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Biomedical subjects

H Sawa

Publications and source records attributed to H Sawa.

At least 163 records · Page 9Linked to original sources
PubMed1990

Contrary effect of lactic acid on expression of neuron-specific enolase and glial fibrillary acidic protein in human glioma cells.

We examined the effect of lactic acid on cultured human glioma cell lines expressing glial fibrillary acidic protein (GFAP), vimentin and neuron-specific enolase (NSE). The growth of the cells was inhibited by the lactic acid in a dose-dependent manner. At 56 mM of lactic acid, the surviving cells of the KNS-42-c2 cell line developed slender processes and increasingly formed bizzar giant cells. In an immunofluorescence study of the lactic acid-resistant cells, the GFAP-positive cells prominently decreased in number, while the NSE-positive cells clearly increased. The vimentin was not affected throughout the experiment. After removing lactic acid from the medium, the GFAP-positive cells gradually increased in number. The method of dot immunoassay was useful for quantifying GFAP in cellular extracts. It indicated that the amount of GFAP decreased in the cells cultured with lactate-containing media and increased to the primary values after removing the lactic acid. These results may suggest that the morphological and immunochemical diversities of glioma cells are secondarily affected by cellular microenvironments such as lactic acid.

Cell Line↗
PubMed1990

Endothelin stimulates angiotensin I to angiotensin II conversion in cultured pulmonary artery endothelial cells.

We studied the effects of endothelin on the conversion of angiotensin I to angiotensin II in pulmonary artery endothelial cells. Endothelin had a novel effect on angiotensin I conversion. When endothelin was added to pulmonary artery endothelial cells, the conversion of angiotensin I to angiotensin II was enhanced about two-fold. The maximum stimulation was achieved at 10(-8) M of endothelin. This stimulatory effect was suppressed by angiotensin converting enzyme inhibitors such an enalapril. When the calcium antagonist, nifedipine, was incubated with 10(-8) M of endothelin, the conversion of angiotensin I to angiotensin II stimulated with endothelin was slightly suppressed by nifedipine. Enalapril (10(-6) M) completely inhibited the conversion of angiotensin I to angiotensin II in the presence of endothelin. These results suggest that endothelin may play an important role in regulating vascular tone by modulating the conversion of angiotensin I to angiotensin II.

Angiotensin I↗
PubMed1990

Platelet-activating factor stimulates angiotensin converting enzyme activity.

We studied the effects of platelet-activating factor (PAF) on the conversion of angiotensin I to angiotensin II in pulmonary artery endothelial cells. PAF had a novel effect on angiotensin I conversion. The apparent Vmax and Km for angiotensin converting enzyme (ACE) were 2.5 nmol/min per dish and 50 mumol/l, respectively. This activity was enhanced by the addition of PAF to cells. When PAF was added to pulmonary artery endothelial cells, the conversion of angiotensin I to angiotensin II was enhanced about twofold at 10(-6) mol/l PAF. Maximal stimulation was achieved at 10(-5) mol/l PAF. This stimulatory effect was suppressed by ACE inhibitors such as enalapril and PAF antagonist CV3988. When cells were incubated with 10(-6) mol/l PAF, the conversion of angiotensin I to angiotensin II stimulated with PAF was suppressed by CV3988. Enalapril (10(-6) mol/l) completely inhibited the conversion of angiotensin I to angiotensin II in the presence of PAF. Bradykinin also suppressed ACE activity, but phosphatidylcholine and lysophosphatidylcholine did not affect its activity. These results suggest that PAF may have an important role in regulating vascular tone by modulating angiotensin conversion.

Angiotensin I↗
PubMed1990

Effect of atrial natriuretic factor on angiotensin converting enzyme.

We studied the effects of atrial natriuretic factor (ANF) on the conversion of angiotensin I to angiotensin II. Pulmonary artery endothelial cells converted 1.22 nmol/min per dish [125I]angiotensin I to angiotensin II, but ANF suppressed the conversion by 0.475 nmol/min per dish. The maximum rate of inhibition of angiotensin converting enzyme (ACE) activity by ANF was 60% at 10(-6) mol/l ANF compared with control conditions. The amino acid fragments of ANF were studied to determine whether its specific structure was necessary for inhibiting ACE in endothelial cells. We found that atriopeptin II (fragment 5-27) inhibited ACE activity as much as ANF. Fragment 7-25 had the same rate of inhibition, but fragment 13-27 had no effect on the conversion of angiotensin I to angiotensin II. These results suggest that the amino acid sequence of Cys (7)-Cys (23) in ANF is important for the inhibition of ACE in pulmonary endothelial cells.

Angiotensin I↗
PubMed1990

[Angiotensinogen: gene expression and protein localization in human tissues].

Angiotensinogen, the precursor of the biologically active peptide angiotensin II, is known to be synthesized in the liver and to be localized in plasma, constituting the circulating renin-angiotensin (R-A) system. Recent animal studies have provided evidence for the local generation of angiotensinogen within tissues, independently of the circulating R-A system. To determine the sites of angiotensinogen synthesis in human tissues, we tested for the presence of angiotensinogen and its mRNA in various organs. Messenger RNAs extracted from the liver, kidneys, heart, and brain were all hybridized with human-angiotensinogen complementary DNA. By using a monoclonal antibody generated by in vitro immunization of spleen cells with the synthetic peptide, we first confirmed that the antibody detected only angiotensinogen on immunoblots. In immunohistochemical studies, intense immunoreactivity was found in atrial muscle and in the muscle fibers of the conduction system. The ventricular working myocytes were not stained. Less intense staining was observed in the glomerular tufts of the kidneys, in a few hepatocytes and Kupffer cells, and in the bile duct epithelium of the liver. Thus we demonstrated that angiotensinogen is also synthesized in extrahepatic tissues, including the heart, and that it is localized mainly in the specific cells of the heart. This suggests that the tissue R-A system plays an important role in the human heart.

Adolescent↗
PubMed1989

Effect of atrial natriuretic factor on angiotensin converting enzyme.

We studied the effects of atrial natriuretic factor on the conversion of angiotensin I to angiotensin II. Atrial natriuretic factor had a novel effect on angiotensin I conversion. Pulmonary artery endothelial cells converted 1.22 nmol/min/dish of [125I]angiotensin I to II in the absence of atrial natriuretic factor, but this activity was suppressed by atrial natriuretic factor. When atrial natriuretic factor was added to pulmonary artery endothelial cells, the conversion of angiotensin I to angiotensin II was suppressed 0.475 nmol/min/dish at 10(-6) M of atrial natriuretic factor.

Angiotensin I↗
PubMed1989

Positive transmission of Creutzfeldt-Jakob disease verified by murine kuru plaques.

Kuru plaque is a pathognomonic feature in the brain of patients with Creutzfeldt-Jakob disease (CJD) and in the brain of CJD-infected mice. Kuru plaques from CJD-infected mice were immunolabeled with rabbit anti-murine prion protein (PrP) absorbed with human PrP, but not so with mouse anti-human PrP. Therefore, the murine kuru plaque is composed of the host (mouse) PrP and can be distinguished antigenically from human PrP. Immunostaining using the anti-murine PrP and formic acid enhancement on tissue sections revealed not only birefringent kuru plaques but also nonbirefringent diffuse and small PrP accumulations. This immunohistochemical detection of kuru plaques provides more positive evidence than heretofore employed histochemical approaches. There were kuru plaques in brains of the first passage mice inoculated with tissues from 30 (91%) of 33 patients with CJD, the 3 negative patients belonging to a type of Gerstmann-Sträussler syndrome. Tissues from 6 other demented patients did not produce kuru plaques. In the evaluation of spongiform changes, mice inoculated with tissues from 23 (70%) of 33 patients were considered cases of successful transmission. In some mice, kuru plaques were present in the absence of spongiform changes. Further inoculations from 9 mice with kuru plaques but no spongiform changes were successful in almost all mice. Therefore, mice with murine kuru plaques in the absence of spongiform changes are also infectious. Thus, the presence of murine-specific kuru plaques can serve as another hallmark of a successful transmission.

Adult↗
PubMed1989

[Comprehensive 10-year strategy for cancer control].

Since 1981, cancer has been No. 1 cause of death in Japan. A "Comprehensive 10-Year Strategy for Cancer Control" is a national project that was strongly promoted by the former Prime Minister Mr. Yasuhiro Nakasone in 1983. The program comprises project research studies and functions supporting them. These include the education and utilization of young researchers (research resident), international cooperation and research resources (cell and gene) bank. The aim of studies is clarification of the mechanism of human carcinogenesis within 10 years and the results will be applied to prevention, diagnosis and therapy of cancers.

Humans↗
PubMed1988

Requirement of ATP in the second step of the pre-mRNA splicing reaction.

The requirement of ATP in the second step of mRNA precursor splicing was examined by dissecting the two steps of the in vitro splicing reaction using a heat-treated nuclear extract from HeLa cells. When a mRNA precursor containing two exons and a single intron from the delta-crystallin gene was initially incubated for 60 min with the heated extract, thereby allowing only the first step of the splicing reaction to occur, and subsequently with a normal extract for 10 min, the final spliced product was produced without any lag. The production of the spliced molecule during the second incubation with the normal extract represents conversion of the intermediates already formed with the heated extract into the spliced product. The conversion was stimulated by the addition of ATP during the second incubation and inhibited by a nonhydrolyzable ATP analogue. These results led us to conclude that ATP is required for the second step of the splicing reaction.

Adenosine Triphosphate↗
PubMed1987

Immunohistochemistry of retinoblastomas.

Immunohistochemical stains using neuronal and glial marker proteins were applied to retinoblastomas tissues from 14 children. Among the neurofilament triplet proteins, NF68Kd positive cells were observed in 12. Few NF160Kd positive cells were noted in 2, and NF210Kd positive cells were not detected. The positive ratio of NF68Kd and gamma-enolase seems to relate to the Flexner-Wintersteiner rosettes. Gamma-enolase positive cells were observed in 13. The distribution in tumor tissues was broader than that of NF68Kd positive cells. The immunoreactivities of NF68Kd were in parallel with those of gamma-enolase. Few GFAP positive cells were present around blood vessels, while S-100 protein and MBP positive cells were never observed. Our results indicate that retinoblastoma possesses predominantly neuronal properties, albeit in an immature form.

Child↗
PubMed1987

Surface proteins localized in ruffling membranes and filopodia of human glioma cells detected using Mab S-11E10.

We prepared mouse monoclonal antibody (Mab S-11E10) for the surface antigen specifically distributed in ruffling membranes and filopodia of cultured human glioma cells. The antibody reacted to the specified structures of other glioma cells (U251MG, KNS 60) as well as those of KNS 42 cells, which were the immunizing source. The antigens, identified by Mab S-11E10, had molecular weights of 65 and 66 kDa. Immunohistochemically, the antibody reacted only to astrocytes in the human brain, but the cross-reactivity was noted in extraneural tissues such as lymphocytes and epithelium of the bowel ducts. In 5 out of 6 low grade astrocytomas, most of the tumor cells were strongly stained, while tumor cells of highly cellular areas of anaplastic astrocytomas and glioblastomas were either not stained or only weakly stained. The specific localization of 65-66 kDa doublet proteins may suggest relation to spreading and locomotion of cells, and may correlate to astrocytic differentiation and/or function.

Antibodies, Monoclonal↗
PubMed1986

Proliferative activity of meningiomas as evaluated by bromodeoxyuridine uptake examination.

Proliferative activity of meningiomas was examined in 12 consecutive cases by administering bromodeoxyuridine (BrdU) before surgical removal and by immunohistochemical staining of the removed tumours using anti-BrdU monoclonal antibody (anti-BrdU MAb) to detect BrdU-labelled tumour cells. The 12 cases consisted of 6 with a primary tumour and 6 with a recurrent tumour. All of the tumours contained labelled cells and the labelling index (LI) was obtained in each tumour. The highest average LI was 13.6% and the second highest was 9.0% both in recurrent cases of histologically malignant meningothelial meningioma. The high LIs of both cases were thought to correspond well with the rapid recurrence of the tumour. The average LI of a case of recurrent haemangiopericytic tumour was 2.0%, and that of a case of meningioma associated with von Recklinghausen disease was 1.5%. The other 8 meningiomas showed the average LIs ranging from 0.1 to 0.9%, which were considered to be the LIs of usual benign meningiomas. The results of the BrdU uptake examination was considered to reflect well the clinical behaviour of meningiomas. The usefulness of the BrdU uptake examination in brain tumours, which can be employed in the clinical practice without any serious side-effects, is stressed.

Adolescent↗