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K Yokomori

Publications and source records attributed to K Yokomori.

At least 19 recordsLinked to original sources
PubMed2000

Expression and imprinting status of human PEG8/IGF2AS, a paternally expressed antisense transcript from the IGF2 locus, in Wilms' tumors.

A large imprinted gene cluster in human chromosome 11p15.5 has been implicated in Beckwith-Wiedemann syndrome and Wilms' tumor. We have identified a paternally expressed imprinted gene, PEG8/IGF2AS, in this locus. It is transcribed in the opposite direction to the IGF2 transcripts and some genomic regions are shared with the IGF2 gene, as in the case of the mouse imprinted Igf2as gene reported previously by T. Moore et al. As to the relationship between these genomic regions, the human and mouse genes are very similar but there is no homology in their middle parts. Interestingly, PEG8/IGF2AS and IGF2 were found to be overexpressed in Wilms' tumor samples, at levels over ten and a hundred times higher than that in normal kidney tissues neighboring the tumors, respectively. These findings indicate that PEG8/IGF2AS is a good marker of Wilms' tumor and also suggest the possibility of PEG8/IGF2AS being one of the candidate Wilms' tumor genes.

Amino Acid Sequence↗
PubMed2000

A human condensin complex containing hCAP-C-hCAP-E and CNAP1, a homolog of Xenopus XCAP-D2, colocalizes with phosphorylated histone H3 during the early stage of mitotic chromosome condensation.

Structural maintenance of chromosomes (SMC) family proteins play critical roles in structural changes of chromosomes. Previously, we identified two human SMC family proteins, hCAP-C and hCAP-E, which form a heterodimeric complex (hCAP-C-hCAP-E) in the cell. Based on the sequence conservation and mitotic chromosome localization, hCAP-C-hCAP-E was determined to be the human ortholog of the Xenopus SMC complex, XCAP-C-XCAP-E. XCAP-C-XCAP-E is a component of the multiprotein complex termed condensin, required for mitotic chromosome condensation in vitro. However, presence of such a complex has not been demonstrated in mammalian cells. Coimmunoprecipitation of the endogenous hCAP-C-hCAP-E complex from HeLa extracts identified a 155-kDa protein interacting with hCAP-C-hCAP-E, termed condensation-related SMC-associated protein 1 (CNAP1). CNAP1 associates with mitotic chromosomes and is homologous to Xenopus condensin component XCAP-D2, indicating the presence of a condensin complex in human cells. Chromosome association of human condensin is mitosis specific, and the majority of condensin dissociates from chromosomes and is sequestered in the cytoplasm throughout interphase. However, a subpopulation of the complex was found to remain on chromosomes as foci in the interphase nucleus. During late G(2)/early prophase, the larger nuclear condensin foci colocalize with phosphorylated histone H3 clusters on partially condensed regions of chromosomes. These results suggest that mitosis-specific function of human condensin may be regulated by cell cycle-specific subcellular localization of the complex, and the nuclear condensin that associates with interphase chromosomes is involved in the reinitiation of mitotic chromosome condensation in conjunction with phosphorylation of histone H3.

Amino Acid Sequence↗
PubMed1999

Competitive polymerase chain reaction for the determination of N-myc amplification in neuroblastoma: report of clinical cases.

If an unfavorable prognosis is suspected in neuroblastoma, decision on a treatment protocol should be based on the N-myc copy number (12). We already demonstrated that the newly developed competitive polymerase chain reaction (competitive PCR) is a promising method for the determination of the N-myc copy number (6), and have started to use this competitive PCR procedure in neuroblastoma patients, together with fine-needle biopsy in selected cases. Seven children were studied. In one infant of 5 months of age whose tumor was diagnosed before undergoing mass screening for neuroblastoma, the competitive PCR procedure was performed with a fine-needle biopsy, and after obtaining a negative report on N-myc amplification within 48 hours, a regular protocol of treatment could be started without delay. We report that competitive PCR is a rapid and accurate method for the determination of the N-myc copy number, requiring only a small amount of material, and anticipate that competitive PCR will become the procedure of choice for the determination of N-myc copy number in neuroblastoma.

Adrenal Gland Neoplasms↗
PubMed1998

Identification of two distinct human SMC protein complexes involved in mitotic chromosome dynamics.

The structural maintenance of chromosomes (SMC) family member proteins previously were shown to play a critical role in mitotic chromosome condensation and segregation in yeast and Xenopus. Other family members were demonstrated to be required for DNA repair in yeast and mammals. Although several different SMC proteins were identified in different organisms, little is known about the SMC proteins in humans. Here, we report the identification of four human SMC proteins that form two distinct heterodimeric complexes in the cell, the human chromosome-associated protein (hCAP)-C and hCAP-E protein complex (hCAP-C/hCAP-E), and the human SMC1 (hSMC1) and hSMC3 protein complex (hSMC1/hSMC3). The hCAP-C/hCAP-E complex is the human ortholog of the Xenopus chromosome-associated protein (XCAP)-C/XCAP-E complex required for mitotic chromosome condensation. We found that a second complex, hSMC1/hSMC3, is required for metaphase progression in mitotic cells. Punctate vs. diffuse distribution patterns of the hCAP-C/hCAP-E and hSMC1/hSMC3 complexes in the interphase nucleus indicate independent behaviors of the two complexes during the cell cycle. These results suggest that two distinct classes of SMC protein complexes are involved in different aspects of mitotic chromosome organization in human cells.

Amino Acid Sequence↗
PubMed1998

An interplay between TATA box-binding protein and transcription factors IIE and IIA modulates DNA binding and transcription.

The basal transcription factor IIE (TFIIE) is thought to be one of the last factors to be assembled into a preinitiation complex (PIC) at eukaryotic promoters after RNA polymerase II and TFIIF have been incorporated. It was shown that a primary function of TFIIE is to recruit and cooperate with TFIIH in promoter melting. Here, we show that the large subunit of TFIIE (E56) can directly stimulate TBP binding to the promoter in the absence of other basal factors. The zinc-finger domain of E56, required for transcriptional activity, is critical for this function. In addition, the small subunit of TFIIE (E34) directly contacts DNA and TFIIA and thus providing a second mechanism for TFIIE to help binding of a TBP/IIA complex to the promoter, the first critical step in the PIC assembly. These studies suggest an alternative PIC assembly pathway in which TFIIE affects both TBP and TFIIH functions during initiation of RNA synthesis.

Binding Sites↗
PubMed1998

A new technique applicable to pediatric laparoscopic surgery: abdominal wall 'area lifting' with subcutaneous wiring.

BACKGROUND: Recently, the authors developed a unique method of laparoscopic surgery without pneumoperitoneum: "area lifting of the abdominal wall with subcutaneous wiring." METHODS: In this gasless procedure, the anterior abdominal wall is pulled upward by a pair of wires placed subcutaneously and held by thick sutures for "hanger lifting." Simultaneous lifting of a pair of subcutaneous wires across the abdomen, produces a wide, roof-shaped intraabdominal space sufficient for laparoscopic surgical procedures. The practical aspects of this gasless technique, as well as the authors' limited experience with this method in 24 children, ranging from 8 days to 15 years of age is presented. These children have had various pathologies including splenomegaly, rectal prolapse, ovarian cyst, gall stone, adrenal neuroblastoma, and abdominal wall abscess. CONCLUSIONS: Gasless laparoscopic surgery with double subcutaneous wiring is safe for children including neonates and those with respiratory compromise because all operative procedures are performed under normal abdominal pressure. Because of the highly elastic abdominal wall musculature inherent in children, this selective area lifting of abdominal wall creates a relatively larger peritoneal volume than in adults.

Abdominal Muscles↗
PubMed1997

Extensive genetic heterogeneity in the neuroblastoma cell line NB(TU)1.

A neuroblastoma cell line displaying genetically unique features was established from a stage III case of a 20-month-old girl. Southern blotting by the probe pTNB6, which contains exon 1 of the N-myc gene, showed that the primary tumor had in total 4 aberrant bands beside the normal amplified band. The established cell line NB(TU)1 had an aberrant N-myc band (9.0 kb) in addition to the normal band (2.9 kb). Cytogenetic analysis revealed that NB(TU)1 has a composite karyotype composed of at least 7 related karyotypes, which are pseudo-diploid and contain complex chromosomal abnormalities, including translocations, deletions and homogeneously staining regions (HSRs). Such extensive abnormalities were considered to be prominent among known neuroblastoma cell lines, and it was suggested that NB(TU)1 had acquired a certain type of genetic instability. Analysis of N-myc bands in 11 clones of NB(TU)1 showed that the intensity ratio of the normal-sized band (2.9 kb) and the aberrant one (9.0 kb) markedly varied among clones. Moreover, 3 clones showed an additional band with the size of 3.7 kb, which was detectable neither in the parent NB(TU)1 nor in the primary tumor. Thus, NB(TU)1 was shown to be composed of heterogeneous cell components. To further detect such ongoing chromosomal instability, we examined micronuclei formation. NB(TU)1 yielded a larger number of micronuclei than 5 other neuroblastoma cell lines. We conclude that NB(TU)1 has acquired genetic instability detectable by both Southern blotting and cytogenetic analysis.

Abdominal Neoplasms↗
PubMed1996

Drosophila TFIIA-S is up-regulated and required during Ras-mediated photoreceptor determination.

Photoreceptor induction in the developing Drosophila eye is triggered by the activation of the Ras pathway. Subsequently, the Ras-mediated activation of site-specific transcription factors leads to the expression of putative "effector" genes. The coactivator function of the basal transcription factor TFIIA has been shown previously to enhance the trans-activation potential of site-specific transcription factors in vitro. Here, we show that the expression of the small subunit of TFIIA (dTFIIA-S) is specifically up-regulated in a transient manner during Ras-mediated photoreceptor induction. Furthermore, although null mutations in dTFIIA-S are cell lethal, a hypomorphic dTFIIA-S allele demonstrates an increased requirement for this factor during photoreceptor development. In addition, the cone cell to R7 photoreceptor transformation caused by ectopic activation of the Ras pathway during eye development is suppressed by the removal of one functional copy of the dTFIIA-S locus revealing the sensitivity of this process to reductions in dTFIIA-S activity. These results are the first in vivo evidence for the coactivator function in transcriptional enhancement proposed for TFIIA.

Animals↗
PubMed1996

Infrequent mutations of the TP53 gene and no amplification of the MDM2 gene in hepatoblastomas.

We have investigated the mutation of the TP53 gene in hepatoblastomas (HBLs) by using polymerase chain reaction-single strand conformation polymorphism and direct sequencing in 38 HBL tumor samples and in two HBL cell lines. We detected the TP53 gene mutation in an anaplastic hepatoblastoma cell line, but no aberration of the TP53 gene (exons 5-9) was found in tumor samples and in the other HBL cell line. The mutation of the cell line was a missense mutation from GAC (asparagine) to CAC (histidine) at codon 281, which was different from the G-to-T transversion of codon 249 that is frequently found in adult hepatocellular carcinomas (HCCs). In addition, we performed Southern blot analysis of the MDM2 gene, but we did not find MDM2 gene amplification in 19 cases tested. Our results suggest that, in contrast to the findings in HCCs in adults, TP53 gene aberrations are not involved in the development or progression of HBLs in children.

Adult↗
PubMed1995

A pregnancy-specific glycoprotein is expressed in the brain and serves as a receptor for mouse hepatitis virus.

Mouse hepatitis virus (MHV), a murine coronavirus known to cause encephalitis and demyelination, uses murine homologues of carcinoembryonic antigens as receptors. However, the expression of these receptors is extremely low in the brain. By low-stringency screening of a mouse brain cDNA library, we have identified a member of the pregnancy-specific glycoprotein (PSG) subgroup of the carcinoembryonic antigen gene family. Unlike other PSG that are expressed in the placenta, it is expressed predominantly in the brain. Transfection of the cDNA into COS-7 cells, which lack a functional MHV receptor, conferred susceptibility to infection by some MHV strains, including A59, MHV-2, and MHV-3, but not JHM. Thus, this is a virus strain-specific receptor. The detection of multiple receptors for MHV suggests the flexibility of this virus in receptor utilization. The identification of this virus in receptor utilization. The identification of a PSG predominantly expressed in the brain also expands the potential functions of these molecules.

Amino Acid Sequence↗
PubMed1995

A novel immunoassay of smooth muscle myosin heavy chain in serum.

We have developed a double monoclonal sandwich enzyme immunoassay to measure smooth muscle myosin heavy chain (MHC). Analytical performance of the assay showed reliable detection of smooth muscle MHC in human sera. The mean of the smooth muscle MHC level in normal human sera was 0.9 +/- 0.9 ng/ml. In sera of patients with aortic dissection, the smooth muscle MHC level sharply elevated at the onset and rapidly decreased to normal levels. Immunoassay of smooth muscle MHC in serum is a promising method for biochemical diagnosis of smooth muscle disorders.

Aortic Dissection↗
PubMed1995

Binding of TAFs to core elements directs promoter selectivity by RNA polymerase II.

The mechanisms that govern core promoter recognition and basal transcription efficiency remain poorly understood. Here, we have assessed the potential role of TAFs and the TFIID complex in directing basal promoter function. Reconstituted transcription reactions revealed the ability of TFIID versus TBP to discriminate between distinct core promoters. A comparison of different partial TBP-TAF assemblages established that a trimeric TBP-TAFII250-TAFII150 complex is minimally required for efficient utilization of the initiator and downstream promoter elements. Depending on the promoter structure, TAFs can increase or decrease the stability of TFIID-promoter interactions. These findings suggest that TAFs play a critical role in promoter selectivity and transcription regulation through direct contacts with core promoter elements.

Amino Acid Sequence↗
PubMed1995

Hirschsprung's disease associated with Ondine's curse: a special subgroup?

The authors report a case of the rare occurrence of congenital central hypoventilation syndrome (Ondine's curse) and long segmental colonic aganglionosis (Hirschsprung's disease). A review of 24 reported cases showed that the proportion of females having this concurrence is higher than for ordinary Hirschsprung's disease. It also appears that the aganglionic segment is much longer in these cases than in ordinary Hirschsprung's disease.

Female↗
PubMed1995

Modified Marcy repair of large indirect inguinal hernia in infants and children.

Based on a review of operative notes of recurrent inguinal hernia cases from the authors' primary series, a surgical technique modified from the Marcy repair is described. With this technique, emphasis is placed on preservation of the intact internal spermatic fascia and reduction in the size of the internal inguinal ring. Through the inguinal approach, the sleeve-like extension of the internal spermatic fascia is incised longitudinally along the cord and up to the internal ring. The cord structures are dissected off the sac, and as much of the fascial tissue as possible is preserved intact. Both edges of the fascial defect are approximated with an unabsorbable suture; great care is taken to not penetrate the wall of the sac. The same suture is then used for high ligation, via a stay suture placed on the transversalis fascia on the other side of the neck, to reduce the size of the internal ring. The technique can be used in premature babies who have a flimsy, easily torn sac, and in some cases of giant hernia with a widely dilated internal inguinal ring, if the direct wall integrity remains adequate.

Adolescent↗
PubMed1995

Flow cytometric nuclear DNA content analysis of renal tumors in children: prognostic significance of nuclear DNA ploidy.

We studied, by flow cytometry, the DNA contents of paraffin-embedded tumor specimens from 90 infants and children with kidney tumors, and analyzed the relationship of DNA ploidy with histological types and prognosis. Data of adequate quality were obtained from 90 cases: 65 tumors with favorable histology, 5 congenital mesoblastic nephromas and 20 tumors with unfavorable histology. The 90 cases had nuclear DNA histogram patterns that were classified as DNA diploid in 64 tumors, aneuploid in 19 and tetraploid in 7. There were no significant correlations between DNA ploidy and histological types or clinical stages. Survival rates for patients with diploidy were 80 and 70% at 2 and 5 years, respectively, and those of patients with aneuploidy were 72 and 61% at 2 and 5 years, respectively. On the other hand, patients with a DNA tetraploid pattern had significantly worse survival rates of 43 and 29% at 2 and 5 years, respectively. Among patients with aneuploidy or tetraploidy, the S-phase fractions in those who died (mean +/- SD: 10.3 +/- 4.1 and 22.1 +/- 11.6%, respectively) appear to be greater than those in their surviving counterparts (8.8 +/- 4.0 and 12.1 +/- 2.8%). Hence, although the differences between diploid and aneuploid DNA patterns were not correlated with differential prognosis in children with kidney tumors, a tetraploid pattern clearly indicates a poor prognosis, especially in combination with histological types and clinical stages.

Adolescent↗
PubMed1995

Neuropathogenicity of mouse hepatitis virus JHM isolates differing in hemagglutinin-esterase protein expression.

The hemagglutinin-esterase (HE) protein of mouse hepatitis virus (MHV) is an optional envelope protein present in only some MHV isolates. Its expression is regulated by the copy number of a UCUAA pentanucleotide sequence present in the leader sequence of the viral genomic RNA. The functional significance of this viral protein so far is not clear. In this report, we compared the neuropathogenicity of two MHV isolates, JHM(2) and JHM(3), which express different amounts of HE protein. Intracerebral inoculation of these two viruses into C57BL/6 mice showed that JHM(2), which expresses an abundant amount of HE protein, was more neurovirulent than JHM(3), which expresses very little HE. Histopathology showed that early in infection, JHM(2) infected primarily neurons, while JHM(3) infected mainly glial cells. JHM(3) eventually infected neurons and caused a delayed death relative to JHM(2)-infected mice, suggesting that the progression of JHM(3) infection in the central nervous system was slower than JHM(2). In vitro infection of JHM(3) in primary mixed glial cell cultures of astrocyte-enriched cultures yielded higher virus titers than JHM(2), mimicking the preferential growth of JHM(3) in glial cells in vivo. These findings suggest that the reduced neuropathogenicity of JHM(3) may correlate with its preferential growth in glial cells. Sequence analysis showed that the S genes of these two viruses are identical, thus ruling out the S gene as the cause of the difference in neuropathogenicity between these two viruses. We conclude that the HE protein contributes to viral neuropathogenicity by influencing either the rate of virus spread, viral cell tropism or both.

Acetylesterase↗