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Biomedical subjects

H Sawa

Publications and source records attributed to H Sawa.

At least 19 recordsLinked to original sources
PubMed1995

Glucose transporter expression and functional role of hexokinase in insulin biosynthesis in mouse beta TC3 cells.

It was previously reported that insulin biosynthesis in mouse beta TC3 cells was regulated by glucose (Nagamatsu, S., and D. F. Steiner. Endocrinology 130: 748-754, 1992). In the present study, we examined the effect of glucose on the glucose transporter expression and hexokinase activities and determined the relationship between them and glucose-stimulated insulin biosynthesis in beta TC3 cells. Reverse transcriptase-polymerase chain reaction and Northern blot analysis revealed that beta TC3 cells expressed GLUT-1 and GLUT-3 glucose transporter mRNAs, but not GLUT-2. The levels of GLUT-1 and GLUT-3 mRNAs were not affected by glucose (0 or 11 mM glucose) over a period of 48 h. Immunoprecipitation of metabolically labeled beta TC3 cells with specific antibodies against GLUT-1 or GLUT-3 proteins revealed no effect of glucose on the biosynthesis of glucose transporters. Hexokinase [low Michaelis constant (Km) hexokinase] activity from cells incubated in 11 mM glucose for 48 h increased nearly twofold compared with cells maintained in 0 mM glucose, although the amount of cellular hexokinase protein detected by immunoblot analysis was unchanged between 0 and 11 mM glucose conditions. Glucokinase (high Km hexokinase) activity, in contrast, was not affected by glucose. Preincubation of beta TC3 cells with 2-deoxyglucose to inhibit hexokinase, thereby inhibiting all glycolysis, resulted in the decrease of glucose-stimulated insulin biosynthesis. Thus, in mouse beta TC3 cells that do not express GLUT-2, there is a close relationship between hexokinase activity and glucose-stimulated insulin biosynthesis, but not between the glucose transporter and glucose-stimulated insulin biosynthesis.

Animals↗
PubMed1995

Effects of beta-1 integrins in the process of implantation.

The expression and function of beta 1 integrins on human decidual cells were investigated. Flow cytometric analysis revealed that the cultured decidual cells expressed a high level of the beta 1 subunit on the cell surface. Mouse blastocysts attached to and spread onto cultured human decidual cells. Attachment of the blastocysts was a necessary prerequisite for the further outgrowth of trophoblasts. The addition of a monoclonal antibody recognizing the beta 1 subunit to the cultured decidual cells did not affect the rates of hatching and attachment of blastocysts. The outgrowth of embryos on decidual cells was inhibited by the addition of the anti-beta 1-subunit antibody in a dose-dependent manner. Furthermore, exposure of decidual cells to the anti-beta 1-subunit antibody significantly inhibited the extent of outgrowth of trophoblasts, implying that blastocyst attachment and outgrowth is mediated by different mechanisms. These observations suggest that beta 1 integrins on decidual cells may be involved in the process of blastocyst development and differentiation after attachment.

Antibodies, Monoclonal↗
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

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

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↗
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↗
PubMed1992

Association of U6 snRNA with the 5'-splice site region of pre-mRNA in the spliceosome.

U6 snRNA is one of the five RNA species required for splicing of nuclear pre-mRNAs. High conservation of its sequence has led to the hypothesis that U6 snRNA plays a catalytic role in splicing. If this is the case, U6 snRNA should be localized close to sites where the splicing reaction occurs. However, this has never been demonstrated. Here, we have shown that U6 snRNA is cross-linked to the 5'-splice site region of pre-mRNA by UV irradiation during the in vitro splicing reaction. We have also detected the cross-link of U6 snRNA and the region around the branchpoint of the intron lariat. The results show that U6 snRNA is present near the splice sites in the splicing reaction and support the idea that U6 snRNA is a catalytic element in the spliceosome.

Base Sequence↗
PubMed1992

[Determination of the neutrophil chemotactic factor in bronchoalveolar lavage fluid in patients with diffuse panbronchiolitis].

It is well known that erythromycin (EM) therapy is effective on chronic lower respiratory tract disease, including diffuse panbronchiolitis (DPB). In this study we investigated the relationship between clinical findings and neutrophil chemotactic activity (NCA) in bronchoalveolar lavage fluid (BALF) in patients with DPB receiving orally EM therapy. The NCA in post-EM therapy BALF was significantly reduced (p less than 0.001) compared with that in BALF before EM therapy (30.17 +/- 7.84% vs 53.05 +/- 10.65%). On the respiratory function before and after EM therapy, DPB patients (20 cases) showed significant improvement of %VC, FEV1.0, RV/TLC (p less than 0.001, each) and V25 (p less than 0.05). And on the post-EM therapy blood gas, PaO2 and AaDO2 level were confirmed to be significantly improved (p less than 0.001). In addition, we examined the correlation between the improvement ratio of clinical finding and the reduction of NCA in BALF after EM therapy in 10 patients with DPB. We found the significant correlation between the improvement ratio of PaO2 and the reduction NCA in BALF of those patients (p less than 0.05). There were no significant relationships between the improvement ratio in other parameters as stated above and the reduction of NCA in BALF. These findings indicate that EM restrains the NCA in BALF of patients with DPB and impairs the accumulation of neutrophils in respiratory tract, ultimately contributes to the improvement of clinical symptoms such as sputum and clinical findings such as PaO2 in patients with DPB.

Adult↗
PubMed1992

Augmented arterial wall expression of type-1 plasminogen activator inhibitor induced by thrombosis.

Type-1 plasminogen activator inhibitor (PAI-1), the primary physiological inhibitor of endogenous plasminogen activators, modulates fibrinolysis, cell migration, and tissue repair. To determine whether genetic expression of PAI-1 is augmented in the walls of vessels exposed to thrombi but not to a direct physical insult such as electrical injury, we induced arterial thrombosis in rabbit carotid arteries with intraluminal surgical silk sutures and performed in situ hybridization for PAI-1 messenger RNA (mRNA) and immunohistochemistry for PAI-1 antigen at selected intervals. PAI-1 activity in plasma remained virtually constant. In contrast, PAI-1 mRNA increased in endothelial cells juxtaposed to thrombi, in smooth muscle cells adjacent to the neointima, and in macrophages surrounding the suture material. PAI-1 protein was detected in regions in which PAI-1 mRNA was expressed. The increased expression of PAI-1 mRNA colocalized with PAI-1 protein in the endothelium juxtaposed to thrombi may potentiate thrombosis by shifting the local balance between fibrinolysis and thrombosis toward thrombosis. Furthermore, it may alter vascular remodeling and predispose to stenosis after interventions such as angioplasty, in which local thrombosis cannot be avoided.

Animals↗
PubMed1992

Expression of the angiotensinogen gene and localization of its protein in the human heart.

BACKGROUND: There have been no reports on the presence of the tissue renin-angiotensin system in the human heart, although the presence of angiotensinogen has been described in the animal heart. METHODS AND RESULTS: To determine whether angiotensinogen is synthesized in the human heart, we examined angiotensinogen messenger RNA (mRNA) synthesis in autopsy hearts by using ribonuclease protection assay. As a result, angiotensinogen mRNA was detected in the atrial muscle, muscles of the conduction system, and the left ventricular wall. In the left ventricular wall, mRNA expression was more prominent in the subendocardial muscles than in the midcardial or epicardial muscles. Using a monoclonal antibody to human angiotensinogen in immunoblotting experiments, we detected two closely spaced bands at approximately 70 kd in the heart, which was quite consistent with the human angiotensinogen molecule. Immunohistochemical studies with this monoclonal antibody demonstrated intense immunoreactivity in the atrial muscles, the muscles of the conduction system, and those of the subendocardial layers. CONCLUSIONS: We conclude that angiotensinogen was synthesized in the human heart. It was evident that the localization of angiotensinogen was not ubiquitous in the cardiac muscles, showing its predilection for the atrial muscles, muscles of the conduction system, and subendocardial layer of the left ventricle.

Angiotensin II↗
PubMed1992

Induction of endothelial cell expression of the plasminogen activator inhibitor type 1 gene by thrombosis in vivo.

BACKGROUND: We have shown previously that products from activated platelets can augment synthesis of plasminogen activator inhibitor type 1 (PAI-1) in cultured endothelial and hepatoma (Hep G2) cells in vitro and increase plasma PAI-1 activity in vivo in rabbits. Accordingly, the effects of activation of platelets associated with thrombosis and thrombolysis in vivo on plasma PAI-1 activity and expression of the PAI-1 gene in endothelium, liver, and other organs were characterized. METHODS AND RESULTS: Endothelial injury giving rise to platelet-rich thrombi was induced with electrical stimulation in carotid arteries in rabbits. Clot lysis and recanalization were induced subsequently with intravenous tissue-type plasminogen activator (t-PA) and verified with Doppler flow probes. Plasma PAI-1 activity (mean +/- SD) increased from 6 +/- 2 arbitrary units (AU)/ml to 129 +/- 48 AU/ml (n = 15) within several hours after recanalization. When t-PA had failed to induce recanalization, the increase was much less (from 7 +/- 2 to 42 +/- 23 AU/ml, n = 11). To define mechanisms responsible for these changes, PAI-1 messenger RNA (mRNA) was evaluated by Northern blot analysis and localized in tissues by in situ hybridization. Strong and consistent induction of PAI-1 mRNA was evident in aorta, heart, and liver of animals subjected to thrombosis (twofold to threefold increases compared with values in controls), particularly in those in which thrombolysis had been induced (fourfold to sixfold). After thrombolysis, an intense, PAI-1 mRNA-specific signal was detected in endothelium of aorta, liver, and heart, with less intense signals in endothelium of lung, adrenals, and kidneys. CONCLUSIONS: The increases in plasma PAI-1 activity follow a preceding increase in endothelial cell expression of the PAI-1 gene as reflected by PAI-1 mRNA levels. Thus, increased synthesis of endothelial cell PAI-1 after thrombosis and thrombolysis may attenuate endogenous fibrinolysis early after coronary thrombolysis, thereby potentiating early, thrombotic reocclusion.

Animals↗
PubMed1992

The studies of cell damaging and cell growth factors which induce cardiomyopathy.

We demonstrated that phosphatidylinositide-specific phospholipase C (PLC) activity was greater in cardiomyopathic hamster hearts (BIO 14.6 and BIO 53.58) then in hamster controls (F1b). Inositol trisphosphate (IP3) production was markedly greater in both of the cardiomyopathic hamsters, BIO 14.6 and BIO 53.58. We have also determined the sarcoplasmic reticulum (SR) function of heart. Calcium uptake into SR markedly increased in BIO 14.6. On the other hand, it significantly decreased in BIO 53.58 compared with F1b. It is well known that IP3 stimulates calcium release from SR. In BIO 14.6, calcium release from SR stimulated by IP3 increased, but its effect decreased in BIO 53.58 compared with F1b. These results suggest that PI response may produce high intracellular calcium levels in both BIO 14.6 and BIO 53.58 myocytes. In addition, in the BIO 53.58 hamster the sarcoplasmic reticulum deteriorate in function. It was concluded from these results that a prolonged high intracellular calcium level may lead to the death of BIO 53.58 myocytes. The expression of angiotensinogen mRNA was observed in the hamster heart. There was no differences in its expression level between F1b, BIO 14.6 and BIO 53.58. There was no effect of ages on its expression in these hamster hearts. We have also determined the distribution of angiotensinogen in these hamsters. At 4 weeks of age, the immunohistochemical study revealed that angiotensinogen was widely distributed in subendocardium in these hamsters. There was no difference in its distribution between F1b, BIO 14.6 and BIO 53.58. But at 20 weeks old of age its immunoreactivity decreased in BIO 53.58.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensinogen↗
PubMed1992

Phosphatidylinositol and inositolphosphatide metabolism in hypertrophied rat heart.

The accumulation of both Inositol-(1,4,5)-trisphosphate (IP3) and Inositol-(1,3,4,5)-tetrakisphosphate (IP4) after hormonal stimulation has a physiological role, possibly in altering Ca2+ levels in cardiac tissue. However, the accumulation of inositol polyphosphate under pathophysiological conditions has not been studied. In our experiments the metabolism of phatidylinositol and IP3 in cardiac myocytes as investigated. It was shown that basal levels of cytosolic phosphatidylinositol specific phospholipase C (PI-PLC), phosphatidylinositol-(4,5)-bisphosphate specific phospholipase C (PIP2-PLC) activities markedly increased in stroke-prone spontaneously hypertensive rats (SHRSP) with age compared with age matched Wistar Kyoto rats (WKY). IP3 kinase and IP3 phosphatase activities also increased in SHRSP hearts with age. Their activities increased in WKY, but to a lesser extent than in SHRSPs. These data suggest that a PI turnover pathway such as the phosphatidylinositol 4,5-bisphosphate-IP3-Ca2+ pathway or the diacylglyceride-protein kinase C pathway may have an important role in the development of hypertrophy in SHRSP heart.

Animals↗
PubMed1992

Chronic subdural hematoma in elderly people: present status on Awaji Island and epidemiological prospect.

The epidemiological aspect of chronic subdural hematoma (CSH) in the elderly who are 65 years old or elder was evaluated on Awaji Island with about 170,000 inhabitants. The overall incidence of CSH was 13.1 per 100,000/year, 3.4 in people under 65 years old, and 58.1 in the elderly. The elderly were 17.7% of all inhabitants. If these incidences of CSH are extrapolated to all of Japan in the year 2020, the incidence will be 16.3 per 100,000/year. This suggests that CSH may become the most common neurosurgical condition.

Adult↗