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Biomedical subjects

D Poulin

Publications and source records attributed to D Poulin.

17 recordsLinked to original sources
PubMed2005

Characterization of complex quantum dynamics with a scalable NMR information processor.

We present experimental results on the measurement of fidelity decay under contrasting system dynamics using a nuclear magnetic resonance quantum information processor. The measurements were performed by implementing a scalable circuit in the model of deterministic quantum computation with only one quantum bit. The results show measurable differences between regular and complex behavior and for complex dynamics are faithful to the expected theoretical decay rate. Moreover, we illustrate how the experimental method can be seen as an efficient way for either extracting coarse-grained information about the dynamics of a large system or measuring the decoherence rate from engineered environments.

Journal Article↗
PubMed2004

Robust polarization-based quantum key distribution over a collective-noise channel.

We present two polarization-based protocols for quantum key distribution. The protocols encode key bits in noiseless subspaces or subsystems and so can function over a quantum channel subjected to an arbitrary degree of collective noise, as occurs, for instance, due to rotation of polarizations in an optical fiber. These protocols can be implemented using only entangled photon-pair sources, single-photon rotations, and single-photon detectors. Thus, our proposals offer practical and realistic alternatives to existing schemes for quantum key distribution over optical fibers without resorting to interferometry or two-way quantum communication, thereby circumventing, respectively, the need for high precision timing and the threat of Trojan horse attacks.

Journal Article↗
PubMed2000

EWS-FLI1, EWS-ERG, and EWS-ETV1 oncoproteins of Ewing tumor family all suppress transcription of transforming growth factor beta type II receptor gene.

Ewing sarcoma-specific chromosomal translocations fuse the EWS gene to a subset of ets transcription factor family members, most commonly the FLI1 gene and less frequently ERG, ETV1, E1A-F, or FEV. These fusion proteins are thought to act as aberrant transcription factors that bind DNA through their ets DNA binding domain. Recently, we have shown (K-B. Hahm et al., Nat. Genet., 23: 222-227, 1999) that the transforming growth factor beta (TGF-beta) type II receptor (TGF-beta RII), a putative tumor suppressor gene, is a target of the EWS-FLI1 fusion protein. Here, we also examined effects of EWS-ETV1 and EWS-ERG on expression of the TGF-beta RII gene. We show that relative to the control, NIH-3T3 cell lines stably transfected with the EWS-FLI1, EWS-ERG, or EWS-ETV1 gene fusion express reduced levels of TGF-beta RII mRNA and protein, and that these cell lines have reduced TGF-beta sensitivity. Cotransfection of these fusion genes and the TGF-beta RII promoter suppresses TGF-beta RII promoter activity and also FLI1-, ERG-, or ETV1-induced promoter activity. These results indicate that transcriptional repression of TGF-beta RII is an important target of the EWS-FLI1, EWS-ERG, or EWS-ETV1 oncogene, and that EWS-ets fusion proteins may function as dominant negative forms of ets transcription factors.

3T3 Cells↗
PubMed1998

Use of niacin, statins, and resins in patients with combined hyperlipidemia.

Patients in the original Familial Atherosclerosis Treatment Study (FATS) cohort were subgrouped into those with triglyceride levels < or = 120 mg/dL (n = 26) and those with triglyceride levels > or = 190 mg/dL (n = 40). Their therapeutic responses to niacin plus colestipol, lovastatin plus colestipol, colestipol alone, or placebo were determined. Therapeutic response was also determined in the same 2 triglyceride subgroups (n = 12 and n = 27, respectively) of patients selected for low levels of high-density lipoprotein (HDL) cholesterol and coronary artery disease. These triglyceride criteria were chosen to identify patient subgroups with high likelihood of "pattern A" (normal-size low-density lipoprotein [LDL] particles and triglyceride < or = 120 mg/dL) or "pattern B" (small dense LDL and triglyceride > or = 190 mg/dL). Our findings in these small patient subgroups are consistent with the emerging understanding that coronary artery disease patients presenting with high triglyceride levels have lower HDL-C, smaller less buoyant LDL-C, and greater very low-density lipoprotein (VLDL) cholesterol and VLDL apolipoprotein B, and are more responsive to therapy as assessed by an increase in HDL-C and reduction in triglycerides, VLDL-C, and VLDL apolipoprotein B. In the FATS high-triglyceride subgroup with these characteristics, a tendency toward greater therapeutic improvement in coronary stenosis severity was observed among those treated with either of the 2 forms of intensive cholesterol-lowering therapy. This improvement is associated with therapeutic reduction of LDL-C and elevation of HDL-C, but also appears to be associated with drug-induced improvement in LDL buoyancy.

Anticholesteremic Agents↗
PubMed1997

Moderate dose, three-drug therapy with niacin, lovastatin, and colestipol to reduce low-density lipoprotein cholesterol <100 mg/dl in patients with hyperlipidemia and coronary artery disease.

The efficacy, safety, and tolerability of a moderate dose, 3-drug lipid-lowering regimen were evaluated among 29 male patients with hyperlipidemia and coronary artery disease. In an initial 12-month phase, regular niacin, 500 mg qid, lovastatin, 20 mg bid, and colestipol, 10 g/bid, were given with dose adjustment for lipid targets and side effects. This was followed by 2 random sequence crossover phases (8 months each) alternating regular niacin with a polygel controlled-release formulation of niacin for use in this regimen. Lipid, lipoprotein, apoprotein, and clinical chemistry determinations were obtained at baseline, during the initial phase, at the 2 crossover phases, and at 6 weeks after therapy. A final questionnaire queried specific side effects and overall preferences. Low-/high-density lipoprotein (LDL/HDL) changed from means of 215/46 mg/dl at baseline, to 94/59 mg/dl after run-in, to 85/52 mg/dl after 8 months of controlled-release niacin, and to 98/56 mg/dl after 8 months of regular niacin (regular niacin vs controlled-release niacin, p <0.005/<0.05). The target of LDL < or = 100 mg/dl was achieved at 8 months by 83% of these patients with controlled-release niacin and by 52% with regular niacin (p <0.01). Compliance was 95% with controlled-release niacin versus 85% with regular niacin (p <0.001). The controlled-release niacin and regular niacin regimens did not differ in terms of uric acid, glucose, insulin, or asparate aminotransferase levels. Overall, 21% of patients called the 3 drugs "very easy" and 72% "fairly easy" to take. The controlled-release niacin-containing regimen was preferred by 21 patients and the regular niacin by 4. In conclusion, these regimens achieve striking lipid changes among hyperlipidemic patients. Controlled release is the preferred niacin preparation in terms of LDL reduction, compliance, patient preference, and achieving the National Cholesterol Education Program guideline of LDL < or = 100 mg/dl. The 2 niacin preparations did not differ in evidence of toxicity.

Cholesterol, LDL↗
PubMed1995

What benefit can be derived from treating normocholesterolemic patients with coronary artery disease?

Controversy still remains regarding the possible clinical or arteriographic benefit of intensive lipid-altering therapy in patients who have coronary artery disease and apparently normal lipid levels. Resolution of this controversy appears to depend on an improved understanding of the role of variables other than total or low density lipoprotein cholesterol levels. A comparison of the "normolipidemic" subgroup of The Familial Atherosclerosis Treatment Study patients and The Harvard Atherosclerosis Reversibility Project patients indicates that low levels of high density lipoprotein cholesterol and elevated levels of apolipoprotein B appear to increase considerably the likelihood of benefit from intensive lipid-altering therapy. Other risk-related variables such as systolic blood pressure and lipoprotein(a) further contribute to the prediction of risk and possibly to the potential for treatment benefit.

Adult↗
PubMed1994

Moderate long-term physical activity improves the age-related decline in bile formation and bile salt secretion in rats.

This study examined the effect of moderate long-term exercise, begun soon after weaning, on the age-related decline in bile formation and the secretory rate maximum (SRm) of taurocholate (TC), the major bile salt (BS) in rats. Eight-month-old sedentary (S) female Sprague-Dawley rats showed a significant decrease in basal and TC-stimulated bile formation when compared with 2.5-month-old S controls. As in younger rats, decreased biliary phospholipid (PL) output was associated with the TC SRm, but this change appeared much more rapidly in S animals, which also exhibited significant increased plasma lipids and higher TC concentrations in plasma and liver at the end of the TC infusion. Exercise significantly improved bile flow (BF), including the bile salt-dependent and -independent fractions under basal and TC-stimulated conditions in 8 month-old rats. Although all the biliary parameters evaluated were improved, maximal BF and PL secretion values were affected the most and were virtually not different from those obtained in younger S animals. Exercise also significantly lowered the age-related elevation of plasma PL. Thus, moderate long-term exercise exerts a beneficial effect on hepatobiliary function and the BS SRm, an effect that may be attributed in part to increased availability of a biliary PL pool previously implicated in regulation of the BS SRm.

Age Factors↗
PubMed1989

[Development of the indications for extra-corporeal lithotripsy and the impact of organizational methods on the indications].

A technology assessment of ESWL for renal stones has been conducted. The development of lithotripsy during the early phase of diffusion of the technique was studied retrospectively for 1985 and 1986. This study permitted the comparison of lithotripsy practice in Paris with that in Lyon. Results show that the proportion of small (less than 10 mm) stones increased from 39% at the beginning of the period to 60% at the end in Paris and simultaneously from 41% to 53% in Lyon. The location of the calculi treated by ESWL changed significantly over the period, but only in Paris where the number of caliceal stones went from 62% to 38% and that of ureteral stones from 1% to 8%. Neither the number of stones treated during one ESWL session, nor the length of hospital stay, changed significantly during the first years of use of this treatment. However, if one excludes hospital stays of more than 15 days, the average hospital stay in Paris decreased where as the opposite was observed in Lyon. The impact of the organization of ESWL users upon medical practice is obvious in relation to the size of stones: in Lyon, where one team provides ESWL therapy for all hospital urology departments, treatment practice is more homogeneous than in Paris and more closely a resembles the international consensus.

Female↗