Biomedical subjects

D Vu

Publications and source records attributed to D Vu.

24 records · Page 2Linked to original sources

PubMed1995

Transforming p21ras mutants and c-Ets-2 activate the cyclin D1 promoter through distinguishable regions.

Several different oncogenes and growth factors promote G1 phase progression. Cyclin D1, the regulatory subunit of several cyclin-dependent kinases, is required for, and capable of shortening, the G1 phase of the cell cycle. The present study demonstrates that transforming mutants of p21ras (Ras Val-12, Ras Leu-61) induce the cyclin D1 promoter in human trophoblasts (JEG-3), mink lung epithelial (Mv1.Lu), and in Chinese hamster ovary fibroblast cell lines. Site-directed mutagenesis of AP-1-like sequences at -954 abolished p21ras-dependent activation of cyclin D1 expression. The AP-1-like sequences were also required for activation of the cyclin D1 promoter by c-Jun. In electrophoretic mobility shift assays using nuclear extracts from cultured cells and primary tissues, several AP-1 proteins (c-Jun, JunB, JunD, and c-Fos) bound the cyclin D1 -954 region. Cyclin D1 promoter activity was stimulated by overexpression of mitogen-activated protein kinase (p41MAPK) or c-Ets-2 through the proximal 22 base pairs. Expression of plasmids encoding either dominant negative MAPK (p41MAPKi) or dominant negatives of ETS activation (Ets-LacZ), antagonized MAPK-dependent induction of cyclin D1 promoter activity. Epidermal growth factor induction of cyclin D1 transcription, through the proximal promoter region, was antagonized by either p41MAPKi or Ets-LacZ, suggesting that ETS functions downstream of epidermal growth factor and MAPK in the context of the cyclin D1 promoter. The activation of cyclin D1 transcription by p21ras provides evidence for cross-talk between the p21ras and cell cycle regulatory pathways.

Animals↗

PubMed1995

Gluconeogenesis and intrahepatic triose phosphate flux in response to fasting or substrate loads. Application of the mass isotopomer distribution analysis technique with testing of assumptions and potential problems.

We measured gluconeogenesis (GNG) in rats by mass isotopomer distribution analysis, which allows enrichment of the true biosynthetic precursor pool (hepatic cytosolic triose phosphates) to be determined. Fractional GNG from infused [3-13C]lactate, [1-13C]lactate, and [2-13C]glycerol was 88 +/- 2, 89 +/- 3, and 87 +/- 2%, respectively, after 48 h of fasting. [2-13C]Glycerol was the most efficient label and allowed measurement of rate of appearance of intrahepatic triose phosphate (Ra triose-P), by dilution. IV fructose (10-15 mg/kg/min) increased absolute GNG by 81-147%. Ra triose-P increased proportionately, but endogenous Ra triose-P was almost completely suppressed, suggesting feedback control. Interestingly, 15-17% of fructose was directly converted to glucose without entering hepatic triose-P. IV glucose reduced GNG and Ra triose-P. 24-h fasting reduced hepatic glucose production by half, but absolute GNG was unchanged due to increased fractional GNG (51-87%). Reduced hepatic glucose production was entirely due to decreased glycogen input, from 7.3 +/- 1.8 to 1.1 +/- 0.2 mg/kg/min. Ra triose-P fell during fasting, but efficiency of triose-P disposal into GNG increased, maintaining GNG constant. Secreted glucuronyl conjugates and plasma glucose results correlated closely. In summary, GNG and intrahepatic triose-P flux can be measured by mass isotopomer distribution analysis with [2-13C]glycerol.

Animals↗

PubMed1995

Systematic screening of an arrayed cDNA library by PCR.

We have developed a PCR-based method for rapid and effective screening of arrayed cDNA libraries. This strategy directly addresses the limitations of conventional hybridization-based schemes and provides a more rapid, cost-effective, and sensitive method compatible with large-scale and routine cDNA clone recovery. To prepare arrayed libraries, 1-2 x 10(6) cDNA clones were propagated as individual plaques on solid medium in 24-well culture dishes at approximately 250 plaque-forming units per well. Phage suspensions were prepared from each well and transferred to a 96-well format. To screen the library, pools were generated that correspond to each individual 96-well plate and to each row and column within "blocks" of six plates each. Library screening for specific cDNA clones was conducted in a systematic and hierarchical fashion beginning with the plate pools. Next, the row/column pools corresponding to each positive plate pool were screened. Finally, isolated clones from within each positive well were identified by hybridization. We have applied this approach to the screening of an arrayed human brain cDNA library resulting in the recovery of cDNAs corresponding to > 25 genes and expressed sequence tags.

Adult↗

PubMed1992

Changes in plasma atrial natriuretic peptide concentration during heart transplantation.

Examination of changes in plasma atrial natriuretic peptide (ANP) concentrations during heart transplantation may provide important information about factors influencing plasma ANP in patients with severe heart failure. Serial changes in plasma ANP during heart transplantation, and atrial content of ANP in native and donor atria, were measured in 12 patients. Preoperative plasma ANP was elevated in all patients (387 +/- 77 pg/mL), whereas atrial content of ANP in native atria was reduced (0.36 +/- 0.082 micrograms/mg protein). Preoperative plasma ANP did not correlate with hemodynamics, but was negatively correlated with creatinine clearance (r = -0.76, P < .01). Intraoperative plasma ANP prior to transplantation was strongly correlated with intraoperative plasma ANP after transplantation (r = 0.84, P < .001). Although postoperative plasma ANP was reduced from preoperative plasma ANP by 75%, these two measurements were also significantly correlated (r = 0.70, P < .02). Postoperative plasma ANP was not correlated with hemodynamics, but was negatively correlated with both creatinine clearance (r = -0.65, P < .05) and content of ANP in the native atria (r = -0.75, P < .01). Multiple linear regression analysis suggested that up to 85% of the variability of early postoperative plasma ANP could be accounted for by the variability in these latter two parameters. The decrease in native atrial ANP content, in the context of elevated plasma ANP concentration, is consistent with prior animal studies suggesting that severe heart failure induces cellular adaptations favoring accelerated ANP synthesis and secretion (with resultant reduction in tissue content).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1989

The effect of vitamin D3 on the production of cytotoxic factors by human peripheral blood mononuclear cells.

Vitamin D3 at a concentration of 300 nM was shown to significantly reduce the yields of cytotoxin produced by human peripheral blood mononuclear cells. Reduction of cytotoxin titers occurred when induction was performed with either concanavalin A, interleukin 2, or ionomycin. Typing of this cytotoxin was accomplished using antisera that were prepared by immunization of rabbits with either recombinant tumor necrosis factor or lymphotoxin. Both antisera were demonstrated to neutralize the cytotoxic activity produced by the peripheral blood mononuclear cells in the presence or absence of vitamin D3. These latter experiments suggested that the cytotoxin in question might be lymphotoxin. Vitamin D3 was also shown to decrease cytotoxin production by a transformed B-cell line known to produce only lymphotoxin, supporting the concept that this vitamin could diminish yields of lymphotoxin at least under certain circumstances. However, purified adherent cells induced by Escherichia coli lipopolysaccharide produced a cytotoxin that was also inhibited by the presence of vitamin D3. Indomethacin failed to influence the effects of vitamin D3 on the production of the cytotoxin. These studies suggest that vitamin D3 may have a role in regulating the secretion of cytotoxic factors which may be important in the defense against neoplastic diseases.

Calcitriol↗

PubMedDate not supplied

Diagnosis of posttraumatic pericardial tamponade by plain film and computed tomography and control of bleeding by embolotherapy of the left inferior phrenic artery.

A 21-year-old male developed pericardial tamponade in a delayed fashion after blunt chest trauma. Tamponade was not suspected clinically and was first seen on computed tomography of the abdomen. Plain films of the chest revealed distortion of the path of a Swan-Ganz catheter due to the ventricular compression. After drainage, left inferior phrenic artery embolization was performed to treat the persistent hemothorax.

Adult↗