Biomedical subjects

F Zhao

Publications and source records attributed to F Zhao.

At least 19 recordsLinked to original sources

PubMed2002

Purification and characterization of the fusion protein trypsin-streptavidin expressed in Escherichia coli.

Expression of fusion protein trypsin-streptavidin (TRYPSA) in Escherichia coli was evaluated and the protein purified. Protein expression was induced by 1 mM isopropylthio-beta-D-galactoside (IPTG), and the enzyme activity was measured by the hydrolysis rate of p-toluenesulfonyl-L-arginine methyl ester (TAME). Expression of the fusion protein in the cell-free extract decreased with increased induction time; correspondingly, that in the inclusion bodies increased. The total expression in Luria-Bertani broth (LB) and Terrific Broth (TB) media reached the highest levels in 2 hr at 30 degrees C. The optimum expression level was 35 and 48 U/L in LB and TB, respectively. Expression of the fusion protein was verified by Western Blot analysis using streptavidin antiserum, and the fusion protein was purified using a benzamidine Sepharose 6B affinity column at room temperature. The molecular size of the soluble purified fusion protein was determined by size-exclusion chromatography using Superose 12 FPLC. A molecular weight of 39-40 kDa was obtained, indicating that the soluble protein exists as a monomer; thus, the presence of the trypsin domain must prevent the streptavidin domain from tetramer formation.

Blotting, Western↗

PubMed2002

The Audioscan: a high frequency resolution audiometric technique and its clinical applications.

The Audioscan is a form of high definition audiometry based on iso-hearing level frequency sweeps, which was developed by Meyer-Bisch in 1990. Compared with traditional tone audiometry, it sweeps across the preset frequency range at a predetermined sweep rate and provides a continuous audiometric curve. Because the device has a maximum frequency range of 125-16 000 Hz with 64 frequencies per octave, the Audioscan method can, theoretically, give 64 times as many values as fixed-frequency audiometry, which may give greater accuracy and sensitivity. An advantage of this is its capacity to detect mild audiometric deficits such as narrow notches situated between the frequencies normally tested. These may represent very limited auditory lesions, at a stage when they cannot be detected by routine audiological methods. Thus, the Audioscan method can give not only a detailed audiometric curve, but also provide important indicators of mild auditory dysfunction. The Audioscan device (e.g. Essilor model) is commercially available for clinical purpose. It is a software-based system, which can also be used for pure tone audiometry and Békésy audiometry. This paper reviews the general aspects of the Audioscan technique and current applications for detecting auditory dysfunction. This would be valuable to provide some guidelines on the Audioscan assessment, and contribute to a clarification of the clinical application of Audioscan and facilitate further research.

Audiometry↗

PubMed2002

Clopidogrel does not suppress blood markers of coagulation activation in aspirin-treated patients with non-ST-elevation acute coronary syndromes.

AIMS: The Clopidogrel in Unstable angina to prevent Recurrent Events (CURE) Study demonstrated that clopidogrel plus aspirin was superior to aspirin alone for prevention of recurrent vascular events in patients with acute coronary syndromes. The aim of this study was to compare the effect of these two regimens on biochemical markers of platelet and coagulation activation. METHODS AND RESULTS: We studied 485 patients with non-ST-elevation acute coronary syndrome who were randomized to clopidogrel (300 mg loading dose followed by 75 mg daily) or placebo for a period of 3-12 months. All patients also received aspirin (recommended dose 75-325 mg daily). Blood levels of P-selectin, prothrombin fragment F1.2, D-dimer, and von Willebrand factor were measured at baseline, day 7 (or hospital discharge), and at day 30 after randomization. Patients receiving clopidogrel plus aspirin compared with aspirin alone had similar baseline geometric mean plasma levels of P-selectin (50.2 vs 51.7 ng.ml(-1), P=0.45), prothrombin fragment F1.2 (1.13 vs 1.12 nmol.l(-1), P=0.94), D-dimer (467 vs 460 ng.ml(-1), P=0.85), and von Willebrand factor levels (1.89 vs 1.85 U.ml(-1), P=0.59) and there also were no significant differences at day 7, or day 30. However, compared with baseline, there was a significant rise in prothrombin fragment F1.2 at day 7 (from 1.12 to 1.39 nmol.l(-1), P<0.0001) and day 30 (from 1.12 to 1.44 nmol.l(-1), P<0.0001), and D-dimer at day 7 (from 464 to 539 nmol.l(-1), P<0.0001) and day 30 (from 464 to 576 nmol.l(-1), P<0.0001). The magnitude of this rise appeared to be greatest in patients who experienced the primary outcome, a composite of cardiovascular death, myocardial infarction, stroke, or refractory ischaemia by the end of the study. P-selectin levels were not elevated at any time point but von Willebrand factor values were elevated at baseline and remained elevated at days 7 and 30. CONCLUSION: Our results indicate that the clinical benefits of clopidogrel are not associated with a parallel reduction in markers of coagulation activation. Early suppression of coagulation markers most likely reflects the effects of heparin. The persistence of thrombin generation despite long-term clopidogrel and aspirin therapy suggests that even more intensive antithrombotic therapy may be required in these patients.

Antigens↗

PubMed2001

Influence of angiogenetic factors and matrix metalloproteinases upon tumour progression in non-small-cell lung cancer.

We attempted to investigate immunohistochemical expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PD-ECGF), c-erbB-2, matrix metalloproteinase-2 (MMP-2), and MMP-9 using surgical specimens of 119 non-small-cell lung carcinoma (NSCLC) cases and to evaluate the relationship between the expression levels of each molecule and clinicopathological factors or prognosis. VEGF expression levels were significantly associated with the local invasion (P = 0.0001), lymph node involvement (pN-factor) (P = 0.0019), pathological stage (p-stage) (P = 0.0027) and lymphatic permeation (P = 0.0389). PD-ECGF expression levels were associated with pN-factor (P = 0.0347). MMP-2 expression levels were associated with pN-factor (P = 0.004) and lymphatic permeation (P = 0.0056). Also, MMP-9 expression levels showed a significant correlation to local invasion (P = 0.0012), pN-factor (P = 0.0093) and p-stage (P = 0.0142). Multivariate analysis showed VEGF to be the most related to local invasion (P = 0.0084), and MMP-2 was the only factor with significant independent impact on lymphatic permeation (P = 0.0228). Furthermore, log-rank analysis showed significant association with poor survival by VEGF, bFGF, MMP-2 and MMP-9. Especially, combined overexpression of VEGF and MMP-2 revealed poor prognosis, our study might provide a basis for the better evaluation of biological characteristics and a new therapeutic strategy based on chemotherapy.

Adult↗

PubMed2001

Cloning and characterization of a novel mouse AP-2 transcription factor, AP-2delta, with unique DNA binding and transactivation properties.

AP-2 transcription factors are sequence-specific DNA-binding proteins expressed in neural crest and other tissues during mammalian development. Three mammalian genes, AP-2alpha, AP-2beta, and AP-2gamma, have been reported previously. A partial predicted AP-2 gene was identified in tandem with AP-2beta on human chromosome 6p12-p21.1. The orthologous mouse gene, which we named Ap-2delta, was identified from a fetal mouse head cDNA library. Northern analysis revealed two transcripts in embryonic and newborn mouse brain, with markedly higher steady-state levels in the former. The predicted Ap-2delta protein comprised 452 amino acids and was highly similar to other AP-2 proteins across the DNA-binding and dimerization domains. Ap-2delta formed homodimers and heterodimers in vitro, bound an optimized AP-2 consensus DNA sequence, and transactivated gene expression in eukaryotic cells. Ap-2delta dimers bound poorly to an AP-2 binding sequence from the human metallothionein IIa promoter in vitro, revealing a sequence specificity not previously observed among other AP-2 proteins. The PY motif and critical residues in the transactivation domain, which are highly conserved in the AP-2 family and believed necessary for transactivation, were divergent in Ap-2delta. The unique protein sequence and functional features of Ap-2delta suggest mechanisms, besides tissue-specific AP-2 gene expression, for specific control of target gene activation.

Amino Acid Sequence↗

PubMed2001

Effects of pretreatment with clopidogrel and aspirin followed by long-term therapy in patients undergoing percutaneous coronary intervention: the PCI-CURE study.

BACKGROUND: Despite the use of aspirin, there is still a risk of ischaemic events after percutaneous coronary intervention (PCI). We aimed to find out whether, in addition to aspirin, pretreatment with clopidogrel followed by long-term therapy after PCI is superior to a strategy of no pretreatment and short-term therapy for only 4 weeks after PCI. METHODS: 2658 patients with non-ST-elevation acute coronary syndrome undergoing PCI in the CURE study had been randomly assigned double-blind treatment with clopidogrel (n=1313) or placebo (n=1345). Patients were pretreated with aspirin and study drug for a median of 6 days before PCI during the initial hospital admission, and for a median of 10 days overall. After PCI, most patients (>80%) in both groups received open-label thienopyridine for about 4 weeks, after which study drug was restarted for a mean of 8 months. The primary endpoint was a composite of cardiovascular death, myocardial infarction, or urgent target-vessel revascularisation within 30 days of PCI. The main analysis was by intention to treat. FINDINGS: There were no drop-outs. 59 (4.5%) patients in the clopidogrel group had the primary endpoint, compared with 86 (6.4%) in the placebo group (relative risk 0.70 [95% CI 0.50-0.97], p=0.03). Long-term administration of clopidogrel after PCI was associated with a lower rate of cardiovascular death, myocardial infarction, or any revascularisation (p=0.03), and of cardiovascular death or myocardial infarction (p=0.047). Overall (including events before and after PCI) there was a 31% reduction cardiovascular death or myocardial infarction (p=0.002). There was less use of glycoprotein IIb/IIIa inhibitor in the clopidogrel group (p=0.001). At follow-up, there was no significant difference in major bleeding between the groups (p=0.64). INTERPRETATION: In patients with acute coronary syndrome receiving aspirin, a strategy of clopidogrel pretreatment followed by long-term therapy is beneficial in reducing major cardiovascular events, compared with placebo.

Aged↗

PubMed2001

Effects of clopidogrel in addition to aspirin in patients with acute coronary syndromes without ST-segment elevation.

BACKGROUND: Despite current treatments, patients who have acute coronary syndromes without ST-segment elevation have high rates of major vascular events. We evaluated the efficacy and safety of the antiplatelet agent clopidogrel when given with aspirin in such patients. METHODS: We randomly assigned 12,562 patients who had presented within 24 hours after the onset of symptoms to receive clopidogrel (300 mg immediately, followed by 75 mg once daily) (6259 patients) or placebo (6303 patients) in addition to aspirin for 3 to 12 months. RESULTS: The first primary outcome--a composite of death from cardiovascular causes, nonfatal myocardial infarction, or stroke--occurred in 9.3 percent of the patients in the clopidogrel group and 11.4 percent of the patients in the placebo group (relative risk with clopidogrel as compared with placebo, 0.80; 95 percent confidence interval, 0.72 to 0.90; P<0.001). The second primary outcome--the first primary outcome or refractory ischemia--occurred in 16.5 percent of the patients in the clopidogrel group and 18.8 percent of the patients in the placebo group (relative risk, 0.86; 95 percent confidence interval, 0.79 to 0.94; P<0.001). The percentages of patients with in-hospital refractory or severe ischemia, heart failure, and revascularization procedures were also significantly lower with clopidogrel. There were significantly more patients with major bleeding in the clopidogrel group than in the placebo group (3.7 percent vs. 2.7 percent; relative risk, 1.38; P=0.001), but there were not significantly more patients with episodes of life-threatening bleeding (2.2 percent [corrected] vs. 1.8 percent; P=0.13) or hemorrhagic strokes (0.1 percent vs. 0.1 percent). CONCLUSIONS: The antiplatelet agent clopidogrel has beneficial effects in patients with acute coronary syndromes without ST-segment elevation. However, the risk of major bleeding is increased among patients treated with clopidogrel.

Acute Disease↗

PubMed2001

Novel TFAP2B mutations that cause Char syndrome provide a genotype-phenotype correlation.

To elucidate further the role, in normal development and in disease pathogenesis, of TFAP2B, a transcription factor expressed in neuroectoderm, we studied eight patients with Char syndrome and their families. Four novel mutations were identified, three residing in the basic domain, which is responsible for DNA binding, and a fourth affecting a conserved PY motif in the transactivation domain. Functional analyses of the four mutants disclosed that two, R225C and R225S, failed to bind target sequence in vitro and that all four had dominant negative effects when expressed in eukaryotic cells. Our present findings, combined with data about two previously identified TFAP2B mutations, show that dominant negative effects consistently appear to be involved in the etiology of Char syndrome. Affected individuals in the family with the PY motif mutation, P62R, had a high prevalence of patent ductus arteriosus but had only mild abnormalities of facial features and no apparent hand anomalies, a phenotype different from that associated with the five basic domain mutations. This genotype-phenotype correlation supports the existence of TFAP2 coactivators that have tissue specificity and are important for ductal development but less critical for craniofacial and limb development.

3T3 Cells↗

PubMed2001

Stroke in relation to cardiac procedures in patients with non-ST-elevation acute coronary syndrome: a study involving >18 000 patients.

BACKGROUND: There are few published data on risk factors for stroke in patients with non-ST-elevation acute coronary syndrome (ACS). We investigated prognostic factors for stroke in 2 large cohorts of patients from the Organization to Assess Strategies for Ischemic Syndromes (OASIS) registry (8010) and the OASIS-2 trial (10 141). METHODS AND RESULTS: A total of 18 151 patients with non-ST-elevation ACS were enrolled in the OASIS program. Data from these 2 studies were pooled (a test for heterogeneity was nonsignificant, P=0.34). Overall, 238 patients (1.3%) had a stroke over a 6-month follow-up. Those who experienced stroke had a 4-fold increase in 6-month mortality (27.0% versus 6.3%, P<0.001). A Cox multivariate regression analysis identified CABG surgery as the most important predictor of stroke (hazard ratio [HR], 4.6), followed by history of stroke (HR, 2.3), diabetes mellitus (HR, 1.7), older age (HR, 1.6 per 10-year increase), higher heart rate (HR, 1.1 per 10-bpm increase), and on-site catheterization facility (HR, 1.4). There was no significant excess in stroke in patients undergoing percutaneous coronary intervention (P=0.21). Patients who underwent early CABG surgery were at a substantially increased risk compared with those who had later CABG (3.3% versus 1.6%; HR, 2.1; P=0.003) or who had no surgery (3.3% versus 1.1%; HR, 3.95; P=0.0001). CONCLUSIONS: In this large cohort of patients with ACS, stroke was an uncommon but serious event associated with high mortality. The performance of early CABG surgery was a powerful independent predictor of stroke.

Acute Disease↗

PubMed2001

Overexpression of macrophage colony-stimulating factor receptor on microglial cells induces an inflammatory response.

Microglia are important in the inflammatory response in Alzheimer's disease (AD). We showed previously that macrophage colony-stimulating factor receptor (M-CSFR), encoded by the c-fms protooncogene, is overexpressed on microglia surrounding amyloid beta (Abeta) deposits in the APP(V717F) mouse model for AD. The M-CSFR is also increased on microglia after experimental brain injury and in AD. To determine the relevance of these findings, we transiently expressed M-CSFR on murine BV-2 and human SV-A3 microglial cell lines using an SV40-promoted c-fms construct. M-CSFR overexpression resulted in microglial proliferation and increased expression of inducible nitric-oxide synthase, the proinflammatory cytokines interleukin-1alpha, macrophage inflammatory protein 1-alpha, and interleukin-6 and of macrophage colony-stimulating factor (M-CSF) itself. Antibody neutralization of M-CSF showed that the M-CSFR-induced proinflammatory response was dependent on M-CSF in the culture media. By using a co-culture of c-fms-transfected murine microglia and rat organotypic hippocampal slices and a species-specific real time reverse transcriptase-polymerase chain reaction assay and enzyme-linked immunosorbent assay, we showed that M-CSFR overexpression on exogenous microglia induced expression of interleukin-1alpha by the organotypic culture. These results show that increased M-CSFR expression induces microglial proliferation, cytokine expression, and a paracrine inflammatory response, suggesting that in APP(V717F) mice increased M-CSFR on microglia could be an important factor in Abeta-induced inflammatory response.

Amidohydrolases↗

PubMed2001

Characteristic changes in T(2)-value, apparent diffusion coefficient, and ultrastructure of substantia nigra evolving exofocal postischemic neuronal death in rats.

To correlate the magnetic resonance (MR) imaging characteristics of exofocal postischemic neuronal death (EPND) in the substantia nigra (SN) with associated histologic changes, we occluded the left middle cerebral artery of rats for 1, 4, 7, or 12 days. Day 1 (post-occlusion) T(2)-weighted images revealed high signal intensity indicative of infarction in the ipsilateral caudate nucleus, putamen, and cortex but not the SN. Diffusion-weighted images (DWIs) on day 1 similarly failed to reveal any changes in the SN. However, on day 4, DWIs revealed high signal intensity in the ipsilateral SN, in which the apparent diffusion coefficient (ADC) transiently decreased (P<0.05) while the T(2)-value increased (P<0.05). These measures returned to and remained at control levels on days 7 and 12. Histologic examination on day 4 revealed dark-staining neurons, markedly swollen perivascular astrocytic end-feet, many swollen neurons with cytoplasmic microvacuoles that mainly originated in the rough endoplasmic reticulum, and strongly roughed neuropils. Reactive astrocytes and dark neurons most frequently appeared on days 7 and 12. The severity of cellular swelling paralleled the change in the ADC. These results demonstrate that a transient high-intensity signal on DWIs, indicative of a decrease in the ADC, is predictive of EPND in the SN.

Animals↗

PubMed2001

Voltammetric behavior of L-cysteine in the presence of CPB at a silver electrode.

The voltammetric behavior of L-cysteine at a silver electrode is described. L-Cysteine can be anodically accumulated at a silver electrode surface as a sparingly soluble silver salt; at more negative potentials, the insoluble compound is stripped cathodically yielding a small current peak at about -1.10 V (vs. SCE). In the presence of cetyl pyridine bromide (CPB), the stripping peak shifts slightly to a more negative potential, and the peak height increases significantly. Thus, the peak becomes more useful for the determination of L-cysteine. In contrast to other surfactants, CPB can improve the accumulation and stripping of L-cysteine obviously. The voltammetric behavior of cysteamine, 3-mercaptopropionic acid and homocysteine is discussed as well.

3-Mercaptopropionic Acid↗

PubMed2001

Dantrolene inhibition of ryanodine receptor Ca2+ release channels. Molecular mechanism and isoform selectivity.

As an inhibitor of Ca(2+) release through ryanodine receptor (RYR) channels, the skeletal muscle relaxant dantrolene has proven to be both a valuable experimental probe of intracellular Ca(2+) signaling and a lifesaving treatment for the pharmacogenetic disorder malignant hyperthermia. However, the molecular basis and specificity of the actions of dantrolene on RYR channels have remained in question. Here we utilize [(3)H]ryanodine binding to further investigate the actions of dantrolene on the three mammalian RYR isoforms. The inhibition of the pig skeletal muscle RYR1 by dantrolene (10 microm) was associated with a 3-fold increase in the K(d) of [(3)H]ryanodine binding to sarcoplasmic reticulum (SR) vesicles such that dantrolene effectively reversed the 3-fold decrease in the K(d) for [(3)H]ryanodine binding resulting from the malignant hyperthermia RYR1 Arg(615) --> Cys mutation. Dantrolene inhibition of the RYR1 was dependent on the presence of the adenine nucleotide and calmodulin and reflected a selective decrease in the apparent affinity of RYR1 activation sites for Ca(2+) relative to Mg(2+). In contrast to the RYR1 isoform, the cardiac RYR2 isoform was unaffected by dantrolene, both in native cardiac SR vesicles and when heterologously expressed in HEK-293 cells. By comparison, the RYR3 isoform expressed in HEK-293 cells was significantly inhibited by dantrolene, and the extent of RYR3 inhibition was similar to that displayed by the RYR1 in native SR vesicles. Our results thus indicate that both the RYR1 and the RYR3, but not the RYR2, may be targets for dantrolene inhibition in vivo.

Adenine↗

PubMed2001

Effects of cryoanalgesia on post-thoracotomy pain and on the structure of intercostal nerves: a human prospective randomized trial and a histological study.

OBJECTIVE: The choice of analgesia in the management of post-thoracotomy pain remains controversial. Although several alternative forms of post-thoracotomy analgesia exist, all have their disadvantages. Cryoanalgesia, localized freezing of intercostal nerves, has been reported to have variable effectiveness and an incidence of long-term cutaneous sensory changes. We carried out an animal study to assess the reversibility of histological changes induced by cryoanalgesia and a prospective randomized trial to compare the effectiveness of cryoanalgesia with conventional analgesia (parenteral opiates). METHODS: In six anaesthetized dogs, intercostal nerves were exposed to a varying duration of cryo-application (30, 60, 90 and 120 s). The nerves were biopsied and examined histologically at regular intervals over the following 6 months. In the clinical study, 200 consecutive patients undergoing thoracotomy were randomized to cryoanalgesia and conventional (parenteral opiates) analgesia groups. Postoperative pain scores, respiratory function tests and use of opiate analgesia were measured for the two groups. RESULTS: Following application of the cryoprobe, degeneration and fragmentation of the axons was evident with associated inflammatory changes. As the endoneurium remained intact, axonal regeneration took place after the resolution of axonal swelling. Over the course of weeks, recovery of the intercostal nerve occurred and was complete after 1 month for the 30 and 60 s groups. For nerves exposed to longer durations of cryoanalgesia, the time taken for complete recovery was proportionally increased. Clinically, there was a statistically significant (P<0.05) improvement in postoperative pain scores and use of opiate analgesia and an improvement (P>0.05) in respiratory function tests for patients in the cryoanalgesia group. The previously suggested cutaneous sensory changes resolved within 6 months with complete restoration of function. CONCLUSIONS: We suggest that cryoanalgesia be considered as a simple, inexpensive, long-term form of post-thoracotomy pain relief, which does not cause any long-term histological damage to intercostal nerves.

Adult↗

PubMed2001

Characterization of a backbone cleavage product of BMS-196854 (Oncostatin M), a recombinant anti-inflammatory cytokine.

PURPOSE: BMS-196843 (Oncostatin M) is a therapeutic recombinant protein in development. Scale-up process changes led to unexpected instability of the bulk drug substance solution during storage. A product with an apparent higher MW than the parent protein was observed by the size-exclusion chromatography (SEC). This study was aimed to fully characterize the product and to identify a solution to stabilize the protein. METHODS: SEC, SDS-PAGE, tryptic mapping, and N-terminal sequencing were performed to characterize the unknown product. The effect of pH, temperature, bulk concentration, and immobilized trypsin inhibitor on the degradation rate was studied to elucidate the mechanism and to identify stabilization strategies. RESULTS: Despite the apparent high MW indicated initially by SEC, the unknown was characterized to be a degradation product resulted from a backbone cleavage between residues Arg145-Gly146. The resulting fragments from the backbone cleavage were, however, still linked through an intramolecular disulfide bond. Thus, the final product had a more open structure with an increased hydrodynamic radius compared to the parent protein, which explains the initial SEC results. The site-specific backbone cleavage was suspected to be catalyzed by trypsin-like protease impurities in the bulk solution. The bulk drug substance solution was subsequently treated with immobilized soybean trypsin inhibitor, and the degradation rate was significantly reduced. Furthermore, increasing the solution pH from 5 to 8 led to an increase in the degradation rate, which was consistent with the expected pH dependency of trypsin activity. In addition, the effect of bulk concentration also supported the involvement of protease impurities rather than a spontaneous peptide bond hydrolysis reaction. CONCLUSION: Trace trypsin-like protease impurities led to an unusual site-specific backbone cleavage of BMS-196854. The proteolytic degradation can be minimized by treating the bulk solution with immobilized soybean trypsin inhibitor and/or controlling the solution pH and storage temperature.

Anti-Inflammatory Agents↗

PubMed2001

Promotion of cell cycle progression by basic helix-loop-helix E2A.

Normal B-cell development requires the E2A gene and its encoded transcription factors E12 and E47. Current models predict that E2A promotes cell differentiation and inhibits G(1) cell cycle progression. The latter raises the conundrum of how B cells proliferate while expressing high levels of E2A protein. To study the relationship between E2A and cell proliferation, we established a tissue culture-based model in which the activity of E2A can be modulated in an inducible manner using E47R, an E47-estrogen fusion construct, and E47ERT, a dominant negative E47-estrogen fusion construct. The two constructs were subcloned into retroviral vectors and expressed in the human pre-B-cell line 697, the human myeloid progenitor cell line K562, and the murine fibroblastic cell line NIH 3T3. In both B cells and non-B cells, suppression of E2A activity by E47ERT inhibited G(1) progression and was associated with decreased expression of multiple cyclins including the G(1)-phase cyclin D2 and cyclin D3. Consistent with these findings, E2A null mice expressed decreased levels of cyclin D2 and cyclin D3 transcripts. In complementary experiments, ectopic expression of E47R promoted G(1) progression and was associated with increased levels of multiple cyclins, including cyclin D2 and cyclin D3. The induction of some cyclin transcripts occurred even in the absence of protein synthesis. We conclude that, in some cells, E2A can promote cell cycle progression, contrary to the present view that E2A inhibits G(1) progression.

Animals↗

PubMed2001

The involvement of Ran GTPase in lipopolysaccharide endotoxin-induced responses.

By functional cloning, we have established that Ran GTPase is involved in LPS-induced signal transduction. This has been accomplished by several functional comparisons of the two cDNAs, Lps(n)/Ran (or RanT/n) and Lps(d)/Ran (or RanC/d), which were isolated from cDNA libraries of LPS responder and hyporesponder mice, respectively. The letter n refers to the "normal" phenotype and the letter d refers to the "deficient" phenotype. Consistent with our previous results, more animal studies indicated that adenoviral transduction of RanC/d cDNA, but not RanT/n cDNA, into sensitive mice conferred significant resistance against endotoxin challenge. Thus the incorporation of RanC/d cDNA into gene therapy protocols as a therapeutic sequence remains very attractive. At steady state, hematopoietic cells transduced with RanC/d cDNA led to about a 10-fold increase in exogenous Ran protein compared with RanT/n cDNA. Furthermore, our cumulative data suggest that a slight elevation of Ran protein in B cells enhances LPS responsiveness, but the same elevation of Ran in macrophages does not. On the other hand, a high level of overexpression of Ran in both macrophages and B cells down-regulates LPS signal transduction. Thus LPS-induced signal transduction in macrophages and B cells is likely to occur via different signaling pathways.

Animals↗

PubMed2001

Electrochemical characteristics of thin nickel hexacyanoferrate films formed on gold and thiol self-assembled monolayers modified gold electrodes.

Nickel hexacyanoferrate (NiHCF) film was prepared and characterized on gold and thiol self-assembled monolayers (SAMs)-modified gold electrodes. It was found that the film exhibited some different electrochemical characteristics compared with that found on a carbon electrode. In the presence of K+, the film exhibited a redox peak at about 0.5 V. The peak potential shifted linearly with the K+ concentration over the range of about 0.1 mM - 0.1 M with slopes of 54 - 60 mV per log[K+]. However, in solutions containing Na+, Li+ or NH4+ ion the film did not generate well-defined peaks, or even a visible redox peak. Therefore, the film showed a selective potential response to K+. The voltammetric behavior of NiHCF film varied with thiols, the preparation procedure and the solution pH. Under certain conditions, the characteristics of the film could be improved to some extent.

Journal Article↗