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Biomedical subjects

H Sawa

Publications and source records attributed to H Sawa.

At least 145 records · Page 8Linked to original sources
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↗
PubMed1991

Requirement of protein factors and ATP for the disassembly of the spliceosome after mRNA splicing reaction.

Pre-mRNA splicing reaction occurs in a large ribonucleoprotein complex called the spliceosome. After the splicing reaction, the spliceosome is disassembled to release the splicing products including spliced mRNA. Here we show that protein factors in a HeLa nuclear extract or a DEAE-cellulose fraction as well as ATP are required to release the splicing products form the spliceosome in which the splicing reaction has already completed.

Adenosine Triphosphate↗
PubMed1991

Alterations of RNase H sensitivity of the 3' splice site region during the in vitro splicing reaction.

We have developed a splicing assay system with an immobilized pre-mRNA to study the mechanism of the splicing reaction after spliceosome assembly. Using this system, we have found that the second step of the splicing reaction could be dissected into two stages. After the 5' splice site reaction, at least two factors interact with the pre-formed spliceosome containing intermediate molecules in an ATP-independent manner to convert the spliceosome into a form competent for the 3' splice site reaction. Then, the 3' splice site reaction occurs on this spliceosome, if ATP is supplied to the reaction mixture. We have also investigated the dynamic state of the 3' splice site region in the spliceosomes during the splicing reaction by probing with RNase H sensitivity. Prior to the 5' splice site reaction, the 3' splice site region was protected from RNase H attack. The region became sensitive immediately after the 5' splice site reaction, and subsequently became resistant again as the spliceosome competent for the 3' splice site reaction was formed. These results suggest that the interaction of the 3' splice site region with some spliceosome components changes significantly during the splicing reaction.

Base Sequence↗
PubMed1991

Distribution of atrial natriuretic peptide in the conduction system and ventricular muscles of the human heart.

Atrial natriuretic peptide (ANP), a cardiac hormone, is known to be located in the atrial specific granules, but its presence and localization in the ventricular muscle of the human heart has not been examined fully. Using a specific antibody to human ANP, we studied the conduction system and ventricular muscle with immunohistochemical and ultrastructural methods in 30 hearts obtained at autopsy. These included 12 normal and 18 diseased hearts. In the normal hearts, ANP-positive granules, which were regularly observed in the atrial myocytes, were found in small quantities in the cells of the penetrating and branching bundles in 4 of 12, and in the cells of the ventricular free walls in 2 of the 12 hearts. In the diseased hearts, the positivity increased significantly (P less than 0.05), being found in 13 of 18 (72.2%) conduction systems and 10 of 18 (55.6%) ventricular muscles. The granules were confirmed to be immunoreactive with ANP by ultrastructural examination. Furthermore, the presence of ANP mRNA in the conduction system as well as in the ventricular myocytes was demonstrated by Northern blot hybridization for which we used the complementary DNA of human ANP. Thus, a small quantity of ANP appears to be synthesized and stored in the conduction system and ventricles of some normal hearts. However, ANP was shown to be present in a larger percentage of the diseased hearts.

Aged↗
PubMed1991

Effect of endothelin on angiotensin converting enzyme activity in cultured pulmonary artery endothelial cells.

We studied the effects of endothelin on angiotensin converting enzyme (ACE) in cultured pulmonary artery endothelial cells. ACE activity was increased 2.5-fold by the addition of 1 x 10(-8) mol/l endothelin-1. Endothelin-1 also stimulated calcium influx and phospholipase C activity in a dose-dependent manner. Calcium influx, phospholipase C and ACE activity were suppressed 60-70% in the presence of endothelin-1 (10(-10) to 10(-6) mol/l) by 50 microliters neomycin. These results suggest that ACE was stimulated by endothelin-1 and that its activity may be closely related to phosphatidylinositol turnover stimulated by endothelin-1.

Angiotensin I↗
PubMed1991

[Effect of erythromycin on neutrophil function in chronic respiratory tract diseases with Pseudomonas infection].

The "low dose and long term" erythromycin (EM) therapy has been reported as effective (or useful) in chronic respiratory tract disease with pseudomonas (P.) infection including diffuse panbronchiolitis (DPB), however the mode of action is still obscure. Therefore in this study we have examined the effect of EM on the interaction between P. aeruginosa and human polymorphonuclear leukocyte (PMN) in vitro. The efficiency of intracellular killing and the ability of superoxide production were employed to evaluate the PMN functions. For the first step, the following results were obtained; 1) Pretreatment of PMN with 20 micrograms/ml EM did not affect the killing ability of PMNs against opsonized P. aeruginosa of standard and clinical isolate from DPB patient. 2) Superoxide production from PMNs was observed by phagocytosis of P. aeruginosa in the presence of serum. This was not affected by exposure of PMNs to 20 micrograms/ml EM even with increased ratios of bacteria to cells. 3) Pretreatment of P. aeruginosa with 20 micrograms/ml EM before opsonization enhanced the killing ability of PMNs in both standard and clinical isolate. 4) Pretreatment of P. aeruginosa with 20 micrograms/ml EM resulted in no effect on superoxide production from PMNs by phagocytosis of the bacteria. These results indicate that EM may modify a certain step of the interaction between bacteria and intracellular host defence mechanisms. Therefore for the second step, we have investigated the susceptibility of EM-exposed bacteria to killing by the cell free (glucose oxidase-glucose) system, which will detect the enzymatic generation of hydrogen peroxide (H2O2). The following results were observed; 1) EM-exposed bacteria was more susceptible to killing than control bacteria.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchiolitis↗
PubMed1991

Phospholipid metabolism in cardiomyopathic hamster heart cells.

We demonstrated that the activities of phosphatidylinositide-specific phospholipase C, inositol 1,4,5-trisphosphate (IP3) kinase, and IP3 phosphatase were enhanced in cardiomyopathic hamster hearts (BIO 14.6 and BIO 53.58) in comparison to control hamsters (F1b). Release of both arachidonic acid and prostacyclin was markedly enhanced by norepinephrine in the cardiomyopathic hamsters. Phospholipase C in heart has high substrate specificity to phosphatidylinositol. IP3 production was markedly enhanced in the cardiomyopathic hamsters. We also determined the intracellular calcium concentration, which was higher in BIO 53.58 hamsters than in BIO 14.6 hamsters at 5-20 weeks of age. There was no significant difference in the intracellular calcium level between F1b and BIO 14.6 hamsters at 5 weeks of age. These results suggest that phosphatidylinositol turnover stimulated by norepinephrine may produce high intracellular calcium levels in both BIO 14.6 and BIO 53.58 myocytes. In addition, in BIO 53.58 hamsters, some mechanism such as the sarcoplasmic reticulum, which controls the intracellular calcium level, may deteriorate in function. We concluded from these results that a prolonged high intracellular calcium level may lead to the death of BIO 53.58 myocytes.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

[Study of pre-operative chemotherapeutic methods for colonic cancer--the concentration in blood and tissues after pre-operative administration of UFT].

As one of the fundamental studies of the pre-operative chemotherapeutic methods in 22 cases with colonic cancer, we studied a progress of the concentration in blood and concentration in tissues including those in the portal vein after administration of UFT. The concentration of 5-FU in blood reached to the peak at 2 hours after administration of UFT and then decreased rapidly, while it was maintained for a long term in comparing with that of 5-FU (oral remedies; tablet and dry syrup). This fact suggested that UFT can be expected for metastatic inhibition and prevention of the recurrence because it showed an effect in free-cancerous cells before and during operation. The anti-tumorous effect was also expected because the concentration of 5-FU in cancerous tissues was significantly higher than that in non-cancerous region. In our study in this time, down staging was considered by pre-operative chemotherapeutic method of colonic cancer in the future because concentration of 5-FU was also highly obtained in metastatic lymph nodes. From the above-mentioned results, pre-operative chemotherapeutic method using UFT was expected as a part of the intensive therapies.

Administration, Oral↗
PubMed1990

Mechanism of increased angiotensin-converting enzyme activity stimulated by platelet-activating factor.

We studied the effects of platelet activating factor (PAF) on angiotensin-converting enzyme (ACE). PAF (1 x 10(-10) to 1 x 10(-6) M) had a novel effect on angiotensin I conversion. Pulmonary artery endothelial cells converted 1 nmol/dish of 125I-angiotensin I to angiotensin II in the absence of PAF. ACE activity was increased to 2.5 nmol/dish by the addition of 1 x 10(-6) M of PAF. To clarify the mechanism of this stimulatory effect of PAF on ACE, Ca2+ influx and inositol 1,4,5-trisphosphate (IP3) release in pulmonary artery endothelial cells were determined. PAF stimulated Ca2+ influx in a dose-dependent manner. PAF also stimulated phospholipase C (PLC) activity and released IP3. To study the relationship between PLC activity and ACE activity, neomycin was added. The Ca2+ influx and IP3 release stimulated by 10(-6) M of PAF were suppressed by about 60-70%. ACE activity was also inhibited up to 70% in the presence of PAF (10(-10) - 10(-6) M) by 50 M of neomycin. These results suggest that ACE was stimulated by PAF, and that its activity in endothelial cells may be mediated by the PI-turnover pathway via changes in PLC activity and IP3-mediated Ca2+ release from intracellular stores.

Angiotensin I↗