Biomedical subjects

Li Chen

Publications and source records attributed to Li Chen.

310 records · Page 18Linked to original sources

PubMedDate not supplied

Cloning and characterization of human CAGLP gene encoding a novel EF-hand protein.

The EF-hand proteins, containing conserved Ca2+ binding motifs, play important roles in many biological processes. Through data mining, a novel human gene, CAGLP (calglandulin-like protein) was predicted and subsequently isolated from human skeleton muscle. The open reading frame of CAGLP is 543 bp in length, coding a putative Ca2+ binding protein with four EF-hand motifs. The deduced amino acid sequence of CAGLP displays high similarity with Bothrops insularis snake protein calglandulin (80%). The results of PCR amplification using cDNA from 17 human tissues indicated that human CAGLP is expressed in prostate, thymus, heart, skeleton muscle, bone marrow and ovary. Functional CAGLP::EGFP (enhanced green fluorescent protein) fusion protein revealed that CAGLP accumulated through-out Hela cells. Western blot using anti-EGFP antibodies indicated that the CAGLP protein has a molecular weight of about 19 kD. A phylogenetic tree showed that CAGLP and calglandulin may be orthologous proteins representing a distinct group in the EF-hand proteins.

Base Sequence↗

PubMedDate not supplied

Matrix is the site of indirect effects of propranolol on the ion channelopathies in cardiac remodeling by L-thyroxine.

Cardiac remodeling by chronic L-thyroxine medication causes exaggerated cardiac arrhythmias in relation to ion channelopathies that involve multichannels. The matrix of lipid membrane is likely the key site where channel lesions, possibly will develop and be benefitted by drug intervention. Cardiac remodeling in rats and guinea pigs was developed by L-thyroxine 0.5 mg/kg SC for 10 days. Propranolol was instituted on days 8-10. Whole cell holding was applied to measure ion currents. An increase in HR, dispersion of QTc, mitochondrial Na+/K+ ATPase, Ca2+/Mg2+ ATPase, and LPO production were found in the model. T3 and T4 levels in plasma were high. Propranolol was effective in regressing cardiac remodeling, together with lowering all the parameters and the enhanced I(Ca.L),I(KS), and I(KR) currents, but T3 and T4 remained basically unchanged. The changes in ion channels are likely the consequence of the cardiac remodeling that is formed by oxidative stress and increased energy consumption provoked by L-thyroxine. The benefit of propranolol on the disordered ion channels is mediated by its ability to ameliorate lesions of the matrix.

Algorithms↗

PubMedDate not supplied

Adaptive optics for vision: the eye's adaptation to point spread function.

PURPOSE: Despite the fact that ocular aberrations blur retinal images, our subjective impression of the visual world is sharp, which suggests that the visual system compensates for subjective influence. If the brain adjusts for specific aberrations of the eye, vision should be clearest when looking through a subject's typical wave aberration rather than through an unfamiliar one. We used adaptive optics techniques to control the eye's aberrations in order to evaluate this hypothesis. METHODS: We used adaptive optics to produce point spread functions (PSFs) that were rotated versions of the eye's typical PSF by angles in 45 degrees intervals. Five normal subjects were asked to view a stimulus with their own PSF or with a rotated version, and to adjust the magnitude of the aberrations in the rotated case to match the subjective blur of the stimulus to that seen when the wave aberration was in typical orientation. RESULTS: The magnitude of the rotated wave aberration required to match the blur with the typical wave aberration was 20% to 40% less, indicating that subjective blur for the stimulus increased significantly when the PSF was rotated. CONCLUSION: These results support the hypothesis that the neural visual system is adapted to an eye's aberrations and has important implications for correcting higher order aberrations with customized refractive surgery or contact lenses. The full visual benefit of optimizing optical correction requires that the nervous system compensate for the new correction.

Diagnostic Techniques, Ophthalmological↗

PubMedDate not supplied

Prognostic significance of vascular endothelial growth factor expression and microvessel density in carcinoma of ampulla of Vater.

BACKGROUND/AIMS: To investigate whether the expression of vascular endothelial growth factor (VEGF) and microvessel density (MVD) are of prognostic significance in ampullary carcinoma. METHODOLOGY: Twenty-two resected tumor specimens from patients with ampullary carcinoma were immunohistochemically stained for VEGF and CD34 (surrogate for vessels) by streptavidin-peroxidase method. RESULTS: Expression of VEGF in tumor tissue was found in 50% of patients. The mean MVD for entire group was 26.4 +/- 12.8. A significantly higher MVD was observed in the tumors with positive VEGF expression (35.0 +/- 9.6) compared with that of negative VEGF expression (17.7 +/- 9.3) (p<0.01). The expression of VEGF and MVD were closely related lymph node status and tumor TNM stage. The positive expression rate of VEGF and the average MVD in patients with lymph node metastases were 85.7% and 33.1 +/- 10.8 respectively, which were significantly higher than those in patients without lymph node metastases (33.3% and 22.8 +/- 11.8 respectively) (p<0.05). The positive expression rate of VEGF and the average MVD in patients with stage III and were 75% and 36.3 +/- 8.4 respectively, which were significantly higher than those in patients with stage I (25% and 18.4 +/- 10.1 respectively) or stage II (50% and 23.8 +/- 13.4 respectively) (p<0.05). The Kaplan-Meier survival curves showed that the 3-year survival rate for patients with positive VEGF expression or a high MVD (9.1% and 10% respectively) were lower than those in patients with negative VEGF expression or a low MVD (63.64% and 58.33% respectively) (p<0.05). CONCLUSIONS: VEGF is positively correlated with MVD in ampullary carcinoma. VEGF and angiogenesis may play an important role in lymph node metastasis and progression of ampullary carcinoma. VEGF and MVD appear to be important prognostic predictor in patients with ampullary carcinoma.

Adult↗