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Biomedical subjects

T Abe

Publications and source records attributed to T Abe.

At least 163 records · Page 9Linked to original sources
PubMed2002

Significance of distal fenestration in graft replacement for chronic aortic dissection.

It is recently controversial whether distal fenestration is necessary in graft replacement for chronic aortic dissection. Several groups started to try the exclusion of intimal entry by the insertion of a stent-graft as a treatment for chronic aortic dissection, while conventional surgical techniques consisted of graft replacement with distal anastomosis to both the true and false channels. It should be kept in mind that the resultant occlusion of the false lumen after obliteration of the false channel could promote spinal cord ischemia. We report a patient with delayed paraplegia after graft replacement without distal fenestration for chronic type B aortic dissection. It is possible that not all cases of chronic aortic dissection are good for stent-grafting.

Aortic Dissection↗
PubMed2002

[Antegrade selective cerebral perfusion for extended total arch replacement using separated graft technique; reassessment from the type of aneurysms and dissections].

One hundred eighty two patients with thoracic aortic aneurysms or dissections who required total arch replacement (TAR) were operated on with separated graft technique and selective cerebral perfusion (SCP) between 1991 and 2000. These patients were divided into 4 groups according to the pathology as follows: group 1; acute type A dissection, group 2; chronic type A dissection, group 3; distal arch aneurysm and group 4; proximal arch aneurysm. For SCP, both the innominate artery and the left common carotid artery were cannulated when the patient was cooled to a rectal temperature of 22 degrees C. Hospital mortalities were 27% in group 1, 14% in group 2, 19% in group 3, and 8% in group 4. Independent predictors of hospital mortality were shock, visceral, and leg ischemia in group 1, and circulatory arrest time of the lower half body to be more than 1 hour and cardiopulmonary bypass time to be more than 5 hours in group 3. Permanent neurological complication occurred in 3% in group 1 and 8% in group 3. Hospital mortality was affected by the type of aneurysms and dissections. It is necessary to give careful consideration to the indication of TAR with SCP, especially in acute type A dissection and distal arch aneurysm.

Aged↗
PubMed2001

Chromosomal aberrations in colorectal cancers and liver metastases analyzed by comparative genomic hybridization.

Comparative genomic hybridization (CGH) was used to screen for changes in the number of DNA sequence copies in 30 primary colorectal cancers and 16 liver metastases, to identify regions that contain genes important for the development and progression of colorectal cancer. In primary colorectal cancer, we found frequent gains at 7p21 (36.7%), 7q31-36 (30%), 8q23-24 (43.0%), 12p (30%), 14q24-32 (33.3%), 16p (40.0%), 20p (33.3%), 20q (63.3%) and 21q (36.3%), while loss was often noted at 18q12-23 (36.7%). In metastatic tumors, there were significantly more gains and losses of DNA sequences than in primary tumors, with gains at 8q23-24 (found in 62.5% of recurrences vs. 43.0% of primary tumors), 15q21-26 (37.5% vs. 20.0%), 19p (43.8% vs. 20.0%) and 20q (81.3% vs. 63.3%) and losses at 18q12-23 (50.0% vs. 36.7%). The pattern of genetic changes seen in metastatic tumors, with frequent gains at 8q23-24 and 20q and loss at 18q12-23, suggests the progression of colorectal cancer. We investigated a clinical follow-up study for all patients examined by CGH and directed our attention to the genetic changes consisting of gains at 8q and 20q. The incidence of liver metastases was higher in patients with primary colorectal cancer with these genetic changes. Gains at 8q and 20q might be useful to identify patients at high risk for developing liver metastases.

Chromosome Aberrations↗
PubMed2001

Reduction in asymmetrical dimethylarginine, an endogenous nitric oxide synthase inhibitor, in the cerebrospinal fluid during aging and in patients with Alzheimer's disease.

To investigate the significance of nitric oxide (NO) -mediated neuron death in aging and Alzheimer's disease (AD), the concentration of asymmetrical dimethylarginine (ADMA), an endogenous NO synthase inhibitor, in the cerebrospinal fluid was determined in neurologically normal controls and patients with AD. The ADMA concentration significantly decreased with age, whereas the arginine concentration was unaltered. In patients with AD, the ADMA concentration was significantly decreased, compared with controls of a similar age (-48%, P=0.0001), and it significantly decreased with decreasing cognitive functions (r(s)=0.58, P<0.05), whereas the arginine concentration did not change. These findings suggest that ADMA may play an important role in regulating NO synthesis in brain aging and AD.

Aged↗
PubMed2001

Analysis of codon usage diversity of bacterial genes with a self-organizing map (SOM): characterization of horizontally transferred genes with emphasis on the E. coli O157 genome.

With increases in the amounts of available DNA sequence data, it has become increasingly important to develop tools for comprehensive systematic analysis and comparison of species-specific characteristics of protein-coding sequences for a wide variety of genomes. In the present study, we used a novel neural-network algorithm, a self-organizing map (SOM), to efficiently and comprehensively analyze codon usage in approximately 60,000 genes from 29 bacterial species simultaneously. This SOM makes it possible to cluster and visualize genes of individual species separately at a much higher resolution than can be obtained with principal component analysis. The organization of the SOM can be explained by the genome G+C% and tRNA compositions of the individual species. We used SOM to examine codon usage heterogeneity in the E. coli O157 genome, which contains 'O157-unique segments' (O-islands), and showed that SOM is a powerful tool for characterization of horizontally transferred genes.

Algorithms↗
PubMed2001

Polymerase chain reaction for detection of carcinoembryonic antigen-expressing tumor cells on milky spots of the greater omentum in gastric cancer patients: a pilot study.

Our recent studies indicate that omental milky spots are frequently involved in the early stage of peritoneal cancer dissemination. We have used carcinoembryonic antigen (CEA)-specific RT-PCR for omental milky spots to predict peritoneal recurrence in gastric cancer patients. CEA mRNA was found to be positive in both 10 peritoneal washes and 16 greater omenta of 30 gastric cancer patients, including all 6 patients who showed positive results for both cytology and RT-PCR of peritoneal wash and omentum. Three of the 6 cases with positive RT-PCR in the greater omentum but not in the peritoneal wash showed recurrence of peritoneal carcinomatosa within 2 years after operation. Micrometastasis on omental milky spots was histologically confirmed in 6 of 30 gastric cancer cases. Non-specific band was detected only in the omentum of 1 case of 15 benign disease (7%), but not in peritoneal washes (0%), probably due to weak expression of CEA in mesothelial cells. Our results show that CEA-specific RT-PCR targeting micro-metastases on omental milky spots is more sensitive than targeting the peritoneal wash or conventional cytology, and suggest that this method is useful for the prediction of peritoneal recurrence in gastric cancer patients.

Adult↗
PubMed2001

Evidence for the association of ultraviolet-C and H(2)O(2)-induced apoptosis with acid sphingomyelinase activation.

Ceramide appears to be a potent second messenger implicated in the regulation of diverse cellular processes such as cell growth and differentiation, gene transcription, ligand binding, and cell death. Environmental stress-induced apoptosis is believed to be associated with the sphingomyelin degradation pathway, which generates ceramide as a second messenger in initiating the apoptosis response. To date, two distinct sphingomyelinases, a lysosomal acid sphingomyelinase (ASM), which is deficient in patients affected with types A and B Niemann-Pick disease (NPD), and a neutral, magnesium-dependent sphingomyelinase (NSM), are candidate enzymes which respond to apoptotic stimulations and cause sphingomyelin hydrolysis and subsequent ceramide generation. Using Epstein-Barr virus (EBV)-transformed lymphoblast cells from type A NPD patient which have defined splicing site mutation in the ASM gene, we showed that ASM-deficient cells were defective in ultraviolet-C (UV-C) and hydrogen peroxide (H(2)O(2)) induced apoptosis. As another induction of apoptosis, we exposed this cell line to serum starvation which influences to p53 expression and leads to apoptosis. There were no differences by the degree of apoptosis between ASM-deficient lymphoblast cells and normal lymphoblast cells. These results are evidence that ASM plays one of the important roles in apoptosis induction by UV-C and H(2)O(2).

Alternative Splicing↗
PubMed2001

Separation of perfluoroalkylsulfinic acids and perfluoroalkylsulfonic acids by ion-exclusion chromatography.

Ion-exclusion chromatography has been successfully applied to the separation of a number of perfluoroalkylsulfinic acids and perfluoroalkylsulfonic acids. The separation of various perfluoroalkylsulfinic and perfluoroalkylsulfonic acids, with different alkyl groups, was investigated on a polymethacrylate-based, weakly acidic, cation-exchange resin (TSK gel OApak-A) in the H+-form and using conductimetric detection. When water was used as the eluent, these perfluoroalkylsulfinic and perfluoroalkylsulfonic acids could not be resolved. When an aqueous solution of benzoic acid and o-phthalic acid was used, the separation of each of these acids occurred. In order to improve their separation, the effect of the addition of methanol and 2,2,2-trifluoroethanol, as organic modifiers, was also investigated.

Calibration↗
PubMed2001

Intermonomer interactions in dimer of bovine heart cytochrome c oxidase.

The X-ray structure of bovine heart cytochrome c oxidase solved for orthorhombic crystals showed a dimeric structure stabilized by four subunit-subunit contacts, namely, subunit Vb-subunit Vb on the matrix side, subunit I-subunit VIa, subunit VIa-subunit I in the transmembrane region and subunit VIb-subunit VIb on the intermembrane side. The same intermonomer contacts as in the orthorhombic crystals were observed in both hexagonal and tetragonal crystals, the X-ray structures of which were determined by the molecular-replacement method. These results suggest that the dimeric structure also exists under physiological conditions. These contacts, especially the subunit IVa-subunit I contact, in which the N-terminal portion of subunit IVa is placed on the surface of subunit I near the dioxygen-reduction site, indicate that the function of the bovine heart enzyme is likely to be controlled by perturbation of the monomer-monomer association.

Animals↗
PubMed2001

Determination of hydrogen sulfide and acid-labile sulfur in animal tissues by gas chromatography and ion chromatography.

A sensitive and reliable method was developed for the determination of hydrogen sulfide and acid-labile sulfur (ALS) in animal tissues using gas chromatography with flame photometric detector (GC-FPD) and ion chromatography (IC). Hydrogen sulfide trapped in alkaline solution was determined by GC-FPD as hydrogen sulfide or by IC as sulfate after oxidation with hydrogen peroxide. Sodium sulfide used as a source of hydrogen sulfide was standardized by IC. Fresh rat liver and heart tissues contained 112.2+/-23.0 and 274.1+/-34.6 nmol/g of ALS respectively. Free hydrogen sulfide was not detected.

Acids↗
PubMed2001

A missense mutation in the Na(+)/glucose cotransporter gene SGLT1 in a patient with congenital glucose-galactose malabsorption: normal trafficking but inactivation of the mutant protein.

The Na(+)/glucose cotransporter gene SGLT1 was analyzed in a Japanese patient with congenital glucose-galactose malabsorption. Genomic DNA was used as a template for amplification by the polymerase chain reaction of each of the 15 exons of SGLT1. The amplification products were cloned and sequenced. About half of the exon 5 clones of the patient contained a C-->T transition, resulting in an Arg(135)-->Trp mutation, whereas the remaining clones contained the normal exon 5 sequence. In addition, whereas some exon 12 clones exhibited the normal sequence, others showed a CAgtaggtatcatc-->CAgacc mutation at the splice donor site of intron 12 that may result either in the skipping of exon 12 or in read-through of intron 12. Neither the Arg(135)-->Trp mutant nor either of the possible intron 12 mutant proteins exhibited Na(+)-dependent glucose transport activity when expressed in Xenopus oocytes. Immunocytochemical analysis indicated, however, that the Arg(135)-->Trp mutant was localized to the oocyte plasma membrane. DNA sequence analysis revealed that the missense mutation in exon 5 and the splice site mutation in intron 12 were inherited from the proband's father and mother, respectively. These results indicate that the patient is a compound heterozygote for this disease, and that the Arg(135)-->Trp mutant of SGLT1 undergoes normal trafficking to the plasma membrane but is non-functional.

Animals↗
PubMed2001

Effect of fluorination: gas-phase structures of N,N-dimethylvinylamine and perfluoro-N,N-dimethylvinylamine.

The gas-phase structures of N,N-dimethylvinylamine, (CH(3))(2)NC(H)=CH(2) (1), and perfluoro-N,N-dimethylvinylamine, (CF(3))(2)NC(F)=CF(2) (2), were determined by gas electron diffraction and quantum chemical methods (B3LYP and MP2 with 6-31G basis sets). The configuration around nitrogen is slightly pyramidal in both compounds, with the sum of the nitrogen bond angles 351.2(12) degrees and 354.8(6) degrees in 1 and 2, respectively. In the parent compound 1, the (CH(3))(2)N group lies nearly in the plane of the vinyl group, and the nitrogen lone pair (lp) is almost perpendicular to this plane (Phi(C=C-N-lp) = 98(6) degrees). In the perfluorinated species 2, however, the (CF(3))(2)N group is oriented perpendicular to the vinyl plane, and the lone pair is parallel to the C=C bond (Phi(C=C-N-lp) = 2(5) degrees). A natural bond orbital analysis provides a qualitative explanation for this conformational change upon fluorination. The sterically unfavorable in-plane orientation of the dimethylamino group in 1 is stabilized by conjugation between the nitrogen lone pair and the C=C pi-bond. The anomeric effect between the lone pair and the C(alpha)-F sigma-bond in addition to steric effects favors the perpendicular orientation of the (CF(3))(2)N group in 2. Both quantum chemical methods reproduce the experimental structures satisfactorily.

Journal Article↗
PubMed2001

Adhesion of adenosine diphosphate-activated platelets to human brain microvascular endothelial cells under flow in vitro is mediated via GPIIb/IIIa.

Employing video-enhanced contrast (VEC) microscopy, we examined whether TAK-029 (GPIIb/IIIa antagonist) inhibits the adhesion of activated platelets to human brain microvascular endothelial cells (HBEC) in vitro. HBECs were cultured on a coverglass and put in the observation chamber of VEC microscopy. Then, activated platelets by adenosine diphosphate (ADP) (2 microM) were perfused over HBEC at a low shear rate of 10 s(-1) for 30 min and washed out. Platelets adhered directly to HBEC. However, platelet adhesion to HBEC was suppressed when platelet rich plasma with ADP (2 microM) plus TAK-029 (GPIIb/IIIa antagonist; 1 microM) was perfused over HBEC for 30 min and washed out. Anti-GPIbalpha antibody (GUR20-5) did not inhibit adhesion of ADP-activated platelets to HBEC. The above results showed adhesion of ADP-activated platelets to HBEC under flow in vitro is mediated via GPIIb/IIIa

Adenosine Diphosphate↗
PubMed2001

Tumour-amplified kinase BTAK is amplified and overexpressed in gastric cancers with possible involvement in aneuploid formation.

Our recent analysis of gastric cancers using comparative genomic hybridization (CGH) revealed a novel high frequent copy number increase in the long arm of chromosome 20. Tumour-amplified kinase BTAK was recently cloned from breast cancers and mapped on 20q13 as a target gene for this amplification in human breast cancers. In the study presented here, we analysed BTAK copy-number and expression, and their relation to the ploidy pattern in 72 primary gastric cancers. Furthermore, wild-type BTAK and its deletion mutants were transfected to gastric cancers to examine changes in cell proliferation and DNA ploidy pattern. Evaluation of 72 unselected primary gastric cancers found BTAK amplification in 5% and overexpression in more than 50%. All four clinical samples with BTAK amplification showed aneuploidy and poor prognosis. Transfection of BTAK in near-diploid gastric cancers induced another aneuploid cell population. In contrast, the c-terminal-deleted mutant of BTAK induced no effect in DNA ploidy pattern and inhibited gastric cancer cell proliferation. These results suggest that BTAK may be involved in gastric cancer cell aneuploid formation, and is a candidate gene for the increase in the number of copies of the 20q, and thus may contribute to an increase in the malignant phenotype of gastric cancer.

Adult↗
PubMed2001

An SH2-domain-containing kinase negatively regulates the phosphatidylinositol-3 kinase pathway.

SHK1 is a novel dual-specificity kinase that contains an SH2 domain in its C-terminal region. We demonstrate that SHK1 is required for proper chemotaxis and phagocytosis. Mutant shk1 null cells lack polarity, move very slowly, and exhibit an elevated and temporally extended chemoattractant-mediated activation of the kinase Akt/PKB. GFP fusions of the PH domain of Akt/PKB or the PH-domain-containing protein CRAC, which become transiently associated with the plasma membrane after a global stimulation with a chemoattractant, remain associated with the plasma membrane for an extended period of time in shk1 null cells. These results suggest that SHK1 is a negative regulator of the PI3K (phosphatidylinositol-3 kinase) pathway. Furthermore, when a chemoattractant gradient is applied to a wild-type cell, these PH-domain-containing proteins and the F-actin-binding protein coronin localize to its leading edge, but in an shk1 null cell they become randomly associated with the plasma membrane and cortex, irrespective of the direction of the chemoattractant gradient, suggesting that SHK1 is required for the proper spatiotemporal control of F-actin levels in chemotaxing cells. Consistent with such functions, SHK1 is localized at the plasma membrane/cortex, and we show that its SH2 domain is required for this localization and the proper function of SHK1.

Actins↗