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Biomedical subjects

H Sawa

Publications and source records attributed to H Sawa.

At least 127 records · Page 7Linked to original sources
PubMed1994

Increased intramural expression of plasminogen activator inhibitor type 1 after balloon injury: a potential progenitor of restenosis.

OBJECTIVES: This study was performed to determine whether altered gene expression of plasminogen activator inhibitor type 1 (PAI-1) occurs within the arterial wall after experimentally induced balloon injury. BACKGROUND: PAI-1, known to inhibit fibrinolysis in the circulation and to be present within atherosclerotic vessels, may influence proteolysis in the arterial wall and neointimal formation after angioplasty. METHODS: In rabbit carotid arteries subjected to balloon injury, both PAI-1 gene and protein expression were assayed sequentially with the use of Northern blotting, in situ hybridization and immunohistochemical studies. RESULTS: In uninjured, normal vessels PAI-1 messenger ribonucleic acid (mRNA) was not detectable by Northern blotting or in situ hybridization. However, injury was followed within 3 h by increases in PAI-1 mRNA (3.2 kb) of 5.9-fold compared with that in contralateral control carotid arteries (Northern blots). PAI-1 mRNA was detectable by in situ hybridization early after injury first in adventitia; after 24 h it was particularly prominent in the media. From 1 to 4 weeks after injury it was consistently detectable and was localized in neointimal vascular smooth muscle and endothelial cells at a time when neointimal thickening was marked. Cells of both types exhibited PAI-1 protein detected immunohistochemically. In vessels maintained in organ culture after balloon injury in vivo, sustained increases in PAI-1 activity appeared in conditioned media as well. CONCLUSIONS: Our results indicate that balloon injury simulating angioplasty in patients induces intramural expression of PAI-1 in vascular smooth muscle and endothelial cells. The decreased cell surface fibrinolytic activity likely to result from the increased PAI-1 expression may initiate or exacerbate mural thrombosis. Accordingly, excessive stimulation with clot-associated mitogens may stimulate vascular smooth muscle cell proliferation, which, coupled with increased accumulation of extracellular matrix attributable to decreased plasmin-mediated degradation, may contribute to restenosis.

Animals↗
PubMed1994

Modulation of expression of monocyte/macrophage plasminogen activator activity and its implications for attenuation of vasculopathy.

BACKGROUND: The binding of urokinase-type plasminogen activator (uPA) to its receptor (uPAR) on cell surfaces has the potential to influence degradation of extracellular matrix (ECM). Thus, uPA bound to monocyte/macrophages and its interactions with plasminogen activator inhibitors types 1 and 2 (PAI-1 and PAI-2) may modify atherogenesis by altering cell-associated proteolytic activity, degradation of ECM, and neointimal formation at sites of vascular injury. METHODS AND RESULTS: To determine whether the expression of proteins on the surface of cells involved in fibrinolysis changes in human cells in response to mediators implicated in atherogenesis, we exposed U937 cells (an immortal human monocyte-like cell line) to transforming growth factor-beta (TGF-beta) and to thrombin. Induction of uPAR mRNA occurred with TGF-beta (5 ng/mL) in a time-dependent fashion (P = .05; n = 4). Thrombin (5 National Institutes of Health [NIH] U/mL) increased uPAR mRNA by 2.8-fold above control (n = 4) without altering PAI-1 mRNA or protein synthesis (n = 4). The increase in uPAR gene expression in cells exposed to either TGF-beta or thrombin translated into a functional increase in cell-surface proteolytic activity. Under control conditions, U937 cells expressed PAI-2 but not PAI-1 mRNA. PAI-2 mRNA expression increased (P < .05; n = 4) with thrombin (5 NIH U/mL) but was suppressed by TGF-beta (5 ng/mL). TGF-beta induced PAI-1 mRNA within 6 hours accompanied by a 9-fold increase in PAI-1 protein from 6 hours (2.9 +/- 1.9 ng/mL) to 24 hours (20.0 +/- 9.6 ng/mL, P = .005; n = 3) paralleled by increased synthesis as shown in metabolic labeling experiments with 35S-methionine and immunoprecipitation of labeled PAI-1. PAI-1 mRNA and protein expression were seen in human coronary artery atherectomy specimens as well and were localized to analogous monocyte/macrophages and to smooth muscle cells as judged from results of in situ hybridization and immunocytochemistry studies. CONCLUSIONS: The results indicate that there is induction of PAI-1 and uPAR in U937 cells exposed to TGF-beta and thrombin. In atheroma, analogous processes may modulate early migration of luminal monocytes into the subintimal space and proteolysis of ECM. Thus, cell surface, monocyte-directed fibrinolysis may influence atherosclerosis, restenosis, or both.

Cell Line↗
PubMed1994

Expression of nerve growth factor receptor by human primitive neuroectodermal tumors.

The expression of low-affinity nerve growth factor receptor (NGF-R) by primitive neuroectodermal tumors (PNETs) was analyzed in vivo and in vitro to investigate the relationship between NGF-R expression and cellular differentiation. NGF-R was expressed in one medulloblastoma cell line and two neuroblastoma cell lines. When these cells were induced to differentiate by treatment with dibutyryl cyclic adenosine monophosphate, NGF-R was overexpressed and there was increased expression of neurofilament proteins. Immunohistochemistry investigation of tumor tissues demonstrated that NGF-R was expressed by a subset of PNETs with a neuronal phenotype marked by neurofilament protein expression, but not by gliomas and PNETs without a neuronal phenotype. Growth inhibition assay demonstrated that NGF inhibited the growth of cells expressing NGF-R. These results indicate that NGF-R expression is a useful marker of neuronal differentiation by PNETs.

Blotting, Western↗
PubMed1993

Neuron-specific glucose transporter (NSGT): CNS distribution of GLUT3 rat glucose transporter (RGT3) in rat central neurons.

The identity of the glucose transporters (GLUT) expressed in neurons in situ has yet to be fully established. In the present study we have isolated the GLUT3 (RGT3) cDNA and produced anti RGT3 polyclonal antibody allowing us to investigate the cellular localization and tissue distributions of RGT3 mRNA and protein in the central nervous system of the rat by the methods of in situ hybridization and immunohistochemistry. Here we demonstrate the direct evidence that RGT3 is present in neurons in adult rat brain. In situ hybridization showed the expression of RGT3 mRNA mostly in the regions of hippocampus, cerebral cortex, striatum, and the granule cell layer of the cerebellum, indicating that RGT3 mRNA is predominantly expressed within neurons. Immunohistochemistry showed that RGT3 protein is widely distributed in the rat brain, and concentrated on the plasma membrane of neurons. Double labeling studies with anti-RGT3, glial fibrillary acidic protein (GFAP), and neuron specific enolase (NSE) antibodies revealed the specific expression of RGT3 protein in neurons. Thus, RGT3 is indicated to be a neuron specific glucose transporter isoform (NSGT), and suggested to play a functionally significant role in rat central neurons.

Amino Acid Sequence↗
PubMed1993

Inhibition of endothelial cell expression of plasminogen activator inhibitor type-1 by gemfibrozil.

Increased concentrations of plasminogen activator inhibitor type-1 (PAI-1) in plasma are associated with impaired fibrinolysis and venous and arterial thrombo-embolic disease. In pilot studies designed to identify pharmacologic approaches capable of diminishing such increases, we found that gemfibrozil attenuated the stimulation of synthesis of PAI-1 in a human, immortal, hepatoma cell line (Hep G2) induced by platelets. The present study was performed to determine whether it exerts analogous effects in non-immortal endothelial cells and whether it may therefore facilitate fibrinolysis locally in vivo. Human umbilical vein endothelial cells were incubated with pharmacologic concentrations of gemfibrozil. Gemfibrozil, 100 microM, suppressed basal PAI-1 production by 15% and attenuated the augmentation of synthesis of PAI-1 induced by lysates from platelets (4 x 10(7)/ml) by 36% over 24 h without inhibiting overall protein synthesis. In addition, the increases in PAI-1 mRNA otherwise induced by platelet lysates over 6 h were suppressed by 49% (Northern blots) without any demonstrable change in the intracellular half-life of PAI-1 mRNA. Pulse-chase experiments demonstrated diminution of PAI-1 protein synthesis in parallel with the changes observed in PAI-1 mRNA. To determine whether these effects of gemfibrozil on endothelial cells in vitro were paralleled by consistent changes in the concentrations of PAI-1 in plasma in vivo, we studied rabbits with induced carotid artery thrombosis and thrombolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Expression of facilitative glucose transporter isoforms in human brain tumors.

The expression of facilitative glucose transporter (GLUT) isoforms in human astrocytic tumors was examined. Reverse transcriptase-polymerase chain reaction of a surgically biopsied glioblastoma was carried out using the degenerative oligonucleotide primers corresponding to the sequences of the human facilitative glucose transporter family, and polymerase chain reaction products were hybridized with human GLUT1, GLUT2, GLUT3, GLUT4, and GLUT5 cDNA probes. The results showed that a biopsied glioblastoma expressed GLUT1, GLUT3, and GLUT4 glucose transporter genes. Northern blot analysis of total RNA (10 micrograms) from a biopsied glioblastoma showed the transcripts of only GLUT1 and GLUT3, suggesting that the expression of insulin-responsive glucose transporter GLUT4 mRNA is relatively low. Immunoblot analysis of biopsied glioblastoma tissues by polyclonal antibodies against the C-terminal synthetic peptides of GLUT1, GLUT3, and GLUT4 showed a single band of each polypeptide. However, elevated expression of GLUT1 and GLUT3 glucose transporters was not observed in the glioblastoma. Astrocytic tumor tissues (n = 14) were also examined immunohistochemically. Reactive products for GLUT1 were observed in the luminal surface of capillaries in all cases, whereas tumor cells were positive for GLUT1 in only two of 14 cases. GLUT3 was positive in astrocytic tumor cells in all cases. Three of 14 cases expressed the GLUT4 protein, which was localized in the cytoplasm of tumor cells. These results suggest that the facilitative glucose transport may be altered in astrocytic tumor cells and thus display a significant change in glucose metabolism.

Amino Acid Sequence↗
PubMed1993

[Effect of erythromycin on neutrophil adhesion molecules].

The mechanisms of erythromycin (EM) in chronic lower respiratory tract diseases including diffuse panbronchiolitis (DPB) has been reported. In this study we investigated the effect of EM on peripheral neutrophil adhesion molecules such as LFA-1 and Mac-1 obtained from six healthy subjects. Pretreatment of neutrophils with each concentration (10 ng/ml approximately 100 micrograms/ml) of EM resulted in no significant reduction in the expression of LFA-1 alpha, beta and Mac-1. Moreover, EM had no capability of reducing these expressions even when neutrophils were pretreated with 1 microgram/ml of EM at time from 0 to 60 min. These findings indicate that EM does not directly reduce the expression of LFA-1 alpha, beta and Mac-1 on peripheral neutrophil obtained from healthy subjects.

Adult↗
PubMed1993

Potentiation by hypercholesterolemia of the induction of aortic intramural synthesis of plasminogen activator inhibitor type 1 by endothelial injury.

Accumulation of plasminogen activator inhibitor type 1 (PAI-1) in the arterial wall may accelerate atherogenesis by inhibiting fibrinolysis, diminishing proteolysis of extracellular matrix proteins, or modifying migration of vascular smooth muscle cells. Increased intramural expression of the PAI-1 gene is induced by thrombosis. To determine whether it occurs also in response to a sustained mechanical insult to endothelium, hypercholesterolemia, or both, rabbits were subjected to sustained aortic injury induced by implantation of indwelling polyethylene tubing, to hyperlipidemia induced by cholesterol and peanut oil feeding over a period of 8 weeks, or both. Sustained vascular injury alone did not increase plasma PAI-1. However, hypercholesterolemia with or without mechanically induced vascular injury increased plasma PAI-1 twofold. The expression of PAI-1 mRNA in aorta (Northern blots) was significantly increased when vascular injury was combined with hyperlipidemia. In situ hybridization showed that the increase with mechanical injury alone occurred in endothelial cells covering the neointima (positive for factor VIII and thrombomodulin), in abnormally differentiated vascular smooth muscle cells (positive for embryonic myosin heavy chain), and in macrophages (positive for the RAM-11 anti-macrophage antibody). Qualitatively similar but much more marked increases in PAI-1 gene expression were seen when arterial injury was accompanied by hypercholesterolemia. Neither vitronectin, known to stabilize PAI-1, nor vitronectin mRNA increased in liver. However, immunocytochemistry and Western blots demonstrated marked aortic accumulation of vitronectin protein with hyperlipidemia, particularly in subendothelial fibrotic regions, accompanied by increased neointimal vitronectin mRNA as shown by in situ hybridization. These results suggest that increased synthesis and stabilization of vascular PAI-1 may potentiate accumulation of extracellular matrix, thereby accelerating atherosclerosis.

Animals↗
PubMed1993

A mechanism of erythromycin treatment in patients with diffuse panbronchiolitis.

Recently, "low-dose and long-term" erythromycin treatment has been reported as effective on diffuse panbronchiolitis (DPB), but its mechanism is still obscure. Patients with DPB were found to have significantly higher percentages of neutrophils in the pre-erythromycin treatment bronchoalveolar lavage fluid (BALF) than healthy nonsmoking volunteers (p < 0.001). They showed a significant reduction in BALF neutrophil percentages after erythromycin treatment (p < 0.01). The neutrophil chemotactic activity (NCA) was significantly elevated in BALF obtained from 19 patients with DPB compared with that from healthy volunteers (p < 0.001). A significant reduction in the NCA was observed in post-erythromycin treatment BALF of 11 patients with DPB (p < 0.001). Additionally, there was a significant correlation between the reduction of NCA and neutrophil percentage in pre- and post-erythromycin treatment BALF (r = 0.726, p < 0.05). Finally, we investigated the effect of erythromycin on the intrapulmonary influx of neutrophils by intratracheal injection of lipopolysaccharide (LPS) and interleukin-8 (IL-8) in mice. The intrapulmonary influx of neutrophils was significantly suppressed (p < 0.001) in mice intraperitoneally injected with erythromycin at 5 mg per animal 2 h before intratracheal injection of LPS (control group: 6.5 +/- 1.6 x 10(5) versus erythromycin-treated group: 1.7 +/- 0.5 x 10(5)), but not 10 h before lung challenge. This inhibition was observed at 6 h after lung challenge and became maximal with 84% suppression at 24 h. Week-long administration of erythromycin did not alter the intrapulmonary influx of neutrophils. The number of neutrophils in the peripheral blood was not affected by erythromycin, indicating that the drug was not toxic.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Complete resection of a spinal meningioma extending from the foramen magnum to the second thoracic vertebral body via the anterior approach: case report.

The authors treated a patient with a huge, ventrally located spinal meningioma, extending from the foramen magnum to the second thoracic vertebral body. Vertebral body corpectomies were performed between the bottom of the second cervical vertebral body and the top of the first thoracic vertebral body, and the tumor was completely resected. Neurological symptoms and signs improved postoperatively.

Adult↗
PubMed1993

[Studies of lymphocyte subpopulations of bronchoalveolar lavage fluid in HTLV-I seropositive patients with uveitis].

To determine whether HTLV-I infection is associated with uveitis, we investigated the bronchoalveolar lavage fluid (BALF) cells in 23 patients with uveitis. Of these, sarcoidosis was diagnosed in 13 patients, but could not be confirmed in the remaining 10 patients (non-sarcoidosis). Three of 13 patients (23.1%) with sarcoidosis and 7 of 10 non-sarcoidosis patients (70.0%) were HTLV-I seropositive. In BALF, no significant differences were observed between the HTLV-I seropositive and seronegative patients. However, in non-sarcoidosis patients, total cell counts, CD3+ and CD+ HLA-DR+ cells in BALF were significantly higher in seropositive patients than in seronegative patients. CD3+ CD25+ cells in BALF were markedly increased in 3 of 7 non-sarcoidosis seronegative patients. These findings indicated that BALF lymphocytes in HTLV-I seropositive non-sarcoidosis patients were more activated than those in seronegative non-sarcoidosis patients, supporting the hypothesis that HTLV-I infection may be associated with uveitis.

Adult↗
PubMed1993

[Detection of codon 72 polymorphism of p53 gene from blood and loss of heterozygosity in brain tumors using polymerase chain reaction].

p53 gene which is known as a tumor suppressor gene locates in chromosome 17p and has a polymorphism at codon 72 (Arginine CGC-->Proline CCC). In this study, we examined the frequency of polymorphism and of heterozygosity in Japanese, and the loss of p53 gene in brain tumor tissues of the patients with heterozygosity using a novel method. The frequencies of heterozygosity, arginine type, proline type were 43%, 42% and 15%, respectively. Heterozygosity was observed in 15 out of 32 patients with brain tumors and loss of heterozygosity (LOH) in these 15 cases was demonstrated in 40%. Although we are not certain whether LOH of p53 region is inevitable process of oncogenesis of some brain tumors, some false negative results may occur. This quick technique requires small amount of samples and no radioactive isotope, therefore, can be applied to detect mutation and LOH occurred in p53 region in terms of the genesis and progression of human neoplasms.

Base Sequence↗
PubMed1992

Evidence for a base-pairing interaction between U6 small nuclear RNA and 5' splice site during the splicing reaction in yeast.

U6 small nuclear RNA (snRNA) is an essential factor in mRNA splicing. On the basis of the high conservation of its sequence, it has been proposed that U6 snRNA may function catalytically during the splicing reaction. If this is the case, it is likely that U6 snRNA interacts with the splice sites in the spliceosome to catalyze the reaction. We have used UV crosslinking to analyze the interactions of U6 snRNA with the splicing substrates during the yeast splicing reaction. Crosslinked products in which the central region of U6 snRNA was joined to the 5' splice site region of mRNA precursor and lariat intermediate were identified. The crosslinking sites were precisely located in one of these products. The results suggest a possible base-pairing interaction between U6 snRNA and the 5' splice site of the mRNA precursor.

Base Sequence↗
PubMed1992

Detection of human papillomavirus DNA in carcinomas of the nasal cavities and paranasal sinuses by polymerase chain reaction.

The authors retrospectively searched for human papillomavirus (HPV) types 16 and 18 in 60 cases of carcinoma arising from the nasal cavities (NC) and paranasal sinuses (PS) by using the polymerase chain reaction (PCR) on DNA extracted from formalin-fixed, paraffin-embedded tissues. In cases of SCC (n = 49), the authors also compared the clinical features of patients with HPV-positive and HPV-negative results to determine the clinical significance of HPV. HPV 16 and 18 were detected in 7 of the 49 cases (14%) of SCC. In the other histologic types of carcinoma (n = 11), neither HPV 16 nor HPV 18 was detected. No significant differences in the clinical features were observed between patients with SCC with HPV-positive and HPV-negative results. The results suggest that HPV 16 and 18 are implicated in the pathogenesis of SCC arising from the NC and PS. However, the presence of HPV is not related to local progression, occurrence of metastases, or the prognosis of the patients.

Adult↗
PubMed1992

Treatment of early recurrent medulloblastoma in children with cisplatin and etoposide: a preliminary report.

The prognosis of recurrent medulloblastoma remains extremely poor. Combination chemotherapy with cisplatin (CDDP) and etoposide (VP-16) was given to five children with early recurrent medulloblastoma. As a rule, CDDP 20 mg/m2 per day and VP-16 60 mg/m2 per day were administered intravenously for 5 days. This cycle was repeated three times at 4-week intervals. After this therapy, cerebellar signs improved in one case and were unchanged in four cases. Weakness and sensory disturbance, however, improved in three of four patients. Moreover, neck and/or back pain resolved in all these four. Radiological findings improved in three cases. Myelosuppression appeared in all patients, but receded rapidly. No other significant complications were noticed. Two patients died 5 and 6 months after this therapy. These results seem to suggest that this therapy has a use in improving neurological symptoms, particularly neck and/or back pain, although its efficacy is limited.

Adolescent↗
PubMed1992

Polyphosphoinositide metabolism in hypertrophic rat heart.

The accumulations of inositol-1,4,5-trisphosphate (IP3) and inositol-1,3,4,5-tetrakisphosphate (IP4) after hormonal stimulation may have a physiological role, possibly by alteration of Ca2+ levels in cardiac tissue. But the accumulation of inositol polyphosphate in a pathophysiological condition has not been studied. We investigated phosphatidylinositol-4,5-bisphosphate (PIP2) metabolism in hypertrophic cardiac myocytes, and clarified that the accumulations of IP3, IP4 and diacylglyceride after stimulation with norepinephrine were significantly enhanced in isolated myocytes from spontaneously hypertensive rat heart. Phospholipase C activity increased with age in SHRSP heart cells. These data suggest that PI turnover pathways, which can be mediated by both phosphatidylinositol-4,5-bisphosphate and diacylglyceride, may play an important role in development of hypertrophy in the hearts of rats with spontaneous hypertension.

Animals↗