[Analysis of spectral performance of varied-doping GaAs photocathodes].

For a quantitative analysis of the effect of varied doping structure on the quantum efficiency of cathode, two kinds of reflective gradient doping GaAs photocathode samples were designed and grown respectively. After activation, the dynamic spectral response curves of the two samples were obtained. The spectral response curves were transformed into quantum efficiency curves. The quantum efficiency curves in different wavebands were fit, and the varied doping coefficient K that reflects the contribution of the varied doping structure to the cathode quantum efficiency was obtained. Results show that, the functional effects of the same material varied doping structure responding to the incident photon of different wavebands are different from each other. The same is true for the different material varied doping structures responding to the same waveband incident photon. The fundamental reasons for these differences are that the positions and the intensities of the inside electric fields which build within the materials under different varied doping structures are different from each other. It offers an effective analysis means to evaluate the structure performance of cathodes grown under different doping ways, and has great value for the study on optimization design of cathode varied doping structure.

Liver dual arterial blood supply maintains liver regeneration: Analysis of signaling pathways in rats.

Liver dual arterial blood supply (LDABS) could increase blood supply to the liver and maintain normal liver regeneration in patients with compromised portal vein. The current study attempted to examine the underlying molecular mechanisms. Male Sprague­Dawley rats randomly received partial hepatectomy (PH) alone or PH followed by LDABS. Liver regeneration was assessed by histological examination, liver function and liver regeneration rate (LRR). Whole­genome oligo microarray analysis was used to compare gene expression profile between rats receiving PH and rats receiving PH plus LDABS. Key genes identification was validated using a MAPK signaling polymerase chain reaction (PCR) array. The extent of liver regeneration in rats receiving PH plus LDABS was comparable to that in rats receiving PH alone. The differentially expressed genes were enriched in 12 signaling pathways in two groups. MAPK signaling pathway, NF­kappa B signaling pathway, and Toll­like receptor signaling pathway were involved in LDABS­mediated liver regeneration, with Retinoblastoma 1 (Rb1), Cyclin D1, Cyclin­dependent kinase 4, Mitogen­activated protein kinase 10 (Mapk10) and CAMP responsive element binding protein 1 genes in the initiation phase, Kirsten rat sarcoma viral oncogene homolog (Kras), tumor protein 53, MYC proto­oncogene, BHLH transcription factor, Cyclin E1 and Heat shock protein family B (small) member 1 genes in the proliferation phase, Kras, Rb1, Jun proto­oncogene, AP­1 transcription factor subunit, Cyclin D2 and Mapk10 genes in the termination phase were identified as key genes in LDABS­mediated liver regeneration using MAPK signaling PCR array analysis.

A new rat model of auxiliary partial heterotopic liver transplantation with liver dual arterial blood supply.

Auxiliary partial heterotopic liver transplantation (APHLT) with portal vein arterialization is a valuable procedure to be considered in the treatment of patients with acute liver failure and metabolic liver diseases. The aim of this study was to develop a new rat model of APHLT with liver dual arterial blood supply (LDABS). A total of 20 rats were used. The donor liver was resected, and the celiac trunk was reserved. Left and medial hepatic lobes accounting for 70% of the liver mass were removed en bloc and the suprahepatic caval vein was ligated simultaneously. Thus, 30% of the donor liver was obtained as the graft. Sleeve anastomosis of the graft portal vein and splenic artery were performed after narrowing the portal vein lumen through suturing. The right kidney of the recipient was removed, and sleeve anastomosis was performed between the celiac trunk of the graft and the right renal artery of the recipient. In addition, end-to-end anastomosis was performed between the infrahepatic caval vein of the graft and the right renal vein of the recipient. Following the reperfusion of the graft, the blood flow of the arterialized portal vein was controlled within the physiological range through suturing and narrowing under monitoring with an ultrasonic flowmeter. The bile duct of the graft was implanted into the duodenum of the recipient through an internal stent catheter. A 70% section of the native liver (left and medial hepatic lobes) was resected using bloodless hepatectomy. The mean operative duration was 154.5±16.4 min, and the warm and cold ischemia times of the graft were 8.1±1.1 min and 64.5±6.6 min, respectively. The blood flow of the arterialized portal vein to the graft was 1.8±0.3 ml/min/g liver weight. The success rate of model establishment (waking with post-surgical survival of >24 h) was 70% (7/10). Following successful model establishment, all rats survived 7 days post-surgery (100%; 7/7). The graft was found to be soft in texture and bright red in color following exploratory laparotomy. In conclusion, a new rat model of APHLT with LDABS without stent for vascular reconstruction was developed. This is a feasible and reliable rat model for liver transplantation study.

Improved donor liver position selection and revascularization for heterotopic auxiliary liver transplantation with portal vein arterialization.

PURPOSE: To establish an animal model of improved donor liver position selection and revascularization for heterotopic auxiliary liver transplantation with portal vein arterialization (HALT-PVA). METHODS: Sprague-Dawley rats were utilized to establish models. Improved HALT-PVA was conducted for the experimental rat: hepatic common artery of donor liver was end-to-side anastomosed to portal vein which was end-to-side anastomosed to the left common iliac artery of host rat, while the segments of inferior vena cava superior and inferior to the donor liver were end-to-side anastomosed to the inferior vena cava of host rat, respectively. For the control rats, liver transplantations were conducted through end-to-end anastomosis between portal vein of donor liver and stand tube placed in right renal artery of host rat, and end-to-side anastomosis between the inferior vena cava inferior to the donor liver with the inferior vena cava of host rat, while the inferior vena cava superior to the donor liver was stitched up. Besides, hepaticoenterostomy were performed to all rats and survival status were monitored. ALT, AST, TBil and CHE were tested continuously after operation, and pathological examination of liver tissues were performed. RESULTS: The survival rate was 93.3% (14/15). ALT, AST, TBil and CHE for experimental group showed a rapider recovery of liver functions than controls. Pathological examinations of liver tissues from the experimental-group rats showed better presentation than the control-group rats. CONCLUSIONS: The improved HALT-PVA better accords with the normal anatomy, with little detriment to implanted liver, and therefore is a good model for HALT-PVA related research.

[Expression of CK20 mRNA in the peripheral blood around postoperative chemotherapy in patients with gastric cancer and its clinical significance].

OBJECTIVE: To investigate whether CK20 mRNA expression level could be considered as an effective molecular indicator for evaluation of chemotherapy sensitivity. METHODS: All samples of peripheral blood were taken from 31 gastric cancer patients undergone radical operation a week before postoperative chemotherapy, at the first day of chemotherapy point, and after the first cycle of chemotherapy respectively, and subjected to FQ RT-PCR assay for CK20 mRNA. The chemotherapy scheme was FOLFOX 4. The control group was 15 healthy volunteers. RESULTS: Aomng the 31 gastric cancer patients, the value of CK20 mRNA before postoperative chemotherapy was increased (2.96+/-2.27 vs 2.22+/-2.12, t=2.10, P<0.05) in 25 positive cases, and then declined after chemotherapy(2.05+/-1.86 vs 2.96+/-2.27, t=2.50, P<0.05) in 24 positive cases. The expression level of CK20 mRNA in patients before chemotherapy was increased in 16 cases(51.6%), declined in 9 cases(29.0%) and stabilized as negative in 6 cases(19.4%). After chemotherapy the level of CK20 mRNA was increased in 7 cases(22.6%), declined in 17 cases (54.8%) and stabilized as negative in 7 cases(22.6%), there was significant difference between the two groups(chi(2)=6.06, P<0.05). CONCLUSIONS: The expression level of CK20 mRNA in the peripheral blood detected by FQ RT-PCR in patients with gastric cancer declines after postoperative adjuvant chemotherapy. Different individuals have different sensitivity to chemotherapeutics. Dynamic monitoring CK20 mRNA should be considered as an effective index to evaluate the efficacy of postoperative adjuvant chemotherapy.

Comparison between gradient-doping GaAs photocathode and uniform-doping GaAs photocathode.

We compared two reflection-mode negative electron affinity (NEA) GaAs photocathode samples that are grown by molecular beam epitaxy with p-type beryllium doping. One sample is uniform doping, and another is gradient doping. Experimental curves of spectral response sensitivity and quantum efficiency are obtained. The thicknesses of the two cathodes are both 2.6 microm. The integrated sensitivity of the uniform doping one is 1966 microA/lm, and that of the gradient-doping one is 2421 microA/lm. The escape probability and diffusion length are fitted from the spectral response curves. For the uniform-doping sample, the escape probability is 0.45 and the diffusion length is 5 microm. For the gradient-doping sample, the escape probability is 0.55 and the diffusion length is 5.5 microm.