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Biomedical subjects

N Takagi

Publications and source records attributed to N Takagi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Native valve salvage for post-traumatic tricuspid regurgitation.

We describe two cases of successful management by native valve salvage of an uncommon tricuspid valve regurgitation following blunt chest trauma. The two patients were diagnosed 13 years and six years, respectively, after the trauma. In both cases, tricuspid valvular insufficiency was caused by anterior leaflet prolapse due to chordal and papillary muscle rupture associated with annular dilatation. Operative repair with implantation of artificial chordae, papillary muscle reinsertion and ring annuloplasty resulted in complete recovery. The need for increased awareness of this lesion in patients suffering blunt chest trauma is emphasized, and the relevant literature reviewed.

Adult↗
PubMed2001

[Long-term results of Rygg's monocusp ventricular outflow patch for the reconstruction of right ventricular outflow tract in tetralogy of Fallot].

Thirty surviving patients after corrective surgery for tetralogy of Fallot with right ventricular outflow tract reconstruction (RVOTR) using monocusp ventricular outflow patch (MVOP) were reviewed retrospectively to determine the long-term results. The age at operation ranged from 2 to 55 years with a mean of 19 years, and follow-up extended to 18.2 years (cumulative: 345.4 patient-year). There were 4 late deaths (1.2% per patient-year), and the cumulative survival rate was 85.3% at 18 years after the corrective surgery. Eight patients (2.3% per patient-year) required intracardiac reoperations mostly resulted from problems after RVOTR with MVOP, such as recurrent stenosis of right ventricular outflow tract (3 cases) or pulmonary valvular incompetence (4 cases). In addition, one patient underwent balloon angioplasty for the recurrent stenosis located in the distal end of MVOP. Freedom from surgical or catheter reintervention for the MVOP-related complication was 60.6% at 18 years after the corrective surgery. MVOP caused compression of the pulmonary artery at the distal end of the anastomosis and reoperation in a younger patients quite early after the corrective surgery. Like other transannular patches, tissue failure and degeneration of MVOP were inevitable, and resulted in severe pulmonary valvular incompetence that required the valve replacement in 4 patients (1.3% per patient-year). Freedom from pulmonary valve replacement was 71.2% at 18 years after the corrective surgery. As long-term results, our experiences emphasize the need for an innovative transannular patch that possesses significantly better long-term durability.

Adolescent↗
PubMed2001

[Case report of systemic lupus erythematosus patient with hemophagocytic syndrome, treated with plasma exchange, with specific reference to clinical profile and serum cytokine levels].

A 42-year-old woman was diagnosed as systemic lupus erythematosus (SLE), because of the findings of polyarthritis, leukopenia, positive antinuclear antibody, and positive anti DNA antibody. She was treated with predonisolone (PSL) at 10 mg per day. She was admitted to our hospital on October 2000 because of spiking high fever, skin eruption, and lymph node swelling. Since her illness of SLE was considered to be worsening, high dose of corticosteroids were given. However, high fever persisted and liver dysfunction was developed with increased serum ferritin. Her bone marrow smear showed hemophagocytosis. We made a diagnosis of hemophagocytic syndrome (HPS) complicated by disseminated intravascular coagulation (DIC). HPS was thought to be induced by viral infection, even though causative viral infection was not detected. Her general condition worsened with persistent high fever and liver dysfunction. Plasma exchange was carried for two consecutive days, followed by cyclosporine A and lipo-dexamethasone, which improved her fever rapidly. Her general condition gradually improved. Serum levels of ferritin, soluble interleukin 2 receptor (sIL 2-R), interferon-gamma and interleukin 6 decreased associated with improvements of her clinical condition. We thought plasma exchange could be effective to decrease serum levels of cytokine, which was suggested to be the pathogenic to HPS. However serum levels of IFN-gamma and IL 6 after plasma exchange did not change in this case. Further studies are required to confirm the effects of plasma exchange for HPS.

Adult↗
PubMed2000

Molecular and biochemical characterization of a serine proteinase predominantly expressed in the medulla oblongata and cerebellar white matter of mouse brain.

A full-length cDNA clone of a serine proteinase, mouse brain serine proteinase (mBSP), was isolated from a mouse brain cDNA library. mBSP, which has been recently reported to be expressed in the hair follicles of nude mice, is most similar (88% identical) in sequence to rat myelencephalon-specific protease. The mBSP mRNA was steadily expressed in the brain of adult mice with a transient expression in the early fetal stage during development. The genomic structure of the mouse gene for mBSP was determined. The gene, which is mapped to chromosome 7B4-B5, is about 7.4 kilobases in size and contains 7 exons. Interestingly, the 5'-untranslated region of the mBSP gene was interrupted by two introns. In situ hybridization analyses revealed that mBSP is expressed in the white matter of the cerebellum, medulla oblongata, and capsula interna and capsula interna pars retrolenticularis of mouse brain. Further, mBSP was immunolocalized to the neuroglial cells in the white matter of the cerebellum. Recombinant mBSP was produced in the bacterial expression system and activated by lysyl endopeptidase digestion, and the activated enzyme was purified for characterization. The enzyme showed amidolytic activities preferentially cleaving Arg-X bonds when 4-methylcoumaryl-7-amide-containing peptide substrates were used. Typical serine proteinase inhibitors, such as diisopropyl fluorophosphates, phenylmethanesulfonyl fluoride, soybean trypsin inhibitor, aprotinin, leupeptin, antipain, and benzamidine, strongly inhibited the enzyme activity. The recombinant mBSP effectively hydrolyzed fibronectin and gelatin, but not laminin, collagens I and IV, or elastin. These results suggest that mBSP plays an important role in association with the function of the adult mouse brain.

Animals↗
PubMed2000

The cell cycle control gene ZAC/PLAGL1 is imprinted--a strong candidate gene for transient neonatal diabetes.

We describe a screen for new imprinted human genes, and the identification in this way of ZAC (zinc finger protein which regulates apoptosis and cell cycle arrest)/ PLAGL1 (pleomorphicadenoma of the salivary gland gene like 1) as a strong candidate gene for transient neonatal diabetes mellitus (TNDM). To screen for imprinted genes, we compared parthenogenetic DNA from the chimeric patient FD and androgenetic DNA from hydatidiform mole, using restriction landmark genome scanning for methylation. This resulted in identification of two novel imprinted loci, one of which (NV149) we mapped to the TNDM region of 6q24. From analysis of the corresponding genomic region, it was determined that NV149 lies approximately 60 kb upstream of the ZAC / PLAGL1 gene. RT-PCR analysis was used to confirm that this ZAC / PLAGL1 is expressed only from the paternal allele in a variety of tissues. TNDM is known to result from upregulation of a paternally expressed gene on chromosome 6q24. The paternal expression, map position and known biological properties of ZAC / PLAGL1 make it highly likely that it is the TNDM gene. In particular, ZAC / PLAGL1 is a transcriptional regulator of the type 1 receptor for pituitary adenylate cyclase-activating polypeptide, which is the most potent known insulin secretagog and an important mediator of autocrine control of insulin secretion in the pancreatic islet.

Cell Cycle↗
PubMed2000

Maternally inherited X chromosome is not inactivated in mouse blastocysts due to parental imprinting.

Mouse embryos having an additional maternally inherited X chromosome (X(M)) invariably die before midgestation with the deficient extraembryonic ectoderm of the polar trophectoderm lineage, whereas postnatal mice having an additional paternally inherited X chromosome (X(P)) survive beyond parturition. A cytogenetic study led us to hypothesize that abnormal development of such embryos disomic for X(M) (DsX(M)) is attributable to two doses of active X(M) chromosome in extraembryonic tissues. To test the validity of this hypothesis, we examined the initial X chromosome inactivation pattern in embryos at the blastocyst stage by means of replication banding method as well as RNA FISH detecting Xist transcripts. X(P) was the only asynchronously replicating X chromosome, if any, in X(M)X(M)X(P) blastocysts, and no such allocyclic X chromosome was ever detected in X(M)X(M)Y blastocysts. In agreement with these findings, only one Xist paint signal was detected in 79% of X(M)X(M)X(P) cells, whereas no such signal was found in X(M)X(M)Y embryos. Thus, the present study supports the hypothesis that two X chromosomes remaining active in the extraembryonic cell lineages due to the maternal imprinting explain the underdevelopment of extraembryonic structures and hence early postimplantation death of DsX(M) embryos.

Aneuploidy↗
PubMed2000

Trans-mesosigmoid cutaneous ureterostomy.

BACKGROUND: A new method was developed in order to create a single stoma cutaneous ureterostomy in which both ureters traverse the abdominal cavity and yet are buttressed by the mesosigmoid and covered by its visceral peritoneum. METHODS: The long mesenterium which is attached to the most mobile part of the sigmoid colon was used for the bilateral ureteral pathway. Tunnels for the ureteral path were made just underneath the visceral peritoneum on the bilateral side of the mesosigmoid. Through the tunnels both ureteral ends were brought from the retroperitoneal space to the mesenterocolonic junction (MCJ) and the MCJ is then approximated and sutured to the inside of the ureteral tract through the abdominal wall. The ureters brought outside the skin, are conjoined and sutured to the V skin flap. Eight patients who carried a high risk for operation and/or had a bladder tumor judged to be incurable underwent this cutaneous ureterostomy. RESULTS: All cases except one with low urinary output could be managed without catheter indwelling during the follow-up period. Three patients suffered from paralytic ileus and one required laparotomy for mechanical ileus during the short postoperative period. Postoperative excretory urography evaluated 14 kidneys during the follow-up period from 2 to 61 months and showed normal upper urinary tract in 11 and a mildly hydronephrotic tract in three. CONCLUSIONS: Transmesosigmoid cutaneous ureterostomy provides a single catheterless stoma even when the available ureters are relatively short. It appears to be a good method for supravesical urinary diversion when indicated.

Aged↗
PubMed2000

Altered interaction between PSD-95 and the NMDA receptor following transient global ischemia.

The postsynaptic density (PSD) is a cytoskeletal specialization involved in the anchoring of neurotransmitter receptors and in regulating the response of postsynaptic neurons to synaptic stimulation. The postsynaptic protein PSD-95 binds to NMDA receptor subunits NR2A and NR2B and to signaling molecules such as neuronal nitric oxide synthase and p135synGAP. We investigated the effects of transient cerebral ischemia on protein interactions involving PSD-95 and the NMDA receptor in the rat hippocampus. Ischemia followed by reperfusion resulted in a decrease in the solubility of the NMDA receptor and PSD-95 in 1% sodium deoxycholate, the decrease being greater in the vulnerable CA1 hippocampal subfield than in the less sensitive CA3/dentate gyrus regions. Solubilization of the kainic acid receptor GluR6/7 and the PSD-95 binding proteins, neuronal nitric oxide synthase and p135synGAP, also decreased following ischemia. The association between PSD-95 and NR2A and NR2B, as indicated by coimmunoprecipitation, was less in postischemic samples than in sham-operated controls. Ischemia also resulted in a decrease in the size of protein complexes containing PSD-95, but had only a small effect on the size distribution of complexes containing the NMDA receptor. The results indicate that molecular interactions involving PSD-95 and the NMDA receptor are modified by an ischemic challenge.

Animals↗
PubMed2000

Altered association of protein tyrosine kinases with postsynaptic densities after transient cerebral ischemia in the rat brain.

Transient cerebral ischemia results in an increase in the tyrosine phosphorylation of proteins associated with postsynaptic densities (PSDs). The authors investigated the possible mechanisms behind this increase by analyzing isolated PSDs for protein tyrosine kinase activity and for the presence of specific tyrosine kinases. Transient (15 minutes) global ischemia was produced in adult rats by four-vessel occlusion, and PSDs were isolated immediately after ischemia or after 20 minutes or 6 hours of reperfusion. Tyrosine phosphorylation of several PSD proteins, including the N-methyl-D-aspartate (NMDA) receptor subunits NR2A and NR2B, was enhanced relative to shams after 20 minutes of reperfusion and underwent a further increase between 20 minutes and 6 hours. The ability of intrinsic PSD tyrosine kinase to phosphorylate PSD proteins, including the NMDA receptor, increased threefold after ischemia. Whereas PSD-associated proline-rich tyrosine kinase 2 (PYK2) and gp145TrkB were elevated immediately after the ischemic event, increases in Src and Fyn were not apparent until 6 hours of reperfusion. The level of PSD-associated pp125FAK decreased after ischemia. The results demonstrate that ischemia results in selective changes in the association of protein tyrosine kinases with the PSD which may account for ischemia-induced increases in the tyrosine phosphorylation of PSD proteins.

Animals↗
PubMed2000

Imprint switching for non-random X-chromosome inactivation during mouse oocyte growth.

In mammals, X-chromosome inactivation occurs in all female cells, leaving only a single active X chromosome. This serves to equalise the dosage of X-linked genes in male and female cells. In the mouse, the paternally derived X chromosome (X(P)) is imprinted and preferentially inactivated in the extraembryonic tissues whereas in the embryonic tissues inactivation is random. To investigate how X(P) is chosen as an inactivated X chromosome in the extraembryonic cells, we have produced experimental embryos by serial nuclear transplantation from non-growing (ng) oocytes and fully grown (fg) oocytes, in which the X chromosomes are marked with (1) an X-linked lacZ reporter gene to assay X-chromosome activity, or (2) the Rb(X.9)6H translocation as a cytogenetic marker for studying replication timing. In the extraembryonic tissues of these ng/fg embryos, the maternal X chromosome (X(M)) derived from the ng oocyte was preferentially inactivated whereas that from the fg oocyte remained active. However, in the embryonic tissues, X inactivation was random. This suggests that (1) a maternal imprint is set on the X(M) during oocyte growth, (2) the maternal imprint serves to render the X(M) resistant to inactivation in the extraembryonic tissues and (3) the X(M) derived from an ng oocyte resembles a normal X(P).

Amnion↗
PubMed2000

X-chromosome inactivation in XX androgenetic mouse embryos surviving implantation.

Using genetic and cytogenetic markers, we assessed early development and X-chromosome inactivation (X-inactivation) in XX mouse androgenones produced by pronuclear transfer. Contrary to the current view, XX androgenones are capable of surviving to embryonic day 7.5, achieving basically random X-inactivation in all tissues including those derived from the trophectoderm and primitive endoderm that are characterized by paternal X-activation in fertilized embryos. This finding supports the hypothesis that in fertilized female embryos, the maternal X chromosome remains active until the blastocyst stage because of a rigid imprint that prevents inactivation, whereas the paternal X chromosome is preferentially inactivated in extra-embryonic tissues owing to lack of such imprint. In spite of random X-inactivation in XX androgenones, FISH analyses revealed expression of stable Xist RNA from every X chromosome in XX and XY androgenonetic embryos from the four-cell to morula stage. Although the occurrence of inappropriate X-inactivation was further suggested by the finding that Xist continues ectopic expression in a proportion of cells from XX and XY androgenones at the blastocyst and the early egg cylinder stage, a replication banding study failed to provide positive evidence for inappropriate X-inactivation at E6. 5.

Animals↗
PubMed2000

Acquired anomalous intrapulmonary venous connection secondary to pulmonary venous stenosis.

An unusual case of acquired development of anomalous intrapulmonary venous connection with pulmonary venous stenosis is presented. Appearances on a chest radiograph resembled the "scimitar" sign in a patient with previous surgery for partial anomalous pulmonary venous return. Spiral CT and pulmonary arteriography showed stenosis of the right upper pulmonary vein and an anomalous intrapulmonary venous connection between the right upper pulmonary vein and the right lower pulmonary vein. We consider the slow progression of pulmonary vein stenosis led to anomalous intrapulmonary venous connection as an intrapulmonary collateral.

Adult↗
PubMed2000

Diabetes mellitus associated with rapidly progressive glomerulonephritis with perinuclear antineutrophil cytoplasm antibodies.

A 55-year-old woman who had been treated for diabetes mellitus for twenty-five years developed interstitial pneumonia and rapidly progressive glomerulonephritis (RPGN). The findings of light microscopy revealed fibrocellular crescent formation in all glomeruli and infiltration of lymphoid cells in interstitium. There were no deposits in the intracapillary area and mesangial area on both immunofluorescence and electron microscopy. Her interstitial pneumonia improved with pulse therapy of methylprednisolone and her hematuria disappeared with mix treatment of cyclophosphamide and double filtration plasmapheresis (DFPP). Her serum creatinine level improved from 2.2 mg/dl to 1.5 mg/dl. Interstitial pneumonia and hematuria did not recur at twelve months after the first hospitalization. This report presents a rare case with RPGN associated with diabetes mellitus who recovered with combination therapy of cyclophosphamide, steroid and DFPP.

Acute Kidney Injury↗
PubMed2000

X chromosome inactivation revealed by the X-linked lacZ transgene activity in periimplantation mouse embryos.

Using H253 mouse stock harboring X-linked HMG-lacZ transgene, we examined X chromosome inactivation patterns in sectioned early female embryos. X-gal staining patterns were generally consistent with the paternal X inactivation in the trophectoderm and the primitive endoderm cell lineages and random inactivation in the epiblast lineages. The occurrence of embryonic visceral endoderm cells apparently at variance with the paternal X chromosome inactivation in 7.5 dpc embryos was explained by the replacement of visceral endoderm cells with cells of epiblast origin. The frequency of cells negative for X-gal staining in 4.5-5.5 dpc XmXp* embryos fluctuated considerably especially in the extraembryonic ectoderm and the primitive endoderm, whereas it was less variable in the embryonic ectoderm. We could not, however, determine whether it is a normal phenomenon revealed for the first time by the use of HMG-lacZ transgene or an abnormality caused by the multicopy transgene.

Animals↗
PubMed1999

Detection and cloning of an X-linked locus associated with a NotI site that is not methylated on mouse inactivated X chromosome by the RLGS-M method.

In looking for genes that escape X chromosome inactivation, we scanned the methylation status of genomic DNA from XX, X0, and XY mice using the method of restriction landmark genomic scanning using methylation-sensitive endonuclease. We detected and cloned a candidate locus and identified the Orf1 gene. Orf1 has sequence similarities to the B2 repetitive element and human CXORF4 (formerly called EXLM1), which escapes X inactivation. The B2 element spans the 3' terminus of the ORF and the 3' UTR of Orf1. The Orf1 gene encompasses 18.5 kb of genomic DNA including 11 exons and 10 introns. Taking advantage of genomic polymorphisms present between MSM and C3H/He, we showed that murine Orf1 is mapped to the proximal region of the X chromosome. Despite the unmethylation of the NotI site, Orf1 is subject to X inactivation.

Amino Acid Sequence↗