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Biomedical subjects

K Kohno

Publications and source records attributed to K Kohno.

At least 451 records · Page 25Linked to original sources
PubMed1985

Chemical synthesis of capped RNA fragments and their ability to complex with eukaryotic ribosomes.

In other to examine the binding ability of the 5'-terminal part of eukaryotic mRNA to 80S ribosome, several kinds of oligoribonucleotides, pA-U-G, m7G5'pppA-U-G, m7G5'pppG-U, m7G5'pppA-U-G-A-C-C, were synthesized chemically. The binding experiments of oligonucleotides to 80S ribosome showed that the capped structure as well as AUG are essential for ribosome binding, and the efficiency is enhanced by the 5'-leader sequence if it would include complementary sequence to the 3'-terminal part of 18S rRNA.

Base Sequence↗
PubMed1984

Isolation and characterization of a cDNA clone for the amino-terminal portion of the pro-alpha 1(II) chain of cartilage collagen.

We have isolated a cDNA clone (pRcol 2) which is complementary to the 5'-terminal portion of the rat pro-alpha 1(II) chain mRNA. A synthetic oligonucleotide was used both as a primer for cDNA synthesis and as a probe for screening a cDNA library. The probe was a mixture of sixteen 14-mers deduced from an amino acid sequence present in the amino-terminal telopeptide of the rat cartilage alpha 1(II) chain. This primer was chosen so that the resulting cDNA would contain the sequence of the 5' end of the mRNA. The nucleotide sequences of the cDNA were determined and compared with that of three other interstitial procollagen chain mRNAs (pro-alpha 1(I), pro-alpha 2(I), and pro-alpha 1(III) chain mRNA). pRcol 2 contains a 521-base pair (bp) insert, including 153 bp of the 5' untranslated region plus 368 bp coding for the signal peptide, the amino-terminal propeptide, and a part of the telopeptide. The signal peptide of the type II collagen chain is composed of about 20 amino acids. There is little homology between the amino acid sequence of the signal peptide in the pro-alpha 1(II) chain and that of three other interstitial procollagen chains. The NH2-terminal propeptide is deduced to contain short nonhelical sequences at its amino and carboxyl ends and an internal helical collagenous domain comprising 25 repeats of Gly-X-Y with one interruption. There is a strong conservation of the amino acid sequence of the carboxyl-terminal part of the NH2-terminal propeptide in the pro-alpha 1(II), pro-alpha 1(I), and pro-alpha 2(I) chains. Type II collagen mRNA does not contain a sequence corresponding to a uniquely conserved nucleotide sequence around the translation initiation site which occurs in mRNA for other procollagen chains.

Amino Acid Sequence↗
PubMed1984

Development of the axon cap neuropil of the Mauthner cell in the goldfish.

Development of the axon cap neuropil of the Mauthner neuron in post-hatching larval goldfish brains was observed electron-microscopically. The axonal initial segment of newly hatched (day-4) larvae is completely covered with synaptic terminals containing clear spherical synaptic vesicles. Profiles of thin terminal axons, the spiral fibers, containing similar synaptic vesicles, rapidly increase in number around the initial segment and form glomerular neuropil similar to the central core of the adult axon cap by day 7. Three types of synapses are formed in the core neuropil. Bouton-type synapses contacting the initial segment are most abundant in day-4 to -14 larvae; they decrease thereafter and are rare on the distal half of the initial segment of day-40 larvae. Asymmetric axo-axonic synapses are commonly observed between spiral fibers in the core neuropil of day-7 to -19 larvae, but become fewer by day 40. Unique symmetrical axo-axonic synapses showing accumulation of synaptic vesicles on either side of apposed membrane thickenings first appear in day-14 core neuropil, gradually increase in number, and become the predominant type in day-40 core neuropil. Thick myelinated axons, which lose their myelin sheaths in the glial cap cell layer, start to penetrate into the axon cap on day 10. They gradually increase in number and form the peripheral part of the axon cap together with the cap dendrites, which finally grow into the axon cap from the axon hillock region of the Mauthner cell by day 40.

Age Factors↗
PubMed1984

Brain abscess secondary to intracranial extradural epidermoid cyst.

A case of brain abscess in the right temporal lobe secondary to an intracranial extradural epidermoid cyst in the right parasellar region is reported. The etiology of the brain abscess in this particular case was deduced using the findings of computed tomography, carried out several times over a 3-year period, after an initial operation to remove the epidermoid cyst. One of the scans showed a very-low-density spot in the right parasellar region compatible with air, suggesting a communication between the intracranial space and the paranasal sinuses.

Brain Abscess↗
PubMed1984

Chromosomal assignment of the gene for human elongation factor 2.

Elongation factor 2 (EF-2), polypeptidyl -tRNA translocase, is an essential factor for protein synthesis in eukaryotic cells and Archebacteria . We isolated diphtheria toxin-resistant human primary embryo cells that contain EF-2 that cannot be ADP-ribosylated by diphtheria toxin and Pseudomonas exotoxin A (PA toxin). Somatic cell hybrids were constructed from mouse L cells and toxin-resistant human embryo cell mutants. Forty-one hybrid clones were isolated, of which 15 clones were resistant to PA toxin. Karyotypic analysis and isozyme studies revealed that there was an absolute correlation between human chromosome 19 and resistance to PA toxin in the hybrids. On subcloning of PA toxin-resistant hybrid cells, we obtained one PA toxin-resistant hybrid subclone containing human chromosome 19 as the only human chromosome. Furthermore, the resistance to PA toxin of hybrid cell strains was lost after infection with poliovirus, for which sensitivity is conferred by human chromosome 19. It was confirmed by using two-dimensional gel electrophoresis that PA toxin resistance in hybrid cells was caused by the presence of EF-2 resistant to ADP-ribosylation by fragment A of diphtheria toxin. These facts suggest that the gene encoding EF-2 is located on human chromosome 19.

ADP Ribose Transferases↗
PubMed1984

Purification and characterization of Serratia marcescens US5 pili.

The pili of Serratia marcescens US5 isolated from a patient with urinary tract infection were purified and characterized. During the aeration culture, the pili were detached from the bacteria and were precipitated by the addition of ammonium sulfate. The purification of the pili was carried out by ion-exchange chromatography and gel filtration on Sepharose 4B. In electron microscopy, the purified pilus showed a filament of 3 nm in diameter and 0.3 micron in average length. The molecular weight of the protein subunit of the purified pili was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Two protein bands appeared. One has a molecular size of 19,000 daltons, and the other has a molecular size of 39,000 daltons. The isoelectric point was 3.7. The content of hydrophobic amino acids in purified pili subunits was 42% of the total amino acid content. Further purification of pili by isopycnic centrifugation failed to remove the large protein band. No identical protein bands to pili proteins were detected in the electrophoresis pattern of the outer membrane proteins extracted from S. marcescens US5 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. These two proteins might be a dimer of a small molecule. A survey of clinically isolated strains of S. marcescens revealed that more than 60% of the strains had this type of pili. These results suggest that these pili are widely distributed among strains of S. marcescens.

Agglutination↗
PubMed1984

Studies on the metabolism of diltiazem in man.

The human urinary metabolites of diltiazem were analyzed by thin-layer chromatography (TLC) and gas chromatography-mass spectrometry. Diltiazem was metabolized by deacetylation, N-demethylation, O-demethylation and conjugation. Metabolite MA, N- monodemethyl -diltiazem, was identified as a new major metabolite in human urine, and four metabolites were identified as deacetyl-diltiazem (M1), deacetyl-N- monodemethyl -diltiazem (M2), deacetyl-O-demethyl-diltiazem (M4), deacetyl-N,O-demethyl-diltiazem (M6) which were known as rat urinary metabolites. Metabolite M2, M4 and M6 were converted in part to glucuronides and/or sulfates. Unchanged diltiazem and metabolite MA were determined in human plasma and urine by TLC-densitometry. Diltiazem and metabolite MA excreted in 24-h urine were 44.4 and 48.5% of the total unconjugated form, respectively. The mean plasma level of metabolite MA was approximately one-third of diltiazem level. On the basis of these findings, a probable metabolic pathway of diltiazem in man is presented.

Adult↗
PubMed1984

[A clinical study on cefotiam with special reference to excretion in bile and concentration in gallbladder tissue].

Following 1 hour intravenous drip infusion of 1.0 g of cefotiam (CTM), 38 patients with cholelithiasis were operated at scheduled intervals. The CTM concentrations in serum, common duct bile, gallbladder bile and gallbladder tissue were measured. The mean level of CTM concentration in serum showed a peak of 53.1 micrograms/ml at 1 hour, and decreased in the level of 1.0 microgram/ml at 5 hours after administration. CTM concentrations in common duct bile revealed a mean level of 162 micrograms/ml at 1 hour and similarly high concentrations from 1 to 5 times of the peak level in serum were maintained for 3.5 hours. In patients with impaired liver function, the levels of CTM concentration were lower than those without them. CTM concentrations in gallbladder bile showed a high value at 2-3.5 hours after administration . In many cases the levels were relatively lower than those in common duct bile, particularly ion patients with cystic duct obstruction and/or with marked chronic cholecystitis. As for gallbladder tissue levels, CTM concentrations showed low levels less than 50 micrograms/g in patients with pathological changes of gallbladder, as well as in gallbladder bile. While, favorable concentrations of 50-100 micrograms/g were obtained in patients without them. There was a positive correlation between CTM concentrations in common duct bile and gallbladder bile, and also between the concentrations in gallbladder bile and those in gallbladder tissue in patients without cystic duct obstruction or marked chronic cholecystitis. Then, in the situation, CTM transfer into gallbladder bile or gallbladder tissue might be mainly dependent on biliary excretion of CTM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Transcription renders chromatin resistant to micrococcal nuclease digestion.

When isolated HeLa cell nuclei were preincubated under transcription conditions with excess E. coli RNA polymerase, chromatin DNA became relatively resistant to digestion by micrococcal nuclease. Quantitation of the DNA content in nuclei after enzyme digestion revealed that approximately twice as much nuclease was required to give the same levels of release of DNA fragments from transcribed as from untranscribed nuclei. Resistance increased with the amount of polymerase and with the time of preincubation. Since the resistance to nuclease was not observed in the presence of rifampicin or by preincubation without UTP, both RNA chain initiation and elongation were considered to be essential for the manifestation of resistance. However, when DNase 1 was used as a probe, such a change in chromatin DNA was not detected.

Chromatin↗
PubMed1983

Allopurinol metabolism in a patient with xanthine oxidase deficiency.

A patient with complete deficiency of xanthine oxidase would not be expected to oxidase allopurinol to oxipurinol if allopurinol did not have any alternative metabolic pathway. 400 mg of allopurinol was administered to a patient with xanthine oxidase deficiency, and plasma allopurinol, oxipurinol, hypoxanthine, and xanthine levels were determined serially by the use of high-performance liquid chromatography (HPLC). Plasma oxipurinol as well as allopurinol was increased after the administration of allopurinol, and oxipurinol reached a maximum level of 13.1 micrograms/ml at 6 hours after the administration. This was the same pattern as that of normal controls. This result demonstrated the existence of some other oxidising enzyme of allopurinol than xanthine oxidase.

Allopurinol↗
PubMed1983

Arterioportal shunts on dynamic computed tomography.

Thirty-two patients, 20 with hepatocellular carcinoma and 12 with liver cirrhosis, were examined by dynamic computed tomography (CT) using intravenous bolus injection of contrast medium and by celiac angiography. Dynamic CT disclosed arterioportal shunting in four cases of hepatocellular carcinoma and in one of cirrhosis. In three of the former, the arterioportal shunt was adjacent to a mass lesion on CT, suggesting tumor invasion into the portal branch. In one with hepatocellular carcinoma, the shunt was remote from the mass. In the case with cirrhosis, there was no mass. In these last two cases, the shunt might have been caused by prior percutaneous needle puncture. In another case of hepatocellular carcinoma, celiac angiography but not CT demonstrated an arterioportal shunt. Thus, dynamic CT was diagnostic in five of six cases of arteriographically demonstrated arterioportal shunts.

Arteriovenous Fistula↗