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Y Sasai

Publications and source records attributed to Y Sasai.

At least 73 records · Page 4Linked to original sources
PubMed1994

Xenopus chordin: a novel dorsalizing factor activated by organizer-specific homeobox genes.

A Xenopus gene whose expression can be activated by the organizer-specific homeobox genes goosecoid and Xnot2 was isolated by differential screening. The chordin gene encodes a novel protein of 941 amino acids that has a signal sequence and four Cys-rich domains. The expression of chordin starts in Spemann's organizer subsequent to that of goosecoid, and its induction by activin requires de novo protein synthesis. Microinjection of chordin mRNA induces twinned axes and can completely rescue axial development in ventralized embryos. This molecule is a potent dorsalizing factor that is expressed at the right time and in the right place to regulate cell-cell interactions in the organizing centers of head, trunk, and tail development.

Activins↗
PubMed1994

Persistent expression of helix-loop-helix factor HES-1 prevents mammalian neural differentiation in the central nervous system.

In the developing mammalian central nervous system, neural precursor cells present in the ventricular zone determine their fate to become neurons or glial cells, migrate towards the outer layers and undergo terminal differentiation. The transcriptional repressor HES-1, a basic helix-loop-helix (bHLH) factor structurally related to the Drosophila hairy gene, is expressed at high levels throughout the ventricular zone, but the level decreases as neural differentiation proceeds. Because of this negative correlation, we tested whether continuous expression of HES-1 inhibits neural differentiation. A HES-1 and lacZ-transducing retrovirus (SG-HES1) and a control lacZ-transducing retrovirus (SG) were injected into the lateral ventricles of mouse embryos, and the fate of the infected neural precursor cells was examined by X-gal staining. The SG virus-infected cells migrated and differentiated into neurons and glial cells. In contrast, the cells infected with SG-HES1 virus remained in the ventricular/subventricular zone, decreased to approximately 10% in number as compared with that of the newborn during the postnatal 4-5 weeks and, when they survived, were present exclusively in the ependymal layer. Furthermore, whereas cultured neural precursor cells infected with SG virus became immunoreactive for neuronal and glial markers, the cells infected with SG-HES1 virus did not. These results show that persistent expression of HES-1 severely perturbs neuronal and glial differentiation.

Animals↗
PubMed1994

Structure, chromosomal locus, and promoter analysis of the gene encoding the mouse helix-loop-helix factor HES-1. Negative autoregulation through the multiple N box elements.

HES-1 is a mammalian helix-loop-helix factor structurally related to the Drosophila hairy and Enhancer of split proteins. It binds more preferentially to the N box (CACNAG) than to the E box (CANNTG) and acts as a negative regulator. In this study, we have isolated and characterized the mouse HES-1 gene. This gene consists of four exons, and the positions of introns are well conserved when compared with those of the Drosophila hairy gene, except for the third intron. Southern blot and interspecies backcross analyses suggest that the mouse HES-1 gene is a single-copy gene and is located around position 26 on chromosome 16. The transcription initiation site, determined by the S1 nuclease and primer extension experiments, is located 31 nucleotides downstream of a TATA box. In the 5'-regulatory region, there are four N box sequences, and the DNase I foot-printing and gel mobility shift analyses show that HES-1 binds to these sequences. Transient transfection assays using C3H10T1/2 cells suggest that there are several positive regulatory regions in the HES-1 gene. However, cotransfection of the HES-1 expression vector leads to approximately 40-fold repression in promoter activity. Furthermore, when the N box sequences are disrupted, this negative regulation is severely impaired. These results raise the possibility that HES-1 gene expression may be negatively autoregulated through the N box sequences.

Amino Acid Sequence↗
PubMed1994

A case of mammary Paget's disease without an underlying carcinoma: microscopic analysis of the DNA content in Paget cells.

A 72-year-old woman had a 7-year history of a scaly red area on the right breast which had enlarged asymptomatically. A biopsy of the nipple was taken, and, following the finding of Paget's disease, a modified radical mastectomy was carried out. On histological examination of the entire breast specimen by serial sections, no evidence of an intraductal adenocarcinoma was found. Fractionation of Paget cells was performed from the epidermis. Stripped skin was treated with EDTA and trypsin, and epidermal cell suspensions were obtained. They were layered onto discontinuous Percoll gradients and centrifuged. Paget cells fell into three fractions with densities of 1.041, 1.058, and 1.078. Electronmicroscopically, the purity of fractionated cells obtained by this method ranged from 55 to 74% with viabilities of from 70 to 90%. Microscopic analysis of the DNA content in these cells was performed. The DNA histogram was close to the normal ploidy. This may explain why the mammary Paget's disease lesions in this case enlarged rather slowly.

Aged↗
PubMed1994

Scanning and transmission electron microscopic studies of lesional epidermis in herpes zoster.

The epidermal skin lesions of herpes zoster were studied by scanning (SEM) and transmission electron microscopy (TEM). When erythematous lesions were observed by TEM, many of the infected keratinocytes showed evidence of cell degeneration, being characterized by swollen nuclei, disappearance of desmosomes, and widening of intercellular spaces. Macrophages and/or lymphocytes migrated through the intercellular spaces between degenerated keratinocytes. In the vesicular lesions, SEM and TEM showed some infiltrating neutrophils, directly adhering to the virus-infected keratinocytes, with swollen nuclei and irregularly clumped chromatin. In some specimens, balloon-degenerated keratinocytes were observed in the cavity. In the pustular stage, ruptured keratinocytes and numerous neutrophils were observed in the reticular-degenerated epidermal tissue. These results suggest that, in herpes zoster, the epidermal damage may be due, at least in part, to cell-mediated host immunity as well as to the cytopathic effect of varicella-zoster virus.

Adult↗
PubMed1994

Bullous pemphigoid in a 19-year-old woman. A case with unusual target antigens.

We report a 19-year-old woman with typical clinical histological and immunofluorescence features of bullous pemphigoid. By immunoblotting, the serum was shown to detect antigens at 240 and 138 kDa. Elevated serum IgE levels were present, and there was a marked peripheral blood eosinophilia. The degree of eosinophilia correlated with small changes in the severity of the skin lesions, and the IgE level showed correlation with marked changes in severity. Another unusual feature was an exacerbation of her disease at the time of her first menses after the onset of the bullous pemphigoid.

Adult↗
PubMed1994

Eosinophilic cellulitis (Wells' syndrome) associated with ascariasis.

A case of eosinophilic cellulitis (Wells' syndrome) in association with ascariasis is described. The clinical and histopathologic features of the patient responded well to an oral anthelminthic drug. According to our search, this association has not previously been reported.

Adult↗
PubMed1994

The effect of orally-administered retinoid on lectin binding in guinea pig keratinocytes.

Retinoids influence proliferation and differentiation of epithelial cells. The present paper was designed to examine the change of lectin binding in isolated keratinocytes from retinoid-treated guinea pigs. Aromatic retinoid, etretinate, in peanut oil (5 mg/kg/day) was given orally for a period of 14 days. Skin samples were obtained from animals on days 1, 3, 7, and 14 after beginning the administration. Free keratinocytes were obtained by treatment with EDTA and trypsin. They were separated into 3 fractions by centrifugation on a continuous colloidal silica (Percoll) density gradient. The cells in each fraction were stained by biotinyl lectins and avidin-FITC, and the fluorescence intensity was measured by cytofluorometry. The lectins used were Concanavalin A (Con A), soybean agglutinin (SBA), peanut agglutinin (PNA), Dolichos biflorus agglutinin (DBA), and Ricinus communis agglutinin (RCA). The PNA-binding was diminished in both the intermediate and lower density fractions at 7 and 14 days. The binding of SBA was reduced in all fractions from 1 to 7 days. With Con A, RCA and DBA, no changes in intensity were found.

Administration, Oral↗
PubMed1994

Detection of genomic DNA with a high sensitivity in tissue sections using a two step cycling in situ PCR procedure.

In situ hybridization has been used for the detection of viral and bacterial mRNA and DNA which has infected tissue sections, but the sensitivity of this method is very limited. In this paper, a new, sensitive and simple non-isotopic in situ hybridization method in combination with a polymerase chain reaction (PCR) technique is described, in which the genomic or viral DNA can be amplified directly on formalin-fixed and paraffin-embedded tissue sections. As low as two copies of target DNA per cell can be detected by this in situ hybridization after in situ PCR. The essential modification concerns a two step cycling PCR procedure that was applied using single primer pairs. The first step, annealing, was achieved at a low temperature for a relatively long time. The second step was performed at a high temperature for a short period of time. This procedure greatly decreased the non-specific amplification of DNA and increased the sensitivity of detection.

Base Sequence↗
PubMed1994

[Three year outcome for infants of birth weight less than 1800 g].

The effectiveness of modern methods of care for very low birthweight infants has been questioned from the standpoint of the possibility that the application of these methods may result in an increase in handicapped children. During 1985, 435 infants of birth weight less than 1800 g were born in Osaka prefecture and 359 of these infants were followed for 3 years to analyze outcome. Proportion of children without handicap, with handicap, and children who died were determined. These results were compared with another study which showed outcome for infants born in 1980 in Osaka. 1. Of the 359 children, 66.9% were alive without handicap, and 14.2% with handicap, and 68 (18.9%) children died, 10 of whom died from congenital disorder. 2. There were significant differences in the proportion of children without handicap in the BW range 1000 g-1500 g between infants cared at children's hospitals which have NICU. and other hospitals. (75% vs 54% P < 0.05) 3. While the proportion of children with handicap was greater for all BW ranges in infants care at children's hospitals which have NICU. than other hospitals, the difference was not significant. 4. There were significant differences in the proportion of children who died in the BW range 1000 g-1500 g between infants cared at children's hospitals which have NICU. and other hospitals. (10% vs 26% P < 0.05) 5. There was an increase in the proportion of children without handicap (67% vs 61%), and with handicap (14% vs 11%), but a decrease in children who died (19% vs 28%) between low birthweight infants born in 1985 and in 1980.

Child, Preschool↗
PubMed1994

[Paraffinoma].

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Diagnosis, Differential↗
PubMed1993

Molecular characterization of HES-2, a mammalian helix-loop-helix factor structurally related to Drosophila hairy and Enhancer of split.

Drosophila hairy (h) plays a crucial role in early development as a pair-rule segmentation gene. h and its structurally related gene Enhancer of split [E(spl)] are also required for normal sensory neurogenesis in late development. To analyze the molecular mechanisms of mammalian development, we recently characterized three rat helix-loop-helix (HLH) factors that show structural homology to the Drosophila h and E(spl) gene products, and found that rat factors exhibit distinct spatiotemporal expression patterns and act as a negative regulator. Here, we report the molecular characterization of another member of this family, designated HES-2. Rat HES-2 protein has a basic HLH domain homologous to h and E(spl) as well as the carboxy-terminal Trp-Arg-Pro-Trp sequence conserved among this family. The HES-2 mRNA is present as early as embryonic day 9.5 and is detected in a variety of tissues of both embryos and adults. DNase-I-footprinting analyses indicate that HES-2 binds to all E box sequences (CANNTG) we tested as well as to the N-box sequences (CACNAG). Further studies of gel-mobility-shift assays show that HES-2 has a higher affinity for the E box than for the N box. Transient transfection analyses suggest that HES-2 decreases the transcription originating from the promoters containing either the E box or the N box. These results indicate that HES-2 acts as a negative regulator through interaction with both E-box and N-box sequences.

3T3 Cells↗
PubMed1993

A point mutation in the 5' splice region of intron 7 causes a deletion of exon 7 in adenosine deaminase mRNA.

An adenosine deaminase (ADA;EC 3.5.4.4)-deficient B lymphoblastoid cell line BAD05 derived from a Japanese patient with severe combined immunodeficiency was characterized. As previously reported, one allele of BAD05 expresses undetectable ADA mRNA, and the other allele produces an aberrant mRNA without exon 7. Genomic ADA DNA of BAD05 spanning from a portion of exon 6 to a portion of exon 8 was amplified by PCR. The amplified fragments were cloned into a vector, and 8 clones were isolated and sequenced. The analytical result showed a single base change of G to A at the invariant 5' GT of intron 7 of ADA gene in one allele of BAD05, which accounts for the elimination of exon 7 during splicing.

Adenosine Deaminase↗
PubMed1993

Purification and characterization of prolyl endopeptidase from rat skin.

An enzyme with the specificity of a prolyl endopeptidase was purified approximately 329-fold from rat skin. The enzyme has a molecular weight of 70,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and a pH optimum of 5.8 as checked with 7-(Succinyl-Gly-Pro)-4- methylcoumarinamide (Suc-Gly-Pro-MCA) as the substrate. The optimal temperature for the enzyme activity was 40 degrees C. The Km and Vmax values for Suc-Gly-Pro-MCA were 0.7 mM and 68 nmol/min per mg protein, respectively. The enzyme activity was markedly inhibited by diisopropyl fluorophosphate, p-chloromercuribenzoic acid, N-ethylmaleimide, Zn2+ and Cu2+, while it was partially inhibited by phenylmethanesulphonyl fluoride. The purified enzyme was shown to release the N-terminal tetrapeptide, Arg-Pro-Lys-Pro, from substance P producing the C-terminal heptapeptide, Gln-Gln-Phe-Phe-Gly-Met- CONH2. In the skin, this enzyme might be related to the inactivation of substance P.

Amino Acid Sequence↗
PubMed1993

Apocrine nevus.

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Apocrine Glands↗
PubMed1993

Collagenase and collagenase inhibitors secreted by cultured human periodontal ligament cells.

We have developed a new assay method for collagenase activity, in the presence of two different types of collagenase inhibitors, in culture medium of periodontal ligament (PDL) cells. Human PDL cells were cultured with serum-free alpha-MEM for 5 days after reaching confluency, and the culture medium was then harvested. Collagenase and collagenase inhibitors in the medium were concentrated by ammonium sulfate precipitation. The precipitate was dissolved, and the suspension was applied to an Ultrogel AcA 54 column for partial purification. Collagenase inhibitor activity was detected as two peaks; a small inhibitor molecule of about 32 kDa sensitive only to dithiothreitol (DTT), and a large one of about 70 kDa considerably more sensitive to 4-aminophenylmercuric acetate (APMA) than to DTT. Therefore, pretreatment of the sample preparation with both DTT and APMA was necessary in order to inactivate the inhibitors prior to assay of latent collagenase. This observation indicates that PDL cells secrete collagenase and two collagenase inhibitors without any stimulation in vitro.

Cells, Cultured↗