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Biomedical subjects

Y Ohshima

Publications and source records attributed to Y Ohshima.

At least 145 records · Page 8Linked to original sources
PubMed1990

Surveying cis-acting sequences of pre-mRNA by adding antisense 2'-O-methyl oligoribonucleotides to a splicing reaction.

We chemically synthesized antisense 12 mer 2'-O-methylribonucleotides and surveyed a scanning (signal-tracking) process as well as sequences within a beta-globin transcript acting in the splicing reaction in vitro. The pre-mRNA transcript contained the sequences of the first exon, first intron, and a major part of the second exon of the human beta-globin gene. We found that the antisense 2'-O-methylribonucleotides could anneal effectively to the target site in the pre-mRNA during the splicing reaction. A 2'-O-methylribonucleotide complementary to the donor (5') splice site completely inhibited authentic splicing and activated an upstream cryptic donor site. A 2'-O-methylribonucleotide complementary to the branch site inhibited normal branch formation and greatly reduced subsequent generation of the spliced product. Six other 2'-O-methylribonucleotides complementary to loci in the exons or the intronic region between the donor and branch sites had no significant effect on the splicing reaction. These observations suggest that an extensive scanning of the present pre-mRNA across the six regions tested is not essential for the splicing reaction. We propose that a short antisense 2'-O-methylribonucleotide provides a practical and convenient method to examine cis-acting sequences of RNA. The advantages of this method in comparison with site-directed mutagenesis or deletion are discussed.

Base Sequence↗
PubMed1990

Antiphagocytic effect of the capsule of Staphylococcus simulans.

An encapsulated strain of Staphylococcus simulans was observed to be more resistant to phagocytosis by human granulocytes than was a nonencapsulated strain. Phagocytosis of the encapsulated strain was enhanced by antisera to S. simulans, but opsonic activity of antisera was removed by absorption with S. simulans capsular material. The encapsulated strain of S. simulans was also more invasive than the nonencapsulated S. simulans in vivo. More encapsulated than nonencapsulated S. simulans were found in heart blood when equal numbers of organisms were injected intraperitoneally into mice. Invasion of the bloodstreams of mice by encapsulated S. simulans was prevented by passive immunization (rabbit antiserum). Thus, the capsule of S. simulans inhibited phagocytosis in vitro and contributed to virulence in vivo.

Animals↗
PubMed1990

Binding of staphylococcal cell surface polysaccharide to human fibrinogen.

The interaction between the binding site of a polysaccharide (called compact colony forming active substance (CCFAS)), obtained from the cell surface of a strain of Staphylococcus, and human fibrinogen (HF) was investigated. The CCFAS was found to bind specifically to both the B beta and gamma chains of HF at pH 7.0 and 8.0, and the A alpha chain at pH 5.0. The binding of CCFAS with fibrinogen fragments obtained by digestion with plasmin were also investigated. Fragments with Mr of 55,000, 24,000, and 19,000 were the major bands precipitated by CCFAS at pH 7.0 and 8.0. Fragments with Mr of 85,000 and 75,000 bound to CCFAS at pH 5.0. Binding of CCFAS (7 micrograms) with fibrinogen could be inhibited by 1.2 micrograms of B beta chain and 1.5 micrograms gamma chain at alkaline pH or 6.2 micrograms of the A alpha chain at pH 5.0. CCFAS was, therefore, assumed to be specifically bonded with HF molecules, in the alkaline range at least, resulting in compact colony forming activity in serum soft agar and paracoagulation.

Cell Membrane↗
PubMed1990

Invagination of a shunt valve: an unusual complication--case report.

The authors present an unusual case of ventriculoperitoneal shunt failure due to invagination of a valve in the proximal portion of the silicone casing of the shunt system. The shunt had been in place for 5 years and the 57-year-old male patient had incurred no head injury during that period. The valve failure was discovered during evaluation of his gradual deterioration, which culminated in his functional incapacitation. Nine such cases have been reported in the literature. This complication is specifically associated with the Holter and Hakim valves and seems to a primary mechanical failure attributable to the structure of these two valves.

Cerebral Hemorrhage↗
PubMed1989

Synthesis of N2, N2, 7-trimethylguanosine cap derivatives.

Several derivatives of N2,N2-7-trimethylguanosine (m3(2,2,7G)-cap, which was found at the 5' ends of small nuclear RNAs, were synthesized by use of S-phenyl N2,N2,7-trimethylguanosine 5'-phosphorothioate (PhSpm3(2,2,7)G) as a key intermediate. This compound was activated by iodine in the presence of phosphoric acid and diphosphoric acid to give N2,N2,7-trimethylguanosine-5'-diphosphate (ppm3(2,2,7)G) and 5'-triphosphate (ppm3(2,2,7)G), respectively. Similar reactions of PhSpm3(2,2,7)G with ADP and GDP gave capped dinucleoside triphosphates, m3(2,2,7)G5'pppA and m3(2,2,7)G5'pppG, respectively.

Adenosine Diphosphate↗
PubMed1989

Pre-mRNA with a trimethylguanosine cap structure can be spliced efficiently in vitro.

A chemically synthesized 2,2,7-trimethylguanosine cap (TMG-cap) analogue was added to an in vitro pre-mRNA splicing system. A slight inhibition of the splicing was observed, but it was much less remarkable than that by a 7-methylguanosine cap analogue. This result does not favor a direct role of the TMG-cap structure of small nuclear RNAs in pre-mRNA splicing, and suggests that the TMG-cap does not effectively interact with the 7-methylguanosine cap binding factors. Using the SP6 in vitro transcription system and a TMG-cap analogue, we prepared a beta-globin transcript which has a TMG-cap at the 5' end. This TMG-capped transcript was spliced accurately and efficiently in vitro.

Binding, Competitive↗
PubMed1989

Clinical and histopathologic characteristics of early lesions of subungual malignant melanoma.

Twenty-one Japanese cases of subungual malignant melanoma were investigated clinically and histologically. In the majority of the cases, the initial sign of the disease was confirmed to be melanonychia striata. Five cases of Clark's Level I melanoma were found in the series. Melanonychia striata had appeared as the initial sign in these five cases. Melanonychia striata is frequently observed in persons who are not white and is attributed to various local and systemic causes. Detailed clinical analysis of the five cases of early subungual melanoma showed that melanonychia striata with the following characteristics may increase the risk of early subungual melanoma developing: it is noticed during adulthood, it is broader than 6 mm, it is brownish with variegated shades or homogenously black, and it is accompanied by periungual pigmentation (Hutchinson's sign). Detection of early lesions of subungual melanoma is beneficial not only for the improvement of prognosis, but also for the preservation of the affected phalanx.

Adult↗
PubMed1989

The gene for the U6 small nuclear RNA in fission yeast has an intron.

The small nuclear RNAs (snRNAs) are a class of metabolically stable small RNAs present in the nuclei of eukaryotic cells. In mammalian cells, there are six major molecular species (U1 to U6 snRNA), which are complexed with proteins, forming small nuclear ribonucleoprotein particles, snRNPs. Of these, the U1, U2, U4, U5, U6 snRNPs are thought to participate in pre-mRNA splicing as part of the spliceosome. Here, we describe the characterization of the gene coding for the Schizosaccharomyces pombe U6 snRNA. Unexpectedly, the Schiz. pombe U6 RNA gene was found to contain an intron-like sequence of 50 base pairs. Northern blot analysis and RNA sequencing revealed that this intron-like sequence is precisely removed from the transcript. The mature U6 RNA of Schiz. pombe has 77% sequence homology with the mammalian U6 RNA. In Schiz. pombe, it is possible that U6 RNA is not only involved in pre-mRNA splicing, but is also a splicing substrate. This is the first report of an intron in a snRNA gene.

Base Sequence↗
PubMed1989

cDNA cloning and nucleotide sequence of rat muscle-specific enolase (beta beta enolase).

The nucleotide sequence of rat muscle-specific enolase cDNA was determined by sequencing three cDNA clones encoding this enolase isozyme. The nearly full-length cDNA consists of 13-bp 5'- and 84-bp 3'-noncoding regions and a poly(A) tail in addition to a 1302-bp coding region encoding a polypeptide composed of 434 amino acid residues. The deduced primary structure of this enolase isozyme is about 80% similar to those determined previously for rat neuron-specific and non-neuronal enolase isozymes. Southern blot analysis suggested strongly the existence of a single copy of the muscle-specific enolase gene per haploid genome. The mRNA for this enolase isozyme was detected in rat skeletal muscle on day 1 after birth and its level increased rapidly during 10-30 days after birth without any change in its size (1500 bases).

Age Factors↗
PubMed1989

Granulocyte activation by a cell surface complex of Staphylococcus saprophyticus: a receptor-mediated phenomenon.

High molecular weight cell surface complex (CSC) from Staphylococcus saprophyticus strain S 1 could be shown to be a potent stimulator of human polymorphonuclear leukocyte (PMN) chemiluminescence whereas human monocytes were not activated. Heating of the CSC (100 degrees C for 5 min) as well as protease treatment significantly (p less than 0.001) inhibited the PMN activating process suggesting that the protein part of the molecule mediates its biological activity. Data on the biochemical character of the CSC are given. Preincubation of PMNs with CSC inhibited another chemiluminescence response to this substance and to homologous opsonized S. saprophyticus, respectively. However, restimulation with formylmethionyl peptides (fMLP) or non-opsonized staphylococci suggested that the PMN function is a receptor-mediated phenomenon. These data were substantiated since fMLP activated PMNs could be evidently re-stimulated with CSC but not with analogue peptides. Evaluation of the bactericidal capacity of human PMNs yielded comparable results.

Bacterial Proteins↗
PubMed1989

Independent removal of two identical or different introns from mRNA precursors in vitro.

In vitro splicing of 11 different RNA transcripts carrying two introns was performed to determine whether the removal of an intron was dependent on its position or removal of the other intron. The original RNA transcript carried two identical units, each consisting of the first exon-first intron-a major part of the second exon of the human beta-globin gene. Five transcripts carrying a mutation in one of the two introns of the original RNA and one carrying mutations in both introns were prepared. One of the other RNA transcripts had a shorter middle exon than did the original transcript. The remaining three RNAs had at least one shortened form of the human beta-globin second intron. The results can be summarized as follows. 1) There was no obligatory order in the excision of the two identical or different introns, although the 5' proximal intron may be removed more rapidly in some cases. The efficiency of removal of the 5' proximal intron seems to be higher than or similar to that of the distal intron. 2) Excision of a mutated intron was inhibited, but no mutation significantly affected the excision of the other intact intron. 3) Except in an RNA transcript with two mutated introns, significant splicing between exon 1 and exon 3 (exon jumping) did not take place. 4) These results support the proposal that the two introns are basically independent of each other as to their removal.

Chromatography, Gel↗
PubMed1989

New methods to investigate ATP requirement for pre-mRNA splicing: inhibition by hexokinase/glucose or an ATP-binding site blocker.

Addition of yeast hexokinase and glucose at various time points of the pre-mRNA splicing reaction rapidly depleted ATP and inhibited further progress of the reaction, indicating that ATP is required for both the first and second steps of splicing. ATP analogues, p-fluorosulfonylbenzoyl-5'-adenosine (FSBA) and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl), which can modify amino acids at the ATP-binding site of a protein, inactivated the splicing activity of the nuclear extract. While the inactivation by the former was irreversible, the splicing activity was complemented by a Micrococcal nuclease-treated extract. This ATP analogue (FSBA) may be a useful tool for identification of ATP-dependent splicing factors.

Adenosine Triphosphate↗
PubMed1988

Three types of rat U1 small nuclear RNA genes with different flanking sequences are induced to express in vivo.

There are about 50 copies of U1 RNA genes/pseudogenes in the rat genome. To date, we have isolated so far 25 phage clones carrying a U1 RNA gene/pseudogene from two rat genomic libraries. The 12 clones were selected by hybridization with the U1 RNA coding region under a stringent condition, and were mapped and sequenced. Here, we report three types of U1 RNA genes with different flanking sequences, all of which were shown to be induced to express in vivo by transfection with their polylinker-inserted maxi U1 RNA genes into cultured rat cells. Although these three classes of U1 RNA genes have few homologous flanking sequences, they provide both upstream and downstream of the genes two conserved blocks, which may possibly play an important role in U1 RNA expression.

Animals↗
PubMed1988

The role of capsule as a barrier to bacteriophage adsorption in an encapsulated Staphylococcus simulans strain.

The polyvalent staphylococcal bacteriophage U16 failed to adsorb to an encapsulated Staphylococcus simulans strain. Partially purified cell wall and teichoic acid of this strain could, however, inactivate bacteriophage U16 to a great extent, indicating the presence of the phage receptor. It is concluded that the capsule of Staphylococcus simulans acts as a barrier for the interaction of the phage with its receptor in the bacterial cell wall.

Abscess↗
PubMed1988

Glycoprotein modifications of sarcoma L-1 tumor cells by tunicamycin, swainsonine, bromoconduritol or 1-desoxynojirimycin treatment inhibits their metastatic lung colonization in Balb/c-mice.

Synthesis and expression of cell surface carbohydrates appear to be involved in recognition events associated with tumor invasion and metastasis. Thus, the potential of murine sarcoma L-1 cells to form experimental lung metastases after i.v. injection was assessed after inhibiting tumor cell protein glycosylation with tunicamycin, swainsonine, bromoconduritol, or 1-desoxynojirimycin. Incubation of sarcoma L-1 cells with 0.5 microgram (or above) of these substances/ml medium for 20-24 h significantly inhibited lung colonization. Cytotoxic side effects or additional organ manifestations could not be found. Gas liquid chromatographic examinations of carbohydrates from treated L-1 cells indicated that sugar synthesis was evidently inhibited. These results suggest that specific glycan structures on tumor cells are required for expression of the metastatic phenotype.

1-Deoxynojirimycin↗
PubMed1988

The role of lectins and lipoteichoic acid in adherence of Staphylococcus saprophyticus.

Staphylococcus saprophyticus strains S 1 and S 35 demonstrated lectin like surface receptors specific for N-acetylgalactosamine (S 1) or N-acetylneuraminic acid (S 35). Adhesion assays with human uroepithelial cells together with blocking experiments with competitive carbohydrates suggested that specific attachment of S. saprophyticus to host cells is apparently mediated by lectins. Staphylococcal lipoteichoic acid (LTA) was also shown to interfere with S. saprophyticus adherence to human uroepithelial cells.

Bacterial Adhesion↗
PubMed1988

Immunomodulatory effects of staphylococcal lipoteichoic acid in early Listeria monocytogenes infection in Balb/c-mice.

Balb/c-mice were intravenously infected with 5 X 10(4) viable cells of Listeria monocytogenes SLCC 4013. Liver, lung and spleen of the animals showed heavy organ colonization 48 h after infection. Pretreatment of experimental animals with staphylococcal lipoteichoic acid (LTA; 2 mg i.p. 7 and 3 days before challenge) significantly reduced the bacterial count in these organs. In vitro, peritoneal macrophages from LTA-treated mice significantly reduced listerial viability as compared to control cells (p less than 0.0025). In vitro, exposure of macrophages from non-treated animals to LTA did not influence their bacterial killing ability.

Animals↗