SIRT1 RNAi knockdown induces apoptosis and senescence, inhibits invasion and enhances chemosensitivity in pancreatic cancer cells

The NAD(+)-dependent deacetylase, sirtuin 1 (SIRT1), has been recently been suspected to have a role in tumorigenesis. We investigated the expression of SIRT1 in pancreatic cancer and the effect of SIRT1-targeted RNA interference (RNAi) on cell proliferation and tumor formation in a pancreatic cancer cell line, PANC1. The expression of SIRT1 was investigated in 49 specimens of pancreatic cancer and adjacent normal pancreatic tissues. SIRT1 was overexpressed in pancreatic cancer tissues at both the mRNA and protein levels, with increased SIRT1 positivity associated with tumors from patients over 60 years old, tumors larger than 4 cm, higher TNM (extent of tumor (T), the extent of spread to lymph nodes (N), and presence of distant metastasis (M)) stage or the presence of lymph node or hepatic metastases. The PANC-1 was stably transfected with a SIRT1 small hairpin RNA (shRNA) expression plasmid and compared with untransfected and PANC-1-negative RNAi cells. Proliferation of PANC-1-SIRT1-RNAi cells was significantly reduced, accompanied by increased rates of apoptosis, G1 arrest and senescence. Furthermore, FOXO3a expression was markedly upregulated in PANC-1-SIRT1-RNAi cells, but no significant difference in p53 expression was observed. The invasive ability of PANC-1-SIRT1-RNAi cells was markedly reduced in vitro, which was linked to increased E-cadherin and reduced-MMP expression. Additionally, PANC-1-SIRT1-RNAi cells had a significantly reduced capacity to form tumors in vivo compared with untransfected and PANC-1-negative RNAi cells. These results suggest that SIRT1 may promote cell proliferation and tumor formation in pancreatic cancer, and downregulation of SIRT1 using shRNA could provide a novel therapeutic treatment.

The epidemiology of human trichinellosis in China during 2004-2009

The endemic foci of human trichinellosis are mainly located in southwestern China. Seroepidemiological surveys of Trichinella spiralis infection in humans were carried out in 10 out of 34 Provinces/Autonomous Regions/Municipals (P/A/M) of China during 2004-2009. The overall seroprevalence was 3.19% (3198/100,282). The highest seroprevalences were mainly located in western China: 8.43% in Yunnan, 6.37% in Inner Mongolia and 5.35% in Sichuan. The seroprevalence of Trichinella infection in humans was related to the habit of eating meat and differed among nationalities. From 2004 to 2009, 15 outbreaks of human trichinellosis, consisting of 1387 cases and four deaths, were reported in the three southwestern-most P/A of China (nine outbreaks in Yunnan, two in Sichuan and four in Tibet), where ethnic groups routinely eat raw meat. Pork is the predominant source of outbreaks of human trichinellosis in China. Out of 15 outbreaks, 12 (85.71%) were caused by eating raw or undercooked pork, and 2 (13.33%) resulted from the consumption of raw wild boar, suggesting the significance of game meat as a source of infection for human trichinellosis. An outbreak of imported trichinellosis involving 49 cases in Yunnan during December 2006 from Laos is the first recorded outbreak of imported trichinellosis in China, but the source of that outbreak could not be identified. The mandatory inspection of pork should be further strengthened in southwestern China.

Influencing factors on the size uniformity of self-assembled SiGe quantum rings grown by molecular beam epitaxy

The size uniformity of self-assembled SiGe quantum rings, which are formed by capping SiGe quantum dots with a thin Si layer, is found to be greatly influenced by the growth temperature and the areal density of SiGe quantum dots. Higher growth temperature benefits the size uniformity of quantum dots, but results in low Ge concentration as well as asymmetric Ge distribution in the dots, which induces the subsequently formed quantum rings to be asymmetric in shape or even broken somewhere in the ridge of rings. Low growth temperature degrades the size uniformity of quantum dots, and thus that of quantum rings. A high areal density results in the expansion and coalescence of neighboring quantum dots to form a chain, rather than quantum rings. Uniform quantum rings with a size dispersion of 4.6% and an areal density of 7.8×10(8) cm(-2) are obtained at the optimized growth temperature of 640°C.

Combination of hsa-miR-375 and hsa-miR-142-5p as a predictor for recurrence risk in gastric cancer patients following surgical resection

BACKGROUND

Recurrence is a major factor leading to treatment failure and death in gastric cancer (GC) patients following surgical resection. Importantly, the prediction of recurrence is critical in improving clinical outcomes. We isolated a group of microRNAs (miRNAs) and evaluated their usefulness as prognostic markers for the recurrence of GC.

PATIENTS AND METHODS

A total of 65 GC patients were selected for systematic analysis, 29 patients with recurrence and 36 patients without recurrence. Firstly, miRNAs microarray and bioinformatics methods were used to characterize classifiers from primary tumor samples (n = 8). Following, we validated these predictors both in frozen fresh and paraffin-embedded tissue samples (n = 57) using quantitative PCR.

RESULTS

We have identified 17 differential miRNAs including 10 up-regulated and 7 down-regulated miRNAs in recurrence group. Using k-top scoring pairs (k-TSP) method, we further ascertained hsa-miR-375 and hsa-miR-142-5p as a classifier to recognize recurrence and nonrecurrence cases both in the training and test samples. Moreover, we validated this classifier in 34 frozen fresh tissues and 38 paraffin-embedded tissues with consistent sensitivity and specificity with training set; among them, 15 cases were matched. A high frequency recurrence and poor survival were observed in GC cases with high level of hsa-miR-375 and low level of hsa-miR-142-5p (P < 0.001). In addition, we evaluated that hsa-miR-375 and hsa-miR-142-5p were involved in regulating target genes in several oncogenic signal pathways, such as TP53, MAPK, Wnt and vascular endothelial growth factor.

CONCLUSION

Our results indicate that the combination of hsa-miR-375 and hsa-miR-142-5p as a predictor of disease progression has the potential to predict recurrence risk for GC patients.

Formation of NH3 and CH2NH in Titan's upper atmosphere

The large abundance of NH3 in Titan's upper atmosphere is a consequence of coupled ion and neutral chemistry. The density of NH3 is inferred from the measured abundance of NH4+. NH3 is produced primarily through reaction of NH2 with H2CN, a process neglected in previous models. NH2 is produced by several reactions including electron recombination of CH2NH2+. The density of CH2NH2+ is closely linked to the density of CH2NH through proton exchange reactions and recombination. CH2NH is produced by reaction of N(2D) and NH with ambient hydrocarbons. Thus, production of NH3 is the result of a chain of reactions involving non-nitrile functional groups and the large density of NH3 implies large densities for these associated molecules. This suggests that amine and imine functional groups may be incorporated as well in other, more complex organic molecules.

An epidemiological overview of swine trichinellosis in China

Trichinellosis is a major food-borne zoonosis with health, social, and economic impacts. Epidemiological data on swine trichinellosis in China from 2005 to 2009 were obtained from seven Provinces/autonomous regions/Municipalities (P/A/M) and analyzed and sero-epidemiological data were acquired from five P/A. The seroprevalence ranged from 0.01% to 29.95% as determined by enzyme-linked immunosorbent assay or an immunochromatographic strip method. The prevalence of Trichinella infection in swine slaughtered at abattoirs varied from 0% to 5.75% in five P/A. Between 2005 and 2009, endemic areas of swine trichinellosis were located mainly in the Western (Guangxi and Qinghai), central (Henan and Hubei), and North-eastern parts (Heilongjiang) of China. Swine trichinellosis in China is transmitted mostly through garbage. Pigs infected with Trichinella are predominately from small backyard farms where animals are raised under poor hygienic conditions, and from rural and mountainous areas where they range freely at pasture. The prevalence of Trichinella in pork sold at the market was reported in four P/A, and varied from 0.06% to 5.6% as determined by trichinoscopy or the digestion method. From 2005 to 2009, 15 outbreaks of human trichinellosis, with 1387 cases and 4 deaths, were recorded in three P/A of South-western China. Twelve (85.71%) of these 15 outbreaks were caused by the eating of raw or undercooked pork, which remains the predominant source of trichinellosis in humans. Pig-rearing practices must be improved, and mandatory inspection of pork further strengthened in rural and mountainous areas in Western China for the control of the disease.

Peripheral venous pressure as an alternative to central venous pressure in patients undergoing laparoscopic colorectal surgery

BACKGROUND

Peripheral venous pressure (PVP) is strongly correlated with central venous pressure (CVP) during various surgeries. Laparoscopic surgery in the Trendelenburg position with pneumoperitoneum typically increases CVP. To determine whether PVP convincingly reflects changes in CVP, we evaluated the correlation between PVP and CVP in patients undergoing laparoscopic colorectal surgery.

METHODS

Both CVP and PVP were measured simultaneously at predetermined time intervals during elective laparoscopic colorectal surgery in 42 patients without cardiac disease. The pairs of venous pressure measurements were analysed for correlation, and the Bland-Altman plots of repeated measures were used to evaluate the agreement between CVP and PVP.

RESULTS

A total of 420 data pairs were obtained. The overall mean CVP was 11.3 (sd 4.5) mm Hg, which was significantly lower than the measured PVP of mean 12.1 (4.5) mm Hg (P=0.005). There was a strong positive correlation between overall CVP and PVP (correlation coefficient=0.96, P<0.0001). The mean bias (PVP-CVP) corrected for repeated measurements using random-effects modelling was 0.9 mm Hg [95% confidence interval (CI) 0.54-1.19 mm Hg] with 95% limits of agreement of -1.2 mm Hg (95% CI -1.75 to -0.62 mm Hg) to 2.9 mm Hg (95% CI 2.35-3.48 mm Hg).

CONCLUSIONS

PVP displays a strong correlation and agreement with CVP under the increased intrathoracic pressure of pneumoperitoneum in the Trendelenburg position and may be used as an alternative to CVP in patients without cardiac disease undergoing laparoscopic colorectal surgery.

The role of adiponectin in metabolic and vascular disease: a review

Adiponectin is a protein secreted by adipose tissue. Unlike other adipocytokines produced by adipose tissue, adiponectin appears to have anti-inflammatory, anti-diabetic, and anti-atherogenic properties. Although secreted solely by adipose tissue, plasma levels of adiponectin are generally negatively related to total adipose mass; with higher plasma adiponectin levels in lean individuals and lower adiponectin levels in obese individuals. Plasma concentrations of adiponectin are lower in patients with insulin resistance compared to insulin sensitive patients; and lower in patients with diabetes compared to non-diabetics. A similar inverse relationship of plasma adiponectin level has been reported with hypertension (HTN), blood pressure level, and albuminuria. However, in chronic kidney disease (CKD) marked elevations in plasma adiponectin concentrations have been described. Plasma adiponectin levels are markedly elevated among patients with end-stage renal disease and are lower following kidney transplantation. Considering the inverse relationship of plasma adiponectin with renal function, the cardiovascular protective role of adiponectin in patients with CKD remains controversial. Further research on the distribution and function of different circulating fractions of adiponectin in patients with CKD will be needed in order to determine if adiponectin is a useful biomarker in patients with CKD.

Melt-processable hydrophobic acrylonitrile-based copolymer systems with adjustable elastic properties designed for biomedical applications

Acrylonitrile-based polymer systems (PAN) are comprehensively explored as versatile biomaterials having various potential biomedical applications, such as membranes for extra corporal devices or matrixes for guided skin reconstruction. The surface properties (e.g. hydrophilicity or charges) of such materials can be tailored over a wide range by variation of molecular parameters such as different co-monomers or their sequence structure. Some of these materials show interesting biofunctionalities such as capability for selective cell cultivation. So far, the majority of AN-based copolymers, which were investigated in physiological environments, were processed from the solution (e.g. membranes), as these materials are thermo-sensitive and might degrade when heated. In this work we aimed at the synthesis of hydrophobic, melt-processable AN-based copolymers with adjustable elastic properties for preparation of model scaffolds with controlled pore geometry and size. For this purpose a series of copolymers from acrylonitrile and n-butyl acrylate (nBA) was synthesized via free radical copolymerisation technique. The content of nBA in the copolymer varied from 45 wt% to 70 wt%, which was confirmed by 1H-NMR spectroscopy. The glass transition temperatures (Tg) of the P(AN-co-nBA) copolymers determined by differential scanning calorimetry (DSC) decreased from 58 degrees C to 20 degrees C with increasing nBA-content, which was in excellent agreement with the prediction of the Gordon-Taylor equation based on the Tgs of the homopolymers. The Young's modulus obtained in tensile tests was found to decrease significantly with rising nBA-content from 1062 MPa to 1.2 MPa. All copolymers could be successfully processed from the melt with processing temperatures ranging from 50 degrees C to 170 degrees C, whereby thermally induced decomposition was only observed at temperatures higher than 320 degrees C in thermal gravimetric analysis (TGA). Finally, the melt processed P(AN-co-nBA) biomaterials were sterilized with ethylene oxide and tested for cytotoxicity in direct contact tests with L929 cells according to the EN DIN ISO standard 10993-5. All tested samples exhibited non-toxic effects on the functional integrity of the cell membrane and the mitochondrial activity. However, the morphology of the cells on the samples was different from that observed on polystyrene as control, indicating slightly cytotoxic effects according to the evaluation guide of the US Pharmacopeial Convention. Thus, the melt-processable, hydrophobic P(AN-co-nBA) copolymers with adjustable mechanical properties are promising candidates for in vitro investigations of tissue growth kinetics.