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Biomedical subjects

K Shimada

Publications and source records attributed to K Shimada.

At least 685 records · Page 38Linked to original sources
PubMed1996

[A case of postrenal acute renal failure in a neonate with bilateral ectopic ureters].

A male neonate was referred to our institute after the placement of right nephrostomy because he presented syndrome of acute renal failure and bilateral hydronephrosis. Voiding cystourethrography revealed bilateral vesicoureteral reflux (right.; grade I, left.; grade V), and renal scintigraphy revealed left hypodysplastic kidney. Endoscopy revealed bilateral ectopic ureters; posterior urethra on the right and bladder neck on the left. We performed bilateral ureterocystoneostomy with bilateral ureteral folding. Postoperative course was uneventful, and the serum creatinine improved to the level of 0.5 mg/dl 6 months after the intervention.

Acute Kidney Injury↗
PubMed1995

A replacement vector used to introduce subtle mutations into mouse genes.

A replacement vector convenient for introducing subtle mutations into various mouse genes has been developed using, a model system, the mouse transthyretin-encoding gene (ttr) and mouse embryonal carcinoma F9 cells. The vector consists of part of ttr carrying a subtle mutation in its second exon, and a cassette of the neomycin-resistance (neo)- and herpes simplex virus thymidine kinase (HSV-tk)-encoding genes flanked with a 3-kb duplication of mostly the second intron of ttr. In the first step ('replacement'), part of the endogenous ttr was replaced by vector DNA via homologous recombination, and two such clones, #33 and #77, were isolated from 185 G418-resistant clones by allele-specific PCR. In the second step ('excision'), gancyclovir-resistant colonies were screened, and 7 and 84% of those isolated from clones #33 and #77, respectively, were demonstrated to carry the subtle mutation in ttr, without the cassette of selection markers. In five independently isolated random integrants of the same vector DNA, the cassette of selection markers was excised efficiently by recombination within the duplication.

Animals↗
PubMed1995

Angiotensin II augments cytokine-stimulated nitric oxide synthesis in rat cardiac myocytes.

BACKGROUND: Nitric oxide (NO) has been shown to modulate cardiac function. We investigated the effect of angiotensin II (Ang II) on NO synthase activity in cardiac myocytes. METHODS AND RESULTS: Using the Griess reagent, we measured the production of nitrite, a stable metabolite of NO, by cultured neonatal rat cardiac myocytes. The expression of inducible NO synthase (iNOS) mRNA was assayed by Northern blotting. Incubation of cardiac myocytes for 24 hours with interleukin-1 beta (IL-1 beta) caused a significant increase in NO production. Ang II significantly augmented NO synthesis in IL-1 beta-stimulated but not in unstimulated cells in a dose-dependent manner. The angiotensin type I receptor antagonist CV 11974 inhibited the effect of Ang II dose-dependently. Simultaneous incubation of Ang II with NG-monomethyl-L-arginine or actinomycin D also completely inhibited the effect of Ang II. The Ang II-induced NO production by IL-1 beta-stimulated cells was accompanied by increased iNOS mRNA accumulation. Phorbol 12-myristate 13-acetate (PMA) also augmented NO synthesis in IL-1 beta-stimulated but not in unstimulated cells in a dose-dependent manner. The protein kinase C inhibitor calphostin C dose-dependently blocked the effect of Ang II. After protein kinase C activity was functionally depleted by treatment of cells with PMA for 24 hours, Ang II did not augment IL-1 beta-induced NO production. CONCLUSIONS: These results indicate that Ang II upregulates IL-1 beta-induced iNOS expression in cardiac myocytes, which is mediated at least partially via activation of protein kinase C.

Angiotensin II↗
PubMed1995

Localization of rat endothelin-converting enzyme to vascular endothelial cells and some secretory cells.

Endothelin is a potent vasoconstrictive peptide that is produced by vascular endothelial cells; it is formed from its precursor, big endothelin, by endothelin-converting enzyme (ECE). In this work, ECE was studied using specific monoclonal antibodies. In immunoblotting, ECE was estimated to be a 300 kDa protein on SDS/PAGE under non-reducing conditions, and 130 kDa under reducing conditions. Cross-linking experiments revealed that ECE is composed of two disulphide-linked subunits. Localization of ECE was studied at the cellular and subcellular levels in various rat tissues and cells. High-level expression of ECE was observed in membrane fractions of simian virus 40-transformed rat endothelial cells by immunoblotting, but the immunoreactive band was absent form aortic smooth muscle cells and cytosolic fractions of endothelial cells. In immunohistochemical analysis, ECE was found to be localized in the endothelial cells of the aorta, lung, kidney, liver and heart. Confocal immunofluorescent microscopy showed that most of the ECE in endothelial cells and cells transfected with ECE cDNA was clustered along the plasma membrane. Intact COS or CHO cells transfected with ECE cDNA rapidly and efficiently cleaved big endothelin-1 added to the culture medium. Thus endothelial cells express ECE on the plasma membrane and the active site of the enzyme faces outside the cells, i.e. it is an ectoenzyme. Other than endothelial cells, ECE was also present in some secretory cells. The enzyme was abundant in the adrenal gland, and localized in chromaffin cells. ECE was also highly condensed in pancreatic islet beta cells. It is concluded that ECE and endothelin may be involved in the regulated secretion of hormones.

Adrenal Glands↗
PubMed1995

Nitroglycerin inhibits the phosphorylation of intermediate filament proteins rather than myosin light chain on porcine coronary artery sustained contraction.

The smooth muscle relaxation induced by nitroglycerin is hypothesized to be mediated by an increase in the cytoplasmic concentration of guanosine 3',5'-monophosphate (cGMP) and subsequent dephosphorylation of the 20-kilodalton myosin light chain (MLC). We investigated this hypothesis in procine coronary arterial smooth muscle stimulated with histamine (3 microM) or K+ (30 mM). Stimulation of [32P]Pi-labeled muscle with histamine or K+ for 2 min resulted in a four- or 6.2-fold increase, respectively, in the incorporation of 32P into MLC. After 48 min of exposure to histamine, MLC phosphorylation decreased to the basal level and the phosphorylation of desmin, synemin, and of three unidentified cytosolic proteins was increased. K+ stimulation resulted in a sustained increase of MLC phosphorylation but had no effect on the phosphorylation of desmin, synemin, or the three unidentified cytosolic proteins. Application of nitroglycerin (1 microM) 48 min after histamine stimulation inhibited the phosphorylation of desmin, synemin, and the three cytosolic proteins. The sustained phase of histamine-induced contraction was also inhibited to a greater extent then the acute phase of histamine-induced contraction and both the acute and sustained phases of K(+)-induced contraction. These results suggest that MLC phosphorylation is required for both phases of K(+)-induced contraction, whereas phosphorylation of intermediate filament proteins is required for the sustained phase of histamine-induced contraction. Intermediate filament proteins, rather than MLC, may also be the target for the relaxant action of nitroglycerin during histamine-induced sustained contraction.

Animals↗
PubMed1995

Identification and characterization of two isoforms of an endothelin-converting enzyme-1.

We report the cloning and sequencing of 5'-terminal region of a beta form of rat ECE-1 cDNA which is different only in its N-terminal amino-acid sequence to the cDNA we have cloned previously (alpha form [K. Shimada et al. (1994) J. Biol. Chem. 269, 18275-18278]). No significant difference was found in the specific activity and substrate specificity between the two isoforms. The expression level of ECE-1 alpha mRNA was higher than that of ECE-1 beta in various rat cells and tissues, suggesting that the physiologically important isoform is ECE-1 alpha. The present findings verified the presence of two forms of ECE-1 over many species, which are created probably through alternative splicing.

Alternative Splicing↗
PubMed1995

Role of age on transmitral flow velocity patterns in assessing left ventricular diastolic function in normal infants and children.

This study demonstrated that both peak E and flow velocity integral of early diastole increased to reach the older children's values by 36 months of age and leveled off thereafter, whereas both peak A and flow velocity integral of atrial contraction had little change. These results suggest that age-related changes in E wave reflect the maturational or developmental alterations in LV diastolic properties, especially in the relaxation process.

Adolescent↗
PubMed1995

Diagnosis of HIV-1 infection with whole saliva by detection of antibody IgG to HIV-1 with ultrasensitive enzyme immunoassay using recombinant reverse transcriptase as antigen.

Whole-saliva samples were collected from 45 asymptomatic carriers, 18 patients with AIDS-related complex (ARC) or AIDS, and 76 medical students by simple spitting with no stimulation and tested by an ultrasensitive enzyme immunoassay (immune complex transfer enzyme immunoassay) for anti-HIV-1 IgG using recombinant reverse transcriptase as antigen and beta-D-galactosidase as label. With as little as 1 microliter of whole saliva, the lowest signals among the 45 asymptomatic carriers, 8 patients with ARC, and 10 patients with AIDS were 38-, 78-, and 3-fold, respectively, higher than the highest signal among the medical students. When the volume of whole saliva for test was increased up to 100 microliters, no significant effect was observed on signals for seropositive cases and signals for the medical students increased only very slightly. Therefore, whole-saliva samples containing extremely low levels of anti-HIV-1 IgG, even 2,000-fold lower than the lowest level among the 45 asymptomatic carriers tested, were considered to be discriminated from those of seronegative individuals. Thus, the sensitivity and specificity were expected to be both 100% with whole saliva even for a larger number of samples, although the number of samples tested was limited.

Adolescent↗
PubMed1995

Isolation of a cDNA clone encoding mouse 3-hydroxyacyl CoA dehydrogenase.

Rae-38, a cDNA clone isolated from mouse embryonal carcinoma F9 cells, was sequenced, and the deduced RAE-38 protein showed about 86% homology to pig 3-hydroxyacyl CoA dehydrogenase (HCDH; EC 1.1.1.35). This clone can be used to elucidate the regulatory mechanism of HCDH gene expression in mammals.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1995

Aldosterone inhibits nitric oxide synthesis in rat vascular smooth muscle cells induced by interleukin-1 beta.

We investigated the effects of aldosterone on nitric oxide (NO) synthesis in vascular smooth muscle cells. We measured the production of nitrite, a stable metabolite of NO, and the expression of inducible NO synthase mRNA and protein in cultured rat vascular smooth muscle cells. Incubation of the cultures with interleukin-1 beta (10 ng/ml) for 24 h caused a significant increase in nitrite generation. The interleukin-1 beta-induced nitrite production by vascular smooth muscle cells was significantly inhibited by aldosterone in a dose (10(-9) approximately 10(-6) M)-dependent manner. Incubation with interleukin-1 beta for 12 approximately 24 h caused inducible NO synthase mRNA expression in vascular smooth muscle cells, whereas aldosterone had a suppressive effect on its expression. Aldosterone also decreased interleukin-1 beta-induced NO synthase protein accumulation. These results indicate that aldosterone inhibits NO synthesis under interleukin-1 beta-stimulated conditions in vascular smooth muscle cells.

Aldosterone↗
PubMed1995

Freemartinism among singleton bovine females born from multiple embryo transfer.

Heterosexual chimerism among singleton females produced by multiple nonsexed embryo transfer (MNET singleton females) was investigated using chromosome typing and PCR (polymerase chain reaction)-amplification of male-specific DNA (msDNA). Of the 22 animals tested, 21 were classified as normal by both methods (i.e., showing no male cells among 100 metaphase spreads in chromosome typing and being msDNA negative in PCR). No morphological abnormalities of the genital organs were observed among 19 MNET single females. One MNET singleton female was, however, classified as a freemartin by PCR (male-specific DNA positive), but it was classified as normal cytogenetically. This individual probably had a low degree of heterosexual chimerism, and it seems that the chimerism derived from MNET was difficult to diagnose by chromosome typing, although it was detectable by PCR. The genital organs of this individual (15-mo-old Aberdeen Angus) were normal in form (both external and internal) and size. However, a very small structure, resembling seminiferous tubule, was found in the left ovary. It may be concluded that most MNET singleton females are expected to have normal reproductive function.

Journal Article↗
PubMed1995

Cloning and functional expression of human endothelin-converting enzyme cDNA.

Endothelin (ET) is a 21-residue potent vasoconstrictive peptide produced by vascular endothelial cells and formed from its precursor, big endothelin (big ET), by endothelin-converting enzyme (ECE). This paper describes the cloning and functional expression of a cDNA encoding a human ECE from human umbilical vein endothelial cells (HUVEC). Human ECE consists of 758 amino acid residues and has high homology to rat and bovine ECE. Immunoblot analysis using a monoclonal antibody risen against rat lung ECE showed the presence of immunoreactive protein in membrane fraction prepared from both HUVEC and COS-1 cells transfected with human ECE cDNA. Both COS-1 cells expressing human ECE and its membrane fraction converted big ET-1 most efficiently among big ETs.

Amino Acid Sequence↗
PubMed1995

Ouabain enhances nitric oxide synthesis in rat vascular smooth muscle cells induced by interleukin-1 beta.

Incubation of cultured rat vascular smooth muscle cells with interleukin-1 beta caused a significant increase in the production of nitrite, a stable metabolite of nitric oxide (NO), in time- and dose-dependent manners. Addition of ouabain to the culture further enhanced interleukin-1 beta-induced nitrite production. Similarly, interleukin-1 beta produced a significant increase in the cellular level of guanosine 3',5'-cyclic monophosphate, and the increase was significantly enhanced by coincubation with ouabain. The calcium ionophore ionomycin also significantly enhanced interleukin-1 beta-induced nitrite generation. These findings indicate that ouabain enhances NO synthesis in vascular smooth muscle cells induced by interleukin-1 beta, presumably through an increase in intracellular calcium ion concentrations.

Animals↗
PubMed1995

Studies on the metabolism of retinol and retinol-binding protein in transthyretin-deficient mice produced by homologous recombination.

Tissue needs for retinoids are believed to be satisfied through the delivery in the circulation of retinol by its specific plasma transport protein, retinol-binding protein (RBP), which circulates as a 1-to-1 protein complex with transthyretin (TTR). The binding of RBP to TTR is thought to prevent filtration of retinol-RBP in the kidney and to play a role in secretion of RBP from hepatocytes. Recently a strain of mice (TTR-) that totally lacks immunoreactive TTR was produced by targeted mutagenesis. We have explored the effects of TTR deficiency on retinol and RBP metabolism in this mutant strain. In pooled plasma from the TTR- mice retinol levels averaged 6% of those of wild type animals. Similarly, plasma RBP in the TTR- mice was found to be 5% of wild type levels. Hepatic retinol and retinyl ester levels were similar for mutant and wild type mice, suggesting that the mutation affects neither the uptake nor storage of dietary retinol. Levels of retinol and retinyl esters in testis, kidney, spleen, and eye cups from TTR- mice were normal. Plasma all-trans-retinoic acid levels for the TTR- mice were 2.3-fold higher than those of wild type (425 versus 190 ng/dl). Kidney RBP levels were similar for the mutant and wild type mice and we were unable to detect intact RBP in urine from TTR- mice. Hepatic RBP levels in the TTR- mice were 60% higher than those of wild type mice (39.8 versus 25.0 micrograms of RBP/g of tissue). These data may suggest that there is a partial blockage in RBP secretion from TTR- hepatocytes that leads to lessened plasma levels of retinol-RBP.

Animals↗
PubMed1995

Arborization of the inferior laryngeal nerve and internal nerve on the posterior surface of the larynx.

The morphological patterns of the inferior laryngeal nerve and internal laryngeal nerve display complex arborizations. This paper attempts to identify and clarify these patterns. Dissections were performed on 105 adult Japanese cadavers, and observations were made on 201 sides. Results showed that the communications between the inferior laryngeal nerve (ILN) and internal laryngeal nerve (ITLN) could be classified into two types and three subtypes. Also, the ITLN displayed three characteristic patterns at the arytenoid cartilage. These communications produce complex arborizations of the ILN as it enters the larynx. This may explain the variety of potential clinical symptoms observed after thyroid surgery or neck dissections.

Adult↗
PubMed1995

Expression of leukocyte chemotactic cytokines in myocardial tissue.

Cytotoxic action of leukocytes may be involved in the pathogenesis of inflammatory heart muscle disorders. We investigated the expression of rat leukocyte chemotactic cytokines--cytokine induced neutrophil chemoattractant (CINC) and JE--in cultured neonatal rat cardiac myocytes; CINC belongs to the interleukin 8 (IL-8) family and JE is a homologue of human monocyte chemoattractant protein 1 (MCP-1). In Northern blot analysis, CINC and JE transcripts were not clearly observed in unstimulated rat cardiac myocytes. However, their expression was clearly observed after exposure to tumour necrosis factor-alpha (TNF-alpha; 100 U/ml) for 2-6 h. We then evaluated IL-8 and MCP-1 mRNA expression in human endomyocardial biopsy specimens from seven patients with idiopathic dilated cardiomyopathy by polymerase chain reaction analysis. Both IL-8 and MCP-1 mRNA transcripts were recognized in all patients studied. These results show for the first time that leukocyte chemotactic cytokines, IL-8 and MCP-1, are expressed in myocardial tissue, which might contribute to the pathogenesis of inflammatory heart muscle disorders.

Animals↗