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Biomedical subjects

S Y Song

Publications and source records attributed to S Y Song.

At least 109 records · Page 6Linked to original sources
PubMed1984

A study of experimental cyanide encephalopathy in the acute phase--physiological and neuropathological correlation.

A study was performed to elucidate the significance of various physiological factors contributing to the pathogenesis of experimental cyanide encephalopathy, such as the systemic arterial blood pressure, venous pressure, common carotid blood flow and local blood flow of the cerebral grey and white matters, and blood gas including pH. The histology and topography of the brain damage was also analysed. Twenty-one cats were divided into four groups. The animals in groups 1, 2 and 3 were subjected to continuous infusion of 0.2% sodium cyanide solution and to the ensuing hypotension below 100 mm Hg by administering a ganglion-blocking drug and by respiratory arrest. Severe damage developed in the deep cerebral white matter, corpus callosum, pallidum and substantia nigra, but the damage of the cerebral cortex and hippocampus was not remarkable. The animals in group 4 that were subjected to cyanide infusion without significant hypotension (above 100 mm Hg), but to the same degree of acidosis as that of the other groups, had similar morphological changes, but to a lesser degree. On the basis of our physiological and morphological findings, we speculated that the pathophysiological factors of tissue hypoxia and subsequent hypotension operated in cyanide leucoencephalopathy. The topographic selectivity seemed to be related to the characteristic cerebral vascular system, and the severity of the white matter lesions was related to the intensity of both hypoxia and hypotension during cyanide infusion, but not to the extent of acidosis, total dose of cyanide or duration of its infusion per se.

Acute Disease↗
PubMed1983

Preliminary crystallographic studies of lobster D-glyceraldehyde-3-phosphate dehydrogenase and the modified enzyme carrying the fluorescent derivative.

When the active-site carboxymethylated D-glyceraldehyde-3-phosphate dehydrogenase is irradiated with ultraviolet light in the presence of NAD+, a fluorescent NAD derivative that is covalently linked to the enzyme is obtained. A preliminary crystallographic study of this fluorescent derivative, as well as of the native and the carboxymethylated enzymes from Palinurus versicolor, showed that they are isomorphous and belong to space group C2 as reported for the native enzyme from Palinurus vulgaris. The three forms of the enzyme, although they have identical unit cell parameters, differ considerably in their diffraction patterns, indicating marked differences in conformation in spite of the fact that they differ chemically only in a restricted region around the active site.

Animals↗
PubMed1983

An experimental study of the pathogenesis of the selective lesion of the globus pallidus in acute carbon monoxide poisoning in cats. With special reference to the chronologic change in the cerebral local blood flow.

Twenty-eight mature cats were exposed to 0.3% carbon monoxide (CO) gas for 90-193 min using artificial ventilation. The systemic blood pressure (BP), venous pressure (VP), blood flow of the left common carotid artery (CF), and blood gas were monitored. The local blood flow (LBF) of the globus pallidus, putamen, or claustrum was measured by the hydrogen clearance method. Pallidal lesions were found histologically in 14 cats. The period of CO inhalation and the time thereafter were divided into the following four stages in the animals with pallidal lesions. Stage 1: Initial phase with rapid increase in the CF and LBF, and rapid decrease in the BP. Stage 2: Middle phase with slow decrease in the BP, CF, and LBF. Stage 3: Terminal phase with rapid decrease in the BP, CF, and LBF. Stage 4: Recovery phase. The changes in stage 3 were not so prominent in the animals without pallidal lesions. The LBF of the globus pallidus of the animals with lesions decreased to 67.3 +/- 20.7% of the initial value at the terminal stage of CO inhalation, while it was 188 +/- 46.7% in those without lesions. The difference was statistically significant (P less than 0.01). The LBF of the putamen or claustrum in the animals with lesions in the globus pallidus was 140 +/- 24.6% at this stage, and it was significantly higher than that of the globus pallidus (P less than 0.01). Other factors, such as CO inhalation time, degree of acidosis, and terminal CO-Hb concentration, did not correlate with the occurrence of the pallidal lesion.

Animals↗
PubMed1977

Chromosomes and causation of human cancer and leukemia. XXII. Karyotypic changes in malignant melanoma.

Detailed karyotypic analysis with G- and C-banding has been performed on cells of four malignant melanomas. The modal number in two cases was in the hypodiploid range, the chromosome numbers varying from 39 to 43. These two tumors had 5 to 13 marker chromosomes. The other two tumors were in the polyploid range, with modal numbers of 63 to 157 chromosomes. The cells had a minimum of 11 and a maximum of 40 marker chromosomes. Chromosome no. 1 was more frequently involved in aberrations than any other chromosome. The most common breakpoints on this chromosome were 1q21, 1q25 and 1q32. Frequent breakpoints were also noticed in the centromeric region in various chromosomes. In chromosome no. 1, however, the centromeric area does not seem to be involved. The more common breakpoints on the various chromosomes were 1q21, 1q25, 1q32, 5p13, 9q13, 11q23, 12q13. No common markers were noticed among these four cases of melanoma, but are noticed in unrelated tumors.

Aged↗
PubMed1976

Nonspecific antigen reactions.

Cell-mediated immune challenge reactions to a number of antigens at tumor sites resulted in regressions of various types of benign, premalignant, and malignant lesions in man. Regressions varied from partial to complete and lasted from several months to more than 10 years. Increased levels of cell-mediated immunocompetence were attained by several means, including reduction of tumor burden, immunopotentiation, or transfer of immunity. Antitumor activities of immune challenge reactions are selective for tumor cells and appear to be independent of the nature of the antigens used or the type of neoplasm. Combinations of immunotherapy with other treatment modalities resulted in augmentation of antitumor effects. Preliminary studies indicate that cellular and noncellular mediators of delayed hypersensitivity induce antitumor activities that may be significant in the regressions of neoplasms induced by cell-mediated immune challenge reactions. Since cell-mediated immune reactions are frequent occurrences, they may be a factor in apparently spontaneous regressions of neoplasms.

Administration, Topical↗
PubMedDate not supplied

Dynamic contrast-enhanced breath-hold MR imaging of thoracic malignancy using cardiac compensation.

The purpose of this paper was to evaluate the use of dynamic gadopentetate dimeglumine-enhanced, breath-hold spoiled gradient-recalled (SPGR) MR imaging with cardiac compensation (CMON) compared to spin-echo MR imaging in patients with thoracic malignancy. We retrospectively reviewed MR images from 29 patients with thoracic tumors. MR imaging included axial electrocardiogram (ECG)-gated T1-weighted, fast spin echo (FSE) T2-weighted, and contrast-enhanced breath-hold fast multiplanar SPGR imaging with CMON, which selects the phase-encoding gradient based on the phase within the cardiac cycle. Images were reviewed for lung masses, mediastinal or hilar tumor, disease of the pleura, chest wall, and bones and vascular compression or occlusion. Contrast-enhanced fast multiplanar SPGR imaging with CMON produces images of the chest that are free of respiratory artifact and have diminished vascular pulsation artifact. ECG-gated T1-weighted images were preferred for depicting mediastinal and hilar tumor. The gadopentetate dimeglumine-enhanced fast multiplanar SPGR images were useful for depicting chest wall tumor, vascular compression or thrombosis, osseous metastases, and in distinguishing a central tumor mass from peripheral lung consolidation. Pleural tumor was depicted best on the FSE T2-weighted images and the contrast-enhanced SPGR images. As an adjunct to spin echo T1-weighted and T2-weighted imaging, contrast-enhanced fast multiplanar SPGR imaging with CMON is useful in the evaluation of thoracic malignancy.

Aged↗
PubMedDate not supplied

K-Ras-independent effects of the farnesyl transferase inhibitor L-744,832 on cyclin B1/Cdc2 kinase activity, G2/M cell cycle progression and apoptosis in human pancreatic ductal adenocarcinoma cells.

Pancreatic ductal adenocarcinoma is a highly lethal malignancy that is resistant to traditional cytotoxic therapy. High rates of activating codon 12 K-Ras mutations in this disease have generated considerable interest in the therapeutic application of novel farnesyl transferase inhibitors (FTIs). However, a comprehensive analysis of the effects of FTI treatment on pancreatic cancer cells has not been performed. Treatment of five different human pancreatic cancer cell lines with FTI L-744,832 resulted in inhibition of anchorage-dependent growth, with wide variation in sensitivity among different lines. Effective growth inhibition by L-744,832 correlated with accumulation of cells with a tetraploid (4N) DNA content and high levels of cyclin B1/cdc2 kinase activity, implying cell cycle arrest downstream from the DNA damage-inducible G2/M cell cycle checkpoint. In addition, sensitive cell lines underwent apoptosis as evidenced by changes in nuclear morphology and internucleosomal DNA fragmentation. L-744,832 at a concentration of 1 microM additively enhanced the cytotoxic effect of ionizing radiation, apparently by overriding G2/M checkpoint activation. The effects of FTI treatment on cell growth and cell cycle regulation were associated with changes in posttranslational processing of H-Ras and N-Ras, but not K-Ras. The results confirm the potential therapeutic efficacy of FTI treatment in pancreatic cancer, and suggest that farnesylated proteins other than K-Ras may act as important regulators of G2/M cell cycle kinetics.

Antineoplastic Agents↗