Biomedical subjects

F Dong

Publications and source records attributed to F Dong.

At least 73 records · Page 4Linked to original sources

PubMed1999

Influence of lymphocytic thyroiditis on the prognostic outcome of patients with papillary thyroid carcinoma.

Both the association between lymphocytic thyroiditis (LT) and papillary thyroid carcinoma (PTC), and the prognostic significance of lymphocytic infiltrate in patients with thyroid malignancy, remain controversial. We examine the above relationships by retrospectively reviewing our series of patients treated for differentiated nonmedullary thyroid carcinoma at University of California-San Francisco over a 25-yr period (1970-1995). Of the 631 patients with complete data for analysis, 128 patients (20.3%) showed concomitant histologic evidence of LT and 503 patients (79.7%) had no evidence of LT. Prognostic outcome was assessed using Kaplan-Meier survival plots and analysis of risk factors by Cox's proportional-hazard modeling. The cohort with LT revealed a higher frequency of PTC (97.7% vs. 87.3%) and female patients (85.2% vs. 66.8%), a lower frequency of extrathyroidal invasion (7.8% vs. 23.3%) and nodal metastases (25.8% vs. 43.3%), and absence of distant metastases (0% vs. 4.8%), respectively, compared with those without LT. At initial surgery, a significantly greater proportion of patients with LT belonged to lower pathological tumor-node-metastasis stages, compared with those without LT (stage 1, 86.7% vs. 73%; stage 2, 4.7% vs. 8.3%; stage 3, 8.6% vs. 15.3%; and stage 4, 0% vs. 3.4%). Over a mean +/- SE follow-up period of 11.1 +/- 0.4 yr, patients with LT had significantly lower cancer recurrence rate (6.3% vs. 24.1%; P < 0.0001) and cancer mortality rate (0.8% vs. 8.0%; P = 0.001), respectively, compared with those without LT. In summary, our series showed a relatively common occurrence of LT in patients with PTC, and we believed that lymphocytic infiltration developed mainly in response to the tumor itself. We also found a more favorable course of PTC in the presence of LT; this supports the hypothesis that lymphocytic infiltration represents a form of immune reaction to control tumor growth and proliferation.

Adolescent↗

PubMed1999

Interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements.

In a study involving 10 different sites, independent results of measurements of ultrasonic properties on equivalent tissue-mimicking samples are reported and compared. The properties measured were propagation speed, attenuation coefficients, and backscatter coefficients. Reasonably good agreement exists for attenuation coefficients, but less satisfactory results were found for propagation speeds. As anticipated, agreement was not impressive in the case of backscatter coefficients. Results for four sites agreed rather well in both absolute values and frequency dependence, and results from other sites were lower by as much as an order of magnitude. The study is valuable for laboratories doing quantitative studies.

1-Propanol↗

PubMed1999

311 cases of chronic osteomyelitis treated by soaking with ganlingsan liquid.

From 1992 to 1995, 311 cases of chronic osteomyelitis (including 145 cases of hematogenic osteomyelitis, 147 cases of traumatic osteomyelitis, 8 cases of secondary osteomyelitis after local infection, 4 cases due to other causes, and 7 cases with cause unknown) were treated by soaking with Ganlingsan liquid. The average treatment course was 69.5 days. The results showed that 260 cases were cured, 26 cases markedly effective, 20 cases improved, and 5 cases ineffective. The evaluation of the function revealed that 150 cases were excellent, 129 cases good, 10 cases improved, and 22 cases poor. 111 patients recovered from abnormal erythrocyte sedimentation rate. External fixation was applied at the same time for the patients accompanied by nonunion of fracture, and the therapeutic effect was also satisfactory.

Administration, Topical↗

PubMed1999

Accessing a WWW reference library of 3D models of pathological organs to support medical education.

A major aspiration of the medical community is to use multimedia databases to disseminate important research or clinical information and for education. We describe a WWW reference library of 3D models of human organs containing pathological and normal organs organised in cases, together with a variety of educational and supporting tools. Although the emphasis is chiefly on the teaching of medical students and the continuing education of physicians, the library is also a potentially-valuable resource for diagnostic investigation. This paper describes the environment, methodologies and tools for supporting 3D models in medical education. The prototype of the system is currently being completed; the full system is scheduled for public access in the year 2000 through multimedia publishers.

Computer-Assisted Instruction↗

PubMed1999

[Tumour suppressor p53 gene sequence mutations in pleomorphic adenoma of salivary gland].

OBJECTIVE: To detect p53 exon 7 and 8 mutation and to study genesis and biological characteristics of pleomorphic adenoma of salivary galand. METHODS: Polymerase chain reaction- single-strand conformational polymorphism (PCR-SSCP) and DNA sequencing analysis were used. RESULTS: PCR-SSCP analysis showed that in 11 patients with positive SSCP, 7 showed abnormal exon 7 and 3 abnormal exon 8. Comparison of SSCP results with DNA sequencing showed that patients all patients with p53 exon 7 and 8 mutations were SSCP positive. Exon 7 mutation pattern was point mutation(T-->C). Exon 8 mutation pattern included base substitution (point mutation) (C-->A) and frame-shiftmutation (base insertion and base loss). CONCLUSIONS: Polycodon and poly-pattern mutations appeared in p53 exon 7 and 8. Pleomorphic adenoma of salivary galand was similar to malignant tumor in p53 gene mutation. Poly-codon mutation could occur in the same case.

Adenoma, Pleomorphic↗

PubMed1999

[p53 gene mutation determined by single-strand conformational polymorphism and DNA sequencing analysis in pleomorphic adenoma of salivary gland].

OBJECTIVE: To detect p53 exon 6 mutation pattern in pleomorphic adenoma of salivary gland. METHODS: Single-strand conformational polymorphism (SSCP) and DNA sequecing were used. RESULTS: SSCP analysis showed that 6 of 11 cases with SSCP positive were exon 6 abnormal. Comparison of the SSCP results with DNA sequecing, 4 cases with p53 exon 6 mutations were SSCP positive. Mutation pattern included base substitution (point mutation, G-->T, T-->G) and frame-shift mutation (base insertion and base loss). CONCLUSION: Poly-codon and poly-pattern mutations appeared in p53 exon 6. PCR-SSCP was a convenient method to detecte gene mutation.

Adenoma, Pleomorphic↗

PubMed1999

[High performance liquid chromatography for analysis of reverse transcription polymerase chain reaction (RT-PCR) products].

The polymerase chain reaction is a powerful method for amplifying specific DNA sequences in vitro. Reverse transcribing mRNA into cDNA expands the use of PCR to monitor mRNA expression in biological system. A method for the analysis of RT-PCR products by HPLC was developed. The separation was performed on a nonporous ion exchange resin column with gradient elution of sodium chloride in 20 mmol/L Tris-HCl buffer (pH 9.0) at a flow rate of 1.0 mL/min and the detection wavelength was 260 nm. lambda-DNA-Hind III digest and a series of RT-PCR products were analyzed for studying the mRNA expression of secreted phospholipase A2 after being injured.

Animals↗

PubMed1998

Stimulation of Stat5 by granulocyte colony-stimulating factor (G-CSF) is modulated by two distinct cytoplasmic regions of the G-CSF receptor.

In a manner similar to many other cytokines, treatment of cells with granulocyte CSF (G-CSF) has been shown to induce the tyrosine phosphorylation of the STAT proteins. Activation of Stat1 and Stat5 by G-CSF requires the membrane-proximal cytoplasmic domain of the receptor, including box1 and box2, while G-CSF-stimulated tyrosine phosphorylation of Stat3 also requires a region distal to box 2. In this study, we show that although the membrane-proximal 55 amino acids of the G-CSF receptor are sufficient for activation of Stat5, the maximal rate of Stat5 activation requires an additional 30 amino acids of the cytoplasmic domain. In contrast, the distal carboxyl-terminal region of the receptor appears to down-regulate Stat5 activation in that deletion of this carboxyl terminus results in increased amplitude and prolonged duration of Stat5 activation by G-CSF. Significantly, expression of a truncated dominant-negative Stat5 protein in hemopoietic cells not only inhibits G-CSF-dependent cell proliferation, but also suppresses cell survival upon G-CSF withdrawal. We further show that a potential protein tyrosine phosphatase may play a critical role in the down-regulation of G-CSF-stimulated Stat5 activation. These results demonstrate that two distinct cytoplasmic regions of the G-CSF receptor are involved in the regulation of the intensity and duration of Stat5 activation, and that Stat5 may be an important player in G-CSF-mediated cell proliferation and survival.

Animals↗

PubMed1998

Rice (Oryza sativa) centromeric regions consist of complex DNA.

Rice bacterial artificial chromosome clones containing centromeric DNA were isolated by using a DNA sequence (pSau3A9) that is present in the centromeres of Gramineae species. Seven distinct repetitive DNA elements were isolated from a 75-kilobase rice bacterial artificial chromosome clone. All seven DNA elements are present in every rice centromere as demonstrated by fluorescence in situ hybridization. Six of the elements are middle repetitive, and their copy numbers range from approximately 50 to approximately 300 in the rice genome. Five of these six middle repetitive DNA elements are present in all of the Gramineae species, and the other element is detected only in species within the Bambusoideae subfamily of Gramineae. All six middle repetitive DNA elements are dispersed in the centromeric regions. The seventh element, the RCS2 family, is a tandem repeat of a 168-bp sequence that is represented approximately 6,000 times in the rice genome and is detected only in Oryza species. Fiber-fluorescence in situ hybridization analysis revealed that the RCS2 family is organized into long uninterrupted arrays and resembles previously reported tandem repeats located in the centromeres of human and Arabidopsis thaliana chromosomes. We characterized a large DNA fragment derived from a plant centromere and demonstrated that rice centromeres consist of complex DNA, including both highly and middle repetitive DNA sequences.

Base Sequence↗

PubMed1998

Prolonged STAT1 activation related to the growth arrest of malignant lymphoma cells by interferon-alpha.

Multiple biologic effects of interferon-alpha (IFN-alpha), including cell growth inhibition and antiviral protection, are initiated by tyrosine phosphorylation of STAT proteins. Although this signal pathway has been intensively investigated, the relevance of STAT signal persistence has received scant attention. Using paired isogenic lymphoma cells (Daudi), which either are sensitive or resistant to growth inhibition by IFN-alpha, we found comparable initial tyrosine phosphorylation of multiple STAT proteins; however, the phosphorylation durations and associated DNA-binding activities diverged. Phosphorylation and DNA-binding capacity of STAT1 decreased after 4 to 8 hours in resistant cells, as compared with 24 to 32 hours in sensitive cells, whereas phosphorylation of STAT3 and STAT5b was briefer in both lines. Functional significance of the prolonged STAT1 signal, therefore, was explored by experimental interruption of tyrosine phosphorylation, either by premature withdrawal of the IFN-alpha or deferred addition of pharmacologically diverse antagonists: staurosporine (protein kinase inhibitor), phorbol 12-myristate 13-acetate (growth promoter), or aurintricarboxylic acid (ligand competitor). Results indicated that an approximately 18-hour period of continued STAT1 phosphorylation was associated with growth arrest, but that antiviral protection developed earlier. These differences provide novel evidence of a temporal dimension to IFN-alpha signal specificity and show that duration of STAT1 activation may be a critical variable in malignant cell responsiveness to antiproliferative therapy.

Antineoplastic Agents↗

PubMed1998

The role of cyclin D3-dependent kinase in the phosphorylation of p130 in mouse BALB/c 3T3 fibroblasts.

We have observed that cyclin D3-dependent kinase activity is increased in the late G1 phase in BALB/c 3T3 fibroblasts. The profile of cyclin D3-associated activity closely parallels that of cyclin D1, which is also induced after mitogenic stimulation of quiescent cells. These activities correlate with the appearance of hyperphosphorylated p130, an Rb family member important in regulating E2F-4 and E2F-5 activity in fibroblastic cells. We demonstrated, however, that only the cyclin D3 activity efficiently phosphorylated p130 in an in vitro kinase assay. This apparent specificity was further demonstrated by experiments which demonstrated that cyclin D3 was physically associated with p130 at the times when D3-dependent kinase activity and p130 hyperphosphorylation were observed. Examination of E2F by electrophoretic mobility shift assay revealed that E2F-4 DNA binding activity existed in a p130.E2F complex at times before D3-dependent kinase activity was apparent and in a free E2F-4 complex after D3 activity developed. Thus, our data suggest that cyclin D3 preferentially phosphorylates p130 and is thereby specifically targeted to overcoming growth-suppressive control mediated through p130 pathways.

3T3 Cells↗

PubMed1998

Molecular characterization of a cDNA that encodes six isoforms of a novel murine A kinase anchor protein.

We have cloned cDNA that encodes six novel A kinase anchor proteins (collectively named AKAP-KL). AKAP-KL diversity is generated by alternative mRNA splicing and utilization of two translation initiation codons. AKAP-KL polypeptides are evident in lung, kidney, and cerebellum, but are absent from many tissues. Different isoforms predominate in different tissues. Thus, AKAP-KL expression is differentially regulated in vivo. All AKAP-KL isoforms contain a 20-residue domain that avidly binds (Kd approximately 10 nM) regulatory subunits (RII) of protein kinase AII and is highly homologous with the RII tethering site in neuronal AKAP75. The distribution of AKAP-KL is strikingly asymmetric (polarized) in situ. Anchor protein accumulates near the inner, apical surface of highly polarized epithelium in tubules of nephrons. Both RII and AKAP-KL are enriched at an intracellular site that lies just below the plasma membrane of alveolar epithelial cells in lung. AKAP-KL interacts with and modulates the structure of the actin cytoskeleton in transfected cells. We also demonstrate that the tethering domain of AKAP-KL avidly ligates RII subunits in intact cells. AKAP-KL may be involved in (a) establishing polarity in signaling systems and (b) physically and functionally integrating PKAII isoforms with downstream effectors to capture, amplify, and precisely focus diffuse, trans-cellular signals carried by cAMP.

A Kinase Anchor Proteins↗

PubMed1998

Activation of the Jak2-Stat5 signaling pathway in Nb2 lymphoma cells by an anti-apoptotic agent, aurintricarboxylic acid.

Biological effects of many hormones and cytokines are mediated through receptor-associated Jak tyrosine kinases and cytoplasmic Stat transcription factors, including critical physiological processes such as immunity, reproduction, and cell growth and differentiation. Pharmaceuticals that control Jak-Stat pathways are therefore of considerable interest. Here we demonstrate that a single Jak-Stat pathway can be activated by aurintricarboxylic acid (ATA), a negatively charged triphenylmethane derivative (475 Da) with anti-apoptotic properties. In prolactin (PRL)-dependent Nb2 lymphocytes, ATA sustained cell growth in the absence of hormone and mimicked rapid PRL-induced tyrosine phosphorylation of Jak2 and activation of Stat5a and Stat5b with tyrosine phosphorylation, heterodimerization, DNA binding, and induction of the Stat5-regulated pim-1 protooncogene. ATA also mimicked PRL activation of serine kinases ERK1 and ERK2. However, unlike PRL, ATA did not regulate Stat1 or Stat3. ATA also did not affect Jak3, which is activated in these cells by interleukin-2 family cytokines. Although the mechanism and specificity by which ATA activates Jak2, Stat5, and ERKs in Nb2 cells are still unclear, the present study demonstrates that certain hormone or cytokine effects on Jak-Stat pathways can be discretely imitated by a low molecular weight, non-peptide pharmaceutical. The results are also consistent with Stat5 involvement in lymphocyte growth and survival.

Apoptosis↗

PubMed1998

Randomized trial to determine optimal dose of vaginal misoprostol for preabortion cervical priming.

OBJECTIVE: To determine the optimal dosage of vaginal misoprostol for cervical priming before vacuum aspiration abortion. METHODS: One hundred twenty women were assigned randomly to receive 200, 400, 600, or 800 microg of misoprostol given vaginally. Vacuum aspiration was performed 3-4 hours after the insertion of misoprostol tablets. The degree of cervical dilation before operation was measured with a Hegar dilator. Preoperative and intraoperative blood loss and associated side effects also were assessed. RESULTS: Twenty-nine (96.7%) women in the 400-microg group and all in the 600-microg and 800-microg groups achieved cervical dilation of at least 8 mm. The success rate for the 200-microg group was only 23.3%, significantly less efficacious than the 400-microg dose (odds ratio 95.3; 95% confidence interval 10.9, 830.9; P < .001). There was no significant difference among the 400-, 600-, and 800-microg groups (P = .364) with respect to achieving cervical dilation at least 8 mm. However, 800 microg was associated with significantly more side effects than 600 microg (preoperative and intraoperative blood loss, P < .001; abdominal pain, P = .005; products of conception at os, P < .001; fever higher than 38.0C, P = .002). When 400 microg and 600 microg were compared, we found that the higher dose also was associated with significantly more side effects. The 600-microg group was used twice in the comparison, but all P values remained significant even after the Bonferroni adjustment for multiple comparisons. CONCLUSION: Vaginal application of 400 microg of misoprostol is the optimal dose for vacuum aspiration preabortion cervical dilation in first-trimester nulliparas.

Abortifacient Agents, Nonsteroidal↗

PubMed1998

Liquid or solid ultrasonically tissue-mimicking materials with very low scatter.

A new tissue-mimicking material for ultrasound, using evaporated milk as the primary absorption component, is described. It has very low backscatter but still exhibits the 1540 m s-1 propagation speed and proportionality of attenuation coefficient and frequency over the diagnostic frequency range. The material can be produced in solid or liquid form with attenuation coefficient slopes spanning the range 0.1-0.7 dB cm-1 MHz-1. The liquid form is useful in phantoms where detailed beam patterns are to be determined, either involving translation of measurement devices in the liquid or phantoms with fibers present for causing the only detectable echoes. In the latter case, the liquid quality allows removal of liquid with one attenuation coefficient slope and replacement with another. The solid form may be more useful than the liquid for two reasons. First, many simulated lesions (including ones that produce essentially no internal echoes) can lie in the scan slice with positions extending over the entire image area without enhancement or shadowing effects being of concern. Second, the lack of significant backscatter from the material in the absence of added scatterers allows the backscatter coefficient to be varied over a considerable range. A critical result is that intrinsic material contrast between targets and surroundings can be accurately predicted in terms of the concentrations of added scatterers and, assuming all scatterers are of the same type, the contrast will be completely independent of frequency. Use of the fungicide thimerosal eliminates deterioration, and ultrasonic properties have been shown to be stable over 2.5 years.

Animals↗

PubMed1998

Non-Rabl patterns of centromere and telomere distribution in the interphase nuclei of plant cells.

At the anaphase of cell divisions, the divided chromosomes move to the two poles, with the centromeres as heads and telomeres as tails. Such a polarized orientation of centromeres and telomeres is believed to be preserved in the interphase and is known as Rabl model. We analyzed the distributions of centromeres and telomeres in interphase nuclei from several plant species. Although Rabl polarity was observed in wheat, rye, barley and oats, non-Rabl patterns were discovered in sorghum, rice and maize. In the non-Rabl patterns, both centromeres and telomeres were dispersed throughout the interphase nucleus, except in the area occupied by the nucleolus. Both Rabl and non-Rabl distribution patterns of centromeres and telomeres were consistent in interphase nuclei derived from meristematic root tip cells, microspore mother cells and differentiated leaf cells. Our study demonstrated that there is a diversity of interphase chromatin organization and that the classical Rabl model is not universal in plant species.

Avena↗

PubMed1998

Cyclin D3-associated kinase activity is regulated by p27kip1 in BALB/c 3T3 cells.

We report that cyclin D3/cdk4 kinase activity is regulated by p27(kip1) in BALB/c 3T3 cells. The association of p27(kip1) was found to result in inhibition of cyclin D3 activity as measured by immune complex kinase assays utilizing cyclin D3-specific antibodies. The ternary p27(kip1)/cyclin D3/cdk4 complexes do exhibit kinase activity when measured in immune complex kinase assays utilizing p27(kip1)-specific antibodies. The association of p27(kip1) with cyclin D3 was highest in quiescent cells and declined upon mitogenic stimulation, concomitantly with declines in the total level of p27(kip1) protein. The decline in this association could be elicited by PDGF treatment alone; this was not sufficient, however, for activation of cyclin D3 activity, which also required the presence of factors in platelet-poor plasma in the culturing medium. Unlike cyclin D3 activity, which was detected only in growing cells, p27(kip1) kinase activity was present throughout the cell cycle. Since we found that the p27(kip1) activity was dependent on cyclin D3 and cdk4, we compared the substrate specificity of the active ternary complex containing p27(kip1) and the active cyclin D3 lacking p27(kip1) by tryptic phosphopeptide mapping of GST-Rb phosphorylated in vitro and also by comparing the relative phosphorylation activity toward a panel of peptide substrates. We found that ternary p27(kip1)/cyclin D3/cdk4 complexes exhibited a different specificity than the active binary cyclin D3/cdk4 complexes, suggesting that p27(kip1) has the capacity to both inhibit cyclin D/cdk4 activity as well as to modulate cyclin D3/cdk4 activity by altering its substrate preference.

3T3 Cells↗

PubMed1998

Retrotransposon-related DNA sequences in the centromeres of grass chromosomes.

Several distinct DNA fragments were subcloned from a sorghum (Sorghum bicolor) bacterial artificial chromosome clone 13I16 that was derived from a centromere. Three fragments showed significant sequence identity to either Ty3/gypsy- or Ty1/copia-like retrotransposons. Fluorescence in situ hybridization (FISH) analysis revealed that the Ty1/copia-related DNA sequences are not specific to the centromeric regions. However, the Ty3/gypsy-related sequences were present exclusively in the centromeres of all sorghum chromosomes. FISH and gel-blot hybridization showed that these sequences are also conserved in the centromeric regions of all species within Gramineae. Thus, we report a new retrotransposon that is conserved in specific chromosomal regions of distantly related eukaryotic species. We propose that the Ty3/gypsy-like retrotransposons in the grass centromeres may be ancient insertions and are likely to have been amplified during centromere evolution. The possible role of centromeric retrotransposons in plant centromere function is discussed.

Amino Acid Sequence↗