Biomedical subjects

M Miyazaki

Publications and source records attributed to M Miyazaki.

At least 289 records · Page 16Linked to original sources

PubMed1998

Stimulation through the T cell receptor leads to interactions between SHB and several signaling proteins.

Shb is a recently described Src homology 2 (SH2) domain-containing adaptor protein. Here we show that Shb is expressed in lymphoid tissues, and is recruited into signaling complexes upon activation of Jurkat T cells. Grb2 binds proline-rich motifs in Shb via its SH3 domains. As a result, a number of proteins detected in anti-Shb and anti-Grb2 immunoprecipitates are shared, including phosphoproteins of 22, 36/38, 55/57 and 70 kDa. Shb-association with p22, which represents the T cell receptor associated zeta chain, occurs through the Shb SH2 domain. The central region of Shb binds p36/38. Since this interaction was inhibited by phosphotyrosine, this region of Shb is likely to contain a non-SH2 PTB (phosphotyrosine binding) domain. The Shb PTB domain was found to preferentially bind the sequence Asp-Asp-X-pTyr when incubated with a phosphopeptide library. A peptide corresponding to a phosphorylation site in 34 kDa Lnk inhibited association between Shb and p36/38. Overexpression of Shb in Jurkat cells led to increased basal phosphorylation of Shb-associated p36/38 and p70 proteins. Inactivation of the Shb SH2 domain by an R522K mutation resulted in a reduced stimulation of tyrosine phosphorylation of several proteins in response to CD3 crosslinking when expressed in Jurkat cells. Together, our results show three distinct domains of Shb all participate in the formulation of multimeric signaling complexes in activated T cells. These results indicate that the Shb protein functions in T cell receptor signaling.

Adaptor Proteins, Signal Transducing↗

PubMed1998

Pontine projections of pulmonary slowly adapting receptor relay neurons in the cat.

Pontine projections of second-order neurons activated by vagal afferents originating from pulmonary slowly adapting receptors were studied electrophysiologically in Nembutal-anesthetized, paralyzed and artificially ventilated cats. Extracellular recordings from these neurons (referred to as P-cells) were made in the nucleus tractus solitarii. Antidromic mapping of the brain stem showed that many P-cells examined projected their axons to the ipsilateral pons as well as the medulla. Axonal arborizations were found in the parabrachial nucleus, i.e. in the area corresponding to the pontine respiratory group. In some P-cells, axonal arborizations were also found in the A5 area. The present results suggest that the P-cells are involved in pontine pneumotaxic mechanisms.

Adaptation, Physiological↗

PubMed1998

Resection of hepatic and pulmonary metastases in patients with colorectal carcinoma.

BACKGROUND: Surgical resection of hepatic or pulmonary metastases has been accepted as appropriate therapy. However, whether aggressive surgery of both hepatic and pulmonary metastases from colorectal carcinoma is of value has not been verified in detail. METHODS: The authors identified 156 patients who had undergone hepatic resection for colorectal carcinoma metastases. This study reviewed six of these patients who underwent resection of both hepatic and pulmonary metastases from colorectal carcinoma. RESULTS: Five of the patients included four who underwent pulmonary resection for pulmonary metastases after initial hepatic resection for hepatic metastases and one patient who underwent hepatic metastasis resection after initial pulmonary metastasis resection. One additional patient underwent a simultaneous resection of hepatic and pulmonary metastases. The median interval between the 2 resections was 23 months. The median follow-up was 32 months after the second resection. At the time of last follow-up, 4 patients were alive and free of recurrent disease at 6, 7, 38, and 64 months, respectively, after their second resection. The remaining 2 patients died of disease at 17 and 32 months, respectively, after the second surgery. CONCLUSIONS: The results of the current study suggest that hepatic and pulmonary resection can result in long term survival in select patients with hepatic and pulmonary metastases from colorectal carcinoma because surgery remains the only potentially curative treatment.

Adult↗

PubMed1998

Cyclin E overexpression responsible for growth of human hepatic tumors with p21WAF1/CIP1/SDI1.

We examined a relationship between p21WAF1/CIP1/SDI1 and cell-cycle-related proteins in 12 human liver tumor cell lines (JHH-1, -2, -4, -5, -6, -7; HLE; HuH-7; Hep3B; PLC/PRF/5; HuH-6; HepG2). Seven (JHH-1, -2, -5, -6, -7; Hep3B; HepG2) out of eight cell lines having p21WAF1/CIP1/SDI1 protein overexpressed cyclin E protein, although one of them (JHH-5) overexpressed a reduced size of cyclin E. The rest (HuH-6) of the 8 cell lines with p21WAF1/CIP1/SDI1 showed a decreased expression of cyclin E. Four cell lines (JHH-4; HLE; HuH-7; PLC/PRF/5) deficient of p21WAF1/CIP1/SDI1 protein did not overexpress cyclin E protein. As to expression of the other cell-cycle-related proteins, cyclin A, cyclin D1, CDK2 or CDK4, no significant difference was detected among the 12 cell lines. These findings indicate that the human liver tumor cell lines which have the p21WAF1/CIP1/SDI1-inducible barriers of the cell cycle progression can go through the G1/S checkpoint by overexpressing cyclin E.

Blotting, Northern↗

PubMed1998

Three-dimensional molecular modeling explains why catalytic function for angiotensin-I is different between human and rat chymases.

Although angiotensin (ANG)-I is a substrate sensitive to chymase, the cleavage site differs among the chymase families. While human chymase (HC) hydrolyses the Phe8-His9 bond of ANG-I to ANG-II, rat chymase (RMCP-I) degrades the Tyr4-Ile5 bond of ANG-I to the inactive fragments. To clarify this different catalysis for ANG-I at the atomic level, three-dimensional structures of HC and RMCP-I were constructed by the molecular dynamic simulation. The energy-refined models clearly showed the significant difference in the electrostatic potential of the solvent surface. From the modeling study of their complex structures with ANG-I, the functional difference between both enzymes was clearly related with the electrostatic difference, especially at the C-terminal substrate-binding site.

Amino Acid Sequence↗

PubMed1998

Haptotactic migration of pancreatic cancer cells induced by bioactive components in bovine liver extract.

BACKGROUND AND OBJECTIVES: Migration into subendothelial tissue in remote organ by cancer cells are crucial events for organ-specific metastasis, including liver metastasis. This study aims to investigate the chemoattractive ingredients in liver extract, which induce migration of liver metastatic cancer cells. METHODS: Cell migrations of SU.86.86 cells, human pancreatic cancer cells raised from liver metastasis, toward the bovine liver extract were studied by chemotaxis or haptotaxis assay. Bovine liver extract was partially purified by chromatographic or gel elutriation method. RESULTS: The soluble fraction of the liver extract did not induce chemotactic migration of SU.86.86 cells. However, the insoluble fraction induced a remarkable haptotactic migratory response. C18 column unbound insoluble fractions eluted from SDS-PAGE induced chemotactic migration of SU.86.86 cells. CONCLUSION: Such bioactive components in liver extract may play an important role in the development of liver metastasis.

Animals↗

PubMed1998

Possible involvement of p21/waf1 in the growth inhibition of HepG2 cells induced by hepatocyte growth factor.

Hepatocyte growth factor (HGF) is a potent mitogen for a variety of cell types, but it is also known as an antimitogenic factor for several types of tumor cell lines. The biological processes by which HGF inhibits tumor cell growth remain poorly understood. Here we report a comparative study of HGF-mediated signal transduction events between two opposite responding types of human hepatoblastoma cell lines, HuH6 and HepG2. Following serum starvation, both cell lines were cultured in hepatocyte growth medium (HGM), a chemically defined medium, in the presence or absence of HGF. Under these culture conditions, cell growth in HuH6 was promoted by HGF, while it was inhibited in HepG2. Phosphorylation of p42/mitogen-activated protein (MAP) kinase was observed within 10 min after HGF stimulation in both cell lines. The level of phosphorylated MAP kinase in HuH6 declined to basal levels after 2 hr. However, in HepG2 the phosphorylated form was detectable at 6 hr. p21/waf1 was induced in both cell lines where levels peaked 4-6 hr after HGF stimulation. In HuH6, a marked decrease of p21/waf1 was observed at 8-12 hr, while a high level of p21/waf1 was sustained for at least 24 hr in HepG2. HGF treatment depressed cdk2 activity in a time-dependent manner in HepG2 while the activity increased in HuH6. When serum-starved HepG2 was growth stimulated with serum in the presence or absence of HGF, the cells treated with HGF underwent growth inhibition correlating with a sustained induction of p21/waf1 and a decrease of cdk2 activity. Immunoprecipitation analysis revealed accumulation of cdk2-associated p21/waf1 in the HGF-treated HepG2. Together, the results suggest that sustained induction of p21/waf1 mediates growth inhibition in HepG2 in the presence of HGF.

Blood Proteins↗

PubMed1998

Hepatic venous hemoglobin oxygen saturation predicts regenerative status of remnant liver after partial hepatectomy in rats.

This study was designed to evaluate the use of hepatic venous hemoglobin oxygen saturation (ShVO2) as an indicator of hepatic oxygen supply-demand relation and also regenerative status of the liver after partial hepatectomy in rats. We assessed the ShVO2 levels for 7 days, as well as hepatic hemodynamics, oxygen consumption, DNA synthesis and energy charge of the remnant liver for 3 days after 50% hepatectomy or sham operation. Total hepatic oxygen consumption (HVO2) per liver weight, hepatic oxygen extraction ratio (HO2ER), and DNA synthesis were significantly elevated at days 1 and 3 after hepatectomy, compared with the preoperative levels. Meanwhile, significantly decreased ShVO2 levels were observed at days 1 and 3, and the ShVO2 levels were significantly correlated with the HVO2. Furthermore, the decreased ShVO2 levels were synchronized with the increased DNA synthesis in the remnant liver. Energy charge levels were also significantly decreased at day 1 after hepatectomy. These results suggest that the regenerating liver demands an increased amount of oxygen for mitochondrial oxidative phosphorylation to restore hepatic energy charge. In conclusion, the ShVO2 after hepatectomy may reflect oxygen metabolic status in the remnant liver and could be useful for estimating liver regeneration.

Animals↗

PubMed1998

Effects of mild and moderate hypothermia on cerebral metabolism and glutamate in an experimental head injury.

In this study we sought to determine the optimal brain temperature for treating compression-induced cerebral ischemia. Six cats each were treated with a deep-brain temperature of 37 degrees C (control), 33 degrees C (mild hypothermia), or 29 degrees C (moderate hypothermia). Intracranial pressure (ICP) and cerebral blood flow (CBF) were monitored, as were arteriovenous oxygen difference (AVDO2) and cerebral venous oxygen saturation (ScvO2). The cerebral metabolic rate of oxygen (CMRO2) was calculated. Extracellular glutamate concentration was measured by microdialysis. ICP was increased by inflation of an epidural balloon until CBF became zero. This ischemia was maintained for 5 min, after which the balloon was deflated. Mild hypothermia showed coupled CBF-metabolic suppression, but moderate hypothermia resulted in disproportionately increased AVDO2, decreased ScvO2, and low CBF/CMRO2 (relative ischemia). Reactive hyperemia after balloon deflation was decreased after both mild and moderate hypothermia, as was the tissue volume showing Evans blue dye extravasation. Extracellular glutamate increased in control animals, an effect most effectively suppressed in the mild hypothermia group. These data favor 33 degrees C as the optimal temperature for treating compression-related cerebral ischemia.

Animals↗

PubMed1998

Control of ICP and the cerebrovascular bed by the cholinergic basal forebrain.

The involvement of the cholinergic basal forebrain in the control of ICP and the cerebrovascular bed was investigated by simultaneous measurement of CBF, BP, ICP and ETCO2 in rats and cats. Single unit spikes were also continuously recorded during ICP changes in the dorsomedial hypothalamic nucleus (DMH) of cats. Glutamate or acetylcholine (Ach) microinjection into the magnocellular basal nucleus (nucleus basalis Meynert: NBM, substantia innominata: SI) of rats or the DMH of cats caused persistent increases in ICP associated with slightly decreased BP. Microinjection of Ach into the NBM or the DMH also induced consistent increases in CBF in the cerebral cortex. Spike activities in DMH neurons increased before and during spontaneous ICP elevation. The firing rate of the DMH neurons increased in phase with the plateau wave-like ICP variations elicited by microinjection of Ach into the cholinoceptive pontine area or the contralateral DMH. Glutamate- or Ach-induced increases in ICP resulted from an increased CBV in response to a reduced cerebral vasoconstrictor tone. Activity within the cholinergic basal forebrain, as well as the central noradrenergic system, contribute to ICP changes and may be the intrinsic neuronal origin of the plateau waves occurring in some pathological conditions.

Acetylcholine↗

PubMed1998

Phase II trial of combination chemotherapy with cisplatin, carboplatin and etoposide in stage IIIB and IV small-cell lung cancer. Fukuoka Lung Cancer Study Group.

PURPOSE: A phase II trial combining cisplatin, carboplatin and etoposide was conducted in previously untreated patients with stage IIIB and IV small-cell lung cancer, in an attempt to increase response rates and prolong survival. METHODS: Previously untreated patients with small-cell lung cancer, with measurable disease, aged < or = 72 years, performance status < or = 2, and adequate hematologic, hepatic and renal function were enrolled in the study. They were treated with 80 mg/m2 cisplatin on day 1, 100 mg/m2 carboplatin on days 2, 3 and 8, and 50 mg/m2 etoposide on days 1, 2, 3 and 8. RESULTS: A total of 46 patients (20 with stage IIIB and 26 with stage IV disease) were enrolled in the study. A total of 186 courses of chemotherapy were given, and the dose was reduced in 27 courses (15%). The chemotherapy was repeated for four or more courses in 30 patients. There were 10 complete responses and 32 partial responses, for a total response rate of 91% (95% confidence interval, 79% to 98%). The median survival time and 2-year survival rates were 18 months and 22% for stage IIIB disease, and 14 months and 15% for stage IV disease. Major side effects were hematologic: leukopenia, anemia, and thrombocytopenia of grade 3 or more occurred in 48%, 46%, and 43% of patients, respectively. CONCLUSIONS: The three-drug regimen of cisplatin, carboplatin and etoposide is feasible and active against small-cell lung cancer.

Aged↗

PubMed1998

The Aspergillus nidulans CCAAT-binding factor AnCP/AnCF is a heteromeric protein analogous to the HAP complex of Saccharomyces cerevisiae.

The Aspergillus nidulans hapC gene was expressed as a fusion protein with MalE or glutathione-S-transferase (GST) in Escherichia coli, and used for the purification of HapC and the preparation of anti-HapC antiserum. The CCAAT-binding factor AnCP/AnCF contains a component with an approximate molecular mass of 32 kDa that cross-reacts with the antibody. The MalE-HapC fusion protein was able to replace authentic HapC in AnCP when incubated under appropriate conditions. Furthermore, reconstitution experiments with recombinant HapC, yHAP2 and yHAP5 polypeptides showed that all three polypeptides were required for the assembly of a complex capable of binding to CCAAT-containing taaG2 promoter DNA. The relationship between AnCP/AnCF and the Saccharomyces cerevisiae HAP complex is discussed.

Aspergillus nidulans↗

PubMed1998

Free fatty acid fractions from some vegetable oils exhibit reduced survival time-shortening activity in stroke-prone spontaneously hypertensive rats.

Previously, we demonstrated that several vegetable oils that included low-erucic rapeseed oil markedly shortened the survival time (by approximately 40%) of stroke-prone spontaneously hypertensive (SHRSP) rats as compared with perilla oil, soybean oil, and fish oil. We considered that a factor other than fatty acids is toxic to SHRSP rats, because the survival time-shortening activity could not be accounted for by the fatty acid compositions of these oils. In fact, a free fatty acid (FFA) fraction derived from lipase-treated rapeseed oil was found to be essentially devoid of such activity. A high-oleate safflower oil/safflower oil/perilla oil mixture exhibited a survival time-shortening activity comparable to that of rapeseed oil, but the activity of this mixed oil was also reduced by lipase treatment. A partially hydrogenated soybean oil shortened the survival time by approximately 40%, but a FFA fraction derived from lipase-treated partially hydrogenated soybean oil shortened it by 13% compared with soybean oil. Fatty acid compositions of the rapeseed oil and a FFA fraction derived from lipase-treated rapeseed oil were similar, but those of hepatic phospholipids of rats fed the oil and FFA were slightly but significantly different. These results support the interpretation that the survival time-shortening activity exhibited by some vegetable oils is due to minor components other than fatty acids, and that an active component(s) were produced in or contaminated soybean oil during the partial hydrogenation processes.

Animals↗

PubMed1998

Segments I and IV resection as a new approach for hepatic hilar cholangiocarcinoma.

Major hepatic resection for biliary tract carcinoma with obstructive jaundice has been reported on as bringing about high surgical morbidity and mortality rates. It has been also revealed that the extent of hepatic resection is closely associated with the occurrence of postoperative complications. Therefore, hepatic resection, limited as much as possible to what is necessary for curative resection, should be performed according to cancer extent. We performed a new surgical approach in 3 patients with hepatic hilar cholangiocarcinoma that included total resection of hepatic segments I and IV (by Couinaud's classification) and bile duct resection with hepaticojejunostomy of 4 to 6 intrahepatic bile duct stumps. All patients underwent curative surgical resections and were discharged within 6 weeks after surgery, without any serious complications. This limited resection of hepatic segments I and IV could be an effective radical surgical procedure for hepatic hilar cholangiocarcinoma, to avoid the occurrence of postoperative liver failure.

Cholangiocarcinoma↗

PubMed1998

Induction of angiotensin converting enzyme and angiotensin II receptors in the atherosclerotic aorta of high-cholesterol fed Cynomolgus monkeys.

Antiatherogenic effects of imidapril and involvement of renin angiotensin system were examined in experimental atherosclerosis induced by feeding a high-cholesterol diet to Cynomolgus monkeys. Eighteen male monkeys were divided into three groups and placed under (1) normal diet (normal group), (2) high-cholesterol diet (control group), (3) high-cholesterol diet with imidapril (20 mg/kg body wt/day, orally) treatment (imidapril group). At the end of the experiment, the normal group showed no apparent atherosclerosis in their aorta evaluated by oil red-O staining, while the control group exhibited marked atherosclerotic involvement of the intimal surface of the aorta (58.4 +/- 9.3%, P < 0.01). Imidapril reduced systolic blood pressure and atherosclerotic involvement (24.1 +/- 5.5%, P < 0.05). Total cholesterol content of the descending thoracic aorta was also significantly reduced in the imidapril group. In the atherosclerotic vessels, angiotensin converting enzyme (ACE) activity evaluated by quantitative in vitro autoradiography was significantly increased in the intimal lesion. Further evaluation revealed angiotensin II (Ang II) type I (AT1) receptor density was significantly increased in the medial lesion and type II (AT2) receptor density in the adventitia. When the progression of atherosclerosis was impeded by imidapril treatment, the ACE activity level as well as the AT1 and AT2 receptor density remained at normal. Expression of mRNA for fibronectin, TGF-beta1, types I and III collagen was studied by Northern blot analysis. No significant differences in types I and III collagen mRNA levels were found between the control and imidapril group. On the other hand, mRNA expression for fibronectin and TGF-beta1 were much lower in the imidapril group than in the control group. These results suggest that increased production of Ang II and activated receptors may be involved in atherosclerotic process in this model and also antiatherogenic effect of imidapril may be derived from reduction of local Ang II production as well as its hypotensive action.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1998

The NMDA-receptor antagonist ketamine abolishes neuropathic pain after epidural administration in a clinical case.

A 14-year-old male patient developed severe right limb pain after traumatic sciatic nerve injury. His pain was diagnosed as neuropathic pain (complex regional pain syndrome, type II). He did not respond to any conventional therapy for limb pain including non-steroidal antiinflammatory drugs, antidepressants, anticonvulsants, continuous epidural administration of local anesthetics and psychotherapy. Following continuous epidural administration of a very low dose of ketamine, an N-methyl-D-aspartic acid (NMDA) receptor antagonist, 25 microg/kg per h for 10 days, complete pain relief was obtained without any side-effects. There has been no recurrence of pain for 8 months after discontinuation of epidural ketamine. The symptoms related to dysfunction of the sympathetic nervous system still remained after complete pain relief. We discuss pain mechanisms, pain relief and the use of ketamine in this case.

Adolescent↗

PubMed1998

Adrenocorticotropic hormone therapy for infantile spasms alters pyruvate metabolism in the central nervous system.

To clarify the mechanism of action of adrenocorticotropic hormone (ACTH) in treating infantile spasms, we evaluated the effects of ACTH on the metabolism of pyruvate in the central nervous system (CNS) of children with infantile spasms. We measured the levels of lactate and pyruvate in cerebrospinal fluid (CSF) and serum, before and during ACTH treatment in 12 children with infantile spasms. We evaluated statistically any correlation between the observed metabolic changes and the clinical response of ACTH. ACTH therapy significantly elevated the levels of lactate and pyruvate in the CSF and serum. The effect was not dose-dependent. During ACTH therapy, the serum levels of lactate and pyruvate and the ratio of lactate to pyruvate (L:P ratio) were unrelated to these levels in CSF. Patients who showed a good initial response to treatment had a significantly higher CSF level of pyruvate and a lower L:P ratio during therapy than did those with a poor initial response. This is the first report that ACTH therapy administered for infantile spasms alters pyruvate metabolism in the CNS. This metabolic change may be involved in part in the action of ACTH in relieving infantile spasms.

Adrenocorticotropic Hormone↗

PubMed1998

Proton magnetic resonance spectroscopy of the brain in patients with Prader-Willi syndrome.

Five patients with Prader-Willi syndrome underwent magnetic resonance imaging and proton magnetic resonance spectroscopy. Magnetic resonance images revealed mild abnormalities, including slight ventriculomegaly, cortical atrophy, and a small brainstem, in all cases. The N-acetylaspartate/Choline (NAA/Cho) and N-acetylaspartate/Creatine (NAA/Cr) ratios were decreased in one (Case 1) and two (Cases 1 and 4) patients, respectively. The Choline/Creatine (Cho/Cr) ratio did not differ from those in control subjects. Thus, in patients with Prader-Willi syndrome, it is thought that there may be neuron loss or a neuron dysfunction caused by a chromosome abnormality. Statistically significant relationships were observed between IQ (DQ) and the NAA/Cho and Cho/Cr ratios: r = 0.895 (P < .05, NAA/Cho ratio) and r = -0.898 (P < .05, Cho/Cr ratio). This suggests that the parietal lobe pathology detected on 1H-magnetic resonance spectroscopy may be associated with more global brain damage and with loss of cognitive functions.

Adolescent↗