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Biomedical subjects

X Y Yang

Publications and source records attributed to X Y Yang.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Pharmacokinetics of epostane in rats].

After rats were given (ig) epostane 50, 100 and 200 mg.kg-1, plasma concentrations of epostane were determined by HPLC. According to concentration versus time data, the pharmacokinetic model of epostane in all rats followed a pattern of one-compartment model. The pharmacokinetic parameters of the three doses were found to be as follows: Ka were 0.578 h-1, 0.553 h-1 and 0.439 h-1; K were 0.308 h-1, 0.282 h-1 and 0.224 h-1; T1/2 were 2.27 h, 2.54 h, 3.12 h and AUC were 786.89 micrograms.h.ml-1, 1644.43 micrograms.h.ml-1, and 3335.35 micrograms.h-1.ml-1 respectively. The tissue distribution of epostane in rats were as follows: highest in adrenal, liver, gastrointestinal tract, uterus and ovary; next in kidney, heart, brain, lung and spleen. The peak concentration times were about 3 h and comparable to plasma peak time. Plasma protein binding of epostane was determined by equilibrant dialysis of the plasma of rats given the drug and found that the degree of binding was not correlated with drug dosage under our experimental conditions. Little epostane was found in the bile, urine and feces. It appears that epostane might have undergone extensive biotransformation in the rat body.

Androstenols↗
PubMed1993

[Protective effects of nicorandil on action potentials in anoxia and reoxygenated ventricular myocardium of guinea pig].

Standard microelectrode techniques were used to study the effects of nicorandil (500 mumol.L-1) on action potentials in anoxia and reoxygenated ventricular myocardium of guinea pig. The main results: (a) Nicorandil shortened the action potentials duration (APD) and increased the ratio of effective refractory period (ERP) to APD90 (ERP/APD90). It did not cause significant changes in resting potential (RP), the maximal rate of rise of phase 0 (Vmax) and action potential amplitude (APA); (b) Exposure of the preparation to anoxic conditions (hypoxia, acidosis, glucose deprivation, and hyperkalemia) for 20 min, resulted in a marked depolarization of RP, a shortening of APD, reductions of APA and Vmax, and an increase in the ratio of ERP/APD90; (c) Nicorandil did not produce any additional effect on these parameters during anoxia except aggravated shortening of APD; (d) The changes of action potential parameters during anoxia were all completely reversed when the preparation was reoxygenated in the absence of the drug for 20 min. In the presence of the drug, however, APD was only partially reversed; (e) Nicorandil decreased the incidence of abnormal automaticity occurring during reoxygenation from 14/16 to 4/16. It is concluded that nicorandil antagonizes the cellular mechanisms which underlie the reoxygenation arrhythmias and prevent the reoxygenation-induced arrhythmias.

Action Potentials↗
PubMed1992

Expression of a 91-kilodalton PEA3-binding protein is down-regulated during differentiation of F9 embryonal carcinoma cells.

Proteins binding to the PEA3 enhancer motif (AGGAAG) activate the polyomavirus early promoter and help comprise the viral late mRNA initiator element (W. Yoo, M. E. Martin, and W. R. Folk, J. Virol. 65:5391-5400, 1991). Because many developmentally regulated cellular genes have PEA3 motifs near their promoter sequences, and because Ets family gene products activate the PEA3 motif, we have studied the expression of PEA3-binding proteins and Ets-related proteins during differentiation of F9 embryonal carcinoma cells. An approximately 91-kDa protein (PEA3-91) was identified in F9 cell nuclear extracts by UV cross-linking to a radiolabeled PEA3 oligonucleotide probe, and expression of PEA3-91 was down-regulated after differentiation of F9 cells to parietal endoderm. The c-ets-1 gene product binds to a sequence in the murine sarcoma virus long terminal repeat that is similar to the PEA3 motif (cGGAAG), but PEA3-91 was not cross-linked to this Ets-1-binding motif, nor did antiserum which recognizes murine c-ets-1 and c-ets-2 proteins have any effect on PEA3-binding activity in mobility shift assays. Furthermore, c-ets-1 mRNA was not detected in undifferentiated or differentiated F9 cells, and c-ets-2 mRNA levels remained high after differentiation. Antiserum against the Drosophila Ets-related E74A protein, however, recognized an approximately 92-kDa protein in F9 cells whose expression during differentiation varied in a manner identical to that of PEA3-91. These data suggest that PEA3-91 is not the product of the ets-1 or ets-2 genes but is likely to be the product of a murine homolog of the Drosophila E74 gene.

Animals↗
PubMed1992

[Gene diagnosis and successful reversion in a patient with preleukemia].

According to the FAB classification, a patient (case 1) could not be diagnosed as MDS-RA, although she had clinical features of MDS, as compared with another patient (case 2) who was diagnosed as RAS and had abnormal karyotype (20q- and 5q-) of bone marrow (BM) cells. BM cells of the two patients were SCD (sister chromatid differentiation) negative. Rearrangement of c-erbB and c-erbA was found in the genome of the BM cells in both patients, when southern blot hybridization was performed with probe v-erbB+A. Therefore, case 1 could be diagnosed as preleukemia. During a period about 3 years of treatment with the drug stanozolol in case 1 there was good effect and successful reversion was obtained. She had then normal hematologic and cytogenetic patterns of BM and PB and the rearrangement of c-erbB of BM cells also disappeared. She has worked for two years since then. The mechanism of effective treatment and successful reversion was discussed briefly. Probe v-erbB was shown to be useful in investigation of gene diagnosis of preleukemia or MDS (shown elsewhere).

Adult↗
PubMed1992

[Diagnosis and treatment of hemothorax in malignant trophoblastic tumors].

From 1949 to 1988, 32 cases of hemothorax were seen in our hospital. The incidence rate of hemothorax among the cases of choriocarcinoma and invasive mole in the whole series were 2.6% and 1.4% respectively. The most frequent symptoms were chest pain, cough, dyspnea, and hemoptysis. Before 1965, when 6-MP was the only agent used, 7 of the 16 patients with hemothorax died directly due to severe intrathoracic hemorrhage, from 1966 to 1988, when intravenous infusion of 5-FU and intrathoracic injection of 5-FU were used, only 4 of the 16 cases died, there was no death directly related to hemothorax. About 75% were followed up for more than 10 years, the longest duration of follow up being more than 28 years in 6 cases. Repeated examinations with serum hCG determination and chest film revealed no evidence of recurrence, nor pleural adhesion and thickening or pulmonocardiac diseases.

Female↗
PubMed1992

[Antiarrhythmic effects of kappa-seleno-carrageenan in experimental animals].

The effect of Kappa-seleno-carrageenan, an organic compound containing selenium, on aconitine, BaCl2 and ouabain-induced arrhythmias were studied. When rats were given ip 9 mg.kg-1.d-1 x 5 d or ig single dose of 35, 70, 140 mg.kg-1, the threshold dose of aconitine was elevated significantly to induce HA. The effect seems to resemble that of ip Na2SeO3 1 mg.kg-1 x d-1 x 5 d. With increasing ig dose, the threshold dose of aconitine was elevated for inducing VE, VT, VF. When ip 9 mg.kg-1 x d-1 x 5 d or ig 70 mg.kg-1 was given, the threshold doses of BaCl2 in inducing VF (in rats) and ouabain in inducing VE (in guinea-pig) were elevated. However, no influence was observed for ip Na2SeO3 1 mg.kg-1 x d-1 x 5 d.

Aconitine↗
PubMed1992

Serum concentration fluctuation and bioavailability comparison between indomethacin sustained-release and conventional capsules during steady state.

The comparison between indomethacin conventional capsule (CC) po 25 mg q 8 h or 25 mg tid and indomethacin sustained-release capsule (SRC) po 25 mg bid in human by crossover design showed that both maximal serum concentration (Cmax) and fluctuation index (FI%) of SRC were significantly lower than those of CC during steady state (P < 0.01). No practical differences were observed between the 2 preparations in the trough serum concentration (Cmin) and area under serum concentration-time profiles (AUC0-tau) (P > 0.05). The time period reaching maximal serum concentration (Tmax) of SRC was much more delayed than that of CC (P < 0.01). It suggested that SRC possesses a better controlled release property and could avoid a higher serum peak concentration of CC.

Adult↗
PubMed1991

Nucleotide sequence of the promoter and fadB gene of the fadBA operon and primary structure of the multifunctional fatty acid oxidation protein from Escherichia coli.

The primary structure of a multifunctional protein, the large alpha-subunit of the Escherichia coli fatty acid oxidation complex, was determined by sequencing the fadB region of the fadBA operon. The amino-terminal sequence of this protein had been established by Edman degradation. The transcription start site of the fadBA operon was located 42 nucleotides upstream of the initiator codon of the fadB gene by primer extension analysis. Sequences of -10 and -35 regions of the promoter responsible for interaction with RNA polymerase were found to be CACACT and TTTGCA, respectively. The location of the promoter of the fadBA operon was defined, and the transcription direction of this operon, from fadB to fadA, as previously proposed [Yang, S.-Y., et al. (1990) J. Biol. Chem. 265, 10424-10429], was corroborated. The multifunctional protein is composed of 729 amino acid residues and has a calculated Mr of 79,593. A putative NAD-binding beta alpha beta-fold necessary for L-3-hydroxyacyl-CoA dehydrogenase function was found in the central region of the fadB gene product. Sequence analyses suggest that the functional domains of the multifunctional protein are arranged in the order enoyl-CoA hydratase:L-3-hydroxyacyl-CoA dehydrogenase: delta 3-cis-delta 2-trans-enoyl-CoA isomerase and suggest that the genes of the E. coli multifunctional protein and rat peroxisomal trifunctional beta-oxidation enzyme evolved from a common ancestral gene.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1991

[Immunohistochemical study on human epithelial ovarian carcinoma after radioimmunodetection with 131I-labelled polyclonal antibodies].

We report the results of our immunohistochemical study on the distribution and the retention time of the injected labelled antibodies in both primary and recurrent ovarian epithelial carcinomas and the regional lymph nodes, following the radioimmunodetection with injection of 131I-labelled polyclonal antibodies (including 5 cases of intravenous injection group and 35 cases of subcutaneous injection group). Six other tumors or tumor-like lesions, 8 normal ovaries and 7 normal fallopian tubes were used for control. The results demonstrated: 1. The labelled antibodies were specific for ovarian epithelial carcinoma, 2. The concentration of the labelled antibodies in the lymph node metastasis was higher in the subcutaneous injection group than in the intravenous injection group. Therefore, the subcutaneous route should be used both for imaging and radioimmunotherapy of lymph node metastasis, 3. The retention time of the antibodies in the lymph node metastasis was not more than 24 days. With this reference, the total dose of radioimmunotherapy can be calculated.

Adenocarcinoma↗
PubMed1991

Renal metastases of choriocarcinoma. A clinicopathological study of 31 cases.

From 1949 through 1978, 31 patients with renal metastasis were diagnosed in a total of 448 cases of choriocarcinoma admitted to our hospital, giving an incidence of 6.9%. Renal metastasis was invariably preceded by pulmonary metastases and usually accompanied by other visceral metastases, indicating that renal metastasis is the result of dissemination of tumor cells secondarily from lung metastasis through the general circulation and should be categorized as arterial metastasis. Pyelogram is useful in the presence of medullary invasion by the tumor. Renal metastatic tumors are very sensitive to chemotherapy. Good response to chemical agents may be due to high drug concentration attained in the kidney tissue during excretion. Since successful treatment of renal metastasis by chemotherapy alone may be obtained, patients can be spared a major operation without jeopardizing the prognosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Nucleotide sequence of the fadA gene. Primary structure of 3-ketoacyl-coenzyme A thiolase from Escherichia coli and the structural organization of the fadAB operon.

The DNA insert of plasmid pK52 contains the fadAB operon coding for the Escherichia coli fatty acid oxidation complex. Studies on the operon's structure and organization revealed that the initiator codon (ATG) of the structural gene for 3-ketoacyl-CoA thiolase, the fadA gene, is located 109 nucleotides 3' to the stop codon (TGA) of the fadB gene that encodes the alpha-subunit, a multifunctional polypeptide. The direction of transcription of this operon is thus from fadB to fadA. The orientation of the fadA and fadB genes is the reverse of what had been published previously. The structural gene for thiolase is 1,164 nucleotides long and starts six nucleotides downstream from a Shine-Dalgarno sequence. 109 nucleotides of 5'-noncoding and 321 nucleotides of 3'-noncoding regions are also reported. The 3-ketoacyl-CoA thiolase beta-subunit is composed of 388 residues and has a calculated Mr of 40,889. The alpha- and beta-subunits were separated by gel filtration in formic acid, and the sequence of the amino-terminal 10 amino acids of the beta-subunit coincided with that deduced from the nucleotide sequence data. Sequence comparisons suggest that Cys-91 of the E. coli enzyme is the active-site cysteine residue and that the consensus sequence of the active sites of 3-ketoacyl-CoA thiolases is Asn-Arg-X1-Cys-X2-Ser-X3-X4-Gln. Although the quaternary structure of E. coli 3-ketoacyl-CoA thiolase is different from that of other thiolases, the sequence is homologous to rat and human peroxisomal and rat mitochondrial 3-ketoacyl-CoA thiolases, to the extent of 42, 41, and 37%, identity, respectively. An evolutionary tree of thiolases was constructed; it suggests that the genes of E. coli and peroxisomal 3-ketoacyl-CoA thiolases diverged after the appearance of eukaryotic cells.

Acetyl-CoA C-Acyltransferase↗
PubMed1990

New refractive method for laser thermal keratoplasty with the Co:MgF2 laser.

We have observed corneal curvature changes from laser thermal keratoplasty with a Co:MgF2 laser. We studied corneal curvature changes in rabbits and have identified specific treatment patterns and laser parameters that can correct myopia and astigmatism. These corneal changes, some as large as 8 diopters, have been stable for at least one year, and slitlamp examination demonstrates clear central corneas with normal appearance.

Animals↗
PubMed1990

Blood magnesium parameters do not differ with age.

The relationship between age and blood magnesium (Mg) parameters has not been defined. Mg measurements in plasma, red blood cells (RBCs), and mononuclear blood cells (MBCs) were made in 104 normal volunteers (43 males and 61 females, ages 11-75 years). MBCs were separated from blood using a discontinuous Ficoll-Hypaque gradient. The mean values (+/- SEM) were as follows: plasma Mg 1.63 +/- 0.01 mEq/L, RBC Mg 4.55 +/- 0.06 mEq/L, MBC Mg content 72.8 +/- 1.0 fg/cell, and MBC Mg concentration 19.6 +/- 0.3 mEq/L. We compared these parameters with age (intervals of 10 years) using analysis of variance (ANOVA) and found no significant differences (p greater than 0.05). Thus, plasma, RBC, and MBC Mg parameters do not vary significantly between the ages of 11 and 75 years.

Adolescent↗
PubMed1990

[Influence of dexamethasone on electrical activities in cultured rat beating myocardial cells infected with Coxsackie B-2 virus].

The effects of dexamethasone (Dex) on electrical activities in cultured rat beating myocardial cells infected with 100 TCID-50 Coxsackie B-2 virus (CB2V) was evaluated by conventional intracellular microelectrode technique. The frequency began to increase, the beating % decreased, and multiform arrhythmias were shown in the infected group 24 h post-challenge. Meanwhile, the cytopathic effect (CPE) appeared rapidly from 1+ to 3+. In the infected and Dex-treated group, the beating % was higher and the arrhythmias and CPE were less than in the infected group at the same intervals. The numbers of non-beating cells increased parallel to the incubation time in the infected group. Decreases of maximal diastolic potential (MDP), maximal upstroke rate (Vmax), overshoot (OS) and action potential amplitude (APA), and abbreviation of action potential duration (APD50 and APD100) in infected and Dex-treated group were less than those in control group during 24-96 h post-challenge. Premature beats, tachycardia, bradycardia and fibrillation occurred in the early stages after infection. It is surmised that steroids can probably save the lives of patients with severe myocarditis if Dex was supplemented.

Action Potentials↗
PubMed1990

Characteristics of paroxysmal nocturnal hemoglobinuria in China. Clinical analysis of 476 cases.

476 cases of paroxysmal nocturnal hemoglobinuria (PNH) were analysed and compared with PNH patients in foreign countries and its classification was discussed. The clinical characteristics in Chinese PNH patients were: males were affected more; the age of onset was young; more common in north China; hemoglobinuria as an initial symptom was less common; thrombosis as a complication was relatively rare; the common causes of death were heart failure, infections and hemorrhage; and bone marrow picture might show mild dyshematopoiesis.

Adolescent↗
PubMed1990

[Evaluation of hysterography in the diagnosis of choriocarcinoma and invasive mole].

From 1963 through 1985, 181 hysterography were performed for 101 patients. The diagnostic accuracy of hysterography was 92.3%. There were no false positive findings, though a negative result may be obtained in patients whose intramural lesion does not communicate with the uterine cavity, as proved by operative findings. Three types of abnormalities were observed on the hysterogram: (1) filling defect, (2) intramural invasion of the uterine wall by the contrast medium and (3) extravasation of the contrast medium into the pelvic veins. The filling defect was usually observed in patients with (1) residual molar tissue in the uterine cavity, (2) intramural lesion and (3) intrauterine adhesions. The above three conditions can be differentiated by the characteristic shape of the filling defect. If it is used in combination with either or both of the other two procedures, ie., B-ultrasound and pelvic arteriography the accuracy of diagnosis will be further improved.

Choriocarcinoma↗