Biomedical subjects

X X Shen

Publications and source records attributed to X X Shen.

4 recordsLinked to original sources

PubMed2006

Fast blind extraction of arbitrary unknown phase shifts by an iterative tangent approach in generalized phase-shifting interferometry.

A novel fast convergent algorithm to extract arbitrary unknown phase shifts in generalized phase-shifting interferometry (PSI) is proposed and verified by a series of computer simulations. In this algorithm an error function is introduced and then the unknown phase shifts are found by an iterative tangent approach. In combination with the statistical method, this algorithm can give the most exact results in the fewest iteration steps. It can be used for generalized PSI of arbitrary frames for both smooth and diffusing objects and can usually reach the exact phase shifts with only four or five iterations for three- or four-frame PSI.

Journal Article↗

PubMed2006

Two-step phase-shifting interferometry and its application in image encryption.

Conventional phase-shifting interferometry (PSI) needs at least three interferograms. A novel algorithm of two-step PSI, with an arbitrary known phase step, by which a complex object field can be reconstructed with only two interferograms is proposed. This algorithm is then applied to an information security system based on double random-phase encoding in the Fresnel domain. The feasibility of this method and its robustness against occlusion and additional noise attacks are verified by computer simulations. This approach can considerably improve the efficiency of data transmission and is very suitable for Internet use.

Journal Article↗

PubMed2000

Expression of glucose transporter 4 mRNA in adipose tissue and skeletal muscle of ovariectomized rats treated with sex steroid hormones.

The effects of 17beta-estradiol (E) and/or progesterone (P) on glucose transporter 4 (GLUT4) expression in the adipose tissue and skeletal muscle of ovariectomized female rats were studied. The Sprague-Dawley rats received daily subcutaneous injections of various doses of E and/or P for 7 days (n=5-6 per dose). The expression of GLUT4 mRNA was assessed by performing ribonuclease protection assays. GLUT4 protein levels were assessed by Western blotting assays. The adipose tissue levels of GLUT4 mRNA were reduced by the administration of 50 microg E, which resulted in unphysiologically high serum E concentrations. Although the GLUT4 mRNA levels did not change after the administration of 10 microg E or 5 mg P, they were reduced significantly to approximately half the control group level by the administration of both hormones (p <0.01). The skeletal muscle GLUT4 mRNA levels were not changed significantly by hormone treatment. These findings suggest that E and P may be involved in the regulation of GLUT4 mRNA expression in adipose tissue.

Adipose Tissue↗

PubMed1997

Hexokinase II activity and messenger ribonucleic acid abundance in adipose tissue and skeletal muscle during pregnancy and lactation in rats.

OBJECTIVE: Our purpose was to investigate the influence of pregnancy and lactation on hexokinase II activity and gene expression in adipose tissue and skeletal muscle of rats. STUDY DESIGN: Intraabdominal adipose tissue and femoral quadriceps muscle were removed from Sprague-Dawley rats at various times (6 to 10 animals per group) during pregnancy and lactation. Hexokinase II messenger ribonucleic acid was assayed by quantitative ribonuclease protection analysis, and hexokinase activity was measured with the glucose-6-phosphate-coupled assay. RESULTS: The amount of hexokinase II messenger ribonucleic acid in adipose tissue on day 20 of pregnancy was 55.4% +/- 8.4% (p < 0.01, unpaired Student t test) of the value for nonpregnant control rats; hexokinase II activity was also decreased in this tissue at this time (39.34 +/- 3.05 vs 27.81 +/- 3.61 mU x min(-1) x mg protein(-1), p < 0.05). Hexokinase II activity and messenger ribonucleic acid abundance in skeletal muscle were unaffected by pregnancy and lactation. CONCLUSION: Both hexokinase II messenger ribonucleic acid abundance and enzyme activity are reduced in adipose tissue of pregnant rats near term, possibly contributing to the insulin resistance associated with late pregnancy.

Adipose Tissue↗