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Biomedical subjects

T Ikeuchi

Publications and source records attributed to T Ikeuchi.

At least 271 records · Page 15Linked to original sources
PubMed1977

Escape synthesis of RNA polymerase subunits and termination factor rho following induction of prophage lambda in Escherichia coli.

Synthesis of RNA polymerase subunits and of transcription termination factor p was studied after thermoinduction of prophage lambdac1857 located at several unusual sites on the chromosome of Escherichia coli. When a lysogen carrying the prophage at the bfe gene was induced at 42 degrees C, the rate of synthesis of core polymerase subunits (alpha, beta and beta') rapidly decreased, followed by a marked increase after about 10 min. The latter increase was observed specifically in the "bfe lysogen" and not in any of the other lysogens tested. Similarly, the rate of synthesis of p factor increased appreciably in the induced ilv lysogen carrying the prophage at the ilv gene, and possibly in the bfe lysogen as well, but not in other lysogens examined. Taken together with other evidence, these results suggest that the enhanced syntheses of beta and beta' subunits of RNA polymerase and of p factor observerd represent "escape synthesis", resulting from the close linkage of the prophage genome to the respective structural genes. In contrast, omega factor synthesis was stimulated upon induction of any of the lysogens used without respect to the site of prophage location, suggesting the involvement of an entirely different mechanism.

Coliphages↗
PubMed1977

Detection of endotoxin in plasma and ascitic fluid of patients with cirrhosis: its clinical significance.

Endotoxin was measured by the Limulus assay in plasma and ascites in 46 patients with cirrhosis having demonstrable esophageal varices, of whom 29 had ascites and 17 did not. It was positive in ascitic fluid in 23 (79.3%) of the former group. In plasma, a positive test was obtained in 22 (75.9%) in the group with ascites and only 4 (23.5%) without ascites, the difference being significant (P less than 0.01). Of the 23 positive ascites specimens, 17 showed high titers (greater than or equal to 10(-3) microgram per ml). Hepatic uptake of 198Au colloid was markedly reduced in 11 of the 17 patients with endotoxemia who were studied by scanning. Death occurred within 6 months in 47.8% of the patients with a positive endotoxin test, whereas only 16.7% of those with a negative test died in the same period (P less than 0.05). No hypotension was noted in patients with toxemia and only 2 ran a fever above 37.5 degrees C. Development of tolerance to endotoxin is suspected. A follow-up study has demonstrated sustained endotoxemia in some of these patients.

Ascitic Fluid↗
PubMed1976

Unbalanced 13q/21q translocation: a revised study of the case previously reported as 21-monosomy.

Reexamination was made on a male infant previously reported as 21-monosomy. Extensive chromosome banding analyses in the patient and parents disclosed an unbalanced de novo translocation between chromosomes 13 and 21. The patient's karyotype was interpreted as 45,XY,--13,--21+der(13),t(13;21) (q2 or 3;q1 or 2)pat. The patient showed many clinical features characteristic of 13q--syndrome.

Aneuploidy↗
PubMed1976

A novel adenosine triphosphatase isolated from RNA polymerase preparations of Escherichia coli. I. Copurification and separation.

Adenosinetriphosphatase (ATPase) [EC 3.6.1,3] activity has been found to exist in most preparations of DNA-dependent RNA polymerase [EC 2.7.7.6] obtained from Escherichia coli by a number of purification procedures so far established. Electrophoretic analysis on polyacrylamide gels demonstrated that ATP hydrolysis and RNA synthesis were catalyzed by two distinct enzyme proteins. It appears that the two enzymes are associated or have similar molecular properties. Separation of the two enzymes, the object of the present work, was achieved by three independent methods: ion exchange chromatography on a phosphocellulose column, electrophoresis in glycerol gradients, or high-salt glycerol gradient centrifugation.

Adenosine Triphosphatases↗
PubMed1976

A novel adenosine triphosphatase isolated from RNA polymerase preparations of Escherichia coli. II. Enzymatic properties and molecular structure.

An adenosinetriphosphatase (ATPase) [EC 3.6.1.3] copurified with the DNA-dependent RNA polymerase [EC 2.7.7.6] from Escherichia coli was isolated to apparent homogeneity and some of its functional as well as structural properties were examined. Although the novel ATPase exhibited metal requirements similar to those of Mg2+, Ca2+-ATPase, its response to NaN3 and antisera appeared completely different from that of the Mg2+, Ca2+-ATPase. The purified ATPase was found to be a large protein with a molecular weight of 9.3X10(5) daltons, composed of identical subunits of 7X10(4) daltons. When viewed under an electron microscope, the ATPase appeared to be very similar to material previously misidentified as the RNA polymerase. The physiological role of the novel ATPase, however, remains unclear.

Adenosine Triphosphatases↗
PubMed1975

An abortus with a normal/trisomy 16 mosaicism: instability of trisomic cells in vitro.

A 46,XX/47,XX,+16 mosaicism was demonstrated in cultured chorionic cells obtained from an abortion material. By tracing polymorphic fluorescent chromosome markers in the abortus and the parents, the karyotypically normal component was confirmed to be non-maternal in origin. The trisomic cells showed a growth disadvantage, and were overtaken by the normal cells in prolonged cultivation.

Cells, Cultured↗
PubMed1975

Prenatal diagnosis of I-cell disease.

A pregnancy from a family in risk of I-cell disease was monitored. The fetus was diagnosed as having I-cell disease based on the findings that (1) lysosomal enzyme activities except for acid phosphatase and alpha glucosidase were clearly elevated in amniotic fluid and were reduced in cultivated amniotic fluid cells, and (2) cytoplasmic inclusions were seen in cultivated amniotic cells by phase contrast microscopy. The accuracy of prediction was confirmed by cultured skin fibroblast of the aborted fetus.

Acid Phosphatase↗
PubMed1975

A male infant with monosomy 21.

A male infant with total monosomy 21 identified by Q-, G- and R-banding is described. His main symptoms are hypertonia, micrognathia, microphthalmus, imperforate anus, ambiguous external genitalia, floating and malopposed thumbs, overlying fingers, right clubfoot and growth retardation. Both parents are phenotypically as well as karotypically normal.

Abnormalities, Multiple↗
PubMed1975

Genetic and physical studies of lambda transducing bacteriophage carrying the beta subunit gene of the Escherichia coli ribonucleic acid polymerase.

The prophage lambdac1857 was inserted into the bfe gene located near rif (the structural gene for the beta subunit of deoxyribonucleic acid [DNA]-dependent ribonucleic acid polymerase) on the Escherichia coli chromosome. Induced lysates (low-frequency transducing lysates) of such a lysogen contained defective lambda phage particles (lambdadrif+) that can specifically transduce the wild-type rif+ gene. Upon transduction into a recipient strain carrying recA, heterogenotes harboring both the wild-type and the mutant rif genes were isolated. Rec+ derivatives of these heterogenotes produce high-frequency transducing lysates that contain lambdadrif+ and normal active phages at a ratio of 1 to 2. The results of marker rescue experiments and of density determination with several transducing phages indicate that most of the late genes are deleted and replaced by a segment of the chromosomal DNA carrying the bfe-rif region. The length of the chromosomal segment seems to vary between approximately 0.5 and 0.6% of the total bacterial DNA among the three independently isolated lambdadrif+ phages. Electron microscopy of heteroduplex DNA consisting of one strand from lambdadrif+-6 and the other from lambdaimm-21 phages directly confirmed that most of the phage DNA of the "left arm" was replaced by the bacterial DNA. The heteroduplex study also demonstrated that the integration of prophage lambda into the bfe region occurred at the normal cross-over point within the phage attachment site.

Centrifugation, Density Gradient↗
PubMed1972

Chromosome pulverization in micronuclei induced by tritiated thymidine.

Cultures of a pseudodiploid cell line (Don) of Chinese hamster origin were exposed to varying doses of tritiated thymidine (TdR-(3)H) for relatively long periods of time. In addition to previously observed chromosomal aberrations) such as breaks and reunions, a substantial number of interphasic cells with micronuclei and of metaphases associated with pulverized chromosomes was found; both phenomena were dependent on exposure time to and concentration of TdR-(3)H. The former phenomenon appeared to result from the effects of the beta-emissions originating in the TdR-(3)H. A possible interpretation for chromosome pulverization induction is presented, emphasizing the derivation of the pulverized material from micronuclei in a common cytoplasm with a metaphase nucleus. These observations further substantiate our previously advanced hypothesis regarding the essential role played by substances present in a mitotic cell in the induction of chromosome pulverization and nuclear membrane dissolution.

Animals↗