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Biomedical subjects

K Miyahara

Publications and source records attributed to K Miyahara.

At least 145 records · Page 8Linked to original sources
PubMed1993

[Safe and easy surgical atrial septectomy for congenital heart diseases].

Surgical atrial septectomy using a Kerrison clamp, which is used in neurosurgery, was done in four elder infants without extra-corporeal circulation. Two (6 and 4 months old) had an atresia of left atrio-ventricular valve with small atrial septal defect, one (8 months) had a transposition of great arteries with closing multiple ventricular septal defects, and one had a pure pulmonary atresia. A purse string suture was put on the right atrial appendage and the clamp in a closing position was inserted into the left atrium through the appendage and the atrial septum. The edge of the atrial septal defect and/or patent foramen ovale was hooked by pulling it slowly. It was closed strictly and pulled out together with a resected atrial specimen. This technique is safer and easier than the Blalock-Hanlon technique and atrial septectomy under extra-corporeal circulation for elder infants for whom balloon atrial septostomy is difficult to be done.

Cardiac Surgical Procedures↗
PubMed1992

The chimeric gene linked to glucocorticoid-suppressible hyperaldosteronism encodes a fused P-450 protein possessing aldosterone synthase activity.

Glucocorticoid-suppressible hyperaldosteronism (GSH) is one variety of primary aldosteronism with hypertension and is inherited in an autosomal dominant mode. A recent report has indicated that GSH is caused by a gene duplication arising from unequal crossing over between the two genes, CYP11B1 and CYP11B2, encoding P-450(11 beta) and P-450C18, respectively (Lifton et al. Nature (1992) 355, 262-265). The nucleotide sequence analysis in the present study has demonstrated that unequal crossing over in the chimeric gene formed by the gene duplication occurs within the region from the 3'-portion of exon 4 through the 5'-portion of intron 4 in Australian GSH patients. Namely, the chimeric gene encodes a fused P-450 protein consisting of the amino-terminal side of P-450(11 beta) (encoded by exons 1-4 of CYP11B1) and the carboxyl-terminal side of P-450C18 (encoded by exons 5-9 of CYP11B2). When a cDNA corresponding to the chimeric gene is transfected into COS-7 cells, the fused P-450 protein expressed in the mitochondria exhibits steroid 18-hydroxylase or aldosterone synthase activity. These results provide the molecular genetic basis for the characteristic biochemical phenotype of GSH patients.

Animals↗
PubMed1992

Characterization of a cis-acting regulatory element involved in human-aromatase P-450 gene expression.

The characteristics of a cis-acting regulatory region involved in the human-aromatase P-450 gene have been examined by transient expression analysis. The region spans from -242 - -166 relative to the cap site of the gene. A fragment containing the region excised from the gene enhances heterologous promoter activity as well as its own promoter activity in a position-independent and orientation-independent manner. The fragment exerts its enhancer activity in human BeWo choriocarcinoma cells in which the aromatase P-450 gene is expressed, but not in other cell lines tested. Deletion of 38 bp from the 3' end of the fragment results in a complete loss of enhancer activity. A gel-retardation assay with nuclear extracts from BeWo cells suggests the existence of a nuclear factor(s) which interacts with the fragment. These results suggest that the regulatory element in the fragment is involved in efficient transcription of the human-aromatase P-450 gene.

Animals↗
PubMed1992

Role of steroid 11 beta-hydroxylase and steroid 18-hydroxylase in the biosynthesis of glucocorticoids and mineralocorticoids in humans.

A gene encoding steroid 18-hydroxylase (P-450C18) was isolated from a human genomic DNA library. It was identified as CYP11B2, which was previously postulated to be a pseudogene or a less active gene closely related to CYP11B1, the gene encoding steroid 11 beta-hydroxylase (P-45011 beta) [Mornet, E., Dupont, J., Vitek, A. & White, P. C. (1989) J. Biol. Chem. 264, 20961-20967]. The nucleotide sequence of the promoter region of the P-450C18 gene is strikingly different from that of the P-45011 beta gene, although the sequences of their exons are 93% identical. The transient expression in Y-1 adrenal tumor cells of CAT constructs with a series of deletion mutants of promoter regions of both genes indicated that the two genes are regulated differently. P-450C18 as expressed in COS-7 cells exhibits steroid 18-hydroxylase activity to catalyze the synthesis of aldosterone and 18-oxocortisol and exhibits steroid 11 beta-hydroxylase activity as well. In contrast, P-45011 beta as expressed in the cultured cells exhibits steroid 11 beta-hydroxylase activity exclusively but fails to catalyze the synthesis of aldosterone and 18-oxocortisol. These results indicate that P-45011 beta and P-450C18 are products of two different genes and that the former participates in the synthesis of glucocorticoids whereas the latter participates in the synthesis of mineralocorticoids in humans.

Amino Acid Sequence↗
PubMed1992

Congenitally defective aldosterone biosynthesis in humans: the involvement of point mutations of the P-450C18 gene (CYP11B2) in CMO II deficient patients.

The gene for steroid 18-hydroxylase (P-450C18) has been recently assigned to encode corticosterone methyl oxidases Type I and Type II which were previously postulated to catalyze the final two steps in the biosynthesis of aldosterone in humans. Molecular genetic analysis of the P-450C18 gene is three patients from three different families affected with CMO II deficiency has indicated that a point mutation of CGG----TGG (181Arg----Trp) in exon 3 and one of GTG----GCG (386Val----Ala) in exon 7 occur exclusively in the gene of the patients. Analysis of PCR products by restriction enzymes (HapII and HphI) has indicated that the patients are homozygous and the unaffected parent is heterozygous for both mutations, in accordance with the established concept that CMO II deficiency is inherited in an autosomal recessive manner. These data clearly provide the molecular genetic basis for the characteristic biochemical phenotype of CMO II clinical variants.

Aldosterone↗
PubMed1992

Effects of reactive oxygen intermediate scavengers on the antitoxoplasmic activity of activated macrophages.

Obioactin, Lonomycin A, muramyl dipeptide, and scavengers of hydrogen radicals and of singlet oxygen were used to study the participation of.OH and 1O2 in the killing of Toxoplasma in cultures of glycogen-induced peritoneal macrophages. Both the scavengers of OH (diazabicyclooctane and histidine) and those of 1O2 (mannitol and sodium benzoate) failed to inhibit the multiplication of Toxoplasma in macrophages that were incubated with either Obioactin, Lonomycin A, or MDP. The results of these experiments demonstrate the apparent lack of an inhibitory effect of.OH and 1O2 on the multiplication of Toxoplasma, whereas the scavengers alone inhibited the growth of the parasites.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1992

Molecular evolution of human paramyxoviruses. Nucleotide sequence analyses of the human parainfluenza type 1 virus NP and M protein genes and construction of phylogenetic trees for all the human paramyxoviruses.

The nucleotide sequences of the NP and M genes of human parainfluenza type 1 virus (HPIV-1) were determined. The NP gene was 1677 nucleotides long excluding polyadenylic acid. The NP gene contained a single large open reading frame (ORF), which encoded a polypeptide of 524 amino acids with a calculated molecular weight of 57,736. The M gene 1173 nucleotides long excluding the poly(A) tract and the sequence also contained a single large ORF which encoded a polypeptide of 348 amino acid with a molecular weight of 38,445, which was inconsistent with 28 kDa previously determined by SDS-PAGE. We aligned the deduced HPIV-1 NP and M protein sequences with 12 and 13 other paramyxoviruses, respectively, suggesting that a common tertiary structure was found in the NPs or Ms of HPIV-1, Sendai virus (SV), HPIV-3 and BPIV-3 and that other common structure was also maintained in these proteins of HPIV-2, SV 41 and 5, MuV, HPIV-4. Phylogenetic trees were constructed for the NP and M proteins of all the paramyxoviruses of which nucleotide sequences had been previously reported. Paramyxoviruses could be subdivided into two groups, i.e., PIV-1 group and PIV-2 group; the former group is composed of HPIV-1, SV, HPIV-3 and BPIV-3, and the latter group consists of HPIV-2, SV 41, SV 5, MuV, HPIV-4 A and HPIV-4 B.

Amino Acid Sequence↗
PubMed1992

Scammonins VII and VIII, two resin glycosides from Convolvulus scammonia.

Two minor ether-soluble resin glycosides, scammonins VII and VIII, were isolated from Radix Scammoniae, the roots of Convolvulus scammonia. In addition to (2S)-2-methylbutyric acid and tiglic acid, they are composed, respectively, of orizabic acid A and a new glycosidic acid named scammonic acid B, with similar macrocyclic ester structures to those of the scammonic acid A-based scammonins I-VI. Isolation of genuine scammonins III-V, which were previously obtained as peracetates, is also described.

Carbohydrate Sequence↗
PubMed1992

Changes in serum lipoprotein(a) and C4b-binding protein levels after acute myocardial infarction.

We investigated changes in serum lipoprotein(a) (Lp(a)) and C4b-binding protein (C4bp) levels following acute myocardial infarction (AMI). Serum lipids, apolipoproteins, C-reactive protein (CRP), sialic acid and haptoglobin (Hp) were also measured and evaluated. The study involved 16 patients (11 men, 5 women, mean age 68.2 +/- 8.4 years) with AMI admitted within 12 h after the onset of illness. CRP rose sharply and immediately after the onset of AMI, reaching its maximum level on the 3rd day of illness. This was followed by temporary increases in sialic acid and Hp, both of which peaked on the 7th day of illness. The Apo A-I level was significantly lower on the 14th day, while the Apo B level was significantly lower on the 3rd day. Serum total cholesterol (T-Ch), HDL-Ch and LDL-Ch showed temporary decreases after the onset of illness. Serial examination of the serum of patients with AMI yielded the following findings; 1) Both Lp(a) and C4bp levels rose temporarily with similar patterns of variation, and 2) they took longer time to peak (around the 14th day) and lasted longer than the increases in the other acute reactive proteins.

Aged↗
PubMed1992

Risk factors in normolipidemic male patients with coronary artery disease in Japanese.

We examined serum lipids, lipoproteins, apolipoproteins (Apo), lipoprotein(a) (Lp(a)), C4b-binding protein (C4bp) and lathosterol in 22 normolipidemic (serum total cholesterol less than 220 mg/dl and serum triglycerides less than 150 mg/dl) male patients with coronary artery disease (CAD) and 33 normal male subjects. Many of the patients in the CAD group with normal total cholesterol (T-Ch) and triglycerides (TG) had higher TG, low-density lipoprotein (LDL)-Ch, beta-lipoprotein (Lipo) and Apo B values and lower high-density lipoprotein (HDL)-Ch, Apo A-I and Apo A-II values than those of the control group. Differences were also observed in the beta-Lipo/HDL-Ch, Apo B/Apo A-I, and HDL-Ch ratios and the atherogenic index [A.I. = (T-Ch--HDL-Ch)/HDL-Ch], all of which are generally accepted as indices for atherosclerosis. Even in CAD patients with normolipidemia, the HDL-Ch/T-Ch ratio and A.I. seemed to be important risk factors. In addition, Lp(a) and lathosterol, an accepted indicator of whole-body cholesterol synthesis, were higher in the CAD group. The CAD group also appeared to have a higher C4bp value, suggesting that this parameter is correlated with other lipids.

Carrier Proteins↗
PubMed1992

Antitumor activity of Toxoplasma lysate antigen against methylcholanthrene-induced tumor-bearing rats.

Growth of the tumor autoinduced by 20-methylcholanthrene (MC) in rats was inhibited after administration of Toxoplasma lysate antigen (TLA). The antitumor activity of TLA was most obvious in the early stage of tumoral growth. When TLA was administered to rats before the appearance of tumour, tumor formation was delayed slightly. Histopathological studies revealed dense growths of spindle tumor cells in untreated control rat, while enlarged central necrosis with the infiltration of lymphocytes and neutrophils was apparent in TLA-treated rats. According to the immunohistological examination of tumor tissue with anti-Thy-1 antibody, the rats treated with TLA showed large Thy-1 positive granular cells, whereas the untreated rats indicated only a few small Thy-1 positive cells. These observations indicate that TLA is a useful modifier of biological responses to MC-induced tumors.

Animals↗
PubMed1992

Role of adherent spleen cells in the induction of cytotoxic activity by Toxoplasma lysate antigen.

In order to identify mechanisms responsible for the anti-tumor effects of Toxoplasma lysate antigen (TLA), we used an in vitro 51Cr release assay to study the functional properties of plastic-adherent cells during induction of splenic cytotoxic activity by TLA. Cytotoxic activity of non-adherent cells was measured in all experiments after a 6 days incubation. Induction of cytotoxic non-adherent cells by TLA required the presence of plastic-adherent spleen cells. In contrast, rhIL-2 alone was able to induce transformation of cytotoxic non-adherent cells from non-adherent spleen cells. Contact between adherent and non-adherent spleen cells was necessary for successful induction of cytotoxic non-adherent cells by TLA. Treatment of spleen cells with anti-macrophage serum prevented induction of cytotoxic activity by TLA. Biologically active IL-2 was not detected in culture supernatants of spleen cells exposed to TLA. These findings suggest that contact between TLA-sensitized non-adherent cells and macrophages is necessary for induction of cytotoxic cells in the presence of TLA. This contact, however, is not necessary for generation of IL-2-induced killer cells.

Animals↗
PubMed1992

Therapeutic effects of Toxoplasma lysate antigen on 20-methylcholanthrene-induced BALB/c mouse tumors.

Therapeutic effects of Toxoplasma lysate antigen (TLA) were studied in mice bearing the tumor in the second passage of 20-methylcholanthrene (MC)-induced tumor cells. Intramuscular administration of TLA 7 days after the tumor-cell inoculation caused apparent inhibition of the tumor growth on day 14. The second treatment facilitated the therapeutic effects. Intravenous transfer of spleen cells prepared from TLA-sensitized mice into tumor-bearing mice also represented the growth inhibitory effects. Prominent effects were seen when the transferred cells were prepared 5 days after sensitization of donor animals. The inhibitory effects were absent in the groups transferred only the adherent cells or the non-adherent cells prepared from sensitized mice. The strongest inhibitory effect was observed in the group to which both adherent and non-adherent spleen cells were transferred simultaneously from sensitized mice. In in vitro experiments, spleen cells obtained from sensitized mice showed cytolytic effect on P-815 or YAC-1 cells after the secondary stimulation in vitro with TLA. Large non-adherent cells containing densely packed granules were induced when cultured with the adherent cells obtained from sensitized mice. These results revealed that TLA can inhibit the growth of the chemically-induced transplantable tumors by activation of adherent and non-adherent spleen cells.

Animals↗
PubMed1992

Characteristics of cytotoxic cells induced by Toxoplasma lysate antigen in mouse spleen.

Spleen cells from Toxoplasma lysate antigen (TLA)-sensitized BALB/c mice showed the strong cytotoxic activity against both natural killer (NK)-sensitive cells (YAC-1 and RL male-1) and NK-insensitive cells (P-815), when incubated with TLA or recombinant human IL-2 (rhIL-2). The increment of TLA concentration in culture medium increased the cytotoxic activity. Treatment of effector cells; spleen cells from TLA-sensitized mice incubated with TLA, with anti-asialo GM1 or anti-Thy-1 plus complement inhibited the cytotoxic activity of effector cells, whereas treatment with anti-mouse Lyt-2.2 serum plus complement had no effect on the cytotoxic activity. Treatment of spleen cells from TLA-sensitized mice with anti-asialo GM1 and/or anti-Thy-1 plus complement inhibited cytotoxic activities of effector cells. These results suggested that spleen cells sensitized with TLA both in vivo and in vitro were asialo GM1 positive and Thy-1 positive, and the majority of cytotoxic cells induced by TLA were similar to lymphokine-activated killer (LAK) cells induced by IL-2.

Animals↗
PubMed1992

Postnephrectomy arteriovenous fistula: a case report.

We report a 57-yr-old woman with severe cardiac failure secondary to postnephrectomy arteriovenous fistula which was successfully removed. A review of the literature shows the rarity of this complication; only 72 cases have been reported in the world literature including 6 cases (including the present case) from Japan. Surgical intervention is generally the treatment of choice from a fistula and provides satisfactory results for cardiac failure which is the major complication of this fistula. A characteristic bruit was observed in all reported cases. Therefore, nonsurgical closure by percutaneous embolization for a small sized shunt may be possible if early diagnosis is obtained by careful auscultation of the loin.

Arteriovenous Fistula↗