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Biomedical subjects

R Fukuda

Publications and source records attributed to R Fukuda.

At least 163 records · Page 9Linked to original sources
PubMed1987

A sequential study of viral DNA in serum in experimental transmission of duck hepatitis B virus.

To understand the relationship among the time of infection, infection patterns, and liver diseases, experimental transmission of duck hepatitis B virus (DHBV) utilizing 165 Japanese white domestic ducklings was performed. Twenty to 25 ducklings were each inoculated with DHBV-positive serum intravenously at day one, 3, 5, 7, 10, and 14 posthatch and were sacrificed during the 1st, 2nd, 3rd, and 4th (and 24th in those inoculated on day one and day 3 posthatch) week after inoculation to obtain sera and the liver. The sera served for the measurement of DHBV DNA by spot hybridization test and DNA polymerase activity, and the liver was subjected to morphological examination including immunostaining for DHBV. The ducklings inoculated with DHBV on 1 day and 3 days posthatch always revealed persistent viremia, whereas those on and after 5 days posthatch showed persistent or transient viremia. The hepatitis activity in the liver was seen in ducklings inoculated with DHBV on and after 3 days posthatch and was very weak consistent with the diagnosis of mild acute hepatitis of humans. The serum transaminase activity was not significantly elevated at the time of occurrence of histological hepatitis activity. Since host immune mechanism establish at 3 to 5 days posthatch in birds, the host immune response seemed to determine whether DHBV infection was persistent or transient and the occurrence of hepatitis activity as seen in human hepatitis B virus (HBV) infection.

Alanine Transaminase↗
PubMed1987

Gastric emptying in deformed stomach.

To evaluate the relationship between the onset of peptic ulcer and gastric emptying, some factors which were thought to regulate gastric emptying, i.e. the stage of the ulcer, the location of the ulcer and gastric acidity were studied in cases of gastric ulcer with deformed stomach and were proven to have little influence on gastric emptying. Further, the main cause of delayed gastric emptying was revealed to be the deformity itself, because the shortening of the distance from the gastric angle to the pyloric ring at the lesser curvature (sac-shaped stomach) and the indentation of the corpus ventriculi (hourglass-shaped stomach) significantly delayed gastric emptying. Moreover, it was found that the healing of gastric ulcer was delayed in cases of deformed stomach with delayed gastric emptying when the ulcer was at an active stage. Therefore the improvement of gastric emptying by some methods was thought to be necessary to promote ulcer healing and prevent ulcer recurrence in gastric ulcer patients who had a deformed stomach.

Acetaminophen↗
PubMed1985

Determination of streptomycin in serum by high-performance liquid chromatography.

A high-performance liquid chromatographic method was developed for monitoring the serum concentration of streptomycin. The method includes clean-up using a Sep-Pak C18 cartridge and quantitation using dihydrostreptomycin as an internal standard. Streptomycin and dihydrostreptomycin were separated by reversed-phase ion-pair chromatography on LiChrosorb RP-18 and detected by UV absorption (195 nm). The calibration graph of serum streptomycin concentration was linear over the range 5-50 micrograms/ml. Streptomycin was added to serum at the level of 20.0 micrograms/ml and its concentration was determined to be 18.9 micrograms/ml with a coefficient of variation of 2.07% (n = 5). The clinical application of this method was confirmed by comparison with fluorescence polarization immunoassay.

Chromatography, High Pressure Liquid↗
PubMed1985

Transcription and replication of eight RNA segments of influenza virus.

A novel quantitation system of both plus- and minus-strand RNAs for all eight genome segments of influenza virus was developed using single-strand cDNAs as the probes for hybridization, and employed for the measurement of various RNA species in influenza virus WSN-infected MDBK cells. The synthesis rate and accumulation level of plus-strand RNAs differed considerably among eight RNA segments and were under temporal control. In contrast, eight vRNA molecules of minus polarity were synthesized coordinately at similar rates. Newly synthesized plus-strand RNAs were rapidly transported into the cytoplasm, particularly during the early phase of virus infection, but vRNAs accumulated in the nuclei until the late infection phase. The present data supported the differential regulation of synthesis and the separate transport between plus- and minus-strand RNAs.

Animals↗
PubMed1985

Cloning of the Escherichia coli gene for the stringent starvation protein.

In order to clone the Escherichia coli gene for the stringent starvation protein (SSP), we determined its N-terminal sequence as well as the sequence of two peptide fragments obtained by cyanogen bromide cleavage of the protein. We then chemically synthesized four sets of oligodeoxyribonucleotide mixtures that represented possible codon combinations for parts of these amino acid sequences. The synthetic oligonucleotides were labelled with 32P at their 5'-termini and used as hybridization probes to detect DNA fragments containing the complementary sequences. Genomic Southern hybridization of E. coli chromosomal DNA gave up to ten DNA fragments hybridizing with each probe but only a few hybridized with two or more of the probes. The latter fragments were cloned in pBR322. By determining partial base sequences with a rapid method and examining proteins encoded by the DNA fragments, we were able to show that we had isolated a clone containing the complete SSP structural gene.

Amino Acid Sequence↗
PubMed1984

Effects of diltiazem on plasma level and urinary excretion of digoxin in healthy subjects.

To evaluate a possible effect of diltiazem hydrochloride (DTZ) on digoxin (DX) kinetics, we performed a study in which a single oral dose of DX (0.5 or 0.75 mg) was given with and without DTZ (30 mg three times daily for 1 wk) to six healthy subjects. DTZ increased plasma DX concentrations at 3, 4, 6, and 12 hr and decreased renal clearance of DX from 3.05 +/- 0.126 to 2.31 +/- 0.234 ml/min/kg. There was no significant change in absorption t 1/2, peak concentration, peak concentration time, distribution t 1/2, biologic elimination t 1/2, or apparent volume of distribution with DTZ.

Absorption↗
PubMed1983

Mechanism of the rifampicin induction of RNA polymerase beta and beta' subunit synthesis in Escherichia coli.

The mechanism of the rifampicin induction of RNA polymerase beta and beta' subunit synthesis was investigated, employing an in vitro coupled system of transcription and translation as well as an in vitro transcription system with purified RNA polymerase holoenzyme. Two independent effects leading to the induction of beta and beta' polypeptide synthesis have been identified for the drug: 1) rifampicin binds to RNA polymerase holoenzyme and inhibits its autorepressor activity, thus relieving the autorepression exerted possibly on the translation of rpoBC mRNA; and 2) rifampicin-RNA polymerase complex functions as a positive effector stimulating the transcription of rpoBC genes, but not of rplL gene. Using a terminally labeled DNA fragment covering the intercistronic region between rplL and rpoB as a probe, the structure of both in vivo and in vitro RNA were analyzed by S1 nuclease-mapping assays. The experimental results indicated that the observed stimulation of the transcription by rifampicin was attributed, at least in part, to relaxation of the transcription attenuation immediately preceding the rpoB gene, resulting in the increase of the read-through transcript to rpoBC genes. Besides the read-through transcript and the processed mature rpoBC mRNA, another RNA species was found in in vivo RNA, which might be transcribed from a weak promoter located in the intercistronic region. However, no clear indication has been obtained of possible enhancement of the transcription initiation by rifampicin from the putative promoter.

Base Sequence↗
PubMed1980

Autogenous and post-transcriptional regulation of RNA polymerase synthesis.

The regulation of gene expression was studied, for the Escherichia coli rpoBC operon, which includes the genes, rpoB and rpoC, for the beta and beta subunits of RNA polymerase, and rplJ and rplL, for the two proteins, L10 and L7/12, of the 50S ribosome. The gene organization agrees well with the accumulated observations indicating the coordinate synthesis of RNA polymerase and ribosomes under various growth conditions for wild-type E. coli cells. On the other hand, the differential regulation of the two essential components observed under restrictive growth conditions, after addition of various drugs or with certain mutants, in particular those carrying mutations in the RNA polymerase genes, was found to take place through two novel regulation systems: The transcriptional termination at an internal attenuation site and the two autogenous and posttranscriptional controls, being specific for the two ribosomal protein genes and the two RNA polymerase subunit genes, respectively. The majority of the transcription initiated from the promoter rpoP beta terminates at an attenuator site between the promoter-proximal rplJL and the promoter-distal rpoBC genes. The frequency of the attenuation seems to control the relative level of RNA polymerase synthesis to that of ribosomes. The expression of rpoBC genes is subject to an autogenous regulation, in which both RNA polymerase holoenzyme and alpha 2 beta complex function as regulatory molecules with repressor activity. The autogenous regulation was found to operate at post-transcriptional step(s), probably at the level of translation. During the study on the regulation of RNA polymerase synthesis, we noticed that the rpoBC operon contained another autogenous regulation circuit, in which the synthesis of L10 and L7/12 was specifically repressed by the L10-L7/12 complex. Molecular mechanisms and physiological meanings of the novel regulations are discussed.

Acridine Orange↗
PubMed1980

Autogenous regulation of the synthesis of ribosomal proteins, L10 and L7/12, in Escherichia coli.

The in vitro synthesis of Escherichia coli ribosomal proteins, L10 and L7/12, is specifically repressed by the addition of the L10-L7/12 complex, while that of other ribosomal proteins encoded by the neighboring operons is not affected. Thus the expression of the rpoBC operon is controlled by two autorepression systems, one for the two ribosomal proteins and the other for RNA polymerase beta and beta' subunits, both operating probably at the translational level.

Bacterial Proteins↗