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Biomedical subjects

K Fukada

Publications and source records attributed to K Fukada.

53 records · Page 3Linked to original sources
PubMed1980

Hormonal control of neurotransmitter choice in sympathetic neurone cultures.

Manipulation of the cellular and hormonal environment of cultures of dissociated primary neurones can be used to explore a neurone's developmental potential and to investigate the factors required for normal development. For example, developing adrenergic sympathetic neurones can be influenced to become cholinergic by both diffusible and membrane-bound factors from certain types of non-neuronal cells; when medium conditioned by incubation on heart cell cultures (CM) is placed on the neurones, they develop the ability to produce acetylcholine (ACh) and they form functional cholinergic synapses with each other. Hormones could also contribute to the control of this transmitter choice, and McLennan et al. recently reported that corticosterone treatment of whole superior cervical ganglia (SCG) greatly inhibited the cholinergic development of these ganglia in culture. It was not clear, however, whether the hormone acted directly on the neurones or indirectly via the non-neuronal cells. To study the role of hormones on this transmitter choice, I have now developed a serum-free medium (based on that of Sato and co-workers) for the preparation of conditioned medium. The results obtained with this system show that glucocorticoids and epidermal growth factor (EGF) exert dramatic and antagonistic effects on the adrenergic-cholinergic transmitter choice and do so indirectly, by controlling the ability of heart cells to produce cholinergic CM.

Acetylcholine↗
PubMed1976

In vitro construction of bacteriophage lambda and plasmid DNA molecules containing DNA fragments from bacteriophage T4.

Restriction endonucleases EcoRI and HindIII generated fragments of T4 cytosine-containing DNA were inserted into bacteriophage vector lambdagtSuIII and plasmid vectors pMB9 and pBR313. Resulting clones were screened for hybridization with 32P labeled T4 tRNA. Recombinant bacteriophages and plasmids were isolated which contained a T4 fragment coding for T4 RNA species 1 and 2 and T4 tRNA Arg. Selected lambda-T4 hybrid bacteriophages were grown to high titer and their DNA analyzed by gel electrophoresis.

Coliphages↗
PubMed1976

Cleavage of T4 species I ribonucleic acid by Escherichia coli ribonuclease III.

T4 Species I RNA, a molecule 140 nucleotides in length with some structural features very much like a tRNA, is specifically cleaved by an enzymatic activity in Escherichia coli extracts to give three segments with 19, 48 and 73 nucleotides. We report the purification and characterization of the E. coli RNase which cleaves two 3' phosphodiester bonds of T4 Species I RNA. This reaction has many properties in common with those catalyzed by E. coli RNase III, although the optimal salt conditions for T4 Species I RNA cleavage differ significantly from those for other RNase III-catalyzed reactions. The reaction is not catalyzed by extracts from an E. coli strain lacking RNase III activity. Furthermore, T4 Species I RNA is cleaved by highly purified E. coli RNase III to yield the same three specific fragments. We conclude that this specific cleavage is due to the action of RNase III, and that the requirement for lower ionic strength may reveal further important properties about this RNA processing enzyme.

Cations, Divalent↗
PubMedDate not supplied

The occurrence of precipitating antibodies in transfused Japanese patients with hereditary ninth component of complement deficiency and frequency of C9 deficiency.

Antibodies to the ninth component of complement (C9) were found in a patient with hereditary C9 deficiency (C9D) who had received multiple transfusions. The incidence of anti-C9 precipitating antibodies following transfusion was investigated in 63,625 patients treated at Kyushu University Hospital, and 475,886 blood donors at the Fukuoka Red Cross Blood Center were studied to determine the frequency of C9D in Japan. Transfusion reactions in recipients having anti-C9 were also monitored. One hundred and eighty-six subjects (15 patients and 171 donors) with C9D were identified (a prevalence of 0.036%). Four of 15 C9-deficient patients had received transfusions. One of the patients who had received several units of blood within 1 week developed low-titer C9-precipitating antibody. This patient was transfused in the presence of the antibody without evidence of adverse reactions. No precipitating antibody was detected in the remaining three patients who had received several units of blood on a single day. These observations suggest that multiple transfusions may contribute to the development of anti-C9.

Chemical Precipitation↗