Biomedical subjects

H Inui

Publications and source records attributed to H Inui.

At least 73 records · Page 4Linked to original sources

PubMed1995

ABR findings in brainstem ischemia: occlusion of the left anterior inferior cerebellar artery.

ABR was measured ipsilaterally following permanent left anterior inferior cerebellar artery (AICA) occlusion to assess the discrepancy in recovery between blood flow and function in the rat brainstem. Three types of wave patterns were classified: in type 1, all components disappeared: in type 2, all components disappeared transiently, then re-appeared; and in type 3, only a significant increase in the latency difference between components I-IV was noted. In type 2, we suggest that all components re-appeared because cochlear blood flow was re-established quickly by collateral circulation.

Animals↗

PubMed1995

Clinical application of ultrasonic blood rheography for vertigo.

The blood flow in the vertebral artery was measured in 507 patients with vertigo using ultrasonic blood rheography. In 150 of the 507 cases (32%), abnormal findings including laterality and decreased flow were detected. Twenty-one cases whose clinical course was observed showed a decrease in the differences in velocity between sides as vertigo improved. VBI (vertebro-basilar insufficiency) showed a worse prognosis in patients with laterality compared with those without and a positive correlation was demonstrated between side differences and fluctuating blood pressure or serum lipids. Some anti-vertiginous drugs improved the difference between sides by increasing the velocity.

Adolescent↗

PubMed1995

The influence of unilateral vertebral artery occlusion on bilateral inner ear blood flow in rats.

We investigated the influence of unilateral vertebral artery (VA) occlusion on bilateral inner ear blood flow in rats using laser Doppler flowmetry for the measurement of bilateral cochlear blood flow (CBF) and photochemically initiated thrombosis for VA occlusion. BP and CBF showed little change by unilateral VA occlusion alone. However, subsequent hypotension induced by venesection not only reduced CBF but also caused imbalance between bilateral CBF reduction rates. CBF changed independently of BP, indicating the existence of a local CBF regulatory system.

Animals↗

PubMed1995

[Intrapleural bleomycin for management of malignant pleural effusions].

We studied the efficacy of intrapleural administration of bleomycin for the management of malignant pleural effusions of non-small cell lung cancer in 24 cases. Bleomycin 60 mg was administered into the pleural space after tube drainage. If the effusion continued, one additional dose was given. The efficacy was seen in 18 cases (75%). The main adverse drug reaction was transient fever among others. There was little toxicity and no cases of pulmonary fibrosis. Intrapleural administration of bleomycin is useful in management of malignant pleural effusions.

Aged↗

PubMed1995

[Concurrent chemoradiotherapy followed by surgery for advanced stage III non-small cell lung cancer (NSCLC)].

Forty-two patients with stage IIIA (bronchoscopically T3 and/or bulky N2) and stage IIIB NSCLC were treated with concurrent chemoradiotherapy (CRT). Treatment consisted of CDDP, 20 mg/m2 and etoposide, 40 mg/m2 by continuous infusion (day 1-5) of weeks 1 and 5 simultaneously with chest radiotherapy (RT), 50 Gy, 2 Gy/Fx, 5 Fx/week. Surgery was attempted 3-5 weeks after RT in pts clinically downstaged. Between 10/90 and 12/92, 43 previously untreated pts were enrolled and 42 were eligible. Pts characteristics were: male/female = 37/5; mean age, 61 yrs (range, 31-74 yrs); stage IIIA/IIIB = 10/32; 15 adenocarcinoma, 24 squamous cell, 2 large cell, 1 unclassified; PS 0/1/2 = 11/24/7. Excluding 1 ineligible pts, 42 pts were evaluated for CRT response. The response rate was 81% (1 CR, 33 PR, 5 NC, 1 PD, 2 NE). Clinical downstaging was achieved in 20 pts (48%). Twenty-one pts (50%) received surgery and 19 of them were completely resected. In 7 resection specimens, no tumor was observed. Toxicity of CRT was well tolerable (Grade 4 leukopenia, 15%; Grade 2-3 esophagitis, 15%). We conclude that this intensive combined modality therapy is acceptable and appears to increase the response rate as well as resectability. Prospective randomized studies should be conducted for further evaluation of this treatment modality.

Adult↗

PubMed1994

Low Grade Amplification of MDM2 Gene in a Subset of Human Breast Cancers without p53 Alterations.

MDM2 protein is thought to bind to p53 tumor suppressor protein leading to inhibition of p53-mediated transactivation. Amplification of the MDM2 gene has been frequently observed in human sarcoma, and relevant overexpression of the MDM2 protein is assumed to contribute to tumorigenesis through inactivation of the p53 function. In order to determine whether MDM2 amplification plays a role in the development of human breast cancer without genetic alteration of p53, we analyzed, MDM2 gene amplification by quantitative hybridization and genetic alteration of p53, in 32 primary tumors and 26 metastatic lymph nodes. Low grade amplification of the MDM2 gene (2-6 fold) was observed in four cases, none of which showed even subtle genetic alterations of p53 or loss of alleles on 17p. Moreover, in three of the four cases with MDM2 gene amplification, the level of gene amplification in the metastatic lymph nodes was slightly higher than that in the primary tumors. These results, taken together with previous findings, suggest that a subset of breast cancers without genetic alteration of p53 may also arise by inactivation of the p53 function through interaction with the overexpressed MDM2 protein induced by gene amplification.

Journal Article↗

PubMed1994

Participation of diacylglycerol kinase in mitogenic signal transduction induced by platelet-derived growth factor in vascular smooth muscle cells.

In rat vascular smooth muscle cells, platelet-derived growth factor (PDGF), stimulated phosphatidic acid synthesis by activating both of the two alternative pathways, diacyglycerol kinase (DGK) and phospholipase D (PLD). Genistein, a tyrosine kinase inhibitor, inhibited PLD activation but not DGK activation, the latter was inhibited selectively by R 59022. PDGF-induced DNA synthesis was partially inhibited by genistein or R 59022, but these inhibitors had no effect on phorbol ester-induced DNA synthesis. Further, the specific effects of these inhibitors on PDGF-induced DNA synthesis were additive.

Alkaloids↗

PubMed1994

Differences in signal transduction between platelet-derived growth factor (PDGF) alpha and beta receptors in vascular smooth muscle cells. PDGF-BB is a potent mitogen, but PDGF-AA promotes only protein synthesis without activation of DNA synthesis.

Cultured vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats express both alpha and beta isoforms of the platelet-derived growth factor (PDGF) receptors at high levels (100,000 and 240,000 sites/cell, respectively). In this cell type, PDGF-BB elicited a mitogenic response; however, PDGF-AA increased only protein synthesis without activating DNA synthesis. Protein kinase C (PKC) was activated by PDGF-AA as well as PDGF-BB with concomitant translocation from cytosol to membrane fractions. However, the hypertrophic effect of PDGF-AA was not affected by depletion of cellular PKC, whereas the mitogenic action of PDGF-BB was partially attenuated by the depletion. Following incubation with PDGF-AA or -BB, phospholipase C-gamma 1 (PLC-gamma 1) and phosphatidylinositol 3-kinase were tyrosine phosphorylated; however, the phosphorylation of Ras-GTPase-activating protein was induced only by PDGF-BB. Both PDGF isoforms resulted in a prompt and transient increase in the level of 1,2-diacylglycerol (DAG), presumably through the action of PLC-gamma 1. After returning to basal levels, the rate of DAG synthesis steadily increased for at least 15 min due to activation of phosphatidylcholine-hydrolyzing phospholipase C (PC-PLC). Incubation with PDGF-BB-activated phospholipase D (PLD) in a PKC-dependent manner resulting in the formation of phosphatidic acid (PA). PA was also formed by the sequential reactions of PC-PLC and DAG kinase in the PDGF-BB-stimulated VSMC, and these sequential reactions were not affected by PKC depletion. In contrast, PDGF-AA stimulation did not result in increased PA synthesis as neither PLD nor DAG kinase activities were affected. PA may be a significant second messenger in the activation of DNA synthesis by PDGF-BB. These results indicate that signaling mechanisms of the PDGF-alpha and -beta receptors in VSMC are distinctly different in signal transduction in VSMC and that the alpha receptor promotes cellular hypertrophy (but not hyperplasia), whereas a mitogenic response is mediated only through the beta receptor.

Animals↗

PubMed1994

Autoradiographic measurement of regional brainstem blood flow: occlusion of the anterior inferior cerebellar artery.

Autoradiography was used to measure regional brainstem blood flow in Wistar rats following permanent left anterior inferior cerebellar artery (AICA) occlusion. With the AICA occluded, blood flow to the left vestibular nucleus decreased 31% while flow to the left cochlear nucleus decreased 47% when compared to the right (unobstructed) side. In the rat, the median pontine branch of the basilar artery was found to provide the principal blood supply to the vestibular nucleus. Electrocochleography was also used to measure the action potential (AP), summating potential (SP) and cochlear microphonics (CM) during left AICA occlusion. The AP disappeared completely after at least 7 min, while the SP polarity changed from negative to positive. Findings also showed that CM2 did not disappear completely in pre-mortem animals.

Action Potentials↗

PubMed1994

Comparison of O6-methylguanine-DNA methyltransferase mRNA levels in Ha-ras mutated and non-mutated rat mammary tumors induced by N-methyl-N-nitrosourea.

Activation of the Ha-ras oncogene in N-methyl-N-nitrosourea (MNU)-induced rat mammary tumors has been well documented. Such Ha-ras activation is thought to be brought about by direct action of carcinogens resulting in a G-->A transition at the second nucleotide of codon 12. However, a DNA repair enzyme, O6-methylguanine-DNA methyltransferase (MGMT), can specifically remove methyl groups from O6-methylguanine, which is a major mutagenic and carcinogenic DNA lesion leading to the G-->A transition. In this study, we compared the amount of MGMT mRNA in MNU-induced rat mammary tumors with and without such Ha-ras activation. A single injection of MNU into 82 female Sprague-Dawley rats induced 80 mammary carcinomas. RNase protection analysis and subsequent sequencing revealed that 42 of 65 randomly selected tumors contained Ha-ras oncogenes activated by the G-->A transition. The amount of MGMT mRNA was then measured by means of reverse transcriptase-mediated polymerase chain reaction (RT-PCR) amplification and Southern hybridization. No obvious difference in the level of MGMT mRNA was detected between the two tumor groups. In addition, in the course of our experiment, five of 42 tumors classified as containing activated Ha-ras oncogenes proved to contain low percentages of tumor cells with the Ha-ras activation. These results suggest that Ha-ras activation in MNU-induced rat mammary tumors may not necessarily be influenced by differences in MGMT activity. They also raise the possibility that activation of other oncogenes and/or inactivation of unidentified tumor suppressor gene(s) may be involved in development of a certain proportion of tumors with activated Ha-ras oncogenes, as is suspected in the case of tumors without Ha-ras activation.

Animals↗

PubMed1994

Enhanced phospholipase D activity in vascular smooth muscle cells derived from spontaneously hypertensive rats.

When cultured in the presence of fetal calf serum, aortic vascular smooth muscle cells (VSMC) derived from spontaneously hypertensive rats (SHR) grow faster than those from normotensive control Wistar-Kyoto (WKY) rats. In order to investigate the mechanism underlying this growth abnormality, we measured phospholipase D (PLD) activity in VSMC taken from both SHR and WKY rats. Upon stimulation with serum, platelet-derived growth factor (PDGF) and porbol 12-myristate 13-acetate (TPA), phosphatidylethanol (PEt) was produced in the presence of ethanol. The responses of the VSMC from SHR (SHR-cells) to all stimuli were significantly greater than those of the VSMC from WKY rats (WKY-cells), which suggests an enhanced PLD activity in the SHR-cells. Since PLD is regarded as an enzyme involved in signal transduction leading to cell proliferation, this PLD hyper-reactivity in the SHR-cells may account at least partially for the growth abnormality in the SHR-cells.

Animals↗

PubMed1993

Molecular cloning of a novel angiotensin II receptor isoform involved in phosphotyrosine phosphatase inhibition.

There are two major isoforms of the angiotensin II receptor, type 1 (AT1) and type 2 (AT2). AT2 is distinguished from AT1 with respect to its ligand selectivity, its insensitivity to non-hydrolyzable GTP analogues, and its as yet unidentified biological functions. In the present study we have expression-cloned AT2 cDNA from a cDNA library of a rat pheochromocytoma cell line (PC12w). Rat AT2 cDNA encodes a 363-amino acid protein that has seven transmembrane domains. AT1 is the closest in homology to AT2 but with only a 32% identity of amino acid sequence. Stably expressed in COS-7 cells, the receptor showed selective binding to AT2-specific ligands PD123319 and CGP42112A but not to the AT1-specific ligand, losartan. Northern blot analysis revealed that the mRNA of rat AT2 was expressed not only in PC12w cells but also in the adrenal glands and in the inferior olive of the brain, both of which are known to contain AT2 type binding sites. The expressed AT2 receptor mediated angiotensin II-induced inhibition of protein tyrosine phosphatase, an action that was dependent on a pertussis toxin-sensitive G-protein-coupled mechanism in COS-7 cells. The AT2-specific ligand CGP42112A was an agonist rather than antagonist in the inhibition of phosphotyrosine phosphatase. AT2 did not cause a decrease in cGMP in PC12w or COS-7 cells expressing AT2 stably. These results indicate that the AT2 receptor is structurally and functionally different from AT1 and suggest novel functional roles of the renin-angiotensin system in cross-talk with phosphotyrosine signaling by modulating protein phosphotyrosine levels.

Amino Acid Sequence↗

PubMed1993

Transduction of mitogenic activity of platelet-derived growth factor (PDGF) AB by PDGF-beta receptor without participation of PDGF-alpha receptor in vascular smooth muscle cells.

In cultured rat vascular smooth muscle cells, platelet-derived growth factor (PDGF) beta receptor was expressed at a high level, whereas PDGF-alpha receptor was not detected. PDGF-BB showed a high binding activity at 4 degrees C in the cells and was not displaced by PDGF-AA or -AB. This result indicates that PDGF-AB as well as PDGF-AA does not bind to the cells lacking PDGF-alpha receptor at 4 degrees C. However, at 37 degrees C, PDGF-AB bound to the cells and induced the internalization of PDGF-beta receptor. DNA synthesis was also stimulated potentially by PDGF-AB as well as PDGF-BB in the cells, although PDGF-AA was completely inactive. At 37 degrees C, PDGF-AB caused tyrosine phosphorylation of a group of proteins including PDGF-beta receptor and phospholipase C-gamma 1, but at a slower rate than PDGF-BB. At 4 degrees C, PDGF-AB did not stimulate protein tyrosine phosphorylation, whereas PDGF-BB did. A chemical cross-linking experiment showed that PDGF-beta receptor was dimerized by PDGF-AB as well as PDGF-BB. These results indicate that PDGF-beta receptor binds PDGF-AB without participation of PDGF-alpha receptor at 37 degrees C (but not at 4 degrees C), and PDGF-AB as well as PDGF-BB acts as a potent mitogen in the vascular smooth muscle cells.

Animals↗

PubMed1993

Differing signal transductions elicited by three isoforms of platelet-derived growth factor in vascular smooth muscle cells.

The differing signal transductions elicited by three isoforms of platelet-derived growth factor (PDGF) were studied in cultured rat vascular smooth muscle cells (VSMC), which show different mitogenic responses to the three PDGF isoforms. PDGF-BB elicited a variety of cellular signals, including the phosphorylation on tyrosine of phospholipase C-gamma 1 (PLC-gamma 1) and the PDGF receptor, formation of inositol 1,4,5-trisphosphate and diacylglycerol, degradation of phosphoinositides (phosphatidylinositol, phosphatidylinositol 4-phosphate, and phosphatidylinositol 4,5-bisphosphate) and elevation of intracellular calcium ([Ca2+]i). However, PDGF-AB failed to show some of these signals, although it stimulated [3H]thymidine incorporation to almost the same extent as PDGF-BB. Importantly, phosphorylation on tyrosine of the PLC-gamma 1 was far less (< 6.25%) in the case of PDGF-AB than that of PDGF-BB when assessed by immunoblotting. On the other hand, calcium ion entry from the extracellular medium was comparable in PDGF-AB- and PDGF-BB- stimulated VSMC. PDGF-AA, which did not stimulate [3H]thymidine incorporation, failed to show any of these effects with the exception of diacylglycerol formation. These observations suggest that the three PDGF isoforms stimulate different signal transduction pathways and that calcium ion entry, but not tyrosine phosphorylation of PLC-gamma 1, is essential for PDGF-induced mitogenesis in VSMC.

Animals↗

PubMed1993

Genetic alterations on chromosome 17 in human breast cancer: relationships to clinical features and DNA ploidy.

We analyzed DNA from 105 primary breast cancers to assess amplification of the ERBB2 gene and loss of heterozygosity (LOH) on chromosome 17 using 4 polymorphic markers, and investigated the relationships of these genetic alterations to clinicopathological characteristics including DNA ploidy. Amplification of the ERBB2 gene was observed in 28% of the tumors. ERBB2 was amplified in tumors of all clinical stages and amplification was significantly linked to lymph node metastasis. LOH at D17S5 was observed in 28 of 57 informative tumors, while 17 of 62 informative tumors showed allelic loss at TP53. Among the 37 tumors informative for both loci, 32% showed LOH at these loci and 49% retained both alleles, indicating that there was a significant relationship between LOH at D17S5 and at TP53. We also examined LOH at the D17S74 and NME1 loci on chromosome 17q. LOH at D17S74 and NME1 was observed in 20% and 22% of the informative tumors, respectively, but there was no significant association between LOH at these loci. Of the 4 loci tested, LOH at TP53, D17S74, and NME1 was associated with clinical stage. Lymph node metastasis was correlated with LOH at NME1. Moreover, allelic loss was more frequent in aneuploid tumors than in diploid tumors. These results suggest that certain combinations of genetic alterations on chromosome 17 may cooperate in the development and/or progression of breast cancer. Furthermore, it seems likely that analysis of these alterations in breast cancer patients may provide useful prognostic information.

Alleles↗

PubMed1993

Regulation of vascular angiotensin release.

To investigate the regulatory mechanism of the vascular renin-angiotensin system, we perfused isolated rat hind legs with plasma-free buffer and quantified angiotensin peptides in the perfusate. Angiotensin release from hind legs was increased in rats pretreated with losartan (DuP 753) and rats fed a low sodium diet with subsequent furosemide and was decreased in nephrectomized rats and rats given dexamethasone, ethynylestradiol, and triiodothyronine. Using these models, we have attempted to identify which step or component of angiotensin metabolism determines angiotensin release level. Changes caused by these manipulations in plasma renin concentration and basal angiotensin release from hind legs were almost parallel, whereas plasma angiotensinogen concentration and the angiotensin release changed in opposite directions. Infusion of renin in hind legs caused a marked increase in angiotensin release and continued even 1 hour after cessation of renin infusion. Infusion of angiotensinogen did not alter the angiotensin release. Angiotensin clearance and angiotensin I conversion were not affected by either nephrectomy or losartan pretreatment. Aortic renin messenger RNA level was extremely low and not increased by nephrectomy or losartan pretreatment, although kidney renin messenger RNA level was increased by losartan pretreatment. These results provide evidence that plasma renin of kidney origin is the major source of vascular functional renin and plays the determining role in the regulation of vascular angiotensin release. Plasma-derived or locally produced angiotensinogen, locally produced renin, converting enzyme, and angiotensin clearance are not considered to be the primary determinant in the regulation of vascular angiotensin release in these acute and subacute experimental models.

Angiotensin I↗

PubMed1992

Phospholipase D mimics platelet-derived growth factor as a competence factor in vascular smooth muscle cells.

Recent studies have suggested the importance of phosphatidylcholine (PC) metabolism in growth factor-stimulated cells. In these cells, PC is hydrolyzed not only by PC-specific phospholipase C but also by phospholipase D (PLD). In the present investigation, we show that the simple addition of PC-hydrolyzing PLD from Streptomyces chromofuscus to the culture medium of vascular smooth muscle cells elicits choline release into the medium accompanied by the formation of phosphatidic acid. In the presence of ethanol, this treatment elicits a formation of phosphatidylethanol (PEt) at the expense of phosphatidic acid. Furthermore, we show here that exogenous addition of S. chromofuscus PLD induces a marked DNA synthesis in quiescent vascular smooth muscle cells. This DNA synthesis induced by S. chromofuscus PLD is, like platelet-derived growth factor (PDGF)-elicited DNA synthesis, largely dependent on the presence of insulin. In addition, S. chromofuscus PLD-induced PEt formation and DNA synthesis were not affected by protein kinase C down-regulation, whereas PDGF-induced PEt formation and DNA synthesis were significantly inhibited. These observations strongly suggest that protein kinase-dependent activation of PLD is involved in mitogenic signal in PDGF-stimulated cells and that exogenously added PLD acts as a competence factor in the same way as PDGF.

Animals↗

PubMed1992

Platelet-derived growth factor AA homodimer stimulates protein synthesis rather than DNA synthesis in vascular smooth muscle cells from spontaneously hypertensive rats but not from normotensive rats.

Platelet-derived growth factor (PDGF) AB and BB isoforms were potent mitogens for cultured vascular smooth muscle cells from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). PDGF-AA promotes protein synthesis in a dose-dependent manner in SHR cells, whereas DNA synthesis was stimulated only slightly. However, this isoform did not activate either DNA or protein synthesis in WKY cells. PDGF-AA stimulated tyrosine phosphorylation of its receptor protein and phospholipase C-gamma 1 in SHR cell but not in WKY cells. These results indicate that vascular smooth muscle cell of SHR is uniquely responsive to PDGF-AA, presumably due to abnormality in receptor expression, in its hypertrophic response.

Animals↗