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Biomedical subjects

C Peng

Publications and source records attributed to C Peng.

At least 37 records · Page 2Linked to original sources
PubMed2000

Activin A in JEG-3 cells: potential role as an autocrine regulator of steroidogenesis in humans.

Activin A has been shown to exert several regulatory functions on human placenta. In the present study, we tested the hypothesis that activin A is an autocrine regulator of trophoblast using a choriocarcinoma cell line, JEG-3, as a model. Messenger RNAs for activin beta(A) subunit, activin binding protein (follistatin), and various activin receptors, including ActR-IA, ActR-IB, ActR-IIA, and ActR-IIB, were detected in JEG-3 cells by reverse transcription-polymerase chain reaction. The expression of activin A in JEG-3 cells was further confirmed by Western blot analysis using an antibody against activin beta(A) subunit. Using Northern blot analysis, Smad-2 and Smad-4 mRNAs were also observed in JEG-3 cells. These data suggest that JEG-3 cells produce activin A and express activin binding proteins and receptors, as well as potential downstream signals. In cultured JEG-3 cells, basal progesterone production was stimulated by activin A but inhibited by follistatin-288. Similarly, in the presence of androstenedione, estradiol production was enhanced by activin A but decreased by follistatin-288. On the other hand, neither activin A nor follistatin affected JEG-3 cell growth. Taken together, these findings strongly suggest that activin A is an autocrine factor that is involved in the regulation of progesterone and estradiol production in JEG-3 cells.

Activin Receptors↗
PubMed2000

Activin, inhibin, and follistatin in zebrafish ovary: expression and role in oocyte maturation.

Activins, inhibins, and follistatins are important regulators of mammalian reproduction. However, their roles in lower vertebrates are poorly understood. In this study, we examined the expression of activin A, inhibin A, and follistatins in the zebrafish ovary and determined their role in final oocyte maturation. Using reverse transcription-polymerase chain reaction with primers specific for activin/inhibin beta(A) subunit and for follistatins, we detected DNA fragments of the expected size, which, upon sequencing, conformed to activin/inhibin beta(A) and follistatin. Western blot analysis using an antibody against activin/inhibin beta(A) subunit revealed two bands with sizes similar to those of activin A and inhibin A. The expression of follistatins was also confirmed by Western blot analysis. These results suggest that activin A, an inhibin A-like molecule, and follistatins are expressed in the zebrafish ovary. In cultured zebrafish follicles, activin A and inhibin A both induced final oocyte maturation in a dose-dependent manner. The effects of activin A and inhibin A were blocked by their binding protein, follistatin-288. Interestingly, follistatin-288 also inhibited final oocyte maturation induced by gonadotropin and by maturation-inducing hormone (MIH), suggesting that activin A and/or inhibin A may be local regulators mediating gonadotropin- and MIH-induced final oocyte maturation. Taken together, these findings suggest that activin A and inhibin A are paracrine regulators of ovarian functions in fish.

Activins↗
PubMed2000

Purification, characterization, and molecular cloning of the gene of a seed-specific antimicrobial protein from pokeweed.

A small cysteine-rich protein with antimicrobial activity was isolated from pokeweed (Phytolacca americana) seeds and purified to homogeneity. The protein inhibits the growth of several filamentous fungi and gram-positive bacteria. The protein was highly basic, with a pI higher than 10. The entire amino acid sequence of the protein was determined to be homologous to antimicrobial protein (AMP) from Mirabilis jalapa. The cDNA encoding the P. americana AMP (Pa-AMP-1) and chromosomal DNA containing the gene were cloned and sequenced. The deduced amino acid sequence shows the presence of a signal peptide at the amino terminus, suggesting that the protein is synthesized as a preprotein and secreted outside the cells. The chromosomal gene shows the presence of an intron located within the region encoding the signal peptide. Southern hybridization showed that there was small gene family encoding Pa-AMP. Immunoblotting showed that Pa-AMP-1 was only present in seeds, and was absent in roots, leaves, and stems. The Pa-AMP-1 protein was secreted into the environment of the seeds during germination, and may create an inhibitory zone against soil-borne microorganisms. The disulfide bridges of Pa-AMP-1 were identified. The three-dimensional modeling of Pa-AMP-1 indicates that the protein has a small cystine-knot folding, a positive patch, and a hydrophobic patch.

Amino Acid Sequence↗
PubMed2000

Treatment of 86 cases of facial spasm by acupuncture and pressure on otopoints.

The combined method of acupuncture with pressure on otopoints (the combination group) was used to treat 86 patients with facial spasm; and simple acupuncture and simple pressure on otopoints were respectively applied in the other two groups of patients as controls. The total effective rates of the combination group, the acupuncture group and the pressure on otopoints group were 95.4%, 92.1% and 62.5% respectively; and the cure rates were 38.4%, 15.8% and 5% respectively. The differences in results of the three groups show statistically marked significance, indicating that the therapeutic effectiveness of the combined method of acupuncture with pressure on otopoints is better than the other two therapeutic methods.

Acupressure↗
PubMed2000

Activins and their receptors in female reproduction.

Activins are growth and differentiation factors belonging to the transforming growth factor-beta superfamily. They are dimeric proteins consisting of two inhibin beta subunits. The structure of activins is highly conserved during vertebrate evolution. Activins signal through type I and type II receptor proteins, both of which are serine/threonine kinases. Subsequently, downstream signals such as Smad proteins are phosphorylated. Activins and their receptors are present in many tissues of mammals and lower vertebrates where they function as autocrine and (or) paracrine regulators of a variety of physiological processes, including reproduction. In the hypothalamus, activins are thought to stimulate the release of gonadotropin-releasing hormone. In the pituitary, activins increase follicle-stimulating hormone secretion and up-regulate gonadotropin-releasing hormone receptor expression. In the ovaries of vertebrates, activins are expressed predominantly in the follicular layer of the oocyte where they regulate processes such as folliculogenesis, steroid hormone production, and oocyte maturation. During pregnancy, activin-A is also involved in the regulation of placental functions. This review provides a brief overview of activins and their receptors, including their structures, expression, and functions in the female reproductive axis as well as in the placenta. Special effort is made to compare activins and their receptors in different vertebrates.

Activin Receptors↗
PubMed2000

[The development of a computer-based visual field analyzer].

Visual field is one of the important visual functions; it is the extent of the visual field defect that can be employed in judging whether the visual function is impaired. The rapid achievements in computer technologies do provide an impulse for improvement of visual field detection, making possible the automatic, rapid, accurate, detailed and large-scaled visual field detection. This paper gives a thorough description about development of the visual field analyzer, model TEC-2A, which is based on PC windows platform, Visual Basic software developing tool, ISA peripheral circuits, standard Goldmann visual field half-ball and standard stimulus.

Adolescent↗
PubMed2000

[A study of sleep apnea monitoring method and instrument].

In this paper the fundamental principle and great significance of sleep apnea monitoring are introduced, and the status quo of this field at home and abroad is described. Several kinds of methods for sleep apnea monitorin are analyzed, and on this basis the authors have developed a cheap and portable sleep apnea monitoring instrument. Experiment results demonstrate that the instrument is of convenience, high accuracy and good performance.

Adult↗
PubMed2000

[Reconstruction technology of electrical impedance tomography].

Electrical impedance tomography(EIT) is a new medical image technology; it has the advantages of low cost, nonionizing radiation, and the capability of production images of physiological function dynamically. EIT reconstruction has always been a project of importance to EIT researchers. In this paper, a review of the development of EIT reconstruction is presented.

Algorithms↗
PubMed1999

Cloning of zebrafish activin type IIB receptor (ActRIIB) cDNA and mRNA expression of ActRIIB in embryos and adult tissues.

A full-length cDNA encoding for activin type IIB receptor (ActRIIB) was cloned from zebrafish embryos. It encodes a protein with 509 amino acids consisting of a signal peptide, an extracellular ligand binding domain, a single transmembrane region, and an intracellular kinase domain with predicted serine/threonine specificity. The extracellular domain shows 74-91% sequence identity to human, bovine, mouse, rat, chicken, Xenopus and goldfish activin type IIB receptors, while the transmembrane region and the kinase domain show 67-78% and 82-88% identity to these known activin IIB receptors, respectively. In adult zebrafish, ActRIIB mRNA was detected by RT-PCR in the gonads, as well as in non-reproductive tissues, including the brain, heart and muscle. In situ hybridization on ovarian sections further localized ActRIIB mRNA to cytoplasm of oocytes at different stages of development. Using whole-mount in situ hybridization, ActRIIB mRNA was found to be expressed at all stages of embryogenesis examined, including the sphere, shield, tail bud, and 6-7 somite. These results provide the first evidence that ActRIIB mRNA is widely distributed in fish embryonic and adult tissues. Cloning of zebrafish ActRIIB demonstrates that this receptor is highly conserved during vertebrate evolution and provides a basis for further studies on the role of activin in reproduction and development in lower vertebrates.

Activin Receptors, Type II↗
PubMed1999

Human ovary and placenta express messenger RNA for multiple activin receptors.

In the present study, we examined the expression of activin receptor (ActR) mRNAs in human ovary and placenta. Primers specific for two type I and two type II activin receptors (ActR-I, ActR-IB, ActR-II, and ActR-IIB) were used in polymerase chain reaction (PCR) to amplify cDNAs prepared from granulosa-luteal cells, placental tissues and isolated trophoblast cells. PCR products with the expected sizes for ActR-I, ActR-IB, ActR-II, and ActR-IIB mRNAs were detected in freshly dissociated and 5-day cultured granulosa-luteal cells; and in trophoblast cells from both first trimester and term placentas. The identity of these PCR products were confirmed by Southern blot hybridization, as well as cloning and sequencing. These results suggest that multiple activin receptors are present in human ovary and placenta and may mediate activin function in these tissues. The demonstration of activin receptor mRNAs in granulosa-luteal and trophoblast cells further supports the notion that activin is an important local regulator in the human ovary and placenta.

Activin Receptors↗
PubMed1999

Maturation of gait dynamics: stride-to-stride variability and its temporal organization in children.

In very young children, immature control of posture and gait results in unsteady locomotion. In children of approximately 3 yr of age, gait appears relatively mature; however, it is unknown whether the dynamics of walking change beyond this age. Because stride dynamics depend on neural control, we hypothesized that motor control would continue to develop beyond age 3. To test this hypothesis, we measured the gait cycle duration on a stride-by-stride basis in 50 healthy 3- to 14-yr-old children (25 girls). Measurements of stride-to-stride variability were significantly larger both in the 3- and 4-yr-old children, compared with the 6- and 7-yr-old children, and in the 6- and 7-yr-old children, compared with the 11- to 14-yr-old children. Measurements of the temporal organization of gait also revealed significant age-dependent changes. The effects of age persisted even after adjusting for height. These findings indicate that mature stride dynamics may not be completely developed even in healthy 7-yr-old children and that different aspects of stride dynamics mature at different ages.

Adolescent↗
PubMed1999

[Resection of caudate lobe of liver: report of 26 cases].

OBJECTIVE: To summarize the experience in caudate lobectomy for 26 cases. METHODS: Caudate lobectomy was performed in 26 cases by Peng's multifunctional operative dissector (PMOD) to transect the liver parenchyma (Curettage and Aspiration technique). Primary liver cancer was noted in 18 cases, hilar cholangiocarcinoma in 4, gallbladder carcinoma in 1, right adrenocortical adenocarcinoma in 1, hepatoangioma in 1 and hepatoangiosarcoma in 1. Five cases underwent isolated caudate lobectomy, 1 combined caudate lobectomy with right trisegmentectomy, 6 combined caudate lobectomy with right hemihepatectomy, 9 combined caudate lobectomy with left hemihepatectomy, and 5 combined caudate lobectomy with segmentectomy. RESULTS: The operations were carried out successfully. Follow up for 2 - 23 months, 1 case died from pulmonary infraction 2 weeks after operation, 1 died from lung metastasis 2 months after operation, 10 died from tumor recurrence or metastasis 3, 11, 12, 15, 15, 15, 15, 19, 30, 30 months after operation respectively. The other 14 cases are still alive for 2 to 18 months. CONCLUSIONS: With PMOD, it is possible to dissect the structure precisely. Therefore the caudate lobe can be isolated from the three porta hepatis without much difficulty. Caudectomy can be performed safely.

Adult↗
PubMed1999

[Computer-aided teaching system of heart sound].

This paper details a full set of plan of the computer-aided teaching of heart sound. By means of digital sound technology one is capable of playing realistically heart sound of various kinds based on database. Each heart sound is demonstrated by a proper explanation of its characteristics and a heart sound graph. This method gets over the shortages of traditional teaching methods. Besides, this system can be used to test users' level of auscultation.

Computer Systems↗
PubMed1999

[Determination of 14 rare earth impurities in Y2O3 by petroleum sulfoxide extraction chromatography].

Petroleum sulfoxide-NH4SCN extraction chromatography was developed for the separation of Y from other rare earth elements. Some chromatographic parameters were chosen and separation factors between Y and other rare earth elements were determined. A column of resin coated with petroleum sulfoxide was used. The Y in the sample was eluted with NH4SCN, then titrated with EDTA. The recovery was 67%-120% and relative standard deviation +/- 4.0%-19.4%. This method can be applied to the determination of trace amounts of rare earth impurities in Y2O3 with a purity of 99.9999%-99.99999%.

English Abstract↗
PubMed1999

[Determination of rare-earth impurities in ultra-highly pure Er2O3 and Ho2O3 by [HEH(HEP)] extraction chromatography-atomic emission spectrometry].

This article applied [HEH(HEP)] (2-ethyhexyldrogen-2-ethylhexyl phosphonate) extraction chromatography to separate 14 rare earth impurities from ultra-highly pure Er2O3 and Ho2O3, and then the impurities were determined by atomic emission spectrometry. The average percentage recovery for each element is in the range of 70%-140%. The relative standard deviations of the determination are +/- 3.3%-2.2%. This method can be applied to the determination of the trace amounts of rare eath impurities in Er2O3 and Ho2O3 with a purity of 99.9999%-99.99999%.

English Abstract↗
PubMed1998

Solid-phase microextraction (SPME) of drugs and poisons from biological samples.

Solid-phase microextraction (SPME), a new solvent-free sample preparation technique, was invented by C. Arthur and J. Pawliszyn in 1990. This method mainly was applied for the extraction of volatile and semi-volatile organic pollutants in water samples. However, since 1995, SPME has been developed to various biological samples, such as whole blood, plasma, urine, hair and breath, in order to extract drugs and poisons in forensic field. The main advantages of SPME are: high sensitivity, solventless, small sample volume, simplicity and rapidity. We have reviewed the papers published in recent years about SPME in biological samples, and sorted out main experimental conditions, such as fibers, matrixes, the extraction approaches and time, as well as the acceleration method. We would expect SPME technique to have a promising future for toxicological analysis in forensic practice.

Body Fluids↗
PubMed1998

Expression of the messenger RNA for gonadotropin-releasing hormone and its receptor in human cancer cell lines.

The presence of gonadotropin-releasing hormone (GnRH) binding sites in biopsy samples of human epithelial ovarian cancer and ovarian tumor cell lines as well as the demonstration of the inhibitory effects of GnRH analogues on the growth of these cells raised the possibility that GnRH is produced locally by ovarian cancer cells. In order to investigate an autocrine/paracrine regulatory mechanism in human carcinomas, we have studied the expression of GnRH and GnRHR mRNA in human ovarian epithelial cell lines (OVCAR-3 and SKOV-3), human choriocarcinoma cell line (JEG-3) and human hepatocarcinoma cell line (HepG 2). Using primers corresponding to published human GnRH and GnRHR cDNA sequences, predicted PCR products were obtained from these cell lines by reverse transcription-polymerase chain reaction (RT-PCR) and confirmed by Southern hybridization. Sequencing analysis of GnRH PCR products showed that their sequences have 100% identity to the published human GnRH cDNA sequence. These results indicated that GnRH and GnRHR genes are expressed in all the cell lines tested in the present study, and strengthen the concept that GnRH may act as an autocrine regulator on the growth of cancer cells.

Blotting, Southern↗