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Biomedical subjects

J Peng

Publications and source records attributed to J Peng.

At least 127 records · Page 7Linked to original sources
PubMed1998

Upregulation of cyclin T1/CDK9 complexes during T cell activation.

Cyclin T1 has been identified recently as a regulatory subunit of CDK9 and as a component of the transcription elongation factor P-TEFb. Cyclin T1/CDK9 complexes phosphorylate the carboxy terminal domain (CTD) of RNA polymerase II (RNAP II) in vitro. Here we report that the levels of cyclin T1 are dramatically upregulated by two independent signaling pathways triggered respectively by PMA and PHA in primary human peripheral blood lymphocytes (PBLs). Activation of these two pathways in tandem is sufficient for PBLs to enter and progress through the cell cycle. However, the expression of cyclin T1 is not growth and/or cell cycle regulated in other cell types, indicating that regulation of cyclin T1 expression is dependent on tissue-specific signaling pathways. Upregulation of cyclin T1 in stimulated PBLs results in induction of the CTD kinase activity of the cyclin T1/CDK9 complex, which in turn correlates directly with phosphorylation of RNAP II in vivo, linking for the first time activation of the cyclin T1/ CDK9 pair with phosphorylation of RNAP II in vivo. In addition, we report here that endogenous CDK9 and cyclin T1 complexes associate with HIV-1 generated Tat in relevant cells and under physiological conditions (HIV-1 infected T cells). This, together with our results showing that HIV-1 replication in stimulated PBLs correlates with the levels of cyclin T1 protein and associated CTD kinase activity, suggests that the cyclin T1/CDK9 pair is one of the HIV-1 required host cellular cofactors generated during T cell activation.

Cell Cycle↗
PubMed1998

Molecular cloning and characterization of a cDNA encoding canine type VII collagen non-collagenous (NC1) domain, the target antigen of autoimmune disease epidermolysis bullosa acquisita (EBA).

Type VII collagen, the major component of anchoring fibrils, serves as tight adhesion of skin basement membrane zone (BMZ) through its amino-terminal non-collagenous (NC1) domain. The NC1 domain is targeted by autoantibodies of an acquired blistering skin disease termed epidermolysis bullosa acquisita (EBA) naturally occurring in humans and dogs. We cloned the full-length canine type VII collagen NC1 domain cDNA and delineated its molecular and immunological characteristics. The canine NC1 domain cDNA consists of 3759 nucleotides encoding for 1253 amino acids, with a molecular mass of approx. 134 kDa and a 17 amino acid signal peptide. The expression of canine type VII collagen was confirmed by Northern blot analysis and by a rabbit antibody raised against a 17 amino acid peptide deduced from canine NC1 sequence. Comparison of canine NC1 with the corresponding human sequence indicated 86.7% and 87.6% identity at the nucleotide and deduced amino acid levels respectively. The protein homology reached greater than 95% within two immunodominant epitope areas. Furthermore, human EBA autoantibodies and a rabbit anti-human NC1 cross-reacted with canine skin BMZ and the newly synthesized canine type VII collagen. The molecular and immunological identities between human and canine NC1 domains suggest that NC1 may be critical for the EBA development.

Amino Acid Sequence↗
PubMed1998

Quantitative characterization of the binding of histamine by heparin.

Tissue histamine is stored in mast cell granules, presumably as a histamine-heparin complex. Heparin is a polyelectrolyte, with a fraction of its anionic charge neutralized by condensed counterions. The interaction of heparin with histamine in aqueous solution was quantitatively characterized by 1H nuclear magnetic resonance (NMR) spectroscopy. Binding constants were determined from chemical shift-pH titration data for the C2H proton of the imidazolium ring for a wide range of histamine, heparin, and Na+ concentrations. The results indicate a binding stoichiometry of 1 histamine per heparin disaccharide repeat unit. The binding is electrostatic, as indicated by the strong dependence of the binding constant on Na+ concentration. From an analysis of the binding constants using the counterion condensation theory of polyelectrolytes, it was determined that the binding of H2A2+ results in displacement of 1.72 Na+ ions from the counterion condensation volume of heparin and that H2A2+ makes 2 ionic interactions with heparin. The displacement of Na+ from the counterion condensation volume of heparin by H2A2+ was also studied by 23Na NMR. From 23Na spin-lattice relaxation time data, it was determined directly that 1.78 Na+ ions are displaced per H2A2+ bound by heparin. The results are discussed in terms of the ion exchange process which takes place when histamine is released by mast cells.

Animals↗
PubMed1998

Identification of a cyclin subunit required for the function of Drosophila P-TEFb.

P-TEFb is required for the transition from abortive elongation into productive elongation and is capable of phosphorylating the carboxyl-terminal domain (CTD) of the largest subunit of RNA polymerase II. We cloned a cDNA encoding the large subunit of Drosophila P-TEFb and found the predicted protein contained a cyclin motif. We now name the large subunit cyclin T and the previously cloned small subunit (Zhu, Y. R., Peery, T., Peng, J. M., Ramanathan, Y., Marshall, N., Marshall, T., Amendt, B., Mathews, M. B., and Price, D. H. (1997) Genes Dev. 11, 2622-2632) cyclin-dependent kinase 9 (CDK9). Recombinant P-TEFb produced in baculovirus-transfected Sf9 cells exhibited 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole-sensitive kinase activity similar to native P-TEFb. Kc cell nuclear extract depleted of P-TEFb failed to generate long DRB-sensitive transcripts, but this activity was restored upon addition of either native or recombinant P-TEFb. Like other CDKs, CDK9 is essentially inactive in the absence of its cyclin partner. P-TEFb containing a CDK9 mutation that knocked out the kinase activity did not function in transcription. Deletion of the carboxyl-terminal domain of cyclin T in P-TEFb reduced both the kinase and transcription activity to about 10%. The CDK-activating kinase in TFIIH was unable to activate the CTD kinase activity of P-TEFb.

Amino Acid Sequence↗
PubMed1998

Identification of multiple cyclin subunits of human P-TEFb.

The transition from abortive into productive elongation is proposed to be controlled by a positive transcription elongation factor b (P-TEFb) through phosphorylation of the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II. Drosophila P-TEFb was identified recently as a cyclin-dependent kinase (CDK9) paired with a cyclin subunit (cyclin T). We demonstrate here the cloning of multiple cyclin subunits of human P-TEFb (T1 and T2). Cyclin T2 has two forms (T2a and T2b) because of alternative splicing. Both cyclin T1 and T2 are ubiquitously expressed. Immunoprecipitation and immunodepletion experiments carried out on HeLa nuclear extract (HNE) indicated that cyclin T1 and T2 were associated with CDK9 in a mutually exclusive manner and that almost all CDK9 was associated with either cyclin T1 or T2. Recombinant CDK9/cyclin T1, CDK9/cyclin T2a, and CDK9/cyclin T2b produced in Sf9 cells possessed DRB-sensitive kinase activity and functioned in transcription elongation in vitro. Either cyclin T1 or T2 was required to activate CDK9, and the truncation of the carboxyl terminus of the cyclin reduced, but did not eliminate, P-TEFb activity. Cotransfection experiments indicated that all three CDK9/cyclin combinations dramatically activated the CMV promoter.

Amino Acid Sequence↗
PubMed1998

The DFRC Method for Lignin Analysis. 4. Lignin Dimers Isolated from DFRC-Degraded Loblolly Pine Wood.

Sixteen lignin dimers were directly isolated by gel permeation and reversed-phase TLC and HPLC from loblolly pine (Pinus taeda L.) sapwood following large-scale application of the new derivatization followed by reductive cleavage (DFRC) procedure. Their structures were elucidated by GC/MS and NMR. These dimers included representatives from all of the common interunit linkages in softwood lignins (beta-1, beta-beta, 5-5, beta-5, and 5-O-4). The DFRC procedure efficiently cleaves beta-aryl ethers, the major structural unit, so beta-ethers were not found among the dimeric products. All but two of the isolated dimers were guaiacyl-guaiacyl (from coniferyl alcohol-derived units in lignin); small amounts of p-hydroxyphenyl/guaiacyl beta-5 and beta-1 dimers were characterized. Several dimers have benzaldehydes as one unit-since aldehydes are not created by the procedure, they are either present in the native lignin or are formed during the minimal preparation of the wood. The dimers isolated and identified here will eventually allow their quantitation to aid in the structural analyses of wide-ranging plant materials.

Journal Article↗
PubMed1998

Gibberellin: inhibitor of an inhibitor of...?

Gibberellin is an endogenous plant growth regulator. Here, we describe our present understanding of how gibberellin regulates plant growth, using recent results gained from studies of gibberellin-signalling mutants of Arabidopsis. These results show that a signalling pathway represses plant growth and that gibberellin releases this repression. In consequence, the well-known growth-promoting properties of gibberellin are due to its activity as an "inhibitor of an inhibitor" [Brian Pw. Sym Soc. Exp Bio 1957; 11:166-182 (Ref. 1)] of plant growth.

Arabidopsis↗
PubMed1998

The ability of positive transcription elongation factor B to transactivate human immunodeficiency virus transcription depends on a functional kinase domain, cyclin T1, and Tat.

By binding to the transactivation response element (TAR) RNA, the transcriptional transactivator (Tat) from the human immunodeficiency virus increases rates of elongation rather than initiation of viral transcription. Two cyclin-dependent serine/threonine kinases, CDK7 and CDK9, which phosphorylate the C-terminal domain of RNA polymerase II, have been implicated in Tat transactivation in vivo and in vitro. In this report, we demonstrate that CDK9, which is the kinase component of the positive transcription elongation factor b (P-TEFb) complex, can activate viral transcription when tethered to the heterologous Rev response element RNA via the regulator of expression of virion proteins (Rev). The kinase activity of CDK9 and cyclin T1 is essential for these effects. Moreover, P-TEFb binds to TAR only in the presence of Tat. We conclude that Tat-P-TEFb complexes bind to TAR, where CDK9 modifies RNA polymerase II for the efficient copying of the viral genome.

Cell Line, Transformed↗
PubMed1998

A clinical investigation on massage for prevention and treatment of recurrent respiratory tract infection in children.

The TCM therapeutic principle of "eliminating the pathogenic factors by supporting the healthy energy" was adopted in massage to treat and prevent recurrent respiratory tract infection of children. Susceptible and healthy children of the same age were used as controls. As a result, the therapeutic effect of the treatment group is significantly better than that of the controls, with all of the immunologic indexes being approximately normal when the patients were reexamined 3 and 6 months after the massage. Statistically, the difference was significant (P < 0.01). Massage has been proved very helpful in improving the general constitution, enhancing the immune functions, preventing and treating the condition, and in health care as well.

Acupuncture Points↗
PubMed1998

[Expression of telomerase in acute leukemia].

To understand the expression patterns of telomerase activity in different types of acute leukemia(AL) and during remission state, the mono-nuclear cells of different bone marrow samples were isolated by desity gradient centrifugation. Telomerase activity of the samples was assayed by telomeric repeat amplification protocol(TRAP) with the cell extracts and the TRAP products were resolved in PAGE. The results showed that the telomerase activity was at higher levels in the acute leukemia compared with the normal controls. Of the acute nonlymphocytic leukemia(ANLL), the telomerase activity presented as M2a > M5b > M1 > M3b. Of the acute lymphocytic leukemia(ALL), the activity presented as L1 > L2. The activity assayed in M2a and L2 remission was as high as that in the normal group. It indicated that the expression of telomerase was enhanced differently among the subtypes of ANLL and ALL, and was down-regulated during the AL remission. It implicates that the expression patterns of telomerase activity in AL is associated with the different proliferation states and differentiation properties of the AL cells.

Adolescent↗
PubMed1998

[Magnetic resonance imaging of hypopharyngeal and cervical esophageal cancer].

Imaging by MR (MRI) and esophageal barium meal of 17 cases of hypopharyngeal and cervical esophageal cancer were analyzed. The results indicate that esophageal barium meal can not demonstrate the invading of neoplasms to the adjacent structure. Therefore, it is difficult to use the only data of esophageal barium meal for TNM staging. The results also indicate that MRI is more useful and reliable in assessing the three dimensional structure and the neoplasms invading to the adjacent structure. This results suggest that MRI is that useful in determining the diagnosis, TNM staging and the determining the appropriate operative therapy for hypopharyngeal and cervical esophageal cancer.

Adult↗
PubMed1998

Alpha-1 adrenergic receptors in liver plasma membranes of cirrhotic patients with portal hypertension: a quantitative study.

OBJECTIVE: To investigate the changes of alpha-1 adrenergic receptors in cirrhotic liver and the relationship between the changes and the pathogenesis of portal hypertension. METHODS: The concentration and affinity of alpha-1 adrenergic receptors in the liver plasma membranes of posthepatitic cirrhotic patients with portal hypertension were quantitatively measured using radioligand binding analysis. RESULTS: Compared with 8 controls without hepatic pathological changes, the maximal binding capacity (Bmax) of 9 posthepatitic cirrhotic patients decreased (129.1 +/- 12.0 vs 142.1 +/- 14.1 fmol/mg protein, P > 0.05), dissociation constant (Kd) values increased (0.3945 +/- 0.0974 vs 0.2382 +/- 0.0548 nmol/L, P < 0.01), and the receptor maximal content (RMC) decreased (417.4 +/- 76.8 vs 739.9 +/- 167.6 fmol/g liver, P < 0.01). CONCLUSIONS: The decreased concentration and affinity of alpha-1 adrenergic receptors may play an important role in the metabolic disturbances of catecholamines often seen in some cirrhotic patients, and have implications in the pathogenesis of portal hypertension.

Adult↗
PubMed1998

[Nasopharyngeal carcinoma and dermatomyositis (analysis of 12 cases)].

The onset relationship between dermatomyositis (DM) and malignant tumor, especially nasopharyngeal carcinoma (NPC), was approached. Approximately 90 cases of DM were admitted in the hospital. Among them 15 cases were complicated with malignant tumor of which 12 cases were complicated with NPC (account for 80% of DM with complicated carcinoma). In addition to treat these patients with prednisone and antibiotics, radiation therapy has been applied for NPC and metastasis in the neck. During the hospitalizations, one patient died, eleven patients' NPC was controlled, and the DM was completely resolved or improved. There is an obvious relationship between DM and carcinoma. DM may improve or even subside with good short term prognosis, as long as the carcinoma is controlled successfully.

Adult↗
PubMed1998

[Simultaneous determination of creatinine, pseudouridine and uric acid in serum and urine by high performance liquid chromatography].

In this paper a sensitive, rapid and simple HPLC method for the simultaneous determination of creatinine (Cr), pseudouridine (Pu) and uric acid(UA) has been established. We have evaluated clinical value of the method in the early diagnosis of diabetic nephropathy (DN). Separation was obtained using Shim-pack CLC-ODS 15 x 0.6 cm column and mobile phase of buffer solution of phosphate (pH 3.0, 0.02 mol/L) with flow rate of 1 mL/min. Detection was performed with UV detector at an automatic adjustment of wavelength. The recoveries of Cr, Pu and UA were 101.4%, 104.9% and 105.0% respectively. The calibration curves were linear within the concentration range of 8.6-274.6 mumol/L for Cr, 0.72-22.93 mumol/L for Pu and 19.1-612.7 mumol/L for UA (n = 6, r > 0.999, p < 0.01). The CV for within day and between day measurements were < 2.5% and < 5.0% respectively. In addition, Pu, Cr and UA were simultaneously determined in serum and urine of 39 patients with diabetic mellitus (DM). 15 patients with nephrotic syndrome (NS) and 53 normal subjects by the method. Results include: 1. the levels of serum Pu in all DM patients (100%) with microalbuminuria (MiAU) and macroalbuminuria (MaAU) were greater than maximum of normal subjects (X + 2S). In addition, in 9 DM patients (41%) with normal albuminuria (NAU) the levels were also greater than the maximum. 2. In patients with DM, there was no correlation between the serum Pu and the urinary albumin excretion (UAE), whereas the serum Pu correlated closely with the serum Cr. However, the incidence for serum Pu increase was significantly greater in patients. 3. The levels of serum Pu in patients with NS were greater than those in control subjects and patients with DM. Conclusion is that the determination of serum Pu could be used as sensitivity index for the early diagnosis of DN.

Chromatography, High Pressure Liquid↗
PubMed1998

[Intrahepatic portal vein compliance in cirrhosis].

OBJECTIVE: To elaborate the effects of increase in portal flow on intrahepatic vein compliance with isolated perfused cirrhotic model (IPCM). METHOD: Cirrhosis was induced by CCl(4) in 80 Wistar rats, which were divided into two groups A and B, by portal with/without hepato-artery. Portal flow was increased and hemodynamic parameters were recorded and analysed. RESULT: In group A, compared with 1.65 +/- 0.28 kPa at basal control, portal pressure was elevated from 2.55 +/- 0.40 kPa to 3.96 +/- 0.67 kPa. Q(35)-Q(55) flow rates were raised from 35 to 55 ml/min, respectively. A correlation existed between portal flows and pressures (r = 0.985, P < 0.01). The low flow rate of 15 ml/min at Q(15) caused a irreversible model injury. A largest flow rate in IPCM was, less than in IPRL. In group B, no low flow-injury was found. CONCLUSION: Portal vein compliance of liver is decreased markedly in cirrhotic portal hypertension, but hepatic flow is increased. There are likely some compensative relations between portal and hepato-arterial system.

Animals↗
PubMed1998

[Purification and properties of antifungal protein X98III from Bacillus subtilis].

Bacillus subtilis BS-98 is one of the antagonistic strains strongly against plant fungal pathogens such as Physalospora piricola Nose. The antifungal protein was purified by ammonium sulphate precipitation and column chromatography on Sephadex G-100 and DEAE-cellulose, and it was named X98III. Molecular weight of X98III is 59,000 by SDS-PAGE and PI value is 4.50 by PAG-IEF, respectively. X98III was demonstrated as glycoprotein and lipoprotein by CAM (cellulose acetate membrane) electrophoresis and special staining. We estimated it contains 6% saccharides by using DNS methods. This protein was also found to be thermostabale and partially sensitive to proteinases. The amino acid analysis of the protein X98III showed that it comprises of 11 different amino acids and Glu, Tyr, Cys are the abundant amino acids. No Asp, Phe and Met were found. Purified X98III has strong inhibiting activity against the pathogens of Physalospora piricola, Phoma asparagi, etc. The antifungal mechanism of X98III was mainly disintegration of the cell wall to make the hyphae abnormal and the spores germinate abnormally or can not germinate at all.

Amino Acids↗