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Biomedical subjects

K Miyasaka

Publications and source records attributed to K Miyasaka.

At least 145 records · Page 8Linked to original sources
PubMed1998

Features of spontaneous improvement in syringomyelia with low-situated cerebellar tonsils.

We analysed six patients who showed spontaneous improvement among the 19 nonsurgically treated cases of syringomyelia with low-situated cerebellar tonsils who visited our outpatient clinic. MR images both before and after improvement were available for two of these patients; CT-myelography before improvement and MR images after improvement were used for two patients; and in the remaining two patients, MR images after improvement only were used. Consequently, we were able to abstract several features from detailed and precise neurological and radiological evaluations of these patients. These features consisted of mild (rather than severe) disability, as well as four radiological features--a rounded shape of the lower edge of the cerebellar tonsils, a low tightness of the foramen magnum, an elevation of the tonsils during the course of the disease. Results of our radiological analyses were consistent with the theories proposed for the pathogenesis of syringomyelia in the light of the CSF flow around the foramen magnum. We propose that the features we have isolated are useful in determining treatment policies and prognoses of patients with syringomyelia accompanied by low-situated cerebellar tonsils.

Adult↗
PubMed1998

Features of spontaneous improvement in syringomyelia with low-situated cerebellar tonsils.

We analysed four patients who showed spontaneous improvement among the 19 nonsurgically treated cases of syringomyelia with low-situated cerebellar tonsils who visited our outpatient clinic. MR images both before and after improvement were available for two of these patients; CT-myelography before improvement and MR images after improvement were used for two patients. Consequently, we were able to abstract several features from detailed and precise neurological and radiological evaluations of these patients. These features consisted of mild (rather than severe) disability, as well as three radiological features--a rounded shape of the lower edge of the cerebellar tonsils, a low tightness of the foramen magnum, an elevation of the tonsils during the course of the disease. Results of our radiological analyses were consistent with the theories proposed for the pathogenesis of syringomyelia in the light of the CSF flow around the foramen magnum. We propose that the features we have isolated are useful in determining treatment policies and prognoses of patients with syringomyelia, accompanied by low-situated cerebellar tonsils.

Adult↗
PubMed1997

Disrupted cholecystokinin type-A receptor (CCKAR) gene in OLETF rats.

OLETF rats develop hyperglycemia, hyperinsulinemia and mild obesity, which is characteristic of human non-insulin-dependent diabetes mellitus (NIDDM). We cloned and sequenced the cholecystokinin type-A receptor (CCKAR) gene in the rats. Comparing the DNA sequences of the OLETF CCKAR gene and LETO CCKAR gene, normal gene, we found a deletion in the OLETF gene, 6847 bases in length, which was flanked by two 3-base-pair direct repeats (5'-TGT-3') at positions -2407/-2405 and 4441/4443, numbered according to the LETO gene sequence, one of which was lost. The promoter region, the first and second exons were missing in the mutant. The region upstream and downstream of the deletion, including exons 3, 4 and 5, was conserved between the two strains, and did not contain any base changes. We found that the gene mapped to chromosome 14 in rats. OLETF rats are the naturally occurring knockout animals with the homozygously disrupted CCKAR gene.

Animals↗
PubMed1997

Reduction of radiation-induced xerostomia in nasopharyngeal carcinoma using CT simulation with laser patient marking and three-field irradiation technique.

PURPOSE: Tumor control and reduction of postirradiation xerostomia in patients with nasopharyngeal carcinoma (NPC) using the three-field irradiation technique based on the CT-based simulation with laser patient marking was investigated. METHODS AND MATERIALS: Seventy-eight patients with NPC were consecutively treated between 1983 and 1993. In 33 patients treated before 1987, target volume was determined using a conventional x-ray simulator with a reference of CT images, and the primary site was treated by the conventional parallel-opposed two-field technique (Group I). In 45 patients treated from 1987, target volume was determined using a CT simulator slice by slice, the treatment field was projected onto the patient's skin by a laser beam projector mounted on a C-arm, and the primary site was irradiated by a three-fields (anterior and bilateral) technique (Group II). In Group II, the shape of each field was determined using a beam's eye view to reduce the dose to the bilateral parotid glands. The three-field technique reduced the dose to the superficial lobe of parotid gland to about two-thirds of the dose given by the two-field technique. Radiation-induced xerostomia was evaluated by clinical symptoms and radioisotope sialography. RESULTS: The 5-year survival rate and disease-free survival rate were 46.6 and 31.2% in Group I, and 46.8 and 46.5% in Group II. A large variation in the volume of parotid glands were demonstrated, ranging from 9 cm3 to 61 cm3 among patients treated with CT simulation. Forty percent of the patients in Group II showed no or mild xerostomia, whereas all of the patients in Group I showed moderate to severe xerostomia (p < 0.01). The radioisotope sialography study showed that the mean secretion ratio by acid stimulation was improved from 3.8% in the Group I to 15.2% in the Group II (p < 0.01). CONCLUSIONS: CT simulation was useful to determine the size and shape of each field to reduce the dose to the parotid gland, of which size varies largely among individual patients. The three-field technique based on CT simulation with laser patient markings is suggested to result in superior complication-free survival in terms of salivary dysfunction than did the conventional two-field technique with x-ray simulatior for NPC.

Adolescent↗
PubMed1997

Interleukin-1beta sensitizes the response of the gastric vagal afferent to cholecystokinin in rat.

Interleukin-1beta (IL-1beta) and cholecystokinin (CCK) are important mediators in the development of anorexic response during disease. The role of IL-1beta and CCK in the peripheral mechanisms of anorexia was studied by recording the mass afferent activity of the gastric vagal nerve in anesthetized rats. The i.v. administration of CCK (1 nmol) increased the activity of the vagal nerve, and this response was raised by 55-72% 2 h after i.v. injection of IL-1beta. It is proposed that IL-1beta-induced anorexia is mediated via the sensitization of type A CCK receptors in the periphery.

Animals↗
PubMed1997

Decreased level of light-induced Fos expression in the suprachiasmatic nucleus of diabetic rats.

We assessed light-induced Fos-immunoreactive cells in the suprachiasmatic nucleus of diabetic rats. The number of Fos-immunoreactive cells significantly decreased in diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rats as compared with control Long-Evans Tokushima Otsuka (LETO) rats. In contrast there was no decrease in the number of Fos-immunoreactive cells in young OLETF rats which have not yet developed diabetes. Two months after the administration of streptozotocin (STZ) to Wistar rats, the number of Fos-immunoreactive cells significantly decreased, although 1 week after the administration of STZ, the number had not yet changed in these STZ-induced diabetic rats. These results suggest that chronic diabetic (hyperglycemic) conditions may affect the light entraining responses in the suprachiasmatic nucleus (SCN).

Animals↗
PubMed1997

Involvement of cholinergic processes in cholecystokinin (CCK) release [corrected] by luminal oleic acid.

Cholecystokinin (CCK) is an important bioactive peptide that stimulates pancreatic enzyme secretion. Circulating CCK is secreted from endocrine cells in the upper small intestine in response to various luminal stimuli and to vascular administration of gastrin releasing peptides. However, the mechanism of its release has not been fully elucidated. In the present study, the vascularly perfused duodenojejunum was isolated from male Wistar rats. The effects of luminal infusion of sodium oleate (2 or 0.4%) or intra-arterial infusion of neuromedin C(10(-7) M) with or without atropine and with a recently synthesized specific bombesin antagonist (EABI) were examined. The CCK release produced by intra-arterial infusion of neuromedin C was inhibited by EABI in a dose-dependent manner. The CCK release produced by luminal sodium oleate was inhibited by atropine, but not affected by EABI. The CCK release stimulated by luminal sodium oleate is mediated, at least in part, by a cholinergic mechanism, but neuromedin C directly stimulates CCK release via its receptor on CCK-producing cells.

Animals↗
PubMed1997

Mouse cholecystokinin type-A receptor gene and its structural analysis.

The mouse cholecystokinin type-A receptor (CCK(A)R) gene was cloned and sequenced, and the exon/intron boundaries were determined by cDNA cloning. The gene, approximately 10 kb in length, contains the entire coding region, and consists of five exons. The deduced amino acid sequence was homologous with that of other species, with the exception of an additional DNA sequence encoding 7 amino acids in exon 5. A region of the 5' end of exon 2 appeared to be alternatively spliced, and generated an isoform shorter by 52 bases. The shorter isoform may encode an 48 amino acid open reading frame due to frameshift of translation. These two mRNA isoforms were expressed equally in the mouse gallbladders.

Alternative Splicing↗
PubMed1997

Analysis of long-term treatment of intracranial germinoma.

PURPOSE: To determine an appropriate treatment policy for intracranial germinoma. METHODS AND MATERIALS: From 1976 to 1992, 51 patients with germinoma (18 with pathologically verified germinoma and 33 diagnosed as having germinoma by neuroimagings) were treated by radiation therapy. Various radiation doses and treatment fields were used. RESULTS: The 10-year cause-specific survival rate for pathologically verified and unverified germinoma was 100% and 96%, respectively. Relapses were noted in four patients, three of whom died from the disease. Two of the four patients with a tumor larger than 4 cm in gross diameter experienced relapse. Two relapses occurred in a nonirradiated spinal canal and two occurred in the irradiation area treated by 25 Gy in 10 fractions and 30 Gy in 20 fractions. No relapse was noted in patients in whom the whole ventricle field was determined precisely using three-dimensional treatment planning. Five patients who were followed at an outpatient clinic experienced significant late neurocognitive dysfunction, which set in after radiotherapy. CONCLUSION: After pathological confirmation, 40 Gy whole-ventricle irradiation using precise three-dimensional treatment planning is appropriate as a standard treatment for most intracranial germinoma.

Adolescent↗
PubMed1997

Stereotactic irradiation without whole-brain irradiation for single brain metastasis.

PURPOSE: The effectiveness of stereotactic irradiation (STI) alone without whole-brain irradiation (WBI) for a single metastatic brain tumor was analyzed retrospectively. METHODS AND MATERIALS: Forty-four patients with this condition were treated using radiosurgery (RS) alone or fractionated stereotactic radiotherapy (FSR) without WBI. RESULTS: The initial response rate was 92% and the overall local control rate was 84% (37 of 44 patients). A total of 39% (18 of 44) of patients experienced intracranial relapse outside the initial target area. Forty-eight percent (21 of 44) of patients required salvage treatment for intracranial relapse. All 7 patients who received WBI as salvage treatment required no further salvage treatment, but 5 of the 14 patients who received salvage STI without WBI required three to four treatments for brain metastasis. Late radiation damage was not seen with initial treatment but was observed with retreatment. The overall median survival time was 261 days, with a standard error of 64 days. Actuarial survival at 12 and 24 months was 34% and 9%, respectively. The actuarial survival rate was significantly affected by the existence of active extracranial disease (p = 0.041). CONCLUSION: The high response rate and short treatment period of STI alone are advantageous in the treatment of single brain metastasis in patients with active extracranial disease with WBI reserved for relapse. Because of the low complication rate, STI alone may be also useful in patients with good prognosis, without extracranial disease.

Aged↗
PubMed1997

Involvement of 5-hydroxytryptamine (5-HT)3 receptor mechanisms in regulation of basal pancreatic secretion in conscious rats.

The effects of 5-hydroxytryptamine (5-HT)3 receptor antagonists (azasetron and granisetron) on basal pancreatic exocrine secretion were examined in conscious rats. Rats were prepared with cannulae draining bile and pancreatic juice separately. Intravenous injection of azasetron significantly increased pancreatic fluid and protein outputs in a dose-dependent manner. These increases were completely abolished by treatment with atropine, but not affected by bilateral truncal vagotomy. Intravenous injection of granisetron also increased pancreatic secretion, significantly. Intragastric injection of azasetron increased pancreatic secretion, although a double dose was required to elicit the stimulatory effect compared with intravenous injection. It is concluded that 5-HT3 receptor activity is involved in regulation of basal pancreatic secretion in conscious rats.

Animals↗
PubMed1997

Interleukin-1 increases activity of the gastric vagal afferent nerve partly via stimulation of type A CCK receptor in anesthetized rats.

The response of mass activity of the gastric vagal afferent nerve to intravenous administration of interleukin-1 beta (IL-1 beta) and the involvement of cholecystokinin (CCK) in the response were investigated in pentobarbital-anesthetized rats. Intravenous administration of 2 micrograms.kg-1 of IL-1 beta caused an increase in the afferent activity, which reached 150% of control activity by 30 min after administration and persisted for more than 80 min. The increase in the nerve activity was significantly reduced in animals pretreated with a type A CCK receptor antagonist. IL-1 beta also significantly increased the CCK concentration in systemic blood. Furthermore, it was confirmed that intravenous administration of CCK produced an increase in the nerve activity via the type A CCK receptor. These findings suggest that systemically applied IL-1 beta increases CCK concentration in systemic blood secreted from mucosal endocrine cells of the small intestine, and that in turn CCK in the gastric blood flow augments or partly participates in the IL-1 beta-induced excitation of the gastric vagal afferent nerve via stimulation of the type A CCK receptor in the stomach. A possible involvement of IL-1-related excitation of the gastric vagal afferent nerve in IL-1-induced anorexia is discussed.

Animals↗
PubMed1997

Clinical assessment of Hokkaido University PACS.

The paper describes the hardware and software used in the Hokkaido University picture archiving and communication system (HUPACS), which has been in use for the past two years. An evaluation of the system is also included. Fuji computed radiography completely replaces conventional X-ray radiographs, and 10:1 data compression is routinely employed. The PACS LAN is connected to the hospital information system through the main-frame computer and it is linked, not only to the radiology department, but also to the outpatient clinics. Image data have been steadily stored in the optical disc library, which contains more than 200,000 images. The original image can be accessed within 1 min. Image quality on a cathode ray tube (CRT) is clinically acceptable. Nevertheless, the transfer time of a newly made image is prolonged in some cases, during periods of heavy usage of the system. During scheduled radiology conferences, image reading tends to take more time on a CRT than on film. An improvement in the ease of operation of the workstations is necessary for full acceptance of CRT diagnoses. Generally speaking, however, HUPACS is working well and is appreciated by most of the clinicians.

Computer Systems↗
PubMed1997

Anti-nuclear antibodies and the optic-spinal form of multiple sclerosis.

We found anti-nuclear antibodies (ANA) (1:20 or higher) in sera from 11 of 16 patients with a diagnosis of the optic-spinal form of multiple sclerosis (OpS-MS) and 13 of 59 patients with other forms of MS (other MS), both rates being significant (P = 0.0004). Six of the OpS-MS patients had a high level of ANA (1:80 or higher), while levels were high in only three of the other MS patients, showing a significant difference (P = 0.0022). Titres of ANA were significantly higher in OpS-MS patients than in other MS patients (P < 0.0001). There was no relationship between the presence of ANA and age in OpS-MS patients, while patients with were older than those without high ANA levels among other MS patients. ANA-positive rate and titres were significantly higher in OpS-MS patients than in sex- and age-matched other MS patients. These results support the concept that OpS-MS constitutes a distinct subgroup among patients with a clinical diagnosis of MS and may indicate that systemic dysregulation of the inflammatory or immune response is more common in OpS-MS patients; the possible pathogenetic relevance of ANA-associated vasculopathy to some patients with a clinical diagnosis of OpS-MS should be considered.

Adult↗
PubMed1997

Evaluation of an extracorporeal membrane oxygenation system using a nonporous membrane oxygenator and a new method for heparin coating.

A new heparin binding method was applied to a miniature extracorporeal membrane oxygenation (ECMO) system with a nonporous membrane oxygenator (the priming volume, 45 mL; the membrane surface area, 0.4 m2; maximal flow rate, 2 L/min) that is resistant to plasma leakage. The authors evaluated the stability of the immobilized heparin in vitro and the feasibility of this system in animals. Samples of hollow fibers and tubing were rinsed at 40 degrees C for 4 days in normal saline, Ringer's lactate, and 1 mol/L NaCl solution. Heparin activities on hollow fibers after rinsing were 99 +/- 2.3% (mean +/- SD), 96 +/- 3.9%, and 93 +/- 2.0% of the control in each solution, while those of the tubing were 87 +/- 4.1%, 86 +/- 3.1%, and 76 +/- 8.6%, respectively. Veno-arterial ECMO using this heparin-coated system was performed on five beagles (8 to 12 kg) for 10 hours. Neither major thrombus formation nor plasma leakage was detected during the procedure in spite of a low flow rate (300 mL/min) and a reduced activated clotting time (mean, 128 seconds). Platelets decreased to 52% of the control (P < .01) at 1 hour, but no progressive decrease was seen thereafter. Antithrombin-III decreased (P < .01) and thrombin/antithrombin III complex increased (P < .05 at 4 hours and P < .01 at 6, 8, and 10 hours) during bypass, but the changes of fibrinogen and fibrinopeptide A were not significant. Fibrinogen/fibrin degeneration products, fibrinopeptide B beta 15-42, and plasma-free hemoglobin levels did not rise significantly. O2 transfer of the oxygenators at a flow rate of 300 mL/min were 12.3 +/- 0.4 mL/min at 30 minutes, 14.3 +/- 1.2 mL/min at 5 hours, and 14.7 +/- 1.7 mL/min at 10 hours (no statistical difference). Histological examination of the brains and the kidneys showed no evidence of thromboembolic sequela in any of the animals. These results suggest that this new system is a promising device for long-term ECMO in which the amount of systemic heparinization can be reduced with the minimal possibility of plasma leakage.

Animals↗
PubMed1997

Copper concentration in hyperintense hepatocellular carcinomas of Long-Evans cinnamon rats on T1-weighted images.

The Long-Evans Cinnamon (LEC) rat has abnormal intrahepatic copper accumulation and spontaneously develops hepatocellular carcinomas following hereditary hepatitis. The hepatocellular carcinomas are very similar to human well-differentiated hepatocellular carcinoma in histopathological features and on MR images. Copper is believed to be one of the causes of hyperintensity of hepatocellular carcinomas compared to surrounding non-cancerous tissues on T1-weighted MR image. Eight LEC rats were studied by MR imaging. We measured copper concentrations from the hepatocellular carcinomas and surrounding non-cancerous liver tissues. Signal intensity of hepatocellular carcinomas without cystic areas was iso- to slightly hyperintense relative to surrounding non-cancerous tissues on T1-weighted images. Histopathologically, most of the tumors resembled human highly or well-differentiated hepatocellular carcinomas. Copper concentrations of the hepatocellular carcinomas were lower than the surrounding non-cancerous liver tissues. Copper may not be the cause of increased signal intensity typically observed on T1-weighted images of hepatocellular carcinomas.

Animals↗
PubMed1997

Aging impairs release of central and peripheral cholecystokinin (CCK) in male but not in female rats.

BACKGROUND: Cholecystokinin (CCK) is an important bioactive peptide which stimulates pancreatic enzyme secretion and is also a neuromodulator in the central nervous system. We examined whether CCK release from the central and peripheral tissues was decreased in old animals, and whether there were sex-related differences. METHODS: Young (5-10-month-old) and old (25-29-month-old) male and female Wistar rats were used. Synaptosomes were prepared from the cerebral cortex, and the vascularly perfused duodenojejunum was isolated to examine central and peripheral CCK release, respectively. In some young female rats, 21 days after bilateral ovariectomy, the peripheral CCK release and the changes in CCK mRNA levels were examined. RESULTS: The central CCK release was impaired in response to the higher concentration of KCl, and the peripheral CCK response to the highest dose of neuromedin C was impaired in old male rats. However, no aging effect was observed in female rats, and ovariectomy did not affect CCK release or CCK mRNA level. CONCLUSIONS: CCK release from both central and peripheral tissues was decreased in old male rats, but not in old female rats.

Aging↗