Biomedical subjects

Xiaodong Luo

Publications and source records attributed to Xiaodong Luo.

7 recordsLinked to original sources

PubMed2006

Reported alcohol consumption and cognitive decline: The northern Manhattan study.

BACKGROUND: Moderate alcohol intake may slow cognitive decline, and both vascular and neurodegenerative mechanisms have been implicated. METHODS: We examined reported alcohol intake and cognitive decline in a community-based cohort of Hispanic, black and white individuals (n = 1,428). The role of the apolipoprotein E epsilon4 (APOE4) allele as a modifier was also studied. RESULTS AND CONCLUSIONS: Reported drinking was as follows: 300 participants (21%) were 'never' drinkers, 622 (44%) 'past' drinkers, 145 (10%) reported taking less than 1 drink weekly, 330 (23%) 1 drink weekly up to 2 daily and 31 (2%) more than 2 drinks daily. A positive relationship was seen between reported alcohol intake and cognition. Drinking less than 1 drink a week (p = 0.09), between 1 drink weekly up to 2 drinks daily (p = 0.001) and more than 2 drinks daily (p = 0.003) were associated with less cognitive decline on the modified Telephone Interview for Cognitive Status compared to never drinkers. This dose-response relationship was not modified by the presence of an APOE4 allele in a subsample.

Aged↗

PubMed2006

Sulfated alkenes from the echinus Temnopleurus hardwickii.

Three new sulfated alkenes (1-3), trimethylammonium (5R)-5,9-dimethyl-(3E)-3,8-decadienyl-1-sulfate, dimethylammonium (5R)-5,9-dimethyl-(3E)-3,8-decadienyl-1-sulfate, and 2'-methyl-4'-oxobutan-2-ylammonium (5R)-5,9-dimethyl-(3E)-3,8-decadienyl-1-sulfate, were isolated from an echinoderm, Temnopleurus hardwickii. Their structures were elucidated by spectral analysis and chemical degradation methods.

Alkenes↗

PubMed2006

A new guaiane diterpenoid from Euphorbia wallichii.

A new guaiane-type diterpenoid, (1alpha,5beta,7alpha)-3,10(18),11-dictytriene-19-acid, was obtained from the roots of Euphorbia wallichii. This is the first isolation of guaiane diterpene from this genus of Euphorbia. The structure was elucidated by spectral methods. And the compound was tested for the cytotoxicities on the cancer cell line P-388 and A-549 in vitro.

Cell Line, Tumor↗

PubMed2005

Testing for nonlinearity in time series without the Fourier transform.

A method to test for nonlinearity in time series, without the need to apply the Fourier transform, is proposed. This method therefore avoids the drawbacks of previously proposed surrogate techniques associated with the estimation of the signal's power spectrum. The test addressed by this algorithm is that the data are generated by a stationary linear system. To achieve this, the algorithm takes advantage of the fundamentally different structure of linear and nonlinear systems.

Journal Article↗

PubMed2005

Optimal phase-space projection for noise reduction.

In this communication we will reexamine the widely studied technique of phase-space projection. By imposing a time-domain constraint on the residual noise, we deduce a more general version of the optimal projector, which includes those appearing in previous literature as subcases but does not assume the independence between the clean signal and the noise. As an application, we will apply this technique for noise reduction. Numerical results show that our algorithm has succeeded in augmenting the signal-to-noise ratio for simulated data from the Rössler system and experimental speech record.

Journal Article↗

PubMed2005

Surrogate test to distinguish between chaotic and pseudoperiodic time series.

In this paper a different algorithm is proposed to produce surrogates for pseudoperiodic time series. By imposing a few constraints on the noise components of pseudoperiodic data sets, we devise an effective method to generate surrogates. Unlike other algorithms, this method properly copes with pseudoperiodic orbits contaminated with linear colored observational noise. We will demonstrate the ability of this algorithm to distinguish chaotic orbits from pseudoperiodic orbits through simulation data sets from the Rössler system. As an example of application of this algorithm, we will also employ it to investigate a human electrocardiogram record.

Journal Article↗

PubMedDate not supplied

Numerical simulation of tissue freezing by liquid nitrogen based cryoprobe.

A model is presented to simulate the cooling processes during tumor cryosurgery with different kinds of flows through the cryoprobe. The heat flux between the cryoprobe wall and the tumor, the heat transfer coefficient under different inflow conditions are obtained numerically. The impact of the inlet mass flow rate, gas volume fraction on these parameters is investigated. It is found that the heat transfer coefficient decreased significantly when inflow changed from two-phase annular flow to droplet flow, and to gas flow. The inlet gas volume fraction and flow velocity only significantly affect the freezing ability of the probe when the inflow is gas or in droplet phase. Simulation of the tumor temperature profiles under different flow conditions show that the heat transfer coefficient is a crucial parameter in temperature prediction during cryosurgery. Results indicate that when the cryoprobe wall is assumed at a constant temperature conventionally, the cooling effect could be overestimated. It would be more reasonable to use the constant wall heat transfer coefficient to simulate the cooling progress under a specific flow.

Cryosurgery↗