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Biomedical subjects

Y S Ding

Publications and source records attributed to Y S Ding.

83 records · Page 5Linked to original sources
PubMed1991

Synthesis of high specific activity (+)- and (-)-6-[18F]fluoronorepinephrine via the nucleophilic aromatic substitution reaction.

The first example of a no-carrier-added 18F-labeled catecholamine, 6-[18F]fluoronorepinephrine (6-[18F]FNE), has been synthesized via nucleophilic aromatic substitution. The racemic mixture was resolved on a chiral HPLC column to obtain pure samples of (-)-6-[18F]FNE and (+)6-[18F]FNE. Radiochemical yields of 20% at the end of bombardment (EOB) for the racemic mixture (synthesis time 93 min), 6% for each enantiomer (synthesis time 128 min) with a specific activity of 2-5 Ci/mumol at EOB were obtained. Chiral HPLC peak assignment for the resolved enantiomers was achieved by using two independent methods: polarimetric determination and reaction with dopamine beta-hydroxylase. Positron emission tomography (PET) studies with racemic 6-[18F]FNE show high uptake and retention in the baboon heart. This work demonstrates that nucleophilic aromatic substitution by [18F]fluoride ion is applicable to systems having electron-rich aromatic rings, leading to high specific activity radiopharmaceuticals. Furthermore, the suitably protected dihydroxynitrobenzaldehyde 1 may serve as a useful synthetic precursor for the radiosynthesis of other complex 18F-labeled radiotracers.

Animals↗
PubMed1991

[The prognostic significance and correlation of ventricular late potentials with programmed electrical stimulation in patients after myocardial infarction].

Seventeen patients (pts) after myocardial infarction (MI) were studied with signal-averaged electrocardiograph and cardiac programmed electrical stimulation (PES). In 7 pts with late potentials (LPs), sustained ventricular tachycardia (SVT) was induced in 6 cases (6/7, 85.7%); while it was induced only in 3 cases the 10 pts without LPs (3/10, 30%). Both have significant difference (P less than 0.01). During following observation, pts with LPs and SVT induced 5 of the 6 appeared clinical SVT or ventricular fibrillation (VF) repetitiously, and 1 died from sudden cardiac death. They also have significant difference (P less than 0.001) with pts without LPs and SVT not induced. These results suggests that LPs is a significant index for predicting future events and its combination with PES is helpful to screen high-risk pts after MI.

Adult↗
PubMed1987

Changes of SCE frequency and chromatin molecular composition in rat progeny whose mothers were treated with oral contraceptives in early pregnancy.

Wistar female rats were fed with oral contraceptives (OC, containing ethinylestradiolum and methylnorethrindronum) in early pregnancy. The dosage used for rats was 6.6 times more than the clinical dosage for humans in weight per kilogram. The SCE frequencies of liver and ovary cells and the changes of chromatin molecular composition in progeny of the rats fed with OC were observed. The results showed that the liver and ovary cells of newborns 12 h after birth exhibited increased SCEs value (liver: p less than 0.03; ovary: p less than 0.0004). These elevated SCE frequencies declined to the normal level about the 15th day after birth. The results for the quantity of nonhistone (NHP) and chromatin RNA in mother rats and their progenies also exhibited a significant increase, and declined to the normal level at the same period mentioned above. The results suggested that the high level of NHP and chromatin RNA may be induced by OC fed in early pregnancy and be maintained for some time after withdrawal of the OC pills. The changes of the chromatin molecular composition are perhaps somehow related to the increased SCE frequencies in the rat-liver cells. We suggest that the external steroids and their metabolites may activate more genes which were originally inactive and result in increased junctions between euchromatin and heterochromatin, resulting in more SCEs in quickly dividing embryo cells. The report here suggests that during early pregnancy the pills taken by women following OC failures may have a potential mutagenic effect on their progeny for some time after the pills have been stopped.

Animals↗