scale for each anatomic site. The authors also evaluated the influence of pixel size on the quality of image compression. At receiver operating characteristic (ROC) analysis, no statistically significant difference was detected at a compression ratio of 20:1. A significant difference was observed with 40:1 compressed images for one reader (P = .023), and with 60:1 for all readers (P = .001 to .012). A root mean squared error (RMSE) was higher in 0.94- x 0.94-mm pixel size images than in 0.94- x 0.47-mm pixel size images at any compression ratio, indicating compression tolerance is lower for the larger pixel size images. The RMSE, subjective image quality, and error images of 10:1 compressed 0.94- x 0.94-mm pixel size images were comparable with those of 20:1 compressed 0.94- x 0.47-mm pixel size images. Wavelet compression can be acceptable clinically at ratios as high as 20:1 for brain MR images when a pixel size at image acquisition is around 1.0 x 0.5 mm, and as high as 10:1 for those with a pixel size around 1.0 x 1.0 mm.

Algorithms↗

PubMed2000

An integrated service digital network (ISDN)-based international telecommunication between Samsung Medical Center and Hokkaido University using telecommunication helped radiotherapy planning and information system (THERAPIS).

This study introduces the integrated service digital network (ISDN)-based international teleradiotherapy system (THERAPIS) in radiation oncology between hospitals in Seoul, South Korea and in Sapporo, Japan. THERAPIS has the following functions: (1) exchange of patient's image data, (2) real-time teleconference, and (3) communication of the treatment planning, dose calculation and distribution, and of portal verification images between the remote hospitals. Our preliminary results of applications on eight patients demonstrated that the international telecommunication using THERAPIS was clinically useful and satisfactory with sufficient bandwidth for the transfer of patient data for clinical use in radiation oncology.

Japan↗

PubMed2000

The role of radiotherapy in treating squamous cell carcinoma of the external auditory canal, especially in early stages of disease.

PURPOSE: Our intent was to investigate the role of radiotherapy in treating external auditory canal squamous cell carcinoma, especially in early stages of disease. MATERIALS AND METHODS: The treatment results for 20 patients treated between 1980 and 1998 were retrospectively analyzed. Radiotherapy was used as an initial treatment without surgery in eight patients and with surgery in 12 patients. The patients treated by radiotherapy alone received 65 Gy in 26 fractions over 6.5 weeks. The patients treated with radiotherapy perioperatively received 30-75 Gy in 12-30 fractions. The follow-up period for survivors including patients died of intercurrent disease ranged from 7 to 205 months (mean: 71 months). RESULTS: The 5-year survival rate calculated by the Kaplan-Meier method for all patients was 59%. According to Stell classification (Laryncol. Otol. 99 (1985) 847), the 5-year survival rates for eight patients with T1 disease and eight with T2 disease were 100 and 38%, respectively. In the eight patients with T1 disease, disease control was 100%. Local control with hearing preservation was achieved in five patients with T1 disease by radiotherapy alone. No late complications related to radiotherapy were observed. CONCLUSIONS: A precise diagnosis of the disease in terms of whether or not it has invaded the bone is important in order to predict the treatment outcome. Radiotherapy with or without surgery is the treatment of choice for patients with T1-stage disease. Surgery with radiotherapy is recommended as standard care for tumors with bony invasion.

Adult↗

PubMed2000

Ipsilateral irradiation for carcinomas of tonsillar region and soft palate based on computed tomographic simulation.

PURPOSE: To reduce xerostomia in selected patients with carcinomas of the tonsillar region and soft palate. METHODS AND MATERIALS: We evaluated the treatment results of 32 patients with tonsillar region and soft palate carcinoma treated by radical radiotherapy between May 1989 and December 1996. They have a unilateral tumor that did not cross midline and have no contralateral neck lymphnode metastasis and treated with an ipsilateral technique (an anterior oblique and a posterior oblique field). All patients were planned with computed tomographic (CT) simulation and given 65 Gy in 26 fractions in 6.5 weeks with or without 5-15 Gy boost irradiation. The median follow-up was 44 months (4-86 months). RESULTS: Five-year overall, cause-specific survival, local control, and regional control rate was 64, 79, 74 and 81%. No failure at the contralateral neck occurred. Moderate or severe symptomatic xerostomia was seen in 3 (9%) patients and ostero-radionecrosis requiring surgery occurred in one (3.3%) of 32 patients. CONCLUSION: It is suggested that the ipsilateral technique is indicated in patients who had an unilateral tonsillar region or soft palate carcinoma that did not cross midline and have no contralateral neck lymphnode metastasis.

Adult↗

PubMed2000

Induction of apoptosis in human cancer cells by TZT-1027, an antimicrotubule agent.

TZT-1027, a newly synthesized dolastatin 10 derivative, is a potent antitumor agent which inhibits microtubule polymerization and perturbs microtubule dynamics. In this report, we investigated whether TZT-1027 inhibited the growth of various human cancer cells, and the cell death caused by TZT-1027 was due to apoptosis. In addition, we elucidated the apoptosis machinery induced by treatment with TZT-1027. The 50% growth-inhibitory concentrations (IC50 values) of TZT-1027 on cancer cells derived from various sources were not more than 5.9 ng/ml. TZT-1027 showed superior cytotoxicity than any other antitumor agents. Next, we evaluated morphological nuclear change, namely, chromatin condensation and DNA fragmentation. We used three cancer cell lines derived from different types in view of having apoptosis related protein, human leukemia HL-60 (in the presence of both Caspase-3 and Bcl-2), human breast cancer MCF-7 (in the absence of Caspase-3), and human prostate cancer DU145 (in the absence of Bcl-2). TZT-1027 induced DNA fragmentation in the presence but not absence of Caspase-3. Nevertheless, apoptic chromatin condensation was observed in all cancer cells even if there was no Caspase-3. Furthermore, we examined whether TZT-1027, microtubule-disrupting agent, influenced cell cycle progression. Flow cytometric analysis revealed the cells treated with TZT-1027, and with the other antimicrotubule agents, to be arrested at the G2/M phase and subsequently to show fragmented DNA smaller than that of G1 phase cells. Moreover, we tested TZT-1027 for its ability to induce Bcl-2 phosphorylation in human cancer cell lines. TZT-1027 and other agents which interacted with microtubules induced Bcl-2 phosphorylation, whereas DNA-damaging agents did not. The present results suggested an association of the growth-inhibitory effect of TZT-1027 with the induction of apoptosis and indicated that the apoptosis induced by TZT-1027 was followed by G2/M arrest even if there was no Caspase-3 or Bcl-2.

Antineoplastic Agents↗

PubMed2000

Effect of high-frequency oscillatory ventilation on the upper airways of kittens.

BACKGROUND: High-frequency oscillatory ventilation (HFOV) has become the preferred method of ventilation for the fragile lungs of neonates and infants because its beneficial effects on lungs are well known; however, its benefits on upper airways are not yet known. We investigated the effects of HFOV and conventional mechanical ventilation (CMV) on the airways of kittens with normal lungs. METHODS: Ten healthy cross-bred kittens, 2-3-months-old, with a mean bodyweight of 0.98 kg, were randomly divided into two groups: HFOV and CMV. Kittens were intubated and ventilated for 24 h. A semiquantitative scoring system was used to grade histopathological tissue changes in the cricoid, mid-trachea, carina and left bonchus. The injury scores of the two groups were ranked and compared using a two-tailed Mann-Whitney rank test. RESULTS: Histopathologic changes were similar and mild in both groups under light microscopic examination. There was no significant difference in airway injury between the two groups. CONCLUSIONS: We conclude that, in this animal model, HFOV results in minimal airway damage when properly managed and causes no greater tracheobronchial injury than CMV.

Animals↗

PubMed2000

Reduction of late complications after irregularly shaped four-field whole pelvic radiotherapy using computed tomographic simulation compared with parallel-opposed whole pelvic radiotherapy.

BACKGROUND: Tumor control and late complication rates of irregularly shaped four-field whole pelvic radiotherapy using CT simulation were compared with those of whole pelvic radiotherapy using parallel-opposed fields in a non-randomized study. METHODS: From 1986 to 1996, 74 patients who underwent surgery for clinical stage I, II or III squamous or adenosquamous cell carcinoma of the uterine cervix were treated with postoperative radiotherapy consisting of 50 Gy in 25 fractions in 6 weeks. Thirty-four patients were treated with an irregularly shaped four-field technique following computed tomography (CT) simulation using beam's eye view and three-dimensional treatment planning and lead blocks. Forty patients received the conventional two-field technique, with CT simulation in 13 patients and X-ray simulation in 27 patients. There was no significant difference in patients' characteristics between the two groups. RESULTS: There was no statistical difference in survival, relapse-free survival or pelvic control rate between the two-field and irregularly shaped four-field groups with a mean follow-up period of 60 months. The actual 5-year pelvic control rate was 94% for the two-field technique and 100% for the irregularly shaped four-field technique. The incidence of grade II-III bowel complications in the irregularly shaped technique group (2.9%, 1/34) was significantly lower than that in the two-field technique group (17.5%, 7/40) (p < 0.05). The actual 5-year complication rates of grade II leg edema were 28.6 and 3.1% for the two-field technique and irregularly shaped four-field technique groups, respectively (p = 0.0123). CONCLUSIONS: Irregularly shaped four-field post-operative pelvic radiotherapy using CT simulation appears to be as effective as parallel-opposed whole pelvic radiotherapy with a lower incidence of bowel complication and chronic leg edema.

Adult↗