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Biomedical subjects

A Kubo

Publications and source records attributed to A Kubo.

At least 289 records · Page 16Linked to original sources
PubMed1988

Nucleotide sequence of the rci gene encoding shufflon-specific DNA recombinase in the IncI1 plasmid R64: homology to the site-specific recombinases of integrase family.

Shufflon is a novel type of DNA rearrangement in which four DNA segments are flanked by seven 19-bp repeat sequences. The site-specific recombination between any inverted repeats results in an inversion of the DNA segment(s) either independently or in groups. The recombination is mediated by a gene designated rci. We have determined the nucleotide sequence of the rci gene and found that it encodes a basic protein with 384 amino acid residues. The rci gene was fused with lacZ and its gene product was identified by Western blot analysis. The Rci protein shows regional homologies to the site-specific recombinases encoded by the bacteriophage genomes, including those of lambda, phi 80, P22, P2, 186, P4 and P1.

Amino Acid Sequence↗
PubMed1988

Radioimmunodetection of human pancreatic tumor xenografts using DU-PAN II monoclonal antibody.

The potential of DU-PAN II, monoclonal antibody (IgM), which was raised against the human tumor cell line, was evaluated for radioimmunodetection of human pancreatic tumors (PAN-5-JCK and EXP-58) grown in nude mice. 125I-labeled DU-PAN II was accumulated into PAN-5-JCK producing DU-PAN II antigen with a tumor-to-blood ratio of 2.72 +/- 3.00, but it did not localize in EXP-58 because of insufficient DU-PAN II. There was no significant uptake of 125I-nonimmunized IgM in PAN-5-JCK. These facts indicated the specific tumor uptake of DU-PAN II. Excellent images of the tumor PAN-5-JCK were obtained 3 days after the injection of 125I-DU-PAN II. Gel chromatography was also investigated with respect to the plasma taken from mice injected with antibody, or incubated with antibody in vitro. The results indicate that circulating antigen affected the tumor uptake of DU-PAN II: The more the tumor grew, the higher the amount of antigen excreted into the blood, leading to the degradation of DU-PAN II before it reached the tumor sites. Consequently, the immunoscintigram of the small tumor was remarkably clear. The catabolism and the radiolysis of the labeled IgM injected are critical points in applying immunoscintigraphy.

Animals↗
PubMed1988

A simple technique to measure regional cerebral blood flow during intravascular balloon clamping.

A case of giant internal carotid ophthalmic aneurysm was presented. In order to clarify whether the patient could tolerate carotid occlusion, a balloon clamping test was performed. before surgery. The cerebral blood flow was measured using early imaging by single photon emission computed tomography (SPECT) with N-isopropyl-(iodine-123)-p-iodoamphetamine (123I-IMP). When the balloon clamping test was performed the tracer was injected, and scanning was performed 35 minutes after removing the catheter. This tracer enabled a "memory of blood flow" during temporary ischemia to determine the character of quick diffusion and slow wash out, that could not be performed by other methods of cerebral blood flow measurement. SPECT with 123I-IMP can simplify the measurement of cerebral blood flow during the balloon clamping test.

Adult↗
PubMed1988

Mechanism of inhibition of reverse transcriptase by quinone antibiotics. II. Dependence on putative quinone pocket on the enzyme molecule.

Inhibition of avian myeloblastosis virus (AMV) reverse transcriptase by natural and synthetic quinones including antibiotics could be accounted for by an oxidation-reduction reaction. The quinones were shown to function as electron acceptors as revealed by the catalytic oxidation of NADH by Clostridium kluyveri diaphorase which was in excellent agreement with enzyme inhibition activity. The kinetics of inhibition of AMV reverse transcriptase by three synthetic quinones with different core structures, i.e., 6-methoxy-5,8-dihydroquinoline-5,8- dione, 5,8-dihydroisoquinoline-5,8-dione and 1,4-naphthoquinone, were studied. These quinones inhibited reverse transcriptase in the same manner as streptonigrin (STN) and were shown to act at a single class of reaction site(s) on the enzyme molecule. In contrast, the quinones with bulky substituents, i.e., 7-(2-nitrophenethylamino)-5,8-dihydroisoquinoline-5,8-dione and 7-methoxy-6-methyl-3-piperidino-5,8-dihydroisoquinoline-5,8-dione, were inactive as inhibitors of reverse transcriptase, whereas they retained competent catalytic activities in the oxidation of NADH by C. kluyveri diaphorase. Based on these observations, the existence of a specific site of interaction on the enzyme molecule, referred to as a quinone pocket, was proposed. The quinone pocket might play a crucial role in the early sequence of events leading to the inhibition of reverse transcriptase by quinones including STN and sakyomicin A (SKM). Access of SKM to a quinone pocket might be restricted due to its bulky structure in the vicinity of the quinone group. This is inferred from unsuccessful inhibition of reverse transcriptase by the quinones with bulky substituents, resulting in much poorer inhibition of reverse transcriptase in spite of more potent electron acceptor activity in the oxidation-reduction system as compared with those of STN.

Animals↗
PubMed1988

Structural studies on minor components of saframycin group antibiotics saframycins F, G and H.

Three minor components of saframycin group antibiotics, saframycins F, G and H were isolated and their structures were determined by comparison with the spectral data of UV, IR, and 1H and 13C NMR of already reported saframycins A and D. Saframycins F, G and H were 21-cyanosaframycin D, 14-hydroxysaframycin A and 25-dihydro-25-beta-ketopropyl-saframycin A, respectively.

Anti-Bacterial Agents↗
PubMed1988

Iodine-131 therapy for parotid oncocytoma.

We present a rare case of a patient with coexisting parotid oncocytoma and chronic thyroiditis who received two therapeutic doses of [131I]iodide for a recurrent oncocytoma (oxyphilic granular cell adenoma), resulting in a definite reduction in tumor volume. We suggest that radioiodine therapy for a recurrent oncocytoma is an effective form of tumor therapy.

Adenoma↗