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Biomedical subjects

A Ishikawa

Publications and source records attributed to A Ishikawa.

At least 109 records · Page 6Linked to original sources
PubMed2002

Biliary papillary neoplasm of the liver.

Biliary papillary neoplasia of the liver characterized by intraductal papillary growth of neoplastic biliary epithelia with a fine fibrovascular stalk has been sporadically reported, and includes intraductal growing cholangiocarcinoma and biliary papillomatosis. In addition, biliary papillary dysplasia and in situ and microinvasive carcinoma with papillary configuration reported in hepatolithiasis and in other chronic biliary diseases, could be included in this category. Usually, they arise in the intrahepatic large bile ducts, and the neoplastic and non-neoplastic parts of the intrahepatic biliary tree show saccular and segmental dilatation with mucin hypersecretion. This neoplasia frequently shows intraductal spreading and peribiliary glandular involvement. Acute repeated episodes of cholangitis or obstructive jaundice are a frequent clinical manifestation. Gastroenteric metaplasia with aberrant expression of cytokeratin 20, MUC2, MUC5AC, and/or MUC6, is frequent in the neoplastic parts, and biliary epithelial dysplasia with such metaplasia may give rise to in situ and then invasive carcinoma in hepatolithiasis. Interestingly, this type tends to contain foci of mucinous carcinoma elements, and this element may be predominant (mucinous carcinoma). Some may progress to "mucinous biliary cystadenocarcinoma" without ovarian mesenchymal stroma and with intraluminal continuous growth into the neighboring bile duct lumens. Interestingly, the biliary papillary neoplasm resembles histologically, phenotypically and clinically intraductal papillary mucinous neoplasm of the pancreas which is now being established as an infrequent, slow-growing pancreatic neoplasm. Recognition of such biliary papillary neoplasm with respect to the pancreatic equivalent may lead to a better understanding and further studies of the intrahepatic biliary neoplasm.

Aged↗
PubMed2001

Observation of the decay B --> Kl+l-.

We report a search for the flavor-changing neutral current decay B-->K(*)l+l- using a 29.1 fb(-1) data sample accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e+e- storage ring. We observe the decay process B-->Kl+l-(l = e, mu), for the first time, with a branching fraction of B(B-->Kl+l-) = (0.75(+0.25)(-0.21)+/-0.09)x10(-6).

Journal Article↗
PubMed2001

Complete genomic sequence of the filamentous nitrogen-fixing cyanobacterium Anabaena sp. strain PCC 7120.

The nucleotide sequence of the entire genome of a filamentous cyanobacterium, Anabaena sp. strain PCC 7120, was determined. The genome of Anabaena consisted of a single chromosome (6,413,771 bp) and six plasmids, designated pCC7120alpha (408,101 bp), pCC7120beta (186,614 bp), pCC7120gamma (101,965 bp), pCC7120delta (55,414 bp), pCC7120epsilon (40,340 bp), and pCC7120zeta (5,584 bp). The chromosome bears 5368 potential protein-encoding genes, four sets of rRNA genes, 48 tRNA genes representing 42 tRNA species, and 4 genes for small structural RNAs. The predicted products of 45% of the potential protein-encoding genes showed sequence similarity to known and predicted proteins of known function, and 27% to translated products of hypothetical genes. The remaining 28% lacked significant similarity to genes for known and predicted proteins in the public DNA databases. More than 60 genes involved in various processes of heterocyst formation and nitrogen fixation were assigned to the chromosome based on their similarity to the reported genes. One hundred and ninety-five genes coding for components of two-component signal transduction systems, nearly 2.5 times as many as those in Synechocystis sp. PCC 6803, were identified on the chromosome. Only 37% of the Anabaena genes showed significant sequence similarity to those of Synechocystis, indicating a high degree of divergence of the gene information between the two cyanobacterial strains.

Anabaena↗
PubMed2001

Tetracycline-regulated gene expression mediated by a novel chimeric repressor that recruits histone deacetylases in mammalian cells.

Regulated gene expression will provide important platforms from which gene functions can be investigated and safer means of gene therapy may be developed. Histone deacetylases have recently been shown to play an important role in regulating gene expression. Here we investigated whether a more tightly controlled expression could be achieved by using a novel chimeric repressor that recruits histone deacetylases to a tetracycline-responsive promoter. This chimeric repressor was engineered by fusing the tetracycline repressor (TetR) with an mSin3-interacting domain of human Mad1 and was shown to bind the tetO(2) element with high affinity, and its binding was efficiently abrogated by doxycycline. The chimeric repressor was shown to directly interact with mSin3 of the histone deacetylase complex. This inducible system was further simplified by using a single vector that contained both a chimeric repressor expression cassette and a tetracycline-responsive promoter. When transiently introduced into mammalian cells, the chimeric repressor system exhibited a significantly lower basal level of luciferase activity (up to 25-fold) than that of the TetR control. When stably transfected into HEK 293 cells, the chimeric repressor system was shown to exert a tight control of green fluorescent protein expression in a doxycycline dose- and time-dependent fashion. Therefore, this novel chimeric repressor provides an effective means for more tightly regulated gene expression, and the simplified inducible system may be used for a broad range of basic and clinical studies.

Base Sequence↗
PubMed2001

Observation of B --> J/psi K(1)(1270).

We report the first observation of the exclusive decay process B-->J/psi K(1)(1270) using a sample of 11.2M BB macro meson pairs collected in the Belle detector at the KEKB asymmetric energy e(+)e(-) collider. We measure branching fractions of B[B(0)-->J/psi K(0)(1)(1270)] = (1.30+/-0.34+/-0.32) x 10(-3) and B[B(+)-->J/psi K(+)(1)(1270)] = (1.80+/-0.34+/-0.39) x 10(-3), where the first error is statistical and the second is systematic. These modes constitute approximately 15% of the total number of B-->J/psi X decays. No evidence is seen for B-->J/psi K(1)(1400) and we set an upper limit for this branching fraction.

Journal Article↗
PubMed2001

Neurons in the lateral paragigantocellular nucleus projecting to the infralimbic cortex in rats: electrical activity and response to changes in blood pressure.

Neurons in the lateral paragigantocellular nucleus (LPGi) are known to project directly to the infralimbic cortex (IL). However, there have been no physiological studies on LPGi neurons projecting to the IL. In urethane-anesthetized rats, the single-unit activities of LPGi neurons were recorded extracellularly to investigate their electrophysiological properties and responses to changes in blood pressure (BP). The LPGi neurons antidromically driven from the IL were restricted to the ventral part of the LPGi and most spontaneously active neurons revealed suppression of activity following a fall in BP. These results suggest that the LPGi neurons in a very restricted location influence the IL in response to changes in BP.

Action Potentials↗
PubMed2001

Observation of Cabibbo suppressed B --> D(*)K- decays at Belle.

We report observations of the Cabibbo suppressed decays B-->D((*))K- using a 10.4 fb(-1) data sample accumulated at the Upsilon(4S) resonance with the Belle detector at the KEKB e(+)e(-) storage ring. We find that the ratios of Cabibbo suppressed to Cabibbo favored branching fractions are B(B--->D0K-)/B(B--->D0pi(-)) = 0.079+/-0.009+/-0.006, B(B(0)-->D+K-)/B(B(0)-->D+pi(-)) = 0.068+/-0.015+/-0.007, B(B--->D(*0)K-)/B(B--->D(*0)pi(-)) = 0.078+/-0.019+/-0.009, and B(B(0)-->D(*+)K-)/B(B(0)-->D(*+)pi(-)) = 0.074+/-0.015+/-0.006. These are the first observations of the B-->D+K-, D(*0)K-, and D(*+)K- decay processes.

Journal Article↗
PubMed2001

Observation of large CP violation in the neutral B meson system.

We present a measurement of the standard model CP violation parameter sin2 phi(1) based on a 29.1 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. One neutral B meson is fully reconstructed as a J/psi K(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psi K(L), or J/psi K(*0) decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin2 phi(1) = 0.99+/-0.14(stat)+/-0.06(syst). We conclude that we have observed CP violation in the neutral B meson system.

Journal Article↗
PubMed2001

Measurement of B(0)(d)-B_(0)(d) mixing rate from the time evolution of dilepton events at the upsilon(4S).

We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.

Journal Article↗
PubMed2001

Measurement of the CP violation parameter sin2 phi(1) in B(0)(d) meson decays.

We present a measurement of the standard model CP violation parameter sin2 phi(1) (also known as sin2beta) based on a 10.5 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. One neutral B meson is reconstructed in the J/psiK(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psiK(L), or J/psipi(0) CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its charged particle decay products. From the asymmetry in the distribution of the time interval between the two B-meson decay points, we determine sin2 phi(1) = 0.58(+0.32)(-0.34)(stat)+0.09-0.10(syst).

Journal Article↗
PubMed2001

Prolonged survival of mouse epididymal spermatozoa stored at room temperature.

The viability and fertility of isolated mouse epididymal spermatozoa kept for up to 7 days at various temperatures (4 degrees C, 22 degrees C, and 37 degrees C) were determined. Spermatozoa kept for 3 days at 22 degrees C were still active, while those kept at 37 degrees C or 4 degrees C exhibited great reduction in motility within 2 days after isolation. In vitro fertilizing abilities of spermatozoa left for 0, 1, 2, and 3 days at 22 degrees C were 69.2, 32.5, 9.5, and 4.9%, respectively, when the cleavage rate to two-cell stage was examined. Transfer of two-cell embryos produced in vitro with spermatozoa left for 1, 2, and 3 days at 22 degrees C resulted in production of fetuses with efficiencies of respectively 30.2, 11.5, and 16.7%, which were lower (63.3%) than that of embryos derived from in vitro fertilization with fresh spermatozoa. These findings indicate that spermatozoa kept for up to 3 days at 22 degrees C can fertilize oocytes, although at relatively low efficiency.

Animals↗
PubMed2001

Quantitative trait locus analysis of abnormal circadian period in CS mice.

CS mice show a free-running period (tau) longer than 24 h and rhythm splitting in constant darkness (DD). These features in behavioral circadian rhythms are distinctive as compared with other inbred strains of mice, which exhibit robust free-running rhythms with T shorter than 24 h. To identify the genes affecting tau, quantitative trait locus (QTL) analysis was initially conducted by using 289 F2 mice derived from a cross between CS and C57BL/6J strain. A suggestive QTL (LOD = 3.71) with CS allele increasing tau was detected on the distal region of Chromosome (Chr) 19. Next, using 192 F2 mice from a cross between CS and MSM strain, the presence of the QTL on Chr 19 was examined, and we confirmed the QTL at the genome-wide significant level (LOD = 4.61 with 10.4% of the total variance explained). This QTL was named long free-running period (Lfp). Three other suggestive QTLs (LOD = 3.24-4.28) were mapped to the midportion of Chr 12 in (CSxC57BL/6J)F2 mice, and to the proximal and middle region of Chr 19 in (CSxMSM)F2 mice, respectively, of which, CS alleles for two QTLs on Chr 19 have the effect of lengthening tau. None of these QTLs were mapped to the chromosomal regions of previously described QTLs for tau and known clock genes (Clock, mPer1, Bmal1, mCrv1, mCry2, mTim, and Csnk1e).

Animals↗
PubMed2001

Co-localization of alpha-synuclein and phosphorylated tau in neuronal and glial cytoplasmic inclusions in a patient with multiple system atrophy of long duration.

Neuronal and glial cytoplasmic inclusions (NCIs and GCIs), which contain alpha-synuclein as a major component, are characteristic cytopathological features of multiple system atrophy (MSA). We report MSA of 19 years' duration in a 73-year-old woman. Her initial symptom was parkinsonism, with dementia appearing about 8 years later. Postmortem examination showed marked atrophy of the frontal and temporal white matter and limbic system, in addition to the pathology typical of MSA. In the limbic system, severe neuronal loss and astrocytosis were observed, and the remaining neurons often had lightly eosinophilic, spherical cytoplasmic inclusions. Interestingly, a double-labeling immunofluorescence study revealed that the NCIs in the dentate gyrus and amygdaloid nucleus, and the GCIs in the frontal and temporal white matter often expressed both alpha-synuclein NACP-5 and phosphorylated tau AT8 epitopes. Double-immunolabeling electron microscopy of the NCIs in the dentate gyrus and the GCIs in the temporal white matter clearly revealed labeling of their constituent granule-associated filaments with NACP-5, and some of them were also labeled with AT8. These findings strongly suggested that some alpha-synuclein filaments were decorated with phosphorylated tau without formation of fibrils such as paired helical filaments. Immunoblotting of sarkosyl-insoluble tau indicated that the accumulated tau consisted mainly of four-repeat tau isoforms of 383 amino acids and 412 amino acids. We consider that the limbic system can be a major site of neurodegeneration in MSA of long duration. The mechanisms of such abnormal tau accumulation in the NCIs and GCIs are unknown.

Aged↗
PubMed2001

Dynamic change of cells expressing MMP-2 mRNA and MT1-MMP mRNA in the recovery from liver fibrosis in the rat.

BACKGROUND/AIMS: The aim of this study was to investigate whether both matrix metalloproteinase-2 (MMP-2) and membrane type 1 MMP (MT1-MMP) participate in the spontaneous resolution of liver fibrosis. METHODS: Transcription of both genes was examined by reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH). Gelatinase activity was investigated by zymography. RESULTS: Gene expression by RT-PCR showed that both genes increased in the process of liver fibrosis, then decreased gradually in the recovery phase. ISH revealed that distribution of positive cells changed quickly in the recovery phase. Positive cells were widely seen in the liver, mainly around fibrous septa, in the aggressive phase, but were exclusively observed at the interface between the resolving fibrous band and the parenchyma, then were diffusely located in the lobules in the recovery phase. Main cells expressing both mRNAs seemed to be stellate cells for their morphology, though they did not express characteristic cell markers. Some hepatocytes and Kupffer cells expressed both mRNAs in the recovery phase. Gelatinase activity of MMP-2 increased in the recovery phase of 8-week-treated rat liver by gelatin zymography. CONCLUSIONS: The results of present study suggest that both enzymes participate in the destruction of extracellular matrix in coordination with MMP-13.

Animals↗
PubMed2001

Clinical and pedigree study on familial cases of West syndrome in Japan.

Nationwide survey on familial cases of West syndrome (WS) in first- and second-degree relatives was conducted by mailing a questionnaire to 64 major university hospitals, children's hospitals, and epilepsy centers in Japan, and by review of the Japanese cases in the literatures. Thirty-four familial cases, 20 males and 14 females, were obtained in 15 families including one with five affected members in two generations and another with three affected male siblings including a half brother by a different father (X-linked WS). A mother and the child or children were involved in three families. Nine families had 21 cryptogenic cases and six families had 13 symptomatic cases, and the etiologies were same among the affected members in each family. Familial cases of WS have characteristic clinical features and genetic mechanisms. Age of onset, seizure types, electroencephalographic abnormalities, early seizure outcome, effective treatment, long-term seizure prognosis, and long-term developmental prognosis were concordant among the affected members in each family. Long-term seizure and developmental prognoses were far better than those in WS in general, with seizure-free rate of 82% and normal mental development rate of 44%. Poor prognosis was limited to specific symptomatic cases. Adrenocorticotropic hormone (ACTH) was a treatment of choice, and even in relapse of WS after ACTH therapy, the patients well responded to antiepileptic drugs. Specific inheritance pattern was difficult to imagine in the majority of the present cases, except for one family with X-linked WS and another family with five patients of maternal inheritance. These results are helpful for the treatment choice and prognostication of clinical course for familial cases of WS.

Adrenocorticotropic Hormone↗
PubMed2001

A case of traumatic renal graft rupture with salvage of renal function.

An 18-yr-old man received a kidney graft from a 60-yr-old female cadaver donor on February 8, 1996. Postoperative course was uneventful and his serum creatinine level was stable at about 1.8 mg/dL. On April 30, 1999, he collided with a truck while riding a motor cycle. Macroscopic hematuria was observed and CT showed an extensive retroperitoneal hematoma. Because his anemia and hypotension were becoming worse after transfusion of 9 units of blood, he was operated on as an emergency case. A large rupture reaching the pelvis and calyces was observed in the upper pole of the grafted kidney. There were also numerous shallow lacerations, but the major arteries and veins were not injured. The rupture was closed by suturing the renal parenchyma with the peritoneum, and the other shallow lacerations were closed by suturing the renal capsule. The kidney could be salvaged without requiring hemodialysis. The serum creatinine was maintained at 2.1 mg/dL during follow-up. A review of the literature showed that 6 cases of traumatic renal graft rupture with salvage of the kidney have been reported. Our present case was the seventh, and was the most severe graft rupture reported so far.

Accidents, Traffic↗