Biomedical subjects

D Piao

Publications and source records attributed to D Piao.

6 recordsLinked to original sources

PubMed2001

Design of near-infrared imaging probe with the assistance of ultrasound localization.

A total of 364 optical source-detector pairs were deployed uniformly over a 9 cm x 9 cm probe area initially, and then the total pairs were reduced gradually to 60 in experimental and simulation studies. For each source-detector configuration, three-dimensional (3-D) images of a 1-cm-diameter absorber of different contrasts were reconstructed from the measurements made with a frequency-domain system. The results have shown that more than 160 source-detector pairs are needed to reconstruct the absorption coefficient to within 60% of the true value and appropriate spatial and contrast resolution. However, the error in target depth estimated from 3-D images was more than 1 cm in all source-detector configurations. With the a priori target depth information provided by ultrasound, the accuracy of the reconstructed absorption coefficient was improved by 15% and 30% on average, and the beam width was improved by 24% and 41% on average for high- and low-contrast cases, respectively. The speed of reconstruction was improved by ten times on average.

Journal Article↗

PubMed2001

Modified cold storage of rat livers with self-made HYD solution.

OBJECTIVE: To investigate the cold preservation effect on rat livers of a modified storage method with self-made HYD solution. METHODS: The vascular bed of rat livers was expanded with an additional 20 to 40 ml self-made HYD solution/100 g liver. After resection of the liver, the extra HYD solution (expressed as % liver weight) was entrapped via portal infusion by tying off the supra- and infra-hepatic inferior vena cava. Forty rats were randomly divided into four groups including control group with conventional storage method, and 20%, 30% and 40% groups according to the amount of extra HYD solution. We compared the preservation effect of the modified storage method with that of the conventional storage method using an isolated perfused rat liver model. RESULTS: Bile production and all the indices of hepatic microcirculation including portal perfusion pressure, endothelin-1 in the effluent, trypan blue distribution time and histology were significantly superior in the modified method groups compared to those in the control group (P < 0.05). The contents of dihydroxybenzoic acid (DHBA) in the modified method groups were significantly lower than those in the control group (P < 0.05). Liver enzymes activities in the 30% group were markedly lower than those in the control group (P < 0.05). The preservation effect on rat liver in the 30% group was the best among the modified method groups. CONCLUSION: The modified cold storage method is effective and may have potential for clinical application in liver preservation.

Alanine Transaminase↗

PubMed2000

New method for preparation of coumarins and quinolinones via Pd-catalyzed intramolecular hydroarylation of C-C triple bonds.

A new and general method has been developed for preparation of coumarins and quinolinones by intramolecular hydroarylation of alkynes. Various aryl alkynoates and alkynanilides undergo fast intramolecular reaction at room temperature in the presence of a catalytic amount of Pd(OAc)(2) in a mixed solvent containing trifluoroacetic acid (TFA), affording coumarins and quinolinones in moderate to excellent yields with more than 1000 turnover numbers (TON) to Pd. The methodology proved to tolerate a number of functional groups such as Br and CHO. On the basis of isotope experiments, a possible mechanism involving ethynyl chelation-assisted electrophilic metalation of aromatic C-H bonds by in-situ generated cationic Pd(II) species has been discussed. Also the involvement of vinylcationic species has been suggested.

Catalysis↗

PubMed2000

Efficient activation of aromatic C-H bonds for addition to C-C multiple bonds

Efficient electrophilic metalation of aromatic C-H bonds leading to new C-C bond formation through regio- and stereoselective addition to alkynes and alkenes has been realized by a catalytic amount (0.02 to 5 mole percent) of palladium(II) or platinum(II) compounds in a mixed solvent containing trifluoroacetic acid at room temperature. Various arenes undergo unexpected selective trans hydroarylation to terminal or internal C&cjs0812;C bonds inter- and intramolecularly with high efficiency (up to a turnover number of 4500 for palladium), especially for electron-rich arenes, giving thermodynamically unfavorable cis-alkenes, and the oxygen- and nitrogen-containing heterocycles. The simplicity, generality, and efficiency of this process should be very attractive to the possible industrial application for the functionalization of arenes.

Journal Article↗

PubMed2000

Study on modified cold storage method of rat livers with self-made hyd solution.

OBJECTIVE: To investigate the cold preservation effect of rat livers by modified storage method with self-made HYD solution. METHODS: The modified method was that the vascular bed of rat livers was expanded with an additional 20 to 40ml self-made HYD solution/100g liver. After removing the liver, the extra HYD solution expressed as % liver weight was entrapped via portal infusion by tying off the supra-and infra hepatic inferior vena cava. According to the amount of extra HYD solution, 40 rats were randomly divided into four groups including: control group with conventional storage method, 20% group, 30% group and 40% group. The preservation effect of modified storage method with that of conventional storage method by using isolated perfused rat liver model was compared. RESULTS: Bile production and all the indices of hepatic microcirculation including portal perfusion pressure, endothelin-1 in the effluent, trypan blue distribution time and histology in modified method groups were significantly superior to those in control group (P < 0.05). The liver enzymes in 30% group were markedly lower than those in control group (P < 0.05). The preservation effect of rat liver in 30% group was the best among the modified method groups. CONCLUSION: The modified cold stage method is effective and may have potential for clinical application for liver preservation.

Alanine Transaminase↗

PubMed1995

[Evaluation of missing diagnosis of metastatic lymph node in gastric cancer].

The missing diagnosis rate of metastatic lymph nodes in 38 cases of radical gastrectomy specimens by methylene blue staining and serial histologic section was evaluated as compared to that by routine examination of one histologic slide of palpable enlarged lympy nodes. The results showed that after 1251 lymph nodes had been picked up by palpation method, 1004 additional minute lymph nodes were dissected out following methylene blue staining with an average of 59.3 lymph nodes in each case. The methylene blue-stained lymph nodes accounted for 44.5% of the total lymph nodes, in which 32 were found to have metastasis which accounted for 13.8% of metastatic lymph nodes. The 2046 metastasis negative lymph nodes according to routine histologic examination were then serially sectioned at 45 microns distance and 25 sections were observed for each lymph node specimen. Minute metastatic foci were found in 23 lymph nodes, accounting for 9.9% of the metastatic lymph nodes. Therefore, 23.7% metastatic lymph nodes escaped detection by the routinely used histologic examination.

Coloring Agents↗