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Biomedical subjects

H Seto

Publications and source records attributed to H Seto.

At least 109 records · Page 6Linked to original sources
PubMed1987

[Whole-body transmission scintigraphy using a line source].

Transmission scanning was proposed to be a useful adjunct to conventional emission scanning for accurately keying radionuclide deposition to radiographic anatomy. After introduction of a scintillation camera, transmission whole-body scintigraphy using a flood source has been performed in a patient with differentiated thyroid carcinoma. Recently immunoscintigraphy with radiolabeled monoclonal anti-tumor antibodies has become popular and transmission whole-body scintigraphy has been re-evaluated to make diagnosis for laterality of metastases. However, there are several problems to handle a flood source for preparation and shielding. We developed a special line source for transmission whole-body scintigraphy. The line source is composed of a plastic tube (inner diameter: 3 mm) with three-way stop in a U-shaped metal. There are several advantages to use this line source as compared to a flood one; (1) a small volume of radioactive solution (less than 5 ml), (2) easy preparation and setting, and (3) less radiation. Moreover good quality of transmission image is obtained using this line source.

Humans↗
PubMed1987

[Attenuation correction of SPECT imaging by dual energy method--quantification of 111In-labeled monoclonal anti-tumor antibody localization].

Application of radiolabeled monoclonal anti-tumor antibodies for diagnosis and therapy has made remarkable progress in the past few years. Quantification of radiopharmaceutical localization is required adequate attenuation correction in SPECT imaging. Attenuation correction by transmission CT (TCT) data is one of the best method at present time. However, if a patient is moved between TCT and SPECT, this method is no more applicable. We developed a new attenuation correction algorithm by dual energy method, using 99mTc and 111In because of similarity of these linear attenuation coefficients. The new algorithm uses data of TCT with an external source of 99mTc, and requires another data from SPECT of 111In labeled monoclonal anti-tumor antibody, which are simultaneously obtained. TCT results in an attenuation map, which then serves as input into the final intrinsic correction algorithm to uncorrected SPECT data. In chest phantom experiment, the attenuation corrected SPECT images revealed nearly same distribution of actual radioactivity of 111In as compared to that of uncorrected one.

Antibodies, Monoclonal↗
PubMed1987

In vivo localization of radiolabeled monoclonal antibody to carcinoembryonic antigen (CEA) in a CEA-producing tumor--comparison with polyclonal antibody.

To compare accumulation of the 125I-labeled antibodies (anti-carcinoembryonic antigen (CEA) monoclonal antibody and polyclonal antibody) to a CEA-producing tumor (SC-2-JCK), an in vivo localization study was performed in nude mice. The tumor-to-blood ratio at 120 hours after injection rose to 4.6 for the monoclonal antibody, but remained at 1.3 for the polyclonal antibody. However, no differences were noted between the antibodies up to 72 hours after injection. In autoradiograms, selective accumulation of the tracer was noted in the tumor for both antibodies. However, no superiority or inferiority of imaging for either of the antibodies could be definitely determined.

Adenocarcinoma, Papillary↗
PubMed1987

Arugomycin, a new anthracycline antibiotic. I. Taxonomy, fermentation, isolation and physico-chemical properties.

Arugomycin (AGM) is a new anthracycline antibiotic produced by strain No. 1098-AV2 which was identified as Streptomyces violaceochromogenes. AGM was isolated by solvent extraction, silicic acid chromatography and Sephadex LH-20 column chromatography. Acid treatment of AGM gave the chromophore, named arugorol, which was identified as 4'-epi-nogalarol, and sugar moieties. AGM inhibited the growth of Gram-positive bacteria and showed antitumor activity against sarcoma S-180 and Ehrlich ascites tumors.

Animals↗
PubMed1987

Arugomycin, a new anthracycline antibiotic. II. Structural elucidation.

The structure of arugomycin was determined by chemical degradation, and NMR and mass spectral analyses to be a new anthracycline antibiotic with arugorol (4'-epi-nogalarol) as the chromophore and two sugar chains comprising diginosyl-decilonitrosyl-2-deoxyfucose, and (4-O-fumaryl-diginosyl)-diginosyl-2-deoxyfucosyl -diginose.

Anthracyclines↗
PubMed1987

Arugomycin, a new anthracycline antibiotic. III. Biological activities of arugomycin and its analogues obtained by chemical degradation and modification.

Biological activities of arugomycin and its analogues obtained by chemical degradation and modification were evaluated. Differences in the sugar moieties affected their biological activities including induction of differentiation of mouse Friend erythroleukemia cells and mouse myeloid leukemia cells, antitumor activities against sarcoma S-180, Ehrlich ascites carcinoma and P388 leukemia, and cytotoxicity against murine leukemia cells. Some relationships were found between the sugar moieties and biological activities.

Animals↗
PubMed1986

13C NMR evidence for bacteriochlorophyll c formation by the C5 pathway in green sulfur bacterium, Prosthecochloris.

The 13C NMR spectra of the pheophorbide of bacteriochlorophyll c, formed in the presence of L-[1-13C]glutamate and [2-13C]glycine and [13C]bicarbonate in Prosthecochloris aestaurii, were analysed. The isotope in the glutamate was specifically incorporated into the eight carbon atoms in the tetrapyrrole macrocycle derived from the C-5 of 5-aminolevulinic acid, while no specific enrichment of these eight carbon atoms was observed in the spectrum of the pigment formed in the presence of [2-13C]glycine. These labelling patterns provide evidence for the operation of the C5 pathway of 5-aminolevulinic acid synthesis for bacteriochlorophyll c formation in the bacterium. The labelling of bacteriochlorophyll c by [13C]bicarbonate is consistent with its formation from 5-[1,4,5-13C]aminolevulinic acid formed by the C5 pathway from [1,2,5-13C]glutamic acid. It is proposed that this glutamate is the transamination product of 2-[1,2,5-13C]oxoglutaric acid, arising by carboxylation of [1,4-13C]succinyl-CoA with 13CO2 catalysed by 2-oxoglutaric acid synthase activity, and that the labelled succinyl-CoA is, in turn, derived by the fixation of 13CO2 by the reductive tricarboxylic acid cycle. The 13C chemical shifts of two sp2 quaternary carbons of bacteriopheophorbide c methyl ester (C-2 and C-4) were reassigned.

Bacteria↗
PubMed1986

13C-NMR evidence of bacteriochlorophyll a formation by the C5 pathway in Chromatium.

The 13C-NMR spectra of bacteriochlorophyll a formed in the presence of L-[1-13C]glutamate and [2-13C]glycine in Chromatium vinosum strain D were analyzed. The isotope in the glutamate was specifically incorporated into eight carbon atoms in the tetrapyrrole macrocycle derived from the C-5 of 5-aminolevulinic acid (ALA), and the 13C in glycine was incorporated into the methyl carbon of the methoxycarbonyl group attached to the isocyclic ring of bacteriochlorophyll a. These labeling patterns provide evidence for the exclusive operation of the C5 pathway in ALA biosynthesis in the bacterium. The 13C chemical shifts of two quaternary carbons (C-9 and C-16) of bacteriochlorophyll a were reassigned in the present study.

Aminolevulinic Acid↗