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Biomedical subjects

Y Yazaki

Publications and source records attributed to Y Yazaki.

At least 721 records · Page 40Linked to original sources
PubMed1991

[Biochemical diagnosis for acute myocardial infarction; myosin light chain].

Immunoassays for cardiac myosin light chains (LC) are important biochemical tests for diagnosis of acute myocardial infarction (AMI). LC appears in the serum 4-12 hours after AMI. The most unique characteristic of the time-course of LC is that the elevation of LC in the serum lasts for 1-2 weeks, which allows the retrospective diagnosis of AMI when cardiac enzymes in the serum are decreased to the normal level. This long time-course is due to the continuous liberation of LC from the infarcted myocardium, which could be confirmed by the cardiac scintigram using anti-myosin heavy chain antibody. The serum LC level is also useful in predicting the extent of the cardiac wall damage since the peak LC level reflected well the ventricular ejection fraction or the presence of mechanical complications, such as the formation of ventricular aneurysm. Immunoassays for cardiac LC have recently been improved by the introduction of ELISA using two monoclonal anti-light chain antibodies. ELISA can be finished within 3 hours, which will help to make cardiac LC measurement one of the most important biochemical tests for diagnosis of acute myocardial infarction.

Enzyme-Linked Immunosorbent Assay↗
PubMed1991

[A case of type B chronic hepatitis showing rapid progression to liver cirrhosis with prolonged positive IgM anti-HBc].

We reported a case of type B chronic hepatitis with high titer of IgM anti-HBc continuously, which progressed to liver cirrhosis rapidly. The patient was a 37-years-old man, and was diagnosed as chronic type B hepatitis with severe activity by laparoscopy and liver biopsy. The titer of IgM anti-HBc persisted high level for more than 2 years. Then the second liver biopsy showed the progression to liver cirrhosis within only about 2 years. It is a very rare case to prolong positive IgM anti-HBc for such a long time. Anti-HBc production of PBMC was enhanced remarkably in this case. We considered that HBc antigens released into serum from hepatocytes with severe exacerbations had enhanced the anti-HBc producing activity of B lymphocytes. And the rapid progression in this case would be due to the episodes of severe exacerbations.

Adult↗
PubMed1991

[Duodenal varices treated successfully by percutaneous transhepatic obliteration: report of a case].

A 73-year-old female with bleeding from duodenal varices treated by percutaneous transhepatic obliteration (PTO) was reported. She was admitted to our hospital because of tarry stool and general malaise. Gastroduodenoscopy revealed tortous elevations in the descending part of the duodenum, and observed intermittent bleeding. Percutaneous transhepatic portography (PTP) was carried out. PTP revealed duodenal varices supplied via the inferior pancreaticoduodenal vein and drained to the inferior vena cava, and continuously obliterated by gelfoam. Duodenal varices disappeared after obliteration and we observed no recurrence of varices for a year endoscopically. In general, it is accepted that the causes of the upper gastrointestinal bleeding secondary to portal hypertension are esophagogastric varices, hemorrhagic gastritis, gastro-duodenal ulcer, and so on. However, we must keep in mind the case with duodenal varices in which bleedings are of unknown origin. We also reviewed duodenal varices reported in Japanese literature from 1968 to 1989.

Aged↗
PubMed1991

[Activation of ras oncogene in myelodysplastic syndrome and acute myelogenous leukemia].

N-ras oncogenes activated by point mutation have been frequently detected in various types of human leukemias. Analysis of a large number of leukemias revealed that activated N-ras oncogenes were observed preferentially in AML, AMoL, T-ALL and Null-ALL but rarely in CML and B-cell leukemia. These results suggest that N-ras oncogene plays an important role in human leukemogenesis. Activated N-ras oncogenes were also detected in myelodysplastic syndrome (MDS) that is considered to be a preleukemic disease. MDS patients bearing an activated N-ras oncogene frequently showed leukemic progression of the disease, suggesting that an activated N-ras oncogene can be a critical factor for prognosis of MDS patients. Thus, detection of an activated N-ras oncogene is useful for diagnosis, prognostic evaluation and therapeutic decision. Recently, we demonstrated that detection of the minimal residual disease by analysis of N-ras oncogene can lead to improvement of the remission rate in leukemias. Moreover, we made it possible to screen N-ras oncogene by a sensitive non-radioactive method. Our research procedure seems to be a good model for clinical application of the molecular biological technique.

Base Sequence↗
PubMed1991

Oxidation-labile subfraction of human plasma low density lipoprotein isolated by ion-exchange chromatography.

We isolated subfractions of human plasma low density lipoprotein (LDL) using ion-exchange chromatography. Plasma LDL from normolipidemic subjects were applied to a DEAE Sepharose 6B column. After elution of the bulk of LDL at 150 mM NaCl (the major fraction), the residual LDL was eluted at 500 mM NaCl and designated as the minor fraction. The minor fraction, only less than 1% of total LDL, tended to be somewhat similar in certain properties to oxidized LDL, e.g., an increased negative charge, higher protein/cholesterol ratio, and a higher flotation density than native LDL. These results were consistent with data reported by Avogaro et al. (1988. Arteriosclerosis. 8: 79-87). However, assays of 125I-labeled LDL binding activity for LDL receptors equal to that of the major fraction. Incorporation of [14C]oleate into cholesteryl ester [acyl-CoA:cholesterol acyltransferase (ACAT) activity] in mouse peritoneal macrophages incubated with the minor fraction was only slightly greater than that with the major fraction. Incubation of the minor fraction with 0.5 microM Cu2+ caused a remarkable stimulation of ACAT activity, while stimulation by the major fraction required incubation with 5 microM Cu2+, suggesting that the minor fraction was relatively labile to oxidation. The minor but definite presence of a plasma LDL subfraction more negative and susceptible to oxidation implicates the possibility of its association with atherogenesis.

Arteriosclerosis↗
PubMed1990

Functional identification of the transcriptional regulatory elements within the promoter region of the human ventricular myosin alkali light chain gene.

We have identified and functionally characterized DNA sequences that regulate the expression of the human ventricular/slow twitch isoform of myosin alkali light chain (VLC1) gene. By using primer extension and S1 nuclease mapping techniques, we have shown that the VLC1 gene is transcribed from the identical site in the ventricular and slow twitch skeletal muscles. Comparison of the VLC1 sequences from +1 to -1296 in the genes for human and mouse showed that the 5'-proximal flanking region, up to about 220 nucleotides, was highly conserved (83% homology). To determine the location of sites that may be important for the function of the VLC1 promoter, a series of transient expression vectors containing progressive deletions of the VLC1 gene 5'-flanking sequence fused to the bacterial chloramphenicol acetyltransferase (CAT) gene was introduced into myogenic and nonmyogenic cells. Deletion mutagenesis of sequences between -357 and +40 revealed the presence of positive and negative activity in all the cells tested. We demonstrated that the minimal promoter sequence required to generate muscle cell-specific expression is the region between -94 to -64 upstream from the cap site and a sequence element located between -107 and -94 was found to have a positive effect in both myogenic cells and nonmyogenic cells. These two proximal regions located between -107 and -64 appear to act together to determine the cell type-specific high level expression of the VLC1 gene in muscle cells. Competition gel retardation assays revealed that the CArG sequence located between -96 and -87 interacts specifically with nuclear extracts from myogenic and nonmyogenic cells and compete for binding with the CArG sequence present in the human cardiac alpha-actin gene and with the serum response element of the c-fos gene. These results strongly suggested that similar, if not identical, the CArG box binding proteins interact with the functionally different promoter element in the VLC1, cardiac alpha-actin, and c-fos genes.

Animals↗
PubMed1990

Stretching cardiac myocytes stimulates protooncogene expression.

Recently cellular protooncogenes have been found to be induced as an early response to pressure overload in cardiac hypertrophy. To examine whether mechanical stimuli directly induce specific gene expression in the heart, we cultured rat neonatal cardiocytes in elastic silicone dishes and stretched these adherent cells. Myocyte stretching stimulated expression of the protooncogene, c-fos, in a stretch length-dependent manner, followed by an increase in amino acid incorporation into proteins. c-fos mRNA levels were enhanced within 15 min by cardiocyte stretching, peaked at 30 min, and declined to undetectable levels by 240 min. In the presence of cycloheximide, a greater increase in c-fos mRNA was seen by stretching. The transfected chloramphenicol acetyltransferase gene linked to upstream sequences of the fos gene including its promoter was also activated by stretching cardiac myocytes. These results suggest that mechanical loading directly regulates gene transcription without the participation of humoral factors in cardiocytes.

Animals↗
PubMed1990

Cerebral microvessel endothelium is producing endothelin.

Endothelin, a potent vasoconstrictor peptide, was recently isolated from the supernatant of the cultured endothelia of the porcine aorta and is now supposed to be the most likely candidate for the endothelium-derived contractile factor (EDCF), which is responsible for the endothelium-dependent vasoconstriction by various stimuli. In this study, the production of endothelin by the endothelia of porcine cerebral microvessels was revealed by the Northern blot analysis with porcine endothelin cDNA probe and the enzyme-linked immunosorbent assay (ELISA) with anti-porcine endothelin antibody. Our results raise the possibility that the endothelia of cerebral microvessels regulate the local blood flow within the brain through the production of endothelin.

Animals↗
PubMed1990

Interleukin 1 increases the production of endothelin-1 by cultured endothelial cells.

We examined the effect of human recombinant interleukin 1 (IL-1) on the production of endothelin-1 by cultured porcine endothelial cells. The induction of endothelin-1 mRNA began within 1 hr of exposure to IL-1, showed twin peaks at 4 and 24 hr, and declined thereafter. Enzyme-linked immunosorbent assay revealed that the amount of endothelin-1 peptide in conditioned media was also increased by IL-1 in a dose- and time-dependent manner. Our results suggested that IL-1, a macrophage-derived cytokine, may affect the contraction and proliferation of vascular smooth muscle cells by stimulating the production of endothelin by endothelial cells.

Animals↗
PubMed1990

Intracellular assembly of newly synthesized canine cardiac myosins.

To investigate how newly synthesized cardiac myosins are assembled into myofilaments, we analysed the distribution of newly produced alpha-myosin heavy chain isozyme in sarcomeres by immunoelectron microscopy using a monoclonal antibody (CMA19), which is specific for alpha-myosin heavy chain. Isozymic changes in myosin heavy chains from beta to alpha type were induced in canine ventricular muscles and cultured ventricular myocytes by administration of 1-thyroxine. We incubated the glycerinated ventricular muscles or cultured ventricular myocytes with the enzyme (horseradish peroxidase) labelled Fab fragment of CMA19. After the reaction with 3, 3'-diaminobenzidine and osmification, we prepared ultrathin sections of the ventricular muscles or cultured ventricular myocytes and analysed their staining patterns by electron microscopy. There was apparent heterogeneity in the staining intensity of the myofilaments among different cells, among different myofibrils and even intramyofibrillarly. Higher magnification revealed that there were scattered foci of strong reaction which appeared to be foci of assembly of the newly synthesized alpha-myosin heavy chain. Immunocytochemical study also showed heterogeneous reactions within myofilaments and that there were scattered foci of myofilament assembly, which were closely associated with polyribosomes producing newly induced alpha-myosin heavy chain. These data suggest that newly synthesized cardiac myosins are assembled into myofilaments from the sites of synthesis, that is polyribosomes. This may explain the heterogeneity of the assembly pattern of newly synthesized cardiac myosins at the subcellular level.

Actin Cytoskeleton↗
PubMed1990

Diagnosis of cardiac allograft rejection by the detection of circulating plasma cardiac myosin light chains.

Twenty adult male Japanese monkeys of the species Macaca fuscata were randomly paired and subjected to heterotopic cardiac transplantation performed by the Ono-Lyndsey method. Without immunosuppression, graft survival ranged between 8 and 27 days, with a mean survival of 14 days. Plasma cardiac myosin light chains were measured by radioimmunoassay, which showed transient increases in myosin levels just following transplantation. Three hearts showed high values at this period and stopped beating when the myosin levels decreased (type 1). The other 7 hearts showed low myosin values after transient increases and 5 of them were rejected with a preceding reincrease in the myosin levels (type 2). Pathological study revealed myocardial necrosis, perivascular cuffing of mononuclear cells and/or neutrophils and/or plasma cells in the type 1 hearts. Measurement of the plasma myosin light chain level was therefore revealed to be of great value in the monitoring of cardiac allograft rejection.

Animals↗
PubMed1990

Monoclonal antibodies to endothelin: application for sandwich immunoassays.

We established 16 monoclonal antibodies (MAbs) to endothelin (ET), a novel and potent vasoconstrictor. They were classified into two groups: eight of them reacted with the C-terminal portion of ET, and the other eight reacted with the non-C-terminal portion. We constructed the sandwich enzyme linked immunosorbent assays (ELISAs) using a combination of a MAb belonging to the former with that belonging to the latter, and could detect about 400 pg/ml of ET.

Animals↗