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Biomedical subjects

C Chen

Publications and source records attributed to C Chen.

At least 1,081 records · Page 60Linked to original sources
PubMed1992

Diurnal rhythms of glycogen metabolism in the liver and skeletal muscle in gold thioglucose induced-obese mice with developing insulin resistance.

The circadian rhythm of glycogen metabolism in liver and skeletal muscle was studied in lean and gold thioglucose (GTG) induced-obese mice. The active forms of glycogen synthase (GSI) and phosphorylase (GPa) and the total activity of these enzymes were measured every three hours over a 24 h period in mice fed ad libitum. Hepatic and muscle glycogen content displayed a marked diurnal rhythm that was similar in lean and obese mice. In skeletal muscle the glycogen content, GSI and GPa were not significantly different in lean and obese animals over the 24 h period. The activities of muscle GSI and GPa were constant in both groups despite the diurnal variation in the muscle glycogen content. The absence of an increase in the glycogen content of skeletal muscle despite the pronounced hyperinsulinemia and hyperglycemia in the obese mice, may indicate the degree of insulin resistance in this tissue or the maximal capacity of muscle tissue to store glycogen. In liver, glycogen concentration and total glycogen storage were higher in obese mice. Unlike muscle, both hepatic GSI and GPa underwent significant changes in activity over the 24 h period. Hepatic GSI was lower and GPa was higher in obese mice. The circadian rhythm in enzyme activities was independent of both blood glucose and insulin levels. The total glycogen storage and the activities of total phosphorylase and GPa were significantly increased in the liver from GTG obese mice over a 24 h period and could be implicated in the development of insulin resistance and glucose intolerance in this model of obesity.

Animals↗
PubMed1992

[Study on radionuclide migrating along the channel].

The study of impedance line along channel had been performed with the radionuclide tracing method in 15 healthy human being and 4 guinea pigs. These images of tracer migrating routes approximately corresponded with classical courses of channel. The study proved that these line-shaped tracer migration were not by the way of lymphatic and blood vessels as well as nerves. This image of radionuclide migrating along channel may used as the guide for the observation of micro-autoradiography. In this study, satisfactory migrating image along the channel was also obtained by 131I instead of 99mTC. So a new way was opened up for both macro- and micro-autoradiographic study.

Adult↗
PubMed1992

Clinical evaluation of the NBD-PC fluorescence polarization assay for prediction of fetal lung maturity.

OBJECTIVES: 1) To examine a fluorescence polarization (FP) assay with an independent set of data that contained more cases of respiratory distress syndrome (RDS) than a previous study, 2) to determine whether the same reference ranges are applicable to infants born to diabetic women, and 3) to evaluate whether adding the lecithin-sphingomyelin ratio (L/S) would substantially improve the prediction of RDS among women with an intermediate FP value (between 0.26-0.289). METHODS: We identified 389 women who had FP analysis performed at the University of Washington Medical Center from February 1986 to October 1988 and who delivered within 3 days of amniocentesis. We reviewed the medical records of these women and their infants to extract information for our study. RESULTS: For FP values of 0.26 or greater, the sensitivity and specificity for prediction of RDS were 90.2 and 84.6%, respectively, compared with 100 and 82.0% in the previous study. For FP values of 0.29 or greater, the sensitivity and specificity were 62.8 and 94.2%, respectively (80.8 and 96.2% in the previous study). Among diabetics, an FP result below 0.26 was associated with the same low risk of RDS as among non-diabetics. Among the patients with FP between 0.26-0.289, the addition of L/S did not provide a clinically useful improvement in the prediction of fetal lung maturity. CONCLUSION: The NBD-PC FP assay can be used as the sole test of fetal lung maturity in most clinical circumstances.

Amniotic Fluid↗
PubMed1992

[Kinetics of pharmacologic effects of radix Aconiti Lateralis Preparata and sini decoction].

In the study of analgesic action of Radix Aconiti Lateralis Preparata and Sini Decoction hot-plate method was used and the time-effect relationship was determined. The biological half-lives were 11.05 h and 6.84 h respectively. In the study of the effect on inflammation induced by egg white in the ankle joints of rats, the method of complement ED50 was used. The residual rates of the dosages after an interval of 6 hours were 0.60 and 0.69, and the biological half-lives were 8.11 h and 11.35 h respectively.

Animals↗
PubMed1992

[Effect of radix Astragali and radix ginseng in enhancing the metabolism of human myocardial cells in vitro].

Our experiment indicated that in Radix Astragali and Radix Ginseng treated human myocardial cell cultures the level of LDH and SDH elevated in varying degrees and in Radix Ginseng treated cells the cAMP showed higher levels but in Radix Ginseng treated ones the same was not observed. This suggests that the metabolism of myocardial cells is enhanced by Radix Astragali or Radix Ginseng.

Cells, Cultured↗
PubMed1992

[Studies on the tissue schizonticide of malaria parasite: synthesis of derivatives of 2-substituted phenoxyprimaquine, 4-methylprimaquine and quinoxaline].

2-Substituted phenoxy-, 4-methyl-6-methoxy-8-aminoquinolines and 7-methoxy-5-aminoquinoxaline were condensed with 1-phthalimido-bromo-alkane to yield 2-substituted phenoxy-, 4-methyl-6-methoxy-8-(1-phthalimidoalkyl)-aminoquinolines (compounds 7-10 and 15-20) and 7-methoxy-5-(1-phthalimidoalkyl)aminoquinoxalines (28-30) which were subsequently reacted with hydrazine hydrate to give 2-substituted phenoxy-, 4-methyl-6-methoxy-8-(1-aminoalkyl)-aminoquinolines (11-14 and 22-27) and 7-methoxy-5-(1-aminoalkyl) aminoquinoxalines (31-33), respectively. The 2-substituted phenoxy-6-methoxy-8-aminoquinolines (4-6) were afforded by reduction of the corresponding 8-nitroquinolines (1-3) which were obtained by condensation of 2-chloro-6-methoxy-8-nitroquinoline and substituted phenols. Among them, compounds 25 and 24 were the most effective when evaluated in Plasmodium yoelii infected mice, no parasitemia was observed after a single oral dose of 10 mg/kg.

Animals↗
PubMed1992

[Studies on the tissue schizonticide of malaria parasite: synthesis of 5-trieluoroacetyl-primaquine and its derivatives].

Primaquine was acylated with trifluoroacetic anhydride to give 6-methoxy-8-(4-trifluoroacetamido-1-methylbutyl) aminoquinoline (compound 2 in Table) and 5-trifluoro-acetyl-6-methoxy-8-(4-trifluoroacetamido-1-methylbutyl )- aminoquinoline (compound 6), bis (trifluoroacetyl) primaquine, which was subsequently hydrolyzed to yield 5-trifluoroacetyl-6-methoxy-8-(4-amino-1-methylbutyl)-aminoquinoline (compound 11), 5-trifluoroacetyprimaquine or trifluoroacetoprimaquine, coded M8506. Similarly, compounds 1, 3-5 and 7-10 were also prepared. Among them, compound 11 appeared to be the most effective by evaluation in mice infected with sporozoites of Plamodium yoelii. With intragastrical dosage of 0.75 mg/kg/d x 3 d of compound 11 to monkeys infected with sporozoites of P. cynomolgi, the radical cure rate of the compound was 92.3%, while that of primaquine was 55.6%. The acute toxicity of compound 11 was two times a low as that of primaquine in mice. The compound did not appear to have mutagenicity, embryotoxicity and chromosomal aberration. When rats received intragastrical doses of 15, 30 and 60 mg/kg/d of compound 11 for 14 and 28 consecutive days respectively, no change was found in histopathological examination at the two lower doses. However, reversible changes were observed at the highest dose. Compound 11, trifluoroacetoprimaquine, was shown to be a promising tissue schizonticide of malaria parasite.

Aminoquinolines↗
PubMed1992

Electrofusion of protoplasts from Porphyra haitanensis and P. yezoensis thalli (Rhodophyta).

In this paper the electrofusion of protoplasts from P. haitanensis and P. yezoensis thalli by using an electrofusion instrument (Shimadzu Company, Japan) under different conditions of AC field, DC pulse, fusion buffer solutions and concentrations of protease are described. The results showed that the fusion rate could reach 21-31% by applying AC field of 30-35V for 25-30s and DC pulse of 300-350 V for 60 microseconds and in the presence of 3 mM Ca2+ and 3 mM Mg2+ in the fusion buffer. The pretreatment with protease had a positive effect on cell fusion. The fusion cells formed cell walls after 7 day's culture and grew into cell aggregates after 41 day's culture.

Buffers↗
PubMed1992

[Synchronized coronary venous retroperfusion: protection from ischemia in coronary angioplasty (PTCA)].

The potentially ischemia-protective effect of ECG-synchronized coronary venous retroperfusion (SRP) with arterial blood via the coronary sinus (CS) was assessed in 26 patients (56 +/- 10 years, 22 male, 4 female) in the clinical scenario of PTCA of a proximal LAD stenosis. In six additional patients the SRP procedure failed due to anatomical or technical reasons. In an intraindividual comparison at least two standardized balloon inflations for 60 seconds at 6-8 atm were performed in randomized order with and without continuous SRP at a flow rate of 200 +/- 46 ml/min. Under both conditions echocardiographic regional wall motion, ST depression in leads V1-6, hemodynamic parameters and symptoms expressed in a pain score were continuously monitored during angioplasty. This study revealed that the echocardiographic regional wall motion score in the perfusion territory of the dilated artery increased from 1.65 +/- 1.81 at baseline to 5.65 +/- 2.88 (p < 0.001) during a one minute dilatation without SRP. With SRP-support the regional wall motion at 1 minute angioplasty was significantly improved to 3.55 +/- 2.80 (p < 0.025). Moreover, the ischemic ECG-changes were markedly less pronounced, whereas the subjective perception of anginal pain was not different as a function of SRP-support. Thus, the simultaneous coronary venous retroperfusion with arterial blood has ischemia-protective potential in elective PTCA of a proximal LAD stenosis and may reduce ischemic dysfunction with prolonged balloon inflations.

Adult↗
PubMed1992

Development of the new antimalarial drug pyronaridine: a review.

This report outlines the structure scheme and development of a new antimalarial drug pyronaridine, which was synthesized from either 2-aminopyridine or pyridine. A series of in vivo and in vitro experimental studies and the assessment of toxicity revealed pyronaridine to be a promising agent against erythrocytic stage of malaria parasites. It exhibited low toxicity and had no cross-resistance to chloroquine. Clinical administration in malaria cases showed high efficacy and mild side-effects. In order to retard the development of resistance of Plasmodium falciparum to pyronaridine, a combination of pyronaridine/sulfadoxine/pyrimethamine was used in the treatment of chloroquine-resistant falciparum malaria in Hainan Province. Further in vivo test was carried out to monitor the sensitivity of P. falciparum to this combined formula for 5 years (1986-1990) in Diaoluo area where chloquine-resistant falciparum malaria was prevalent. Drug resistance was not demonstrated in this field study.

Administration, Oral↗
PubMed1991

Cloning of the cocaine-sensitive bovine dopamine transporter.

A cDNA encoding the dopamine transporter from bovine brain substantia nigra was identified on the basis of its structural homology to other, recently cloned, neurotransmitter transporters. The sequence of the 693-amino acid protein is quite similar to those of the rat gamma-aminobutyric acid, human norepinephrine, and rat serotonin transporters. Dopamine transporter mRNA was detected by in situ hybridization in the substantia nigra but not in the locus coeruleus, raphe, caudate, or other brain areas. [3H]Dopamine accumulation in tissue culture cells transfected with the cDNA was inhibited by amphetamine, cocaine, and specific inhibitors of dopamine transport, including GBR12909.

Amino Acid Sequence↗
PubMed1991

Natural auto- and polyreactive antibodies differing from antigen-induced antibodies in the H chain CDR3.

We describe three sets of natural (preimmune) polyreactive antibodies and Ag-induced antibodies that share the same VH-VL combinations. The amino acid homology in the VH and VL segments averaged 92%. These sets were found among 49 neonatal and adult natural mAb that were compared with 35 Ag-induced monoclonals produced during the memory response to phosphocholine (PC)-keyhole limpet hemocyanin. Both groups of monoclonals had been selected on the basis of a restricted fine specificity pattern, namely the ability to recognize PC-protein and p-nitrophenyl phosphocholine but not PC. All of the antibodies were tested for reactivity against a panel of 15 self and foreign Ag. Despite their common fine specificity as the basis for selection, 33/49 natural antibodies were poly/auto reactive whereas 0/35 Ag-induced antibodies had such poly/auto reactive properties. The natural antibodies were encoded by genes representing nine different VH families and several V kappa and V lambda families. There were a few replacement substitutions distinguishing the Ag-induced antibodies from the natural antibodies in each set; however, the most noteworthy difference was the extreme variability of CDR3 in the natural antibodies that differed in both length and amino acid sequence from each other and from Ag-induced antibodies. The results suggest that CDR3 of the H chain may play a critical role in distinguishing poly- from monospecific combining sites in natural and Ag-induced antibodies.

Amino Acid Sequence↗
PubMed1991

Conformation of endothelin in aqueous ethylene glycol determined by 1H-NMR and molecular dynamics simulations.

The solution conformation of a 21-residue vasoconstrictor peptide endothelin-1 (ET-1) in water-ethylene glycol has been determined by two-dimensional 1H-NMR spectroscopy and constrained molecular dynamics simulations. The N-terminus (residues 1-4) appears to undergo conformational averaging and no single structure consistent with the NMR constraints could be found for this region. Residues 5-8 form a turn, and residues 9-16 exist in a helical conformation. A flexible 'hinge' between residues 8-9 allows various orientations of the turn relative to the helix. Another 'hinge' at residue 17 connects the extended C-terminus to the bicyclic core region (residues 1-15). Residues important for binding and biological activity form a contiguous surface on one side of the helix, with the two disulfides extending from the other side of the helix.

Computer Simulation↗