PubMed Health⌕ Search

Biomedical subjects

Q M Guo

Publications and source records attributed to Q M Guo.

7 recordsLinked to original sources
PubMed2001

Silencing of Wnt signaling and activation of multiple metabolic pathways in response to thyroid hormone-stimulated cell proliferation.

To investigate the transcriptional program underlying thyroid hormone (T3)-induced cell proliferation, cDNA microarrays were used to survey the temporal expression profiles of 4,400 genes. Of 358 responsive genes identified, 88% had not previously been reported to be transcriptionally or functionally modulated by T3. Partitioning the genes into functional classes revealed the activation of multiple pathways, including glucose metabolism, biosynthesis, transcriptional regulation, protein degradation, and detoxification in T3-induced cell proliferation. Clustering the genes by temporal expression patterns provided further insight into the dynamics of T3 response pathways. Of particular significance was the finding that T3 rapidly repressed the expression of key regulators of the Wnt signaling pathway and suppressed the transcriptional downstream elements of the beta-catenin-T-cell factor complex. This was confirmed biochemically, as beta-catenin protein levels also decreased, leading to a decrease in the transcriptional activity of a beta-catenin-responsive promoter. These results indicate that T3-induced cell proliferation is accompanied by a complex coordinated transcriptional reprogramming of many genes in different pathways and that early silencing of the Wnt pathway may be critical to this event.

Animals↗
PubMed2001

[Studies on the chemical constituents of Eclipta prostrata (L)].

AIM: To study the chemical constituents of Eclipta prostrata (L). METHODS: The constituents of E. prostrata were systematically separated with the Bohlmann method and percolation and hot extraction methods, and various chromatographies. The structures were elucidated by chemical and spectroscopic means. RESULTS: Ten compounds were isolated from the Eclipta prostrata. Their structures were determined as wedelolactone (1), demethylwedelolactone (2), isodemethylwedelolactone (3), alpha-formylterthienyl (4), strychnolactone (5), beta-sitosterol (6), nonacosanol (7), stearic acid (8), lacceroic acid (9), 3,4-dihydoxy benzoic acid (10). Fourteen ocmpounds, including hydrocarbons and its esters were identified by GC-MS from the least polar fractions. CONCLUSION: Compound 3 is a new coumestan named isodemethylwedelolactone. Compounds 2-10 and compounds characterized by GC-MS analysis were obtained for the first time from Eclipta prostrata.

Coumarins↗
PubMed2001

[Effects of opioids on Ca2+/calmodulin dependent protein kinase signal pathway in NG108-15 cells].

AIM: To observe the change of Ca2+/calmodulin dependent protein kinase II (CaMK II) signal pathway in opioid dependent NG108-15 cells. METHODS: NG108-15 cells were used as an in vitro model system. Competitive protein binding assay and radioimmunoassay were used to examine the intracellular cAMP accumulation. Calmodulin activity was assayed by PDE method. CaMK II activity was assayed by gamma-32 P incorporation of syntide-2. RESULTS: DPDPE long-term treatment increased calmodulin activity and CaMK II activity in both cytoplasm and nucleus of NG108-15 cells. Specific calmodulin antagonist W-7 was found to significantly inhibit the elevation of calmodulin and CaMK II activity which resulted from DPDPE long-term treatment, and CaMK II inhibitor KN-62 also inhibited elevation of CaMK II activity by DPDPE long-term treatment. When naloxone was added to NG108-15 cells which were long-term treated by DPDPE, calmodulin and CaMK II activity increased, indicating that naloxone withdrawal can increase Ca2+/CaMK II pathway activity. CONCLUSION: The results indicate that Ca2+/CaMK II pathway was involved in the mechanisms of opioids dependence when DPDPE was long-term administered to NG108-15 cells.

Analgesics, Opioid↗
PubMed2000

Identification of c-myc responsive genes using rat cDNA microarray.

c-Myc functions through direct activation or repression of transcription. Using cDNA microarray analysis, we have identified c-Myc-responsive genes by comparing gene expression profiles between c-myc null and c-myc wild-type rat fibroblast cells and between c-myc null and c-myc null cells reconstituted with c-myc. From a panel of 4400 cDNA elements, we found 198 genes responsive to c-myc when comparing wild-type or reconstituted cells with the null cells. The plurality of the named c-Myc-responsive genes that were up-regulated, including 30 ribosomal protein genes, are involved in macromolecular synthesis and metabolism, suggesting a major role of c-Myc in the regulation of protein synthetic and metabolic pathways. When ectopically overexpressed, c-Myc induced a different and smaller set of c-Myc-responsive genes as compared with the physiologically expressed c-Myc condition. Thus, these results from expression profiling suggest a new primary function for c-Myc and raise the possibility that the physiological and transforming functions of c-myc may be separable.

Animals↗
PubMed2000

[Treatment of non-invasive aspergillosis of maxillary sinus by functional endoscopic sinus surgery].

OBJECTIVE: To evaluate the treatment of non-invasive aspergillosis of the maxillary sinus by using functional endoscopic sinus surgery (FESS) and the correlated factors that affect the treatment. METHOD: 41 cases of local, non-invasive aspergillosis of the maxillary sinus undergone FESS were studied. RESULT: The period of convalescence of double pathway (via ostium of maxillary sinus and canine fossa) was 4.7 weeks while single pathway (via ostium of maxillary sinus only) was 9.3 weeks. There was significant difference (P < 0.01). The period of convalescence of group using anti-fungal drugs to wash the operative cavity was 6.4 weeks while the group without using drugs was 6.7 weeks. There was no statistic significance (P > 0.05). CONCLUSION: FESS is effective in treating of non-invasive aspergillosis of the maxillary sinus. The operation of double pathway is superior to that of single pathway. Whether to use antifungal drugs to wash the operative cavity has no obvious effect on the efficacy.

Adult↗