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L Dong

Publications and source records attributed to L Dong.

At least 37 records · Page 2Linked to original sources
PubMed2003

Tetrasomy 12p--unusual presentation in CVS.

CVS direct preparations usually achieve limited resolution and are better at detecting numerical rather than structural abnormalities. A CVS direct preparation analyzed using G-banding revealed a 47,XY,+G karyotype in 5 of 11 cells and was reported as mosaic for trisomy 21. Subsequent analysis of the CVS culture found only normal male cells. Amniocentesis revealed both normal male cells and cells with an extra F-group chromosome. Fluorescence in situ hybridization (FISH) identified this chromosome to be an isochromosome from the short arm of chromosome 12 [i(12)(p10)]. The amniocyte karyotype was reported as 47,XY,+i(12)(p10)[12]/46,XY[8].ish i(12)(p10)(wcp12+), which is associated with Pallister-Killian syndrome. Reexamination of the CVS direct preparation by FISH with a chromosome 12 centromere probe confirmed the karyotype of this tissue to be 47,XY,+mar[5]/46,XY[6].nuc ish 12cen(D12Z3 x 3)/12cen(D12Z3 x 2). Thus, multiple studies, including amniocentesis and fluorescence in situ hybridization, may be required to fully and accurately evaluate abnormalities detected by CVS. This case also indicates that mosaicism for supernumerary isochromosomes may have a complex origin.

Abnormalities, Multiple↗
PubMed2001

TCDD-inducible poly(ADP-ribose) polymerase: a novel response to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes pleotropic effects in mammalian species through modulating gene expression. Here we analyzed TCDD-induced mRNA expression by using mRNA differential display and report the cloning of a novel TCDD-inducible poly(ADP-ribose) polymerase (TiPARP). TiPARP cDNA contains an open reading frame of 657 amino acid residues; the carboxyl half shares sequence similarity to the catalytic domain of PARP, a family of enzymes that catalyze poly ADP-ribosylation of proteins. Expression of the cDNA by in vitro transcription/translation reveals a protein of approximately 75 kDa. The expressed TiPARP exhibits PARP activity toward histone. TiPARP is highly homologous to RM1 which is induced during long-term potentiation, a memory formation process, and to TIL which is induced in T cells infiltrating progressing tumors. TiPARP mRNA is expressed in a broad range of mouse tissues. Together, these data demonstrate that TiPARP is a novel target of TCDD that may contribute to multiple responses to TCDD by modulating protein function through poly ADP-ribosylation.

Amino Acid Sequence↗
PubMed2001

Binding specificity of Escherichia coli trigger factor.

The ribosome-associated chaperone trigger factor (TF) assists the folding of newly synthesized cytosolic proteins in Escherichia coli. Here, we determined the substrate specificity of TF by examining its binding to 2842 membrane-coupled 13meric peptides. The binding motif of TF was identified as a stretch of eight amino acids, enriched in basic and aromatic residues and with a positive net charge. Fluorescence spectroscopy verified that TF exhibited a comparable substrate specificity for peptides in solution. The affinity to peptides in solution was low, indicating that TF requires ribosome association to create high local concentrations of nascent polypeptide substrates for productive interaction in vivo. Binding to membrane-coupled peptides occurred through the central peptidyl-prolyl-cis/trans isomerase (PPIase) domain of TF, however, independently of prolyl residues. Crosslinking experiments showed that a TF fragment containing the PPIase domain linked to the ribosome via the N-terminal domain is sufficient for interaction with nascent polypeptide substrates. Homology modeling of the PPIase domain revealed a conserved FKBP(FK506-binding protein)-like binding pocket composed of exposed aromatic residues embedded in a groove with negative surface charge. The features of this groove complement well the determined substrate specificity of TF. Moreover, a mutation (E178V) in this putative substrate binding groove known to enhance PPIase activity also enhanced TF's association with a prolyl-free model peptide in solution and with nascent polypeptides. This result suggests that both prolyl-independent binding of peptide substrates and peptidyl-prolyl isomerization involve the same binding site.

Amino Acid Sequence↗
PubMed2001

Intensity modulated radiation therapy (IMRT) following prostatectomy: more favorable acute genitourinary toxicity profile compared to primary IMRT for prostate cancer.

PURPOSE: To report our initial experience on postprostatectomy IMRT (PPI), addressing acute genitourinary (GU) toxicity in comparison to primary IMRT (PI) for prostate cancer. METHODS AND MATERIALS: From April 1998 to December 1999, 40 postprostatectomy patients were treated with intensity modulated radiation therapy (IMRT) to a median prescribed dose of 64 Gy (mean dose of 69 Gy). The Radiation Therapy Oncology Group (RTOG) scoring system was used to assess acute GU toxicity. Target volume and maximum and mean doses were evaluated. The mean doses to the bladder and irradiated bladder volume receiving >65 Gy were assessed. These were compared to those of 125 patients treated with PI to a prescribed dose of 70 Gy (mean dose of 76 Gy). RESULTS: The acute GU toxicity profile is more favorable in the PPI group with 82.5% of Grade 0-1 and 17.5% of Grade 2 toxicity compared to 59.2% and 40.8%, respectively, in the PI group (p < 0.001). There was no Grade 3 or higher toxicity in either group. The target volume was larger in the PPI group, while the maximum and mean doses to the target were higher in the PI group. The mean dose delivered to the bladder was higher in the PPI group. The irradiated bladder volume receiving >65 Gy was significantly larger in the PI group (p < 0.001). CONCLUSIONS: PPI can be delivered with acceptable ute GU toxicity. The larger PPI target volume may be related to the difficulty in delineating prostatic fossa. Despite a larger target volume and a higher mean dose to the bladder, PPI produced a more favorable acute GU toxicity profile. This may be related to a combination of lower mean and maximum doses and smaller bladder volumes receiving >65 Gy in the PPI group, as well as urethral rather than bladder irradiation. The findings have implications in the evaluation of IMRT treatment plan for prostate cancer, whereby the irradiated bladder volumes above 65 Gy may be more meaningful than the mean dose to the bladder. Longer term toxicity results are awaited.

Aged↗
PubMed2001

Corrections to moving chemical reaction boundary equation for weak reactive electrolytes under the existence of background electrolyte KCl in large concentrations.

In this report, the moving chemical reaction boundary (MCRB) was formed by the weak reaction electrolytes of NH3.H2O and CH3COOH under the existence of background electrolyte KCl in large concentrations, the experiments were compared with the predictions by the moving chemical reaction boundary equation (MCRBE) for weak reactive electrolytes. It was found that the experimental results are far from the predictions with the MCRBE. So the MCRBEs must be corrected under the given experimental conditions. The corrected MCRBEs are given for the MCRB formed with weak reactive electrolytes coupled with KCl at high concentrations.

Electrolytes↗
PubMed2001

Partial purification and biochemical characterization of a heteromeric protein phosphatase 2A holoenzyme from maize (Zea mays L.) leaves that dephosphorylates C4 phosophoenolpyruvate carboxylase.

The activity and allosteric properties of plant phosphoenolpyruvate carboxylase (PEPC; EC 4.1.1.31) are controlled posttranslationally by specific reversible phosphorylation of a strictly conserved serine residue near the N-terminus. This up/down-regulation of PEPC is catalyzed by a dedicated and highly regulated serine/threonine (Ser/Thr) kinase (PEPC-kinase) and an opposing type-2A Ser/Thr phosphatase (PP2A). In marked contrast to PEPC-kinase, the PP2A holoenzyme from photosynthetic tissue has been virtually unstudied to date. In the present investigation, we have partially purified and characterized the native form of this PP2A from illuminated leaves of maize (Zea mays L.), a C4 plant, using maize [32P]PEPC as substrate. Various conventional chromatographic matrices, together with thiophosphorylated C4 PEPC-peptide and microcystin-LR affinity-supports, were exploited for the enrichment of this PP2A from soluble leaf extracts. Biochemical and immunological results indicate that the C4-leaf holoenzyme is analogous to other eukaryotic PP2As in being a approximately 170-kDa heteromer comprised of a core PP2Ac-A heterodimer (approximately 38- and approximately 65-kDa subunits, respectively) complexed with a putative, approximately 74-kDa B-type regulatory/targeting subunit. This heterotrimer lacks any strict substrate specificity in that it dephosphorylates C4 PEPC, mammalian phosphorylase a, and casein in vitro. This activity is independent of free Me2+, insensitive to levamisole and the Inhibitor-2 protein that targets PP1, activated by several polycations such as protamine and poly-L-lysine, and highly sensitive to inhibition by microcystin-LR and okadaic acid (IC50 approximately 30 pM), all of which are diagnostic features of yeast and mammalian PP2As. In addition, this C4-leaf PP2A holoenzyme (i) is inhibited in vitro by physiological concentrations of certain C4 PEPC-related metabolites (L-malate, PEP, glucose 6-phosphate, but not the activator glycine) when either 32P-labeled maize PEPC or rabbit muscle phosphorylase a is used as substrate, suggesting a direct effect on this Ser/Thr phosphatase; and (ii) displays, at best, only modest light/dark effects in vivo on its apparent molecular mass, component core subunits and activity against C4 PEPC, in marked contrast to the opposing activity of PEPC-kinase in C4 and Crassulacean acid metabolism leaves. This report represents one of the few studies of a heteromeric PP2A holoenzyme from photosynthetic tissue that dephosphorylates a known target enzyme in plants, such as PEPC, sucrose-phosphate synthase or nitrate reductase.

Darkness↗
PubMed2001

Research and prediction of coordination reactions between CPA-mA and some metal ions using artificial neural networks.

The complex relationship between maximum absorption wavelength (lambda(max)), molar absorptivity (epsilon) of the coordination compounds formed from m-acetyl-chlorophosphonazo (CPA-mA) and the metal ions, the acidity of coordination reaction, some properties of metal ions and the properties of more than 20 coordination compounds were studied using artificial neural networks with extended delta-bar-delta EDBD back learning algorithms in this paper. Six parameters: the pH of coordination reactions, metal ion radius (R), relative atomic weight (Wt), ionic electronic energy (E), metal ion standard Gibbs' free energy (deltaG0) and hard-soft acid-base dual scale (f) were used as input parameters, to predict the lambda(max) and epsilon of the coordination compounds. The structures of networks and the learning times were optimized. The best networks structure is 6-7-2. The optimum number of learning times is about 160,196. It is shown that the maximum relative error is no more than 6% in the testing set. The trained networks are used to simulate the complicated relations between the metal ion properties, coordination reaction conditions and the properties of coordination compounds. This optimized networks have been used for the prediction of the lembda(max) and epsilon of coordination compounds formed from Tb3+, Ho3+ with CPA-mA separately and with satisfactory results.

Journal Article↗
PubMed2001

Study of the reaction of proteins with Beryllon II-AlIII by the Rayleigh light scattering technique and its application.

The determination of proteins with tetrasodium 2-(3,6-disulfo-8-hydroxynaphthylazo)-1,8-dihydroxynaphthalene-3,6-disulfonate (Beryllon II) by Rayleigh light scattering (RLS) was studied. The weak RLS of the Beryllon II-bovine serum albumin (BSA) complex can be greatly enhanced by the addition of Al3+ in the pH range 5.6-7.2; there was a maximum RLS platform at 400-420 nm. Based on the reaction between Beryllon II, Al3+ and proteins, a new method for the determination of proteins was developed. This method is very sensitive [0.20-41.42 micrograms ml-1 for BSA and 0.18-48.15 micrograms ml-1 for human serum albumen (HSA)], rapid (< 2 min), simple (one step) and tolerant towards most interfering substances. The effects of different surfactants were also examined. Four samples of protein in human serum were determined; the maximum relative error was no more than 5% and the recovery was 96-105%.

Aluminum↗
PubMed2001

A method of simulating dynamic multileaf collimators using Monte Carlo techniques for intensity-modulated radiation therapy.

A method of modelling the dynamic motion of multileaf collimators (MLCs) for intensity-modulated radiation therapy (IMRT) was developed and implemented into the Monte Carlo simulation. The simulation of the dynamic MLCs (DMLCs) was based on randomizing leaf positions during a simulation so that the number of particle histories being simulated for each possible leaf position was proportional to the monitor units delivered to that position. This approach was incorporated into an EGS4 Monte Carlo program, and was evaluated in simulating the DMLCs for Varian accelerators (Varian Medical Systems, Palo Alto. CA, USA). The MU index of each segment, which was specified in the DMLC-control data, was used to compute the cumulative probability distribution function (CPDF) for the leaf positions. This CPDF was then used to sample the leaf positions during a real-time simulation, which allowed for either the step-shoot or sweeping-leaf motion in the beam delivery. Dose intensity maps for IMRT fields were computed using the above Monte Carlo method, with its accuracy verified by film measurements. The DMLC simulation improved the operational efficiency by eliminating the need to simulate multiple segments individually. More importantly, the dynamic motion of the leaves could be simulated more faithfully by using the above leaf-position sampling technique in the Monte Carlo simulation.

Biophysical Phenomena↗
PubMed2001

[Effects of methyl mercury chloride on nuclear factor-kappa B DNA binding activities of nuclear protein extracts from developing rat cerebra and cerebella].

The effects of methyl mercury chloride (MMC) on DNA binding activities of nuclear factor kappa B(NF-kB) in developing rat cerebella and cerebra were investigated with electrophoretic mobility shift assays(EMSAs). The bindings of NF-kB in nuclei of rat cerebra and cerebella to kB probes showed two bands on gel shift in both control and experiment groups. NF-kB I and NF-kB II DNA binding activities of nuclear protein extracts from rat cerebra exposed to MMC in uterus, was lower than control groups on postnatal day 3 and 7, while that from rat cerebella was higher than control groups. The results suggested that the reactive abilities of neural cell to MMC between cerebra and cerebella were different. In binding reaction mixture, the quantities of MMC increased with the increase of NF-kB DNA binding activities of nuclear protein extracts.

Animals↗
PubMed2001

Effects of signal transduction inhibitor 571 in acute myelogenous leukemia cells.

STI571 is a 2-phenylalaminopyrimidine derivative that inhibits c-abl, Bcr-Abl, and platelet-derived growth factor receptor tyrosine kinases. Recently, inhibition of stem cell factor (SCF)-induced c-kit phosphorylation and cell proliferation by STI571 was reported in the human myeloid cell line MO7e. Because approximately 70% of acute myelogenous leukemia (AML) cases are c-kit positive, we evaluated in vitro effects of STI571 on c-kit-positive cell lines and primary AML blast cells. At concentrations >5 microM, the drug marginally inhibited SCF-independent proliferation of cell lines and most of AML blasts. Treatment of AML cells with cytarabine and STI571 showed synergistic effect at low concentrations. Western blotting analysis documented a distinct band of M(r) 145,000 specific for c-kit in cell lines and in AML samples. There was no correlation between the level of the c-kit expression evaluated by Western blotting and percentage of c-kit-positive blasts as measured by flow cytometry. Neither in cell lines nor in primary AML cells, c-kit autophosphorylation was detectable under standard growth conditions. SCF-induced phosphorylation of c-kit in MO7e cells was inhibited by STI571. In a c-kit-positive AML-4 cell line, as well as in AML samples, c-kit phosphorylation was not induced by SCF exposure, suggesting that in these cases, the receptor could not be functionally activated. In conclusion, with the exception of MO7e, SCF did not induce phosphorylation of c-kit, and cell proliferation was not modulated in the presence of STI571. We did not detect any SCF-independent c-kit phosphorylation in our experimental systems. Consequently, STI571 exerted only a limited inhibitory effect on the cell growth.

Benzamides↗
PubMed2001

[Phosphorus behavior in soil-water system of paddy field and its environmental impact].

A field experiment with rice showed that P fertilizer application increased the concentrations of resin P in soil and total P in soil surface water, and both of them declined subsequently over time. Compared with applying mineral P fertilizer only, the integrated application of mineral-P and manure resulted in a higher resin P level within 20 days after P application. The total P concentration in soil surface water in the treatment of integrated application of mineral-P and manure was 3.4 times higher than that in the treatment of mineral-P fertilizer application only after 7 days of P application, and also, was 2.8 times higher than that in the treatment where P application rate was doubled. The potential of Ploss from surface water in the treatment of integrated application with manure was more than that in the treatment of applying-P fertilizer only. The effect of applied P sorts on P concentration in soil surface water could be ignored after 33 days of P application. Two drainages were conducted for rice growth, which caused the net P loss loading and its apparent P loss ratio in range of -0.038-0.076 kg.m-2 and 0.034-0.100%, respectively. To minimize P loss from rice production area, field drainage should be avoided in the initial week of P-fertilizer application or field harrowing.

Environment↗
PubMed2001

[The follow-up of 12 pregnant women with anticoagulation therapy after mechanical heart valve replacement].

OBJECTIVE: The article discusses the effect of warfarin on pregnant women and their fetus, and the methods of anticoagulation therapy during pregnancy. METHODS: The pregnancy, delivery, and anticoagulation therapy of 12 pregnant women with mechanical heart valve replacement were followed-up. RESULTS: All the patients received oral anticoagulant therapy during pregnancy. The mean dose of imported warfarin was (2.71 +/- 1.24) mg/d (4 cases); domestic warfarin, (3.14 +/- 0.28) mg/d (6 cases); domestic acenocumarol tablet (3.14 +/- 1.08) mg/d (2 cases). No thromboembolism and major hemorrhage occurred. A total of 8 person/times had minor bleeding. Ten patients had term delivery, 2 had premature birth, No abnormal fetus was observed. Only 1 newborn had low birth weight (2,100 g). CONCLUSION: The anticoagulation therapy with low dosage of warfarin (< 5 mg/d) is safe and convenient for the mothers during pregnancy following mechanical heart valve replacement and has low fetus abnormal rate.

Adult↗
PubMed2001

[Study of the route of intrahepatic metastasis of primary hepatic carcinoma].

OBJECTIVE: To study the relationship between pylic countercurrent blood-flow and intrahepatic metastasis of hepatocarcinoma. METHODS: Portal vein-hepatic artery fistula and pylic countercurrent blood flow in the liver were examined by color Doppler ultrasound. Patients examined were divided into four groups: group 1, hepatocarcinoma with background of hepatitis, group 2, hepatocarcinoma without background of hepatitis, group 3, hepatitis and group 4, normal liver. RESULTS: Pylic countercurrent flood flow was most frequently observed in group 1 patients. Intrahepatic metastasis was more frequent in group 1 than in group 2 patients. There was no statistically significant difference in the frequency of portal vein-hepatic artery fistula formation around and inside of tumor between group 1 and group 2 patients. CONCLUSION: Intrahepatic metastasis of hepatocarcinoma is due to countercurrent blood flow in the portal system.

Bile Ducts, Intrahepatic↗
PubMed2001

[Difference of T helper cell subsets and B7 co-stimulatory molecule expressions by alveolar macrophages in bronchoalveolar lavage fluid between patients with allergic asthma and chronic obstructive pulmonary disease].

OBJECTIVE: To elucidate the differences of T helper cell subsets and expressions of B7 co-stimulatory molecules by alveolar macrophages (AM) between patients with allergic asthma and chronic obstructive pulmonary disease (COPD). METHODS: Bronchoalveolar lavage fluid (BALF) cells were obtained from 16 normal control volunteers, 16 patients with allergic asthma and 16 patients with COPD. IFN-gamma and IL-4 levels in the supernatant of BLAF lymphocytes cultured with PHA were determined using sandwich ELISA and the CD80 (B7-1) and CD86 (B7-2) expressed by AM stimulated with LPS were determined using avdin-biotin complex technique. RESULTS: In COPD group, IFN-gamma level was significantly higher than those of the control group and asthma group (P < 0.01). IFN-gamma in asthma group was lower than that of the control group (P < 0.01). IL-4 level and the ratio of AM expressing CD86 in asthma group were higher than those of the control group and COPD group (P < 0.01). The IL-4 level and ratio of AM expressing CD86 showed no significantly difference between COPD and control group (P > 0.05). The IL-4 levels in 3 groups were significantly positively correlated with the ratio of AM expressing CD86 (r = 0.61, P < 0.05). No difference of the ratio of AM expressing CD80 was found among three groups (P < 0.05). CONCLUSION: Asthma is characterized by a predominance of Th2-type response in BALF T cells, and COPD of Th1-type response in BALF T cells. The increased expression of co-stimulation of CD86 in AM is probably involved in Th2-type response in the airway inflammation in allergic asthmatics.

Adult↗
PubMed2001

[GATA-2 gene expression in leukemia patients and its significance].

OBJECTIVE: To investigate GATA-2 gene expression in leukemia patients and its clinical significance. METHODS: GATA-2 gene transcripts were detected by reverse transcriptase polymerase chain reaction (RT-PCR), and bcr/abl or PML/RAR alpha transcripts were detected in patients with chronic myeloid leukemia (CML) and acute promyelocytic leukemia (APL), respectively. RESULTS: The GATA-2 transcripts were revealed in 93% of acute myeloid leukemia (AML), in 70% of acute lymphoblastic leukemia (ALL), and 83% of CML patients, but not in normal bone marrow and peripheral blood cells. GATA-2 expression in remission patients was similar to newly diagnosed or relapsed patients. In post-transplantation patients, GATA-2 expression was significantly decreased. In these cases GATA-2 transcripts could be detected with bcr/abl fusion gene disappeared in 2 of 12 CML, whereas neither GATA-2 nor PML/RARalpha transcripts could be detected in APL. CONCLUSION: GATA-2 transcripts was highly expressed in leukemia patients and had no change in remission but significantly decreased in post-transplantation patients. Detection of GATA-2 expression would give information about the residual leukemia stem cells.

Bone Marrow Cells↗
PubMed2001

[Cloning, sequencing of beagle E-selectin genomic DNA and comparison of it with other species].

OBJECTIVE: Selectins are a group of members of Cell Adhesion Molecular family; they play very important roles in inflammation and neovascularization. The aim of this study is to clone, sequence Beagle E-selectin genomic DNA and make homogeneous analyses to compare it with those of other animals. METHODS: Twelve fragments of genomic DNA of Beagle E-selectin were obtained by PCR, and the 12 fragments were cloned in T-vector. At last, the genomic DNA sequences of Beagle E-selectin were obtained through gene sequencing, assembling and base calling, and the gene structure was analyzed. RESULTS: The sequence of Beagle E-selectin genomic DNA that contained the whole open reading box was acgured. The results of homogeneous analyses showed a great extent of E-selectin gene homology among human, porcine and dog. CONCLUSION: The demonstration of a large extent of the gene homology has substantiated in this connection the important roles of E-selectin in transplantation immunity and neoplasm development.

Animals↗