Biomedical subjects

Y Peng

Publications and source records attributed to Y Peng.

At least 73 records · Page 4Linked to original sources

PubMed2000

Maternal cold inducible RNA binding protein is required for embryonic kidney formation in Xenopus laevis.

We cloned a major isoform of Xenopus homologue of cold inducible RNA binding protein (CIRP), XCIRP-1. XCIRP-1 was neither cold inducible nor essential for cell division during early embryonic development. Suppression of XCIRP-1 dose dependently produced tailbuds with deformations of the brain and internal organs. The defects were XCIRP-1 specific as they could be rescued by sense transcript. Suppression of XCIRP-1 also disrupted the morphogenetic migration of the C3 blastomeres (lineaged to become the embryonic kidney, the pronephros). In animal cap explants, depletion of XCIRP-1 inhibited activin/retinoic acid induced expressions of pronephros related Xlim-1 and WT1 genes. These results suggest that XCIRP-1 is required for the specification and morphogenetic lineage migration of the pronephros.

Abnormalities, Multiple↗

PubMed2000

Soluble CD8 attenuates cytotoxic T cell responses against replication-defective adenovirus affording transprotection of transgenes in vivo.

The T cell coreceptor, CD8, enhances T cell-APC interactions. Because soluble CD8alpha homodimers can antagonize CD8 T cell activation in vitro, we asked whether secretion of soluble CD8 would effect cytotoxic T cell responses in vivo. Production of soluble CD8 by a replication-defective adenovirus vector allowed persistent virus expression for up to 5 mo in C57BL/6 mice and protected a second foreign transgene from rapid deletion. Soluble CD8 selectively inhibited CD8 T cell proliferation and IFN-gamma production and could also attenuate peptide-specific CD8 T cell responses in vivo. These finding suggest that gene vector delivery of soluble CD8 may have therapeutic applications.

Adenoviridae↗

PubMed2000

Bis(1-acetonylpyridinium) pyridinium hexaiodobismuth(III).

The crystal structure of the title complex, (C(8)H(10)N)(2)(C(5)H(6)N)[BiI(6)], contains discrete [BiI(6)](3-) anions, and (HNC(5)H(5))(+) and (CH(3)COCH(2)NC(5)H(5))(+) cations separated by normal van der Waals contacts. The [BiI(6)](3-) anion has the Bi atom on an inversion centre. The (HNC(5)H(5))(+) cation also lies about an inversion centre and is disordered. The (CH(3)COCH(2)NC(5)H(5))(+) cation lies in a general position.

Journal Article↗

PubMed2000

Evaluation of L-DOPA biotransformation during repeated L-DOPA infusion into the striatum in freely-moving young and old rats.

The aim of this study was to assess changes in L-3, 4-dihydroxyphenylalanine (L-DOPA) biotransformation in response to two-pulse infusion of L-DOPA into the striatum of freely-moving young (3-4 month) and old (21-26 month) male Wistar rats. In addition, the effects of L-DOPA infusion on the vesicular dopamine (DA) store in young rats were also studied. Both L-DOPA-induced DA overflow and uptake of the perfused L-DOPA by the striatum were used to study L-DOPA biotransformation during microdialysis. High potassium-induced DA depletion was performed to assess the dynamics of the vesicular DA store following L-DOPA infusion. Concentric microdialysis probes were stereotaxically implanted in the lateral striatum of rats of both age groups and microdialysis was begun 24 h later. All rats received 2x20 min infusions of 3 mgr L-DOPA separated by an interval of 60 min. In the striatum of both groups, L-DOPA-induced DA overflow and uptake of exogenous L-DOPA were both significantly enhanced during the second infusion compared to the first. In young rats, when a 20-min infusion of 3 mgr L-DOPA was given between 2x20 min infusions of 100 mM potassium, no increased DA release was seen at the second high potassium challenge compared with the first. Our results suggest that the enhancement of DA overflow induced by the second L-DOPA infusion is, at least partially, due to an increase in L-DOPA biotransformation, and not simply to an enlarged DA pool. In contrast to the in vitro results, our own in vivo results show that L-DOPA utilization in the aging striatum does not deteriorate with age.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2000

Characterization of the functionally related sites in the neural inducing gene noggin.

Previously we have shown that blocking bone morphogenetic protein (BMP) receptor signaling by a dominant negative BMP receptor causes neurogenesis in Xenopus animal caps (ACs), whereas the physiological neural inducer noggin acts as a homodimer physically binding to BMP-4 and disrupting its signaling at the ligand level. The present study attempted to elucidate the relationship between the structure and function of noggin. By replacing some cysteine residues with serine residues through a site-directed mutagenesis strategy, we generated three noggin mutants, C145S, C205S, and C(218, 220, 222)S (3CS). Although mRNAs encoded by these mutants were translated as efficiently as wild-type (WT) noggin mRNA, they behaved differently when expressed in vivo. Expression of WT noggin or C205S in Xenopus ACs converted the explants (prospective ectoderm) into neural tissue, indicated by the neural-like morphology and expression of the pan neural marker NCAM in the ACs. In contrast, ACs expressing C145S or 3CS sustained an epidermal fate like the control caps. Similar results were observed in the mesoderm where C205S (but not C145S and 3CS) displayed dorsalizing activity as well as WT noggin. Altogether, our results suggest that Cys145 alone or Cys(218, 220, 222) as a whole in noggin protein is required for the biological activities of noggin, probably participating in the dimerization of noggin with BMP-4 or itself.

Animals↗

PubMed2000

Histone acetylation is a checkpoint in FGF-stimulated mesoderm induction.

We have previously demonstrated that the transcription factor, AP-1 (c-jun/c-fos heterodimer), mediates fibroblast growth factor (FGF) signaling during mesoderm induction in Xenopus embryo. In the present studies, we show that histone acetylation is involved in FGF-mediated signaling leading to mesoderm induction. Histone acetylation is a dynamic process regulated by the activities of two histone-modifying enzymes, the histone acetyltransferase(s) and histone deacetylase(s) (HDACs). We found that basal and FGF-regulated activator protein 1 (AP-1) activity in Xenopus embryo is markedly reduced by treatment of trichostatin A (TSA), a specific inhibitor of HDAC. However, activity of another transcription factor, NFkappaB, is enhanced by TSA treatment. AP-1-mediated mesoderm induction in the animal caps is dramatically suppressed by TSA at a dose-dependent manner. This suppression can be rescued by ectopic expression of HDAC3 at early stage. Finally, we found that histone acetylation in animal caps is inhibited by FGF whereas enhanced by TSA (as a control). Therefore, we propose that histone acetylation is a checkpoint for transduction of the FGF/AP-1 signals to induce mesoderm. Published 2000 Wiley-Liss, Inc.

Acetylation↗

PubMed2000

A nonparametric mixture model for cure rate estimation.

Nonparametric methods have attracted less attention than their parametric counterparts for cure rate analysis. In this paper, we study a general nonparametric mixture model. The proportional hazards assumption is employed in modeling the effect of covariates on the failure time of patients who are not cured. The EM algorithm, the marginal likelihood approach, and multiple imputations are employed to estimate parameters of interest in the model. This model extends models and improves estimation methods proposed by other researchers. It also extends Cox's proportional hazards regression model by allowing a proportion of event-free patients and investigating covariate effects on that proportion. The model and its estimation method are investigated by simulations. An application to breast cancer data, including comparisons with previous analyses using a parametric model and an existing nonparametric model by other researchers, confirms the conclusions from the parametric model but not those from the existing nonparametric model.

Algorithms↗

PubMed2000

Identification of functionally important domains in the N-terminal region of telomerase reverse transcriptase.

Telomerase is a ribonucleoprotein reverse transcriptase responsible for the maintenance of one strand of telomere terminal repeats. The key protein subunit of the telomerase complex, known as TERT, possesses reverse transcriptase-like motifs that presumably mediate catalysis. These motifs are located in the C-terminal region of the polypeptide. Hidden Markov model-based sequence analysis revealed in the N-terminal region of all TERTs the presence of four conserved motifs, named GQ, CP, QFP, and T. Point mutation analysis of conserved residues confirmed the functional importance of the GQ motif. In addition, the distinct phenotypes of the GQ mutants suggest that this motif may play at least two distinct functions in telomere maintenance. Deletion analysis indicates that even the most N-terminal nonconserved region of yeast TERT (N region) is required for telomerase function. This N region exhibits a nonspecific nucleic acid binding activity that probably reflects an important physiologic function. Expression studies of various portions of the yeast TERT in Escherichia coli suggest that the N region and the GQ motif together may constitute a stable domain. We propose that all TERTs may have a bipartite organization, with an N-GQ domain connected to the other motifs through a flexible linker.

Amino Acid Sequence↗

PubMed2000

Acid incubation causes exocytic insertion of NHE3 in OKP cells.

Incubation of opossum kidney clone P (OKP) cells in acid media (pH 6. 8) causes activation of Na(+)/H(+) exchanger 3 (NHE3) at 6, 12, and 24 h. OKP cell NHE3 protein abundance was increased by 45% at 24 h of acid incubation but was unaffected at 3-12 h. By contrast, apical membrane NHE3, measured by surface biotinylation, increased approximately twofold at 6, 12, and 24 h, mirroring the increase in activity. Acid incubation caused a 76% increase in exocytic insertion of NHE3 into the apical membrane but had no effect on endocytic internalization at 6 h. Latrunculin B, an inhibitor of microfilament organization, inhibited the acid-induced increases in apical membrane NHE3, exocytic insertion of NHE3, and NHE3 activity at 6 h. These studies demonstrate two mechanisms for acid-induced increases in NHE3 activity. Beginning at 6 h, there is an increase in apical membrane NHE3 that is due to stimulated exocytic insertion and is required for increased NHE3 activity. At 24 h, there is an additional increase in total cellular NHE3.

Acidosis, Renal Tubular↗

PubMed2000

Dual effect of heparin and low molecular weight heparin on cultured smooth muscle cells.

The effects of heparin and low molecular weight heparin (LMWH) on the growth of cultured human aortic smooth muscle cells (hASMCs) were studied. The fourth-passage hASMCs were planted onto a 24-well plate (5 wells for each concentration of heparin or LMWH) and cultured by DMEM containing 5% either old or fresh human serum (HS), 10% fetal calf serum (FCS), and differing concentrations of heparin or LMWH (heparin and LMWH were presented as hexuronic acid) together with corresponding control groups (without heparin or LMWH) for 24h. hASMCs growth was estimated both morphologically and by 3H-TdR incorporation. The results revealed that both heparin and LMWH inhibited the proliferation of healthy growth hASMCs, but promoted the proliferation of weak growth hASMCs. These results suggest for the first time that heparin and LMWH have a dual regulative role (inhibition and promotion) in hASMCs growth and indicate that they may play an important role in controlling the proliferation of vascular smooth muscle cells and maintaining the integrity of vascular structure.

Aorta↗

PubMed2000

Study on DNA polymorphism at D1S8 locus in Hebei Han population.

OBJECTIVE: To study the polymorphism at D1S8 locus and to provide basic information for the construction of DNA fingerprint database and the application in forensic medicine. METHODS: Minisatellite variant repeat-polymerase chain reaction (MVR-PCR) and polyacrylamide gradient gel electrophoresis followed by silver staining were used to detect the variant repeat sequences at D1S8 locus of 240 unrelated individuals in Hebei Han population, and digital codes were obtained. RESULTS: Each individual obtained about 30 digital codes, in which none of two unrelated individuals had the same code. The probability of identity of 30 digital codes was 3.55x10(-11). The percentages of three repeat units, a-type, t-type and o-type were 54.77%, 42.54% and 2.69% respectively. The heterozygosity (H) was 0.9837. The excluding probability of paternity(EPP) and polymorphism information content(PIC) were 0.9669 and 0.9833 respectively. CONCLUSION: Because of its high polymorphic nature, D1S8 locus is a valuable marker for forensic identification and paternity testing.

Chromosome Mapping↗

PubMed2000

[New full length cDNA cloned from normal pituitary and pituitary tumors].

OBJECTIVE: To clone new full length cDNA from normal pituitary and pituitary tumors. METHODS: cDNA libraries of human normal pituitary and pituitary tumors were constructed, and large-scale sequencing and bioinformatics were used. Silico cloning and rapid amplification of cDNA ends (RACE) were also used. RESULTS: 67 new full length cDNAs were cloned: 41 were cloned from normal pituitary, and 26 from pituitary tumors. Of the 67 cDNAs, 16 were related with endocrine function; at least 2 with a classical signal peptide were secretory protein, and 3 with classical transmembrane domains were transmembrane protein. Among the 5 cloned new full length cDNAs involved in signal transduction pathway of hormone, at least 2 participated in signal transduction pathway of receptors with tyrosine kinase activition. CONCLUSION: During short time, 67 new full length cDNA were cloned from normal pituitary and pituitary tumors by large-scale producing expressed sequence tags. Some of them may play an important role in the regulation of physiological and pathological processes of pituitary.

Cloning, Molecular↗

PubMed2000

Clinical significance of changes in beta-adrenoreceptors in peripheral lymphocytes in patients with essential hypertension.

OBJECTIVE: To explore the relationship of beta-adrenoreceptor density and function with the condition of patients with essential hypertension. METHODS: In the present study, 69 male patients with essential hypertension at different stages were compared with a group of age-matched normotensive controls. beta-adrenoreceptor maximum bound volume (Bmax) in peripheral lymphocytes was measured by 3H-dihydroalprenolol (3 H-DHA) radio ligand binding. beta-adrenoreceptor responsiveness was determined by Salbutamol (injection). RESULTS: In patients with essential hypertension at stages I and II, Bmax was significantly higher (P < 0.01 and P < 0.001, respectively) and the chronotropic doses of Salbutamol required to increase the heart rate by 30 beats/min (CD30) were significantly lower (P < 0.01 and P < 0.001, respectively) than in age-matched normotensive control subjects. In patients with essential hypertension at stage III, Bmax was significantly lower and CD30 was significantly higher (both P < 0.01) than those in the age-matched normotensive control subjects. Bmax was significantly higher and CD30 was significantly lower (both P < 0.001) in patients with essential hypertension and with left ventricular hypertrophy (LVH) than that in patients with essential hypertension but without LVH. In patients with essential hypertension and heart failure, Bmax was significantly lower and CD30 was significantly higher (both P < 0.001) than those in patients with essential hypertension without heart failure. CONCLUSIONS: The changes of beta-adrenoreceptor density and function were related to hypertension, hypertension complicated with ventricular hypertrophy, and heart failure. They may be viewed as indexes of the condition in the patients with essential hypertension.

Adrenergic beta-Agonists↗

PubMed2000

[Studies on 5 kinds of methods combination for detection of smear and culture negative pulmonary tuberculosis].

OBJECTIVE: To evaluate the diagnostic value of 5 kinds of methods used jointly for smear and culture negative pulmonary tuberculosis. METHODS: The high specificity methods were PCR examination for sputum TB-DNA, immunological examination (ELISA method) for serum LAM IgG, PPD IgG, SCIC and PPD 0.1 U skin test. Smear and culture positive cases were 31, smear and culture negative 54, healthy control 53, other lung disease 30. Methods were used for every case synchronously, then the sensitivity and specificity of single method and the diagnostic value of single and joint examination for smear and culture negative patients were evaluated. RESULTS: In single examination sensitivity of PCR, LAM IgG, PPD IgG, SCIC, PPD 0.1 U was 96.8%, 69.2%, 62.1%, 32.0%, 53.8% respectively; specificity was 96.2%, 98.1%, 98.1%, 98.1% correspondingly. The positive detection rate of single examination for sputum TB negative patients was just 21.4%-44.4%. In combination examination the positive rates increased remarkblely by the number combined from 2 to 5, they were 66.9%, 70.5%, 80.4%, 85.7% respectively and they were more notable than that of TB positive group. The specificity of combination examination was slightly decreased by the number combined. It decreased just by 9% and the specificity of most examination methods kept on no less than 90%. CONCLUSIONS: For diagnosis of smear and culture negative pulmonary tuberculosis combination examination using the high specificity methods can increase the sensitivity obviously and the specificity just decrease slightly. It is valuable for widely use of combination method in detection of smear and culture negative patients.

Adolescent↗

PubMed2000

[Study on the pharmacokinetics of Imipenem cilastatin in burn patients during the acute phase].

OBJECTIVE: To investigate the pharmacokinetic characteristics of Imipenem/cilastatin in burn patients during the acute phase. METHODS: Imipenem concentrations in the plasma, blister and, interstitial fluids and urine of 6 burn patients (P group) were determined during the acute phase by high performance liquid chromatography after the first initial dose. Pharmacokinetic parameters were thus produced and statistically analyzed by program package STAT 5. Ten healthy volunteers served as control group (C group). RESULTS: Compared to those in control group, pharmacokinetic parameters of Imipenem exhibited evident difference, such as prolonged half-life [(1.56 plus minus 0.55) h vs (1.06 plus minus 0.24) h] and enlarged distributing volume (16.16 plus minus 4.26) vs (13.96 plus minus 7.10). Imipenem could be detected in the blister and interstitial fluids of burn patients 1 hr after the initial dose. Renal clearance of Imipenem was positively correlated to creatinine clearance (r = 0.5834). CONCLUSION: The intervals between doses should better be prolonged when loaded-dosage of Imipenem was administered in burn patients during the acute phase. Imipenem could penetrate II and III degree burn wound when given in the acute phase. Attention should be paid to renal function when Imipenem was given.

Adult↗

PubMed2000

[Cell cycle analysis and pathological changes of malignant tumors treated with electrochemical therapy].

To investigate the mechanism and to observe the effectiveness of electrochemical therapy(ECT), 33 patients of late stage cancers which treated by ECT were included in this study. Flow cytometry (FCM) and pathology were used to observe the changes of tumor cells before and after ECT. Tumor cells of G1, G2/M, S phases and aneuploid cells were found to be killed almostly and the ratio of apoptosis was elevated greatly after ECT. Also, pathological evidence proved the death of tumor cells and some characters of apoptosis. So, ECT can non-selectively kill tumor cells and induce the apoptosis of them, and FCM was a way to evaluate the effectiveness of ECT.

Adult↗

PubMed2000

[Effects of sulpiride on morphine-induced reward and its relation to cyclic AMP levels in mice].

This study examined the effects of sulpiride, a dopamine D2 receptor antagonist, on morphine rewarding properties and its relation to cyclic AMP levels in brain. The morphine-induced reward in mice was observed in a conditioned place preference test. Cyclic AMP was estimated by radioimmunoassay. The time of staying in morphine pairing compartment and the cAMP levels in brain of mice in the morphine group increased as compared with those in other groups (P < 0.05), but there was no significant difference in the time of staying in morphine pairing compartment and the cAMP levels in brain between the saline group and the sulpiride plus morphine groups (P > 0.05). These suggest that the inhibition of morphine-induced reward by sulpiride be due to the prevention of an increase in cyclic AMP levels in brain.

Animals↗

PubMed2000

[The development of an instrument for testing body water equillibrium in hemodialysis patients].

In order to obtain a real-time and correct test for body water equilibrium in hemodialysis patients, an instrument based on bioimpedance measurement has been developed. The hardware and software design of the instrument was introduced in this paper. The instrument is of safty and good duplicity. Preliminary clinical experiments shows that it can reflect the state of body water with relative high sensitivity.

Adult↗