Biomedical subjects

Xin Feng

Publications and source records attributed to Xin Feng.

25 records · Page 2Linked to original sources

PubMed2003

Dantrolene: effects on abnormal intracellular Ca(2+) handling and inotropy in postinfarcted rat myocardium.

The present study was designed to investigate the effects of dantrolene on intracellular Ca(2+) ([Ca(2+)](i)) handling and inotropy in rat infarcted myocardium. Dantrolene-treated rats with myocardial infarction were placed into two different dosage groups. The infarcted control group received placebo only. Isometric contractility and intracellular Ca(2+) transients were recorded simultaneously in isolated papillary muscles. Diastolic [Ca(2+)](i) was significantly lower in muscle preparations from infarcted rats receiving dantrolene compared to the placebo control group. Additionally, treatment with dantrolene in infarcted rats significantly improved the inotropic response to 10(-4) M isoproterenol. The protein levels of the sarcoplasmic reticulum Ca(2+) ATPase were increased in infarcted rat hearts with dantrolene treatment. We conclude that dantrolene improved the inotropic response to beta-adrenoceptor stimulation in rat postinfarcted myocardium, which is related to improved intracellular Ca(2+) handling, and lowered diastolic Ca(2+) concentration.

Animals↗

PubMed2003

Multiple approaches to data-mining of proteomic data based on statistical and pattern classification methods.

The data-mining challenge presented is composed of two fundamental problems. Problem one is the separation of forty-one subjects into two classifications based on the data produced by the mass spectrometry of protein samples from each subject. Problem two is to find the specific differences between protein expression data of two sets of subjects. In each problem, one group of subjects has a disease, while the other group is nondiseased. Each problem was approached with the intent to introduce a new and potentially useful tool to analyze protein expression from mass spectrometry data. A variety of methodologies, both conventional and nonconventional were used in the analysis of these problems. The results presented show both overlap and discrepancies. What is important is the breadth of the techniques and the future direction this analysis will create.

Artificial Intelligence↗

PubMed2003

Nitric oxide induced ectopic firing in a lumbar nerve root with cauda equina compression.

Nitric oxide is thought to be involved in the pathophysiology of radiculopathy attributable to herniated intervertebral disc, but its effect on ectopic firing, which is the main source of sciatica, has not been investigated. The authors investigated whether ectopic firing is elicited when the lumbar nerve root is exposed to nitric oxide using rats with and without cauda equina compression. A group of animals had partial L3 laminectomy, and a silicone tube was inserted in the epidural space to compress the cauda equina. A sham operation group and nontreated control group also were prepared. Seven days later, ectopic firing of the nerve root was recorded from the sural nerve. The animals with cauda equina compression showed significantly higher spontaneous firing rates than other groups. After a lumbar epidural administration of sodium nitroprusside, only the animals with cauda equina compression showed a marked increase in the firing rate. These results showed that the nerve roots became hyperexcitable under compression as indicated by increased spontaneous firing and marked sensitivity to nitric oxide. This mechanism may play an important role in the development of sciatica.

Animals↗

PubMed2003

A novel approach for high-quality microarray processing using third-dye array visualization technology.

Historically, microarray image processing has been technically challenging in obtaining quality gene expression data. After hybridization of Cy3- and Cy5-labeled samples, images are collected and processed to obtain gene expression ratio measurements for each of the elements on the array. The hybridization process often brings in contaminating noise, which can make correct identification of the signal difficult. In addition, spot intensity levels are highly variable due to the expression differences of different genes, and weak spots are often difficult to detect. These conditions are further complicated by inherent irregularities in spot position, shape, and size commonly found on high-density microarrays, making image processing an often labor-intensive task that is difficult to reliably automate. We previously reported a novel third-dye array visualization (TDAV) technology that allows prehybridization visualization and quality control of printed arrays. Here, we present a new microarray image processing approach utilizing TDAV. By incorporating the third-dye image, we show that overall quality of the microarray data is significantly improved, and automation of processing is feasible and reliable. Furthermore, we demonstrate use of the third-dye image to better quality control microarray image analysis. Both the principle and implementation of the approach are presented in detail, with experimental results.

Algorithms↗

PubMed2003

[Predictors associated with clinical deterioration in SARS patients].

BACKGROUND: To study the predictive factors associated with clinical deterioration in SARS patients. METHODS: The clinical data of 60 SARS patients were analyzed by logistic regression and Cox's proportional hazards analysis. RESULTS: In logistic regression models, both older age (P=0.009) and severe lymphopenia (P=0.004) were significant predictors of clinical deterioration. In Cox's proportional hazard models, severe lymphopenia was significant predictor associated with prolongation of stay in hospital. CONCLUSION: Older age and severe lymphopenia seem to be statistically significant for predicting the clinical deterioration in SARS patients.

Adult↗

PubMed2002

Overexpression of Na+/Ca2+ exchanger gene attenuates postinfarction myocardial dysfunction.

We monitored myocardial function in postinfarcted wild-type (WT) and transgenic (TG) mouse hearts with overexpression of the cardiac Na(+)/Ca(2+) exchanger. Five weeks after infarction, cardiac function was better maintained in TG than WT mice [left ventricular (LV) systolic pressure: WT, 41 +/- 2; TG, 58 +/- 3 mmHg; P < 0.05; maximum rising rate of LV pressure (+dP/dt(max)): WT, 3,750 +/- 346; TG, 5,075 +/- 334 mmHg/s; P < 0.05]. The isometric contractile response to beta-adrenergic stimulation was greater in papillary muscles from TG than WT mice (WT, 13.2 +/- 0.9; TG, 16.3 +/- 1.0 mN/mm(2) at 10(-4) M isoproterenol). The sarcoplasmic reticulum (SR) Ca(2+) content investigated by rapid cooling contractures in papillary muscles was greater in TG than WT mouse hearts. We conclude that myocardial function is better preserved in TG mice 5 wk after infarction, which results from enhanced SR Ca(2+) content via overexpression of the Na(+)/Ca(2+) exchanger.

Adrenergic beta-Agonists↗

PubMedDate not supplied

Peptide identification using peptide amino acid attribute vectors.

We describe the theoretical basis for a peptide identification method wherein peptides are represented as vectors based on their amino acid composition and grouped into clusters. Unknown peptides are identified by finding the database cluster and peptide entries with the shortest Euclidian distance. We demonstrate that the amino acid composition of peptides is virtually as informative as the sequence and allows rapid peptide identification more accurately than peptide mass alone.

Algorithms↗