Dean-flow-coupled elasto-inertial three-dimensional particle focusing under viscoelastic flow in a straight channel with asymmetrical expansion-contraction cavity arrays

In this paper, 3D particle focusing in a straight channel with asymmetrical expansion-contraction cavity arrays (ECCA channel) is achieved by exploiting the dean-flow-coupled elasto-inertial effects. First, the mechanism of particle focusing in both Newtonian and non-Newtonian fluids was introduced. Then particle focusing was demonstrated experimentally in this channel with Newtonian and non-Newtonian fluids using three different sized particles (3.2 μm, 4.8 μm, and 13 μm), respectively. Also, the effects of dean flow (or secondary flow) induced by expansion-contraction cavity arrays were highlighted by comparing the particle distributions in a single straight rectangular channel with that in the ECCA channel. Finally, the influences of flow rates and distances from the inlet on focusing performance in the ECCA channel were studied. The results show that in the ECCA channel particles are focused on the cavity side in Newtonian fluid due to the synthesis effects of inertial and dean-drag force, whereas the particles are focused on the opposite cavity side in non-Newtonian fluid due to the addition of viscoelastic force. Compared with the focusing performance in Newtonian fluid, the particles are more easily and better focused in non-Newtonian fluid. Besides, the Dean flow in visco-elastic fluid in the ECCA channel improves the particle focusing performance compared with that in a straight channel. A further advantage is three-dimensional (3D) particle focusing that in non-Newtonian fluid is realized according to the lateral side view of the channel while only two-dimensional (2D) particle focusing can be achieved in Newtonian fluid. Conclusively, this novel Dean-flow-coupled elasto-inertial microfluidic device could offer a continuous, sheathless, and high throughput (>10 000 s(-1)) 3D focusing performance, which may be valuable in various applications from high speed flow cytometry to cell counting, sorting, and analysis.

Characterization, tissue distribution and regulation of neuropeptideY in Schizothorax prenanti

In this study, the full-length neuropeptide Y (npy) complementary (c)DNA was cloned in ya fish Schizothorax prenanti. npy cDNA was composed of 789 nucleotides with a 288 nucleotide open reading frame encoding a protein of 96 amino acids. The deduced amino acid sequences contained a 28 amino acids signal peptide followed by a 36 amino acids mature neuropeptide Y (NPY). The npy mRNA was expressed mainly in the brain and eye as detected by real-time quantitative polymerase chain reaction RT-PCR (rt-qPCR). The S. prenanti NPY was detectable from blastulation to hatch, suggesting that npy might be involved in the late embryonic development of S. prenanti. An experiment was conducted to determine the expression profile of npy during feeding of a single meal and during long-term fasting. The expression level of npy in fed fish was significantly decreased at 0.5, 1.5, 3 and 9 h post-feeding (hpf) than in fasting fish. Fasting for 14 days induced an increase in npy messenger (m)RNA expression in the brain. Overall, the results suggest that NPY is a conserved peptide that might be involved in the regulation of feeding and other physiological function in S. prenanti.

Characterization of Schizothorax prenanti cgnrhII gene: fasting affects cgnrhII expression

In this study, the role of chicken gonadotropin-releasing hormone II (cgnrhII) in feeding regulation was investigated in Schizothorax prenanti. First, the full-length S. prenanti cgnrhII cDNA consisted of 693 bp with an open reading frame of 261 bp encoding a protein of 86 amino acids. Next, cgnrhII was widely expressed in the central and peripheral tissues. Last, there were significant changes in cgnrhII mRNA expression in the fasted group compared to the fed group in the S. prenanti hypothalamus during 24 h fasting (P < 0.05). Furthermore, the cgnrhII gene expression presented a significant decrease in the fasted group compared with the fed group (P < 0.05) on days 3, 5 and 7, after re-feeding, there was no significant changes in cgnrhII mRNA expression level between refed and fed group on day 9 (P > 0.05). Thus, the results suggest that cGnRH II expression is influenced by fasting and the gene may be involved in feeding regulation in S. prenanti.

Regulation of selenoprotein P concentration and expression by different sources of selenium in broiler breeders and their offspring

An 8-wk experiment using 180 Lingnan Yellow broiler breeders was conducted to investigate the effect of different sources of Se on the concentration and gene expression of selenoprotein P (SEPP1) in broiler breeders and their offspring. After receiving a low-Se basal diet for 8 wk, broiler breeders were randomly allocated to 3 treatments (6 replicates per treatment) and fed corn-soy-based diets supplemented with 0.15 mg/kg of Se from sodium selenite (SS), Se-enriched yeast (SY), and selenomethionine (SM), respectively. Fertile eggs from different replicates were collected during the last week of the experiment and then incubated in different incubator trays in the same incubator. The concentrations and mRNA levels of SEPP1 were determined in liver and kidney of broiler breeders and their offspring, as well as the serum SEPP1 concentration. Compared with SS, both SY and SM significantly increased (P < 0.05) the concentration and mRNA level of SEPP1 in 1-d-old chicks. In broiler breeders, the serum and liver SEPP1 concentrations were notably increased by the use of organic Se (P < 0.05), whereas no differences were found in the kidney. Moreover, the SEPP1 mRNA level in the liver was remarkably elevated (P < 0.05) in organic Se treatments, but also no differences were observed in the kidney. Results of this study indicate that the use of organic Se (SY or SM) in maternal diets is very effective for increasing the concentration and mRNA level of SEPP1, especially in their offspring. No differences between SY and SM were observed.

Effect of selenium sources on the expression of cellular glutathione peroxidase and cytoplasmic thioredoxin reductase in the liver and kidney of broiler breeders and their offspring

In total, 180 Lingnan Yellow broiler breeders were used to investigate the effect of different sources of selenium (Se) on the expression of cellular glutathione peroxidase (GPx1) and cytoplasmic thioredoxin reductase (TrxR1) in the liver and kidney of broiler breeders and their offspring by quantitative real-time PCR. There were 6 replicates of 3 dietary treatments. Broiler breeders were fed corn-soy-based diets supplemented with 0.15 mg/kg of Se from sodium selenite, Se-enriched yeast (SY), or selenomethionine (SM). At the end of the feeding trial, liver and kidney mRNA levels of GPx1 and TrxR1 were determined by quantitative real-time PCR, as well as the activity of GPx1 and TrxR1 in liver and kidney of breeders and their offspring. The results showed that, compared with sodium selenite, SY or SM significantly increased (P < 0.05) the activity of TrxR1 in the liver and kidney of broiler breeders and their offspring but not the GPx1 activity. The liver GPx1 and TrxR1 mRNA levels in SY or SM groups were higher (P < 0.05) than that in the sodium selenite group. And the kidney TrxR1 mRNA levels were also significantly increased (P < 0.05) by using SY or SM, whereas there was no significant difference in the kidney GPx1 mRNA levels between the organic or inorganic sources of Se used.

Differences between karyotypically normal and abnormal human embryonic stem cells

OBJECTIVES

To compare different biological characteristics of human embryonic stem cells (HESCs) between those with normal and those with abnormal karyotype.

MATERIALS AND METHODS

Culture-adapted HESCs (chHES-3) with abnormal karyotype were compared with karyotypically normal cells, with regard to pluripotency and differentiation capacity, ultrastructure, growth characteristics, gene expression profiles and signalling pathways.

RESULTS

We found a new abnormal karyotype of HESCs. We observed that chHES-3 cells with normal and abnormal karyotypes shared similarities in expression markers of pluripotency; however, karyotypically abnormal chHES-3 cells had a tendency for differentiation towards ectoderm lineages and were easily maintained in suboptimal culturing conditions. Abnormal chHES-3 cells displayed relatively mature cell organelles compared to normal cells, and karyotypically abnormal chHES-3 cells had increased survival and population growth. Genes related to cell proliferation and apoptosis were up-regulated, but genes associated with genetic instability (p53, Rb, BRCA1) were down-regulated in the karyotypically abnormal cells.

CONCLUSION

Karyotypically abnormal chHES-3 cells had a more developed capacity for proliferation, resistance to apoptosis and less genetic stability compared to normal chHES-3 cells and may be an excellent model for studying and characterizing initial stages that determine transition of embryonic stem cells into cancer stem cells.

Protein phosphatase-1 regulates Akt1 signal transduction pathway to control gene expression, cell survival and differentiation

AKT pathway has a critical role in mediating signaling transductions for cell proliferation, differentiation and survival. Previous studies have shown that AKT activation is achieved through a series of phosphorylation steps: first, AKT is phosphorylated at Thr-450 by JNK kinases to prime its activation; then, phosphoinositide-dependent kinase 1 phosphorylates AKT at Thr-308 to expose the Ser-473 residue; and finally, AKT is phosphorylated at Ser-473 by several kinases (PKD2 and others) to achieve its full activation. For its inactivation, the PH-domain containing phosphatases dephosphorylate AKT at Ser-473, and protein serine/threonine phosphatase-2A (PP-2A) dephosphorylates it at Thr-308. However, it remains unknown regarding which phosphatase dephosphorylates AKT at Thr-450 during its inactivation. In this study, we present both in vitro and in vivo evidence to show that protein serine/threonine phosphatase-1 (PP-1) is a major phosphatase that directly dephosphorylates AKT to modulate its activation. First, purified PP-1 directly dephosphorylates AKT in vitro. Second, immunoprecipitation and immunocolocalization showed that PP-1 interacts with AKT. Third, stable knock down of PP-1alpha or PP-1beta but not PP-1gamma, PP-2Aalpha or PP-2Abeta by shRNA leads to enhanced phosphorylation of AKT at Thr-450. Finally, overexpression of PP-1alpha or PP-1beta but not PP-1gamma, PP-2Aalpha or PP-2Abeta results in attenuated phosphorylation of AKT at Thr-450. Moreover, our results also show that dephosphorylation of AKT by PP-1 significantly modulates its functions in regulating the expression of downstream genes, promoting cell survival and modulating differentiation. These results show that PP-1 acts as a major phosphatase to dephosphorylate AKT at Thr-450 and thus modulate its functions.

Risk factors of biliary complications following liver transplantation: retrospective analysis of a single centre

BACKGROUND

Despite improvements that have been achieved in surgical techniques and organ preservation, biliary complications remain one of the most serious morbidities following liver transplantation. However, factors related to biliary complications after liver transplantation are not completely understood. The objective of this study was to identify retrospectively possible risk factors of biliary complications following liver transplantation.

METHODS

Data on 279 patients who underwent liver transplantation between January 1999 and November 2005 were collected retrospectively. Selected variables from preoperative, intraoperative and postoperative data were first analysed using univariate logistic regression. Filtered factors with p<0.1 in the first step were further investigated to identify factors independently associated with biliary complications following liver transplantation.

RESULTS

The overall incidence of biliary complications was 22.6%. Multivariate regression revealed that biliary cirrhosis (p = 0.038), anhepatic phase time (p = 0.04), and incidence of hepatic artery abnormality (p = 0.001) after transplantation were factors that were significantly related to biliary complications. Use of a T tube for biliary reconstruction and living grafts were not associated with biliary complications following liver transplantation.

CONCLUSION

This study suggests that further technical refinement-namely, shortening the anhepatic phase duration, shielding the hepatic artery, and refining biliary duct reconstruction-can reduce the incidence of biliary complications following liver transplantation.

Estimation of standard liver volume for liver transplantation in the Chinese population

INTRODUCTION

The accurate assessment of standard liver volume (SLV) is necessary for the safety of both the donor and the recipient in living donor liver transplantation. However, the accuracy of SLV formulas relates to cohorts or races. This study examined the accuracy of a simple linear formula versus previous formulas of SLV for Chinese adults.

METHODS

Among 112 patients with normal liver, we created a new formula for SLV with stepwise regression analysis using the following variables: age, gender, body weight, body height, body mass index, and body surface area. The agreement between the actual liver volume (LV) and calculated LV using various formulas was prospectively evaluated among 63 living donors by paired-sample student's t-test and Lin's concordance correlation coefficient.

RESULTS

A new formula was developed SLV (mL) = 949.7 x BSA (m(2)) - 48.3 x age - 247.4 where age was counted as 1 for those <40, 2 if 41-60, and 3 if >60 years old. The calculated LV using our formula showed no significant difference from the actual LV using the paired-samples student's t-test (P = .653). Lin's concordance correlation coefficient showed substantial agreement between estimated LV using our formula and actual LV. Furthermore, this study also observed an almost perfect agreement between our formula and the Yoshizumi et al formula.

CONCLUSION

Our formula, which accurately estimated LV among Chinese adults, may be applicable to adults of other ethnicitis.

RNA interference-mediated silencing of the polo-like kinase 1 gene enhances chemosensitivity to gemcitabine in pancreatic adenocarcinoma cells

Gemcitabine is the first-line chemotherapeutic agent for advanced adenocarcinoma of the pancreas; however, chemoresistance to gemcitabine remains a major cause of failure for the clinical treatment of this disease. Polo-like kinase 1 (Plk-1) is highly expressed in pancreatic cancer cell lines and pancreatic tumour tissues, and is involved in a wide variety of cell cycle processes. Nevertheless, its biological role and implication for gemcitabine resistance are not clearly defined. In this study, we used RNA-interference (RNAi)-mediated depletion of Plk-1 to determine its potential for sensitizing pancreatic tumour cells to gemcitabine. We showed that the level of Plk-1 protein was correlated significantly with gemcitabine resistance in human pancreatic adenocarcinoma cells and that overexpression of Plk-1 reduced sensitivity to gemcitabine in these cells. In addition, small interfering RNA (siRNA)-mediated knockdown of Plk-1 caused cell cycle arrest at G2/M and the reduction of cellular proliferation. More importantly, the treatment of pancreatic cancer cells with Plk-1 siRNA followed by exposure to gemcitabine dramatically decreased cell viability and increased cellular apoptosis, as compared with treatment with either agent alone. These observations indicate that down-regulation of Plk-1 expression by RNAi enhances gemcitabine sensitivity and increases gemcitabine cytotoxicity in pancreatic tumour cells. This is the first demonstration that the combination of Plk-1 gene therapy and gemcitabine chemotherapy has synergistic anti-tumour activity against pancreatic carcinoma in vitro. This combination treatment warrants further investigation as an effective therapeutic regimen for patients with resistant pancreatic cancer and other tumours.

Ion source and low energy injection line for a central region model cyclotron

At CIAE, a 100 MeV H(-) cyclotron (CYCIAE-100) is under design and construction. A central region model (CRM) cyclotron was built for various experimental verifications for the CYCIAE-100 project and for research and development of high current injection to accelerate milliampere H(-) beam. The H(-) multicusp source built in 2003 has been improved recently to make the source operation more stable. A new injection line for axial low energy high current injection has been designed and constructed for the CRM cyclotron.