[Difference in imaging and metal metabolism between hepatic and cerebral type Wilson disease]

Objective: To evaluate the difference of metal metabolism, damage to structure and functional activity in brains between hepatic and cerebral type Wilson disease (WD). Methods: Forty patients with WD, including 20 with cerebral type and 20 with hepatic type, and 20 age-matched healthy controls in the First Affiliated Hospital, Sun Yat-sen University between Jul 2013 and May 2016 were enrolled.All study subjects underwent diffusion tensor imaging (DTI), resting state functional MRI (rs-fMRI) and susceptibility weighted imaging (SWI) of the brain.Six regions of interest (ROIs) were chosen.The values of fractional anisotropy (FA), λ in ROIs were determined on DTI, FA and fiber volumes between ROIs were also determined on DTI.The values of amplitude of low frequency fluctuation (ALFF) and regional homogeneity (REHO) in ROIs were determined on rs-fMRI.The values of corrected phase (CP) were calculated on SWI.The copper and iron content were measured.The difference of imaging and metal metrics between cerebral type and hepatic type WD were evaluated. Results: DTI metrics differed between patients with the cerebral and hepatic types of WD.ALFF values in the caudate nucleus, and thalamus were lower (P=0.037, 0.040), and REHO values in the caudate nucleus were lower (P=0.029), in patients of cerebral type than in hepatic type patients.CP values of the right caudate nucleus and left putamen in cerebral type WD patients were lower than in hepatic type patients (P=0.020, 0.23). The serum iron content of hepatic type WD patients was higher than the normal (P=0.013), and the urine copper content was higher than the cerebral type patients (P=0.021). Conclusions: Metal deposition and damage to the structure and functional activity in the brain may occur in hepatic type WD patients.The structural and functional activity damage of the brain in hepatic type is less severe than that in cerebral type patients, while the metal deposition is not significant different between hepatic and cerebral type.

[Prevalence of and risk factors for delayed onset of lactation in Chinese lactating women in 2013]

Objective: To study the prevalence of delayed onset of lactation (later than 3 days) in lactating women in China and to analyze its influencing factors. Methods: Data were extracted from Chinese National Nutrition and Health Surveillance-Mothers, from mothers with children under 2 years of age (in 2013). A total of 11 178 women who were lactating or had lactated were selected from 55 counties of 30 provinces (excluding the Tibet Autonomous Region) in China, using the multi-stage stratified cluster randomization sampling method. Basic information, including onset of lactation, initiation of breastfeeding, breastfeeding difficulties and breastfeeding knowledge were collected using a questionnaire investigation. The prevalence of delayed onset of lactation were analyzed by the weighted processing of complex sampling from the 6^th national population census data. A multiple logistic regression was used to analyze the factors associated with delaged onset of lactation. Results: Among 11 178 lactating women, 3 388 had an onset of lactation later than 3 d. The prevalence of delayed onset of lactation was 30.3%. After complex weighting, the prevalence of delayed onset of lactation was 31.2% (95% CI: 25.7%-36.8%) for lactating women in China. Delivery by Caesarean section (OR=1.28, 95%CI: 1.06-1.53) and initiating breastfeeding ≥4 h (OR= 2.34, 95%CI: 1.76-3.11) were the negative factors for delayed onset of lactation. Compared with those living in large cities, lactating women living in medium or small cities (OR=1.39, 95%CI: 1.05-1.84) had a higher risk of delayed onset of lactation. Compared with the lactating women doing housework, the risk of delayed onset of lactation was lower (P<0.05) among those whose occupations were as leaders of Enterprises/Institutions (OR=0.68, 95%CI: 0.47-0.99), in catering and service trades (OR=0.61, 95%CI: 0.43-0.86), in agriculture/forestry/fishery/herdsmen fields (OR=0.65, 95%CI: 0.44-0.96) and who were unemployed (OR= 0.64, 95%CI: 0.46-0.90). Breastfeeding education during pregnancy might lower the risk of delayed onset of lactation (OR=0.78, 95% CI: 0.62-0.98). Conclusion: The prevalence of delayed onset of lactation was relatively high for Chinese lactating mothers. Caesarean section and late initiation of breastfeeding were the primary risk factors. Lactating mothers living in medium or small cities and those doing housework appear to be high-priority groups for intervention. Based on our findings, breastfeeding education during pregnancy is recommended to lower the risk of delayed onset of lactation.

[Focus on nutrition of lactating women and promoting maternal and child health]

Breastfeeding has been existing from the beginning of human beings. The focus has usually been on breast milk and breastfed infants. However, there have been a few studies on nutrition and health status of lactating women worldwide. Many of these studies suggested that the nutrition and health status of the women not only can affect milk volume and nutrient contents, but also may have short- and long-lasting effects on their health status. Therefore, more research should focus on breastfeeding and the improvement of nutrition and the health status of lactating women.

[Risk factors for prevalence of folic acid deficiency in Chinese lactating women in 2013]

Objective: The study aimed to assess the folic acid status of lactating women in China and to analyze factors related to folic acid deficiency in these subjects. Methods: The data on lactating women were extracted from the Chinese National Nutrition and Health Surveillance in 2013. By a multi-stage stratified cluster random sampling method, 10 331 lactating women were selected for the study. The lactating women, 0-24 months postpartum, were from 55 sites in 30 provinces of China, excluding the Tibet Autonomous Region. A standard questionnaire was used to obtain general information and dietary intake during the previous one month period was collected using a food frequency questionnaire. A total of 20% of the total number of lactating women were randomly selected to analyze serum folic acid. Finally, 1 894 lactating women, with questionnaire results and serum folic acid data, were included in the study. Serum folic acid concentrations were analyzed using an electro-chemiluminescence immunoassay method. Folic acid deficiency was defined as a serum folic acid level <2 ng/ml. A multiple logistic regression analysis was used to analyze the factors associated with folic acid deficiency in these women. Results: After excluding abnormal values, 1 894 lactating women were included in the study. Based on our findings, the prevalence of folate deficiency was 3.0% (56/1 894) in lactating women in China. The prevalence of folic acid deficiency was 0.3% (1/388), 1.3% (7/550), 6.0% (38/639) and 3.2% (10/317) in larger, medium or small cities, general rural counties and poor rural counties, respectively. The prevalence of folic acid deficiency was 6.3% (17/269) and 2.4% (39/1 623) for minority and Han ethnic groups, respectively, and was 6.3% (52/823) and 0.4% (4/1 071) for subjects in northern and southern areas of China, respectively. Binary unconditionally logistic regression was used to analyze the factors associated with folic acid deficiency in the lactating women. The results showed that, compared with those living in the south and those in the Han ethnic group, those living in the north and belonging to the minority ethnic group had a greater risk of folic acid deficiency, with (OR=3.63, 95% CI: 1.64-8.05) and (OR=5.42, 95% CI: 1.75-16.74), respectively. With each month of age during childhood, the prevalence of folic acid deficiency decreased by 10% (OR=0.90, 95%CI: 0.85-0.96). Compared with low income subjects, those with middle incomes had OR (95%CI) of 0.25 (0.10-0.60) for folic acid deficiency. A lesser intake of cereal was associated with a greater risk of folic acid deficiency in lactating women (OR=3.04, 95%CI: 1.18-7.79). A lesser intake of tubers was a protective factor for folic acid deficiency in lactating women (OR=0.29, 95% CI:0.12-0.70). Conclusion: The folic acid status of Chinese lactating women has, in general, recently improved. However, living in northern areas, during early lactating periods, belonging to an ethnic minority, living in rural areas, having a low income, lower intake of cereal and excessive intake of tubers were risk factors for folic acid deficiency in lactating women. In these women, folic acid intervention should be considered a priority.

[Biomechanics analysis of the impact of maxillofacial injury on skull base damage]

OBJECTIVE

To analyze the impact of maxillofacial injury on skull base.

METHODS

A three-dimensional(3D)finite-element model of cranio-maxillofacial bone was established by CT scan data. A lead cylinder in base diameter of 3 cm was designed as an impactor. There regions(upper right maxilla, left infraorbital margin and left zygomatic body)subjected to an impact at the speed of 8.6 m/s(about 30 km/h)was simulated. Thirteen landmarks at the skull base were selected. The values of stress at the end of 0.5, 1.0, 1.5, 2.0 ms were obtained, and the results were analyzed.

RESULTS

The dynamic process of the fracture of the jaw and the stress distribution and conduction of the skull base were successfully simulated in three parts of the face. When the impact was on the right maxillary bone region, the stress values of the three points(medial foramen rotundum, medial foramen rotundum, anterior clivus reached the peak at each time point, 26.2, 22.4, 21.5 MPa(t=0.5 ms)and 70.0, 55.0, 45.0 MPa(t=1.0 ms)and 38.0, 26.5, 39.5 MPa(t=1.5 ms)and 26.0, 19.0, 23.0 MPa(t=2.0 ms), respectively. When the impact was on the left margo infraorbitalis orbitaeta region, the stress values of the two points(medial left foramen rotundum, posterior clivus)reached the peak at each time point, 8.8, 16.0 MPa(t=0.5 ms)and 10.0, 18.0 MPa(t=1.0 ms)and 5.5, 6.0 MPa(t=1.5 ms)and 11.5, 12.5 MPa(t=2.0 ms), respectively. When the impact was on the body of left zygomatic bone, the stress values of posterior clivus were 45.0 MPa(t=0.5 ms), 40.0 MPa(t=1.0 ms), 12.0 MPa(t=1.5 ms), 42.5 MPa(t= 2.0 ms), respectively.

CONCLUSIONS

According to the difference of stress distribution and conduction of maxillofacial and skull base bone, the speed and the path of force transfer to the skull base were different. Finite-element dynamic simulation can be used for the biomechanics research on maxillofacial trauma.

Systematic review with network meta-analysis: comparative effectiveness and safety of strategies for preventing NSAID-associated gastrointestinal toxicity

BACKGROUND

Many strategies are used to prevent nonsteroidal anti-inflammatory drug (NSAID)-associated gastrointestinal toxicity, but the comparative effectiveness remains unclear.

AIM

To evaluate the comparative effectiveness of clinical strategies for preventing gastrointestinal toxicity induced by NSAIDs.

METHODS

MEDLINE, EMBASE and the Cochrane Library (from their inception to May 2015) were searched for randomised controlled trials comparing the risk of gastrointestinal adverse events in patients taking nonselective NSAIDs, selective cyclooxygenase(COX)-2 inhibitors or nonselective NSAIDs/COX-2 inhibitors plus gastroprotective agents [proton pump inhibitors (PPIs), histamine-2 receptor antagonists, misoprostol]. Both pairwise meta-analysis and Bayesian network meta-analysis were performed.

RESULTS

Analyses were based on 82 trials including 125 053 participants. Network meta-analysis demonstrated that selective COX-2 inhibitors + PPIs [Risk ratio (RR), 95% Credible Interval (CrI): ulcer complications 0.07, 0.02-0.18], selective COX-2 inhibitors (RR, 95% CrI: ulcer complications 0.25, 0.15- 0.38; symptomatic ulcer 0.12, 0.04-0.30), nonselective NSAIDs + PPIs (RR, 95% CrI: ulcer complications 0.28, 0.18-0.41; symptomatic ulcer 0.11, 0.04-0.23), nonselective NSAIDs + misoprostol (RR, 95% CrI: ulcer complications 0.47, 0.24-0.81; symptomatic ulcer 0.41, 0.13-1.00) were associated with significantly lower risk of clinical gastrointestinal events compared with nonselective NSAIDs. For all effectiveness endpoints, selective COX-2 inhibitors + PPIs was associated with the lowest absolute event probability and the highest rank, followed by selective COX-2 inhibitors and thirdly by nonselective NSAIDs + PPIs.

CONCLUSION

The combination of selective COX-2 inhibitors plus PPIs provides the best gastrointestinal protection, followed by selective COX-2 inhibitors, and thirdly by nonselective NSAIDs plus PPIs.

Effects of Coated Compound Proteases on Apparent Total Tract Digestibility of Nutrients and Apparent Ileal Digestibility of Amino Acids for Pigs

Two experiments were conducted to evaluate effects of coated compound proteases (CC protease) on apparent total tract digestibility (ATTD) of nitrogen (N) and energy, and apparent ileal digestibility (AID) of amino acids (AA) and nutrients in diets for pigs. In Exp. 1, 12 crossbred barrows (initial body weight: 20.14±1.71 kg) were housed in individual metabolism crates and allotted into 2 treatments with 6 piglets per treatment according to weight in a randomized complete block design. The 2 diets were corn-soybean meal basal diets with (0.2 g/kg) or without CC protease supplementation. The CC protease supplementation increased (p<0.05) the digestible and metabolizable N and energy values and the digestibility and retention rate of N in the diet. The ATTD of energy and nutrients had been improved (p<0.05) in the diet supplemented with CC protease. In Exp. 2, 12 crossbred barrows (initial body weight: 20.79±1.94 kg), fitted with T-cannulas at the distal ileum, were blocked by body weight into 2 groups with 6 pigs each. The diets were the same as those in Exp. 1. The CC protease increased (p<0.05) the AID of crude protein and some essential AA including arginine, isoleucine and leucine. The AID and ATTD of energy and nutrients had been improved (p<0.05) by supplemental CC protease, but the hindgut digestibility of nutrients was unaffected. Overall, the CC protease improved the ATTD of N and energy and AID of some indispensible AA and nutrients in the corn-soybean meal diet for pigs. Therefore, the CC protease supplement could improve the utilization of protein in the corn-soybean meal diet and thus contribute to lower N excretion to the environment.

Evaluation of left atrial function by speckle tracking echocardiography in patients with systemic lupus erythematosus

Left atrial (LA) function plays a key role in maintaining optimal cardiac output. Left ventricular diastolic dysfunction (LVDD) has been reported in systemic lupus erythematosus (SLE), but whether LA functional abnormalities also occur in patients with SLE is unknown. Toward this aim we evaluated left atrial function and volume by strain and strain rate derived from speckle tracking echocardiography (STE) and their associations with LVDD. Sixty SLE patients were compared with age- and gender-matched normal controls. The LA strain (S) and strain rate (SR) during systole, early diastole and late diastole (SRs, SRe and SRa, respectively) were measured by STE. The LA volume index (LAVI), traditional parameters of LA and left ventricular diastolic function also were analysed. Global strain and positive SRe were significantly reduced in the SLE group compared with the control group (26.2% ± 9.5% vs 32.5% ± 9.8% and −2.4 ± 1.0 s−1 vs −3.1 ± 1.2 s−1, both p < 0.05). The SRs in the SLE and control groups were not significantly different (2.1 ± 0.7 s−1 vs 2.4 ± 0.8 s−1, p = 0.2). The positive SRa was increased in the SLE group compared with the control group (−2.1 ± 0.8 s−1 vs −1.6 ± 0.5 s−1, p < 0.05) and the LAVI was larger in the SLE group than in the control group (32.4 ± 8.0 vs 25.8 ± 7.1 ml/m2, p < 0.001). Patients with SLE exhibiting varying grades of LVDD displayed significant differences in LA parameters, including LAVI, SRs, SRe and SRa (all p < 0.05). Multivariate linear analysis additionally revealed that SLICC/ACR damage index (SDI) was independently and inversely associated with global strain, SRs and positive SRe. LA functions were changed in SLE patients, demonstrating impairment in conduit function, decrease in storage function and increase in pump function. Meanwhile, the magnitude of this impairment was predictively associated with the severity of LVDD. The results from this study demonstrate that STE is capable of detecting various aspects of LA functional impairment during SLE progression, and should be further explored as a diagnostic tool for improving the outcomes of SLE patients.

Spontaneous spinal epidural haematoma

Spontaneous spinal epidural haematoma (SSEH) is a rare clinical condition with unknown aetiology. Prompt diagnosis and treatment are paramount because of the risk of permanent neurological deficits without appropriate intervention. We described a case of a 48-year-old man presenting with complete quadriplegia and hypoesthesia. Magnetic resonance imaging revealed cervical cord compression due to a haematoma posterior to the spinal cord. Surgical decompression and evacuation of the haematoma was performed within 12 hours after admission to the authors' hospital. Both the patient's motor and sensory functions recovered soon after the operation. Early surgical decompression for SSEH with neurologic impairment is therefore recommended for the recovery of this patient and also serves as a relevant reference for orthopaedic clinics.

Foundation number: CXZZ20140414170821148.

Parathyroid hormone-related peptide (PTHrP): prokaryotic expression, purification, and preparation of a polyclonal antibody

Parathyroid hormone-related peptide (PTHrP) plays important roles in promoting cancer occurrence and in the development of bone metastases. To increase our knowledge of the biological functions of PTHrP, the prokaryotic expression vector pET-PTHrP was successfully constructed and the His-PTHrP fusion protein was expressed in Escherichia coli. Anti-PTHrP polyclonal antibody was then prepared from rabbits. Finally, the goat tissue expression profile of PTHrP was analyzed by Western blot with the anti-PTHrP polyclonal antibody. The results showed that the expression of PTHrP in goat mammary glands was significantly higher than that in other organs. This indicates that PTHrP may play important roles in the goat mammary gland. The antibody prepared will be a useful tool for detecting PTHrP and will be valuable in future studies investigating the role of PTHrP in calcium metabolism in the goat model.

An animal experimental study of porous magnesium scaffold degradation and osteogenesis

Our objective was to observe the biodegradable and osteogenic properties of magnesium scaffolding under in vivo conditions. Twelve 6-month-old male New Zealand white rabbits were randomly divided into two groups. The chosen operation site was the femoral condyle on the right side. The experimental group was implanted with porous magnesium scaffolds, while the control group was implanted with hydroxyapatite scaffolds. X-ray and blood tests, which included serum magnesium, alanine aminotransferase (ALT), creatinine (CREA), and blood urea nitrogen (BUN) were performed serially at 1, 2, and 3 weeks, and 1, 2, and 3 months. All rabbits were killed 3 months postoperatively, and the heart, kidney, spleen, and liver were analyzed with hematoxylin and eosin (HE) staining. The bone samples were subjected to microcomputed tomography scanning (micro-CT) and hard tissue biopsy. SPSS 13.0 (USA) was used for data analysis, and values of P<0.05 were considered to be significant. Bubbles appeared in the X-ray of the experimental group after 2 weeks, whereas there was no gas in the control group. There were no statistical differences for the serum magnesium concentrations, ALT, BUN, and CREA between the two groups (P>0.05). All HE-stained slices were normal, which suggested good biocompatibility of the scaffold. Micro-CT showed that magnesium scaffolds degraded mainly from the outside to inside, and new bone was ingrown following the degradation of magnesium scaffolds. The hydroxyapatite scaffold was not degraded and had fewer osteoblasts scattered on its surface. There was a significant difference in the new bone formation and scaffold bioabsorption between the two groups (9.29 ± 1.27 vs 1.40 ± 0.49 and 7.80 ± 0.50 vs 0.00 ± 0.00 mm3, respectively; P<0.05). The magnesium scaffold performed well in degradation and osteogenesis, and is a promising material for orthopedics.

Development and performance evaluation of an electromagnetic-type shock wave generator for lipolysis

This study aims at the design and development of electromagnetic-type intermittent shock wave generation in a liquid. The shock wave generated is focused at a focal point through an acoustic lens. This hardware device mainly consists of a full-wave bridge rectifier, 6 capacitors, a spark gap, and a flat coil. A metal disk is mounted in a liquid-filled tube and is placed in close proximity to the flat coil. Due to the repulsive force existing between the coil and disk shock waves are generated, while an eddy current is induced in the metal disk. Some components and materials associated with the device are also described. By increasing the capacitance content to enhance electric energy level, a highly focused pressure can be achieved at the focal point through an acoustic lens in order to lyse fat tissue. Focused pressures were measured at the focal point and its vicinity for different operation voltages. The designed shock wave generator with an energy intensity of 0.0016 mJ/mm(2) (at 4 kV) and 2000 firings or higher energy intensities with 1000 firings is found to be able to disrupt pig fat tissue.

QAM accommodated double-side band fast OFDM based on IDCT

In this paper, we theoretically and experimentally prove that sub-carriers in double-side band fast orthogonal frequency division multiplexing (DSB-FOFDM) are orthogonal over a symbol interval independent of the signal phase and amplitude. Therefore, the commonly utilized DSB-FOFDM is quadrature amplitude modulation (QAM) accommodated; while previously DSB-FOFDM was usually modulated by amplitude shift keying (ASK) or binary phase shift keying (BPSK). In our proof-of-concept experiments, bit error ratio (BER) performance of 10 Gb/s quadrature phase shift keying (QPSK) modulated DSB-FOFDM was equivalent to that of 10 Gb/s QPSK modulated OFDM after 500 km standard single mode fiber (SSMF) transmission. 10 Gb/s QPSK modulated DSB-FOFDM largely outperformed the commonly utilized 4-ASK modulated DSB-FOFDM in BER performance. Additionally, BER performance of 10 Gb/s 16-QAM modulated DSB-FOFDM was equivalent to that of 10 Gb/s 16-QAM modulated OFDM after 500 km SSMF transmission.

Transcriptome analysis of glioma cells for the dynamic response to γ-irradiation and dual regulation of apoptosis genes: a new insight into radiotherapy for glioblastomas

Ionizing radiation (IR) is of clinical importance for glioblastoma therapy; however, the recurrence of glioma characterized by radiation resistance remains a therapeutic challenge. Research on irradiation-induced transcription in glioblastomas can contribute to the understanding of radioresistance mechanisms. In this study, by using the total mRNA sequencing (RNA-seq) analysis, we assayed the global gene expression in a human glioma cell line U251 MG at various time points after exposure to a growth arrest dose of γ-rays. We identified 1656 genes with obvious changes at the transcriptional level in response to irradiation, and these genes were dynamically enriched in various biological processes or pathways, including cell cycle arrest, DNA replication, DNA repair and apoptosis. Interestingly, the results showed that cell death was not induced even many proapoptotic molecules, including death receptor 5 (DR5) and caspases were activated after radiation. The RNA-seq data analysis further revealed that both proapoptosis and antiapoptosis genes were affected by irradiation. Namely, most proapoptosis genes were early continually responsive, whereas antiapoptosis genes were responsive at later stages. Moreover, HMGB1, HMGB2 and TOP2A involved in the positive regulation of DNA fragmentation during apoptosis showed early continual downregulation due to irradiation. Furthermore, targeting of the TRAIL/DR5 pathway after irradiation led to significant apoptotic cell death, accompanied by the recovered gene expression of HMGB1, HMGB2 and TOP2A. Taken together, these results revealed that inactivation of proapoptotic signaling molecules in the nucleus and late activation of antiapoptotic genes may contribute to the radioresistance of gliomas. Overall, this study provided novel insights into not only the underlying mechanisms of radioresistance in glioblastomas but also the screening of multiple targets for radiotherapy.

Upregulated Hoxc6 expression is associated with poor survival in gastric cancer patients

Human Hox genes (Homeobox) have crucial roles in development and differentiation, regulating numerous processes including apoptosis, receptor signalling, differentiation, motility and angiogenesis. Aberrant expression of Hoxc6 gene has been reported in several tumor tissues and cancer cell lines. The prognostic significance of Hoxc6 in gastric cancer remains largely unknown.This study was aimed to investigate the clinical significance of Hoxc6 in gastric cancer.Total RNA of paired tissue samples (n=25) and a tissue microarray containing 161 paired tissues from patients with gastric cancers at different stages were collected. Quantitative real-time PCR and immunochemistry assay were carried out to investigate the expression of Hoxc6. Hoxc6 mRNA was increased in gastric cancer tissues ( 16 of 25) compared with the adjacent normal mucosa (P<0.05). Immunohistochemical detection showed that expression of Hoxc6 was associated with the depth of tumor invasion (P<0.05). Patients with higher expression levels of Hoxc6 had a shorter overall survival rate (P<0.05).Hoxc6 might contribute to the progression of gastric carcinogenesis and may be a significant predictor of poor survival in patients with gastric cancer after curative operations.

Probing the location of displayed cytochrome b562 on amyloid by scanning tunnelling microscopy

Amyloid fibres displaying cytochrome b562 were probed using scanning tunnelling microscopy (STM) in vacuo. The cytochromes are electron transfer proteins containing a haem cofactor and could, in principle, mediate electron transfer between the tip and the gold substrate. If the core fibres were insulating and electron transfer within the 3D haem network was detected, then the electron transport properties of the fibre could be controlled by genetic engineering. Three kinds of STM images were obtained. At a low bias (<1.5 V) the fibres appeared as regions of low conductivity with no evidence of cytochrome mediated electron transfer. At a high bias, stable peaks in tunnelling current were observed for all three fibre species containing haem and one species of fibre that did not contain haem. In images of this kind, some of the current peaks were collinear and spaced around 10 nm apart over ranges longer than 100 nm, but background monomers complicate interpretation. Images of the third kind were rare (1 in 150 fibres); in these, fully conducting structures with the approximate dimensions of fibres were observed, suggesting the possibility of an intermittent conduction mechanism, for which a precedent exists in DNA. To test the conductivity, some fibres were immobilized with sputtered gold, and no evidence of conduction between the grains of gold was seen. In control experiments, a variation of monomeric cytochrome b562 was not detected by STM, which was attributed to low adhesion, whereas a monomeric multi-haem protein, GSU1996, was readily imaged. We conclude that the fibre superstructure may be intermittently conducting, that the cytochromes have been seen within the fibres and that they are too far apart for detectable current flow between sites to occur. We predict that GSU1996, being 10 nm long, is more likely to mediate successful electron transfer along the fibre as well as being more readily detectable when displayed from amyloid.

Source apportionment of sediment-associated aliphatic hydrocarbon in a eutrophicated shallow lake, China

Chaohu Lake, one of the most eutrophicated lakes in China, has been suffering from long-term outside pollution, urban sewage, river outflows, and agricultural runoff which expectedly have been the main contributors of hydrocarbons. However, the contributions from these various sources have not been specified. The present study is aimed at identifying the potential sources of hydrocarbons in surface sediment around the whole lake and assessing the relative contributions using principal components analysis-multiple linear regression (PCA-MLR). Sixty-one surface sediments covering the whole Chaohu Lake and three main estuaries of inflowing rivers were collected, dried, extracted, and analyzed for 27 normal alkanes (n-alkanes, from C(12) to C(38), defined Σ(27)AH) and unresolved complex mixture (UCM) by GC/MS. Diagnostic ratios and PCA-MLR were utilized to apportion their sources. The concentrations of Σ(27)AH and UCM ranged from 434 to 3,870 ng/g and 11.9 to 325 μg/g dry weight, respectively, for all samples. The concentrations of Σ(27)AH in western region and estuary of Nanfei River were slightly higher but without statistical significance than those from eastern region and estuaries of Yuxi River and Hangbu River. The concentration of UCM from western region was significantly higher than that obtained from eastern region. These results reflect the importance of input of urban runoff by Nanfei River and serious eutrophication in western region. Aliphatic hydrocarbons in Chaohu Lake were mainly derived from high plant wax with mixed sources of phytoplankton and petroleum. Weak microbial decomposition of n-alkanes would be expected to occur from the low ratios of isoprenoid hydrocarbons pristine (pri) and phytane (phy) to n-C(17) and n-C(18), respectively. Higher plant, fossil combustion, petroleum residue, and phytoplankton were proposed as the main origines of aliphatic hydrocarbons by PCA while the contributions of individual n-alkane homologues, pri and phy from the identified sources (31 % from higher plant, 30 % from fossil combustion, 26 % from petroleum, and 19 % from phytoplankton) were well predicted using MLR. The distribution profile and corresponding diagnostic ratios of normal alkanes show the promising potential as a useful proxy for estimating the source and loading of pollutants in Chaohu Lake.

Altering the ordering and disordering of a triangular nanographene at room temperature

Molecular self-organization has the potential to serve as an efficient and versatile tool for the spontaneous creation of low-dimensional nanostructures on surfaces. We demonstrate how the subtle balance between intermolecular interactions and molecule-surface interactions can be altered by modifying the environment or through manipulation by means of the tip in a scanning tunnelling microscope (STM) at room temperature. We show how this leads to the distinctive ordering and disordering of a triangular nanographene molecule, the trizigzag-hexa-peri-hexabenzocoronenes-phenyl-6 (trizigzagHBC-Ph6), on two different surfaces: graphite and Au(111). The assembly of submonolayer films on graphite reveals a sixfold packing symmetry under UHV conditions, whereas at the graphite-phenyloctane interface, they reorganize into a fourfold packing symmetry, mediated by the solvent molecules. On Au(111) under UHV conditions in the multilayer films we investigated, although disorder prevails with the molecules being randomly distributed, their packing behaviour can be altered by the scanning motion of the tip. The asymmetric diode-like current-voltage characteristics of the molecules are retained when deposited on both substrates. This paper highlights the importance of the surrounding medium and any external stimulus in influencing the molecular organization process, and offers a unique approach for controlling the assembly of molecules at a desired location on a substrate.

PIK3CA exon 20 mutations as a potential biomarker for resistance to anti-EGFR monoclonal antibodies in KRAS wild-type metastatic colorectal cancer: a systematic review and meta-analysis

BACKGROUND

We conducted a systematic review and meta-analysis to dissect the association between PIK3CA mutations and resistance to anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MoAbs) according to PIK3CA exon of mutations in metastatic colorectal cancer (mCRC).

METHODS

We systematically identified studies exploring the association between PIK3CA mutations and clinical outcomes of mCRC patients treated with anti-EGFR MoAbs. The primary clinical outcomes included objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). The pooled relative risk (RR) or hazard ratio (HR) was estimated by using fixed effect model or random effect model according to heterogeneity between studies.

RESULTS

Thirteen studies were considered eligible, with 576 mCRC patients included. In KRAS wild-type mCRC patients, we observed a lower ORR in patients with PIK3CA exon 20 mutations [3 studies, 377 patients; ORR = 0% versus 37%; RR = 0.25; 95% confidence interval (CI) 0.05-1.19; P = 0.082], although the result was not statistically significant because of the small sample size. Only one study provided survival data according to the PIK3CA exon of the mutations, in which PIK3CA exon 20 mutations were statistically significantly associated with shorter PFS (HR = 2.52; 95% CI 1.33-4.78; P = 0.013) and OS (HR = 3.29; 95% CI 1.60-6.74; P = 0.006) in KRAS wild-type mCRC patients treated with anti-EGFR MoAbs. The predictive power of exon 20 mutation is greater than exon 9 mutations and all exons mutations in terms of ORR, PFS, and OS.

CONCLUSION

These analyses suggest that PIK3CA exon 20 mutations may be a potential biomarker for resistance to anti-EGFR MoAbs in KRAS wild-type mCRC.

Ultrabroadband optical circular polarizers consisting of double-helical nanowire structures

Recently, it was demonstrated by Gansel et al. [Science 325, 1513 (2009)] that 3D single-helical metamaterials can serve as broadband circular polarizers in the IR range. In this study, we propose a structured metamaterial with double-helical nanowires to construct circular polarizers with boarder wavelength bands in the visible-light and near-IR regions. Using the finite-difference time-domain method, we confirmed that the circular polarizers with the double-helical structures have operation bands more than 50% broader than those of the single-helical structures.

Complete mitochondrial genome of Cabot's tragopan, Tragopan caboti (Galliformes: Phasianidae)

Cabot's tragopan, Tragopan caboti, is a globally threatened pheasant endemic to southeast China. The complete mitochondrial genome of Cabot's tragopan was sequenced. The circular genome contains 16,727 bp, encoding a standard set of 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes, plus the putative control region, a structure very similar to that of other Galliformes. As found in other vertebrates, most of these genes code on the H-strand, except for the NADH dehydrogenase subunit 6 (nad6) and eight tRNA genes (Gln, Ala, Asn, Cys, Tyr, Ser(UCN), Pro, Glu). All protein-coding genes initiated with ATG, except for cox1, which began with GTG, and had a strong skew of C vs G (GC skew = -0.29 to -0.73). One extra 'C' nucleotide was found in the NADH dehydrogenase subunit 3 (nad3). All the tRNA gene sequences have the potential to fold into typical cloverleaf secondary structures. Conserved sequences in three domains were identified within the control region (D-loop). These results provide basic information for phylogenetic analyses among Galliform birds, and especially Tragopan species.

Modeling local structure using crystal field and spin Hamiltonian parameters: the tetragonal Fe(K)(3+)-O(I)(2-) defect center in KTaO(3) crystal

The local structure and the spin Hamiltonian (SH) parameters, including the zero-field-splitting (ZFS) parameters D and (a+2F/3), and the Zeeman g factors [Formula: see text] and [Formula: see text], are theoretically investigated for the Fe(K)(3+)-O(I)(2-) center in KTaO(3) crystal. The microscopic SH (MSH) parameters are modeled within the framework of the crystal field (CF) theory employing the CF analysis (CFA) package, which also incorporates the MSH modules. Our approach takes into account the spin-orbit interaction as well as the spin-spin and spin-other-orbit interactions omitted in previous studies. The superposition model (SPM) calculations are carried out to provide input CF parameters for the CFA/MSH package. The combined SPM-CFA/MSH approach is used to consider various structural models for the Fe(K)(3+)-O(I)(2-) defect center in KTaO(3). This modeling reveals that the off-center displacement of the Fe(3+) ions, Δ(1)(Fe(3+)), combined with an inward relaxation of the nearest oxygen ligands, Δ(2)(O(2-)), and the existence of the interstitial oxygen O(I)(2-) give rise to a strong tetragonal crystal field. This finding may explain the large ZFS experimentally observed for the Fe(K)(3+)-O(I)(2-) center in KTaO(3). Matching the theoretical MSH predictions with the available structural data as well as electron magnetic resonance (EMR) and optical spectroscopy data enables predicting reasonable ranges of values of Δ(1)(Fe(3+)) and Δ(2)(O(2-)) as well as the possible location of O(I)(2-) ligands around Fe(3+) ions in KTaO(3). The defect structure model obtained using the SPM-CFA/MSH approach reproduces very well the ranges of the experimental SH parameters D, [Formula: see text] and [Formula: see text] and importantly yields not only the correct magnitude of D but also the sign, unlike previous studies. More reliable predictions may be achieved when experimental data on (a+2F/3) and/or crystal field energy levels become available. Comparison of our results with those arising from alternative models existing in the literature indicates considerable advantages of our method and presumably higher reliability of our predictions.