Inverse pseudo Hall-Petch relation in polycrystalline graphene

Understanding the grain size-dependent failure behavior of polycrystalline graphene is important for its applications both structurally and functionally. Here we perform molecular dynamics simulations to study the failure behavior of polycrystalline graphene by varying both grain size and distribution. We show that polycrystalline graphene fails in a brittle mode and grain boundary junctions serve as the crack nucleation sites. We also show that its breaking strength and average grain size follow an inverse pseudo Hall-Petch relation, in agreement with experimental measurements. Further, we find that this inverse pseudo Hall-Petch relation can be naturally rationalized by the weakest-link model, which describes the failure behavior of brittle materials. Our present work reveals insights into controlling the mechanical properties of polycrystalline graphene and provides guidelines for the applications of polycrystalline graphene in flexible electronics and nano-electronic-mechanical devices.

Molecular dynamics simulations on the frictional behavior of a perfluoropolyether film sandwiched between diamond-like-carbon coatings

We perform molecular dynamics simulations to investigate the nanoscale frictional behavior of a perfluoropolyether (PFPE) film sandwiched between two diamond-like-carbon (DLC) coatings. We show that the PFPE films behave like a solid and can perform either a motion-station movement or a continuous motion with fluctuating velocities. The former movement is caused by the alternating stick and slip at the two individual interfaces, while the latter is due to the dynamic sliding motions simultaneously occurring at both interfaces. We reveal that these motion characteristics are governed by the competition between the two interfacial adhesion energies, which are strongly affected by the thermal vibrations and interface roughness fluctuations. We also find that the Amonton's law modified by incorporating the adhesion effect can be used to describe the mean friction traction vs normal pressure relation, but large fluctuations are present at low contact pressures. The magnitude of atomic level friction forces at the interface is found to be highly nonuniform. The directions of atomic level friction forces can even be opposite. With increasing the normal pressure, the nonuniformity of atomic level friction forces decreases first and then increases again. This change can be explained by the concurrent effects from the large difference in material stiffness and the changes in surface roughness under normal pressure. The present work reveals interesting insights into the sliding mechanisms in sandwiched structures and provides useful guidelines for the design of nanoscale lubricant systems.

Facile Fabrication of Antibacterial Core–Shell Nanoparticles Based on PHMG Oligomers and PAA Networks via Template Polymerization

Antibacterial core–shell nanoparticles based on poly(hexamethylene guanidine hydrochloride) (PHMG) oligomers and poly(acrylic acid) (PAA) networks are efficiently fabricated via a facile one-step co-polymerization of acrylic acid and N,N′-methylenebisacrylamide on PHMG templates in aqueous solution. Dynamic light scattering, Fourier-transform infrared spectroscopy, and transmission electron microscopy observations were used to characterize the size, morphology, and structure of the nanoparticles, as well as the interactions between the components. Also, the stability of the nanoparticle dispersion against storage, pH value, salt, and temperature was investigated. The results show that the crosslinked PAA/PHMG nanoparticles are stabilized by electrostatic interactions. The core–shell structure of the nanoparticles was confirmed by transmission electron microscopy observation. The size of the nanoparticles increases substantially with extension of storage or with increase of the salt concentration. The nanoparticle dispersion is stable in a pH range of 2.0–4.0. The size change of the nanoparticles with pH of the medium is parabolic, and the minimum size is reached at pH 3.0. A rise of temperature leads to a slight and recoverable size increase of the nanoparticles. Antibacterial efficiency was evaluated quantitatively against Escherichia coli and Staphylococcus aureus by the plating method according to Standard JC/T 897–2002. The antibacterial activity against these two bacteria are both above 99.0 % at a nanoparticle concentration of 5 mg mL–1. This makes the nanoparticle dispersion a good candidate for the application of antibacterial water-based coatings and textiles coating.

SRAP analysis of genetic diversity of nine native populations of wild sugarcane, Saccharum spontaneum, from Sichuan, China

Saccharum spontaneum is a wild sugarcane species that is native to and widely distributed in China. It has been extensively used in sugarcane breeding programs, and is being tested for the development of bioenergy cultivars. In order to provide basic information for the exploitation of this species, we analyzed genetic variation among and within native S. spontaneum populations collected from Sichuan, China. Eighty plants from nine native populations were sampled. Twenty-one sequence-related amplified polymorphism primer pairs generated 235 clearly scorable bands, of which 185 were polymorphic (78.7%). Nei's genetic diversity was 0.2801 and Shannon's information index was 0.4155 across the populations. Genetic diversity parameters, G(ST) value (0.2088) and N(m) value (1.8944), showed that the genetic variation within populations was greater than that among populations. In the cluster analysis, one major grouping was formed by populations from Ya'an and another one by populations from Sichuan basin; a population from Baoxing formed a single cluster. In order to fully comprehend the genetic diversity of cold-tolerant local germplasm in this species, germplasm should be collected from the heterogeneous environments along the northern regions of this species' distribution. The germplasm that we collected should be a valuable resource for Saccharum breeding.

Patterned graphone--a novel template for molecular packing

Precise positioning and packing of nanoscale building blocks is essential for the fabrication of many nanoelectro-mechanical devices. Carrying out such manipulations at the nanoscale still remains a challenge. Here we propose the use of graphone domain arrays embedded in a graphene sheet as a template to precisely position and pack molecules. Our atomistic simulations show that a graphone domain is able to adopt well-defined three-dimensional geometries, which in turn create 'energy wells' to trap molecules by means of physisorption. Using the C60 molecule as a model block, the stable trapping conditions are identified. The present work presents a novel route to position and pack molecules for nanoengineering applications.

Atomic scale fluctuations govern brittle fracture and cavitation behavior in metallic glasses

We perform atomistic simulations on the fracture behavior of two typical metallic glasses, one brittle (FeP) and the other ductile (CuZr), and show that brittle fracture in the FeP glass is governed by an intrinsic cavitation mechanism near crack tips in contrast to extensive shear banding in the ductile CuZr glass. We show that a high degree of atomic scale spatial fluctuations in the local properties is the main reason for the observed cavitation behavior in the brittle metallic glass. Our study corroborates with recent experimental observations of nanoscale cavity nucleation found on the brittle fracture surfaces of metallic glasses and provides important insights into the root cause of the ductile versus brittle behavior in such materials.

Effect of loading conditions on the dissociation behaviour of catch bond clusters

Under increasing tensile load, the lifetime of a single catch bond counterintuitively increases up to a maximum and then decreases exponentially like a slip bond. So far, the characteristics of single catch bond dissociation have been extensively studied. However, it remains unclear how a cluster of catch bonds behaves under tensile load. We perform computational analysis on the following models to examine the characteristics of clustered catch bonds: (i) clusters of catch bonds with equal load sharing, (ii) clusters of catch bonds with linear load sharing, and (iii) clusters of catch bonds in micropipette-manipulated cell detachment. We focus on the differences between the slip and catch bond clusters, identifying the critical factors for exhibiting the characteristics of catch bond mechanism for the multiple-bond system. Our computation reveals that for a multiple-bond cluster, the catch bond behaviour could only manifest itself under relatively uniform loading conditions and at certain stages of decohesion, explaining the difficulties in observing the catch bond mechanism under real biological conditions.

Downregulation of fibulin-3 gene by promoter methylation in colorectal cancer predicts adverse prognosis

Fibulin-3 gene has been identified as an antagonist of angiogenesis. We investigated the protein expression and promoter methylation status of fibulin-3 gene in colorectal cancer (CRC) and analyzed its correlation with clinicopathological factors. The study population enrolled 85 paired CRC specimens and adjacent normal tissues, as well as 32 cases of colorectal adenoma. Genomic DNA was extracted from paraffin-embedded samples using manual microdissection. Methylation-specific polymerase chain reaction (MSP) was used to determine the promoter methylation status and fibulin-3 gene expression was detected by immunohistochemistry. The results showed that, downregulation or silence of fibulin-3 protein was found in 57.6% (49/85) of CRC tissues, which was significantly higher than that of adjacent normal tissues (28.2%, 24/85) and colorectal adenoma (34.4%, 11/32) (P<0.05). Furthermore, 33 out of 85 (38.8%) CRC specimens showed hypermethylation in fibulin-3 promoter region, and fibulin-3 methylation was closely correlated with its loss of expression. Also, downregulation of fibulin-3 was associated with advanced stage (P=0.008) and lymph node metastasis (P=0.013). Survival analyses and Cox proportional hazard models indicated that fibulin-3 downregulation was an independent factor related to adverse overall survival (OS) and disease-free survival (DFS) of CRC. In conclusion, we found aberrant methylation caused fibulin-3 downregulation in CRC, and fibulin-3 downregulation was correlated with tumor stage, lymph node metastasis and poor survival, which maybe use as a potential prognostic factor for CRC.

Long-term outcomes of late course accelerated hyper-fractionated radiotherapy for localized esophageal carcinoma in Mainland China: a meta-analysis

Published data on the long-term survival results of patients with localized esophageal carcinoma receiving late course accelerated hyper-fractionated radiotherapy (LCAF RT) versus conventional fractionated radiotherapy (CF RT) are inconclusive. In order to derive a more precise estimation of the both treatment-regimes, a meta-analysis based on systematic review of published articles was performed. A meta-analysis was performed using trials identified through Pubmed and Chinese national knowledge infrastructure. Results in 5-year survival and 5-year local control were collected from randomized trials comparing LCAF RT with CF RT. Review Manager (The Cochrane Collaboration, Oxford, England) and Stata software (Stata Corporation, College Station, TX, USA) were used for data management. A total of 11 trials were involved in this analysis with 572 cases and 567 controls. Our results showed that LCAF RT, compared with CF RT, significantly improved the 5-year survival (odds ratio [OR]= 2.93, 95% confidence interval [CI]: 2.15-4.00, P < 0.00001) and 5-year local control (OR = 3.96, 95% CI: 2.91-5.38, P < 0.00001). LCAF RT was more therapeutically beneficial than CF RT in the localized esophageal carcinoma.

Sliding-induced non-uniform pre-tension governs robust and reversible adhesion: a revisit of adhesion mechanisms of geckos

Several mechanisms have been proposed in the literature to explain the robust attachment and rapid, controllable detachment of geckos' feet on vertical walls or ceilings, yet, it is still debatable, which one is ultimately responsible for geckos' extraordinary capabilities for robust and reversible adhesion. In this paper, we re-examine some of the key movements of geckos' spatula pads and seta hairs during attachment and detachment, and propose a sequence of simple mechanical steps that would lead to the extraordinary properties of geckos observed in experiments. The central subject under study here is a linear distribution of pre-tension along the spatula pad induced by its sliding motion with respect to a surface. The resulting pre-tension, together with a control of setae's pulling force and angle, not only allows for robust and strong attachment, but also enables rapid and controllable detachment. We perform computational modelling and simulations to validate the following key steps of geckos' adhesion: (i) creation of a linear distribution of pre-tension in spatula through sliding, (ii) operation of an instability envelope controlled by setae's pulling force and angle, (iii) triggering of an adhesion instability leading to partial decohesion along the interface, and (iv) complete detachment of spatula through post-instability peeling. The present work not only reveals novel insights into the adhesion mechanism of geckos, but also develops a powerful numerical simulation approach as well as additional guidelines for bioinspired materials and devices.

Transcriptional inactivation of secreted frizzled-related protein 1 by promoter hypermethylation as a potential biomarker for non-small cell lung cancer

Epigenetic silencing of secreted frizzled-related protein (SFRP) genes, antagonists of the WNT pathway, contributes to the pathogenesis of several cancers including non-small cell lung cancer (NSCLC). We hypothesize that methylation analysis of SFRPs family could improve their use as a panel of biomarkers for diagnosing and staging of NSCLC in China. The expression of four SFRP members (SFRP1, 2, 4, and 5) in NSCLC samples was screened by RT-PCR and quantitative real-time PCR. Only SFRP1 was significantly downregulated in NSCLC, as compared to adjacent normal tissues and benign pulmonary disease tissues (P=0.006). Promoter hypermethylation of SFRP1 was found in 32.1% (25/78) NSCLC specimens and was closely correlated with loss of expression, besides SFRP1 hypermethylation was associated with lymph metastasis (P=0.039) and disease progression within one year (P=0.027). Furthermore, methylated SFRP1 was detected in 28.2% (22/78) of plasma samples from NSCLC patients while only 4% (2/50) in cancer-free controls, and the concordance of SFRP1 methylation status in tumor tissues and corresponding plasmas was satisfactory (P <0.001). In conclusion, epigenetic inactivation of SFRP1 is a common event contributing to lung carcinogenesis and maybe used as a potential biomarker for NSCLC in Chinese population.

Study of Materials Deformation in Nanometric Cutting by Large-scale Molecular Dynamics Simulations

Nanometric cutting involves materials removal and deformation evolution in the surface at nanometer scale. At this length scale, atomistic simulation is a very useful tool to study the cutting process. In this study, large-scale molecular dynamics (MD) simulations with the model size up to 10 millions atoms have been performed to study three-dimensional nanometric cutting of copper. The EAM potential and Morse potential are used, respectively, to compute the interaction between workpiece atoms and the interactions between workpiece atoms and tool atoms. The material behavior, surface and subsurface deformation, dislocation movement, and cutting forces during the cutting processes are studied. We show that the MD simulation model of nanometric cutting has to be large enough to eliminate the boundary effect. Moreover, the cutting speed and the cutting depth have to be considered in determining a suitable model size for the MD simulations. We have observed that the nanometric cutting process is accompanied with complex material deformation, dislocation formation, and movement. We find that as the cutting depth decreases, the tangential cutting force decreases faster than the normal cutting force. The simulation results reveal that as the cutting depth decreases, the specific cutting force increases, i.e., "size effect" exists in nanometric cutting.

Edge-stress-induced warping of graphene sheets and nanoribbons

We show that edge stresses introduce intrinsic ripples in freestanding graphene sheets even in the absence of any thermal effects. Compressive edge stresses along zigzag and armchair edges of the sheet cause out-of-plane warping to attain several degenerate mode shapes. Based on elastic plate theory, we identify scaling laws for the amplitude and penetration depth of edge ripples as a function of wavelength. We also demonstrate that edge stresses can lead to twisting and scrolling of nanoribbons as seen in experiments. Our results underscore the importance of accounting for edge stresses in thermal theories and electronic structure calculations for freestanding graphene sheets.

Normal gestation after 5 years on home parenteral nutrition

A case of normal gestation after 5 years on HPN is reported. The patient had her entire jejunum and ileum and right colon resected because of gangrene and has subsisted normally on HPN ever since. From the second trimester on, her HPN formula was supplemented to meet the requirement for growth and development of the foetus. Anaemia, hypoalbuminaemia, low plasma zinc levels and jaundice became manifest in the final trimester. These responded readily to readjustment of her HPN formula. A normal baby weighing 2020 g was delivered by Caesarean section at 36 weeks. Long-term HPN, final trimester abnormalities and HPN formula adjustments are discussed.

Adjuvant chemotherapy of cisplatin, 5-fluorouracil and leucovorin for complete resectable esophageal cancer: a case-matched cohort study in east China

It is still controversial whether adjuvant chemotherapy of cisplatin, 5-fluorouracil and leucovorin can increase the overall survival of esophageal cancer patients, and which subgroup of patients get most benefits from it. Between 1998 and 2004, 66 esophageal cancer patients with adjuvant chemotherapy and 160 well-matched patients without chemotherapy were included in this study. Nine markers were measured in the protein level to analyze prognostic significance. In the whole group, adjuvant chemotherapy did not improve the survival of esophageal cancer patients. There was also no significant difference for survival in stage I (P=0.59 and P=0.59), stage II (P=0.28 and P=0.28) and stage III patients (P=0.144 and P=0.06) between the observation and the chemotherapy group. Chemotherapy was most effective for the patients who had metastases in cervical and/or celiac lymph nodes (IV subgroup). One and 3-year disease-free survival and overall survival were significantly better than for those who did not receive the chemotherapy(P=0.038, and 0.016, respectively). Bcl-2 expression was a bad prognostic factor, and was more predictive in the adjuvant chemotherapy group than in the no-chemotherapy group. Adjuvant chemotherapy significantly improved the treatment result of stage IV patients compared with the observation group. Bcl-2 could be used to analyze prognosis and guide the adjuvant treatment.

Computational analysis of adhesion force in the indentation of cells using atomic force microscopy

A mechanical model was developed to study the indentation of an atomic force microscopic (AFM) tip on a cell with adhesion mediated by receptor-ligand binding. The effects of indentation rate, indentation depth, indenter size, and the mechanical properties of cells on the adhesion force were investigated. It was found that the presence of adhesion between the cell and AFM tip may affect both the loading curve and unloading curve, which may in turn change the extracted elastic modulus values using the conventional indentation models. It was found that an increase in the receptor-ligand reaction rate may lead to a transition from a decrease of the maximum adhesion force with the indentation rate to an increase of the maximum adhesion force with the indentation rate. It was also found that factors such as indenter size, indentation depth, and cell mechanical properties influence the maximum adhesion force, and their corresponding underlying mechanisms were discussed.

Direct identification of propargyl radical in combustion flames by vacuum ultraviolet photoionization mass spectrometry

We have developed an effusive laser photodissociation radical source, aiming for the production of vibrationally relaxed radicals. Employing this radical source, we have measured the vacuum ultraviolet (VUV) photoionization efficiency (PIE) spectrum of the propargyl radical (C(3)H(3)) formed by the 193 nm excimer laser photodissociation of propargyl chloride in the energy range of 8.5-9.9 eV using high-resolution (energy bandwidth = 1 meV) multibunch synchrotron radiation. The VUV-PIE spectrum of C(3)H(3) thus obtained is found to exhibit pronounced autoionization features, which are tentatively assigned as members of two vibrational progressions of C(3)H(3) in excited autoionizing Rydberg states. The ionization energy (IE = 8.674 +/- 0.001 eV) of C(3)H(3) determined by a small steplike feature resolved at the photoionization onset of the VUV-PIE spectrum is in excellent agreement with the IE value reported in a previous pulsed field ionization-photoelectron study. We have also calculated the Franck-Condon factors (FCFs) for the photoionization transitions C(3)H(3) (+)(X;nu(i),i = 1-12)<--C(3)H(3)(X). The comparison between the pattern of FCFs and the autoionization peaks resolved in the VUV-PIE spectrum of C(3)H(3) points to the conclusion that the resonance-enhanced autoionization mechanism is most likely responsible for the observation of pronounced autoionization features. We also present here the VUV-PIE spectra for the mass 39 ions observed in the VUV synchrotron-based photoionization mass spectrometric sampling of several premixed flames. The excellent agreement of the IE value and the pattern of autoionizing features of the VUV-PIE spectra observed in the photodissociation and flames studies has provided an unambiguous identification of the propargyl radical as an important intermediate in the premixed combustion flames. The discrepancy found between the PIE spectra obtained in flames and photodissociation at energies above the IE(C(3)H(3)) suggests that the PIE spectra obtained in flames might have contributions from the photoionization of vibrationally excited C(3)H(3) and/or the dissociative photoionization processes involving larger hydrocarbon species formed in flames.

Cytotoxicity of Marchantia convoluta leaf extracts to human liver and lung cancer cells

The cytotoxicity of three extracts (petroleum ether, ethyl acetate and n-butanol) from a plant used in folk medicine, Marchantia convoluta, to human non-small cell lung carcinoma (H1299) and liver carcinoma (HepG2) cell lines was tested. After 72-h incubation of lung and liver cancer cell cultures with varying concentrations of extracts (15 to 200 microg/mL), cytotoxicity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and reported in terms of cell viability. The extracts that showed a significant cytotoxicity were subjected to gas chromatography-mass spectrometry analysis to identify the components. The ethyl acetate, but not the petroleum ether or n-butanol extract, had a significant cytotoxicity against lung and liver carcinoma cells with IC50 values of 100 and 30 microg/mL, respectively. A high concentration of ethyl acetate extract (100 microg/mL) rapidly reduced the number of H1299 cells. At lower concentrations of ethyl acetate extract (15, 30, and 40 microg/mL), the numbers of HepG2 cells started to decrease markedly. Gas chromatography-mass spectrometry analysis of the ethyl acetate extract revealed the presence of several compounds such as phytol (23.42%), 1,2,4-tripropylbenzene (13.09%), 9-cedranone (12.75%), ledene oxide (7.22%), caryophyllene (1.82%), and caryophyllene oxide (1.15%). HPLC analysis result showed that there were no flavonoids in ethyl acetate extract, but flavonoids are abundant in n-butanol extract. Further studies are needed regarding the identification, toxicity, and mechanism of action of active compounds.

Suppression of transforming growth factor-beta1 gene expression by Danggui buxue tang, a traditional Chinese herbal preparation, in retarding the progress of renal damage in streptozotocin-induced diabetic rats

Danggui buxue tang (DBT), a preparation containing Angelica sinensis (danggui) and Astragalus membranaceus (huangqi) at a ratio of 1 : 5, is used widely in China for stimulating red blood cell production and enhancing cardiovascular function. The present study was undertaken to characterize the effects of this preparation on diabetic nephropathy using streptozotocin-diabetic rats as a model. Streptozotocin-dependent alterations in renal weight/body weight ratio, urinary albumin and beta (2)-microglobulin concentrations, urinary albumin excretion rate, and creatinine clearance were ameliorated after eight weeks of treatment with either DBT or the angiotensin-converting enzyme inhibitor, benazepril. DBT, but not benazepril, partially attenuated the increases in blood glucose, triglycerides and cholesterol in STZ-diabetic rats. Additionally, the increased expression of transforming growth factor-beta (1) mRNA in the renal cortex due to streptozotocin-induced diabetes was modestly attenuated by these treatments. However, eight weeks of treatment with DBT failed to modify the concentration of angiotensin II in plasma or kidney, indicating that the ability of the preparation to retard the progression of kidney disease was not attributable to inhibition of the renin-angiotensin system. We propose that DBT alleviates renal alterations in diabetes and slows the progression of diabetic nephropathy by suppressing transforming growth factor-beta (1) mRNA expression. The preparation may therefore be useful as an adjuvant therapy for controlling diabetes and its complications.

NPI-031G (puerarin) reduces anxiogenic effects of alcohol withdrawal or benzodiazepine inverse or 5-HT2C agonists

Because extracts of kudzu have been used as a hangover remedy in China for many centuries, we tested the ability of NPI-031G (puerarin), an isoflavone isolated from kudzu, to counteract anxiogenic effects associated with withdrawal from chronic alcohol exposure. NPI-O31G (50 and 150 mg/kg ip) significantly increased the social interaction and locomotor activity reduced by withdrawal from 17 days of alcohol (7%) diet. The effects of NPI-031G resembled those of the benzodiazepine antagonist, flumazenil (5 mg/kg), and the 5-HT(2C) antagonist, SB 242084 (1 mg/kg). In a separate study, control rats were pretreated with NPI-031G (30 min) and then given the anxiogenic compounds DMCM, a benzodiazepine inverse agonist, or Ro 600175, a 5-HT(2C) agonist. NPI-031G significantly counteracted the reduction in social interaction induced by either compound. To identify a potential mechanism of action of NPI-031G, synaptoneurosomes were isolated from the cerebral cortex of untreated rats and chloride uptake assays were carried out. NPI-031G did not have any effect on the stimulation of chloride uptake by muscimol, a GABA(A) agonist. However, it reduced the potentiation of muscimol-stimulated chloride uptake by flunitrazepam, a benzodiazepine agonist, at a concentration of 100 microM. A reduction in [3H]flunitrazepam binding was also seen at this concentration. These findings are consistent with NPI-031G being a weak benzodiazepine site antagonist.

Inhibitory effects of eicosapentaenoic acid (EPA) on the hypoxia/reoxygenation-induced tyrosine kinase activation in cultured human umbilical vein endothelial cells

We have previously reported that the n-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) inhibited the abnormal gap junctional intercellular communication (GJIC) induced by hypoxia/reoxygenation (H/R) via suppressing tyrosine kinase (TK) activation (Zhang et al., Prostaglandins Leukot Essent Fatty Acids, 1999; 61: 33-40). However, the mechanisms by which EPA-inhibited TK activation remained unidentified. In this study we investigated whether reactive oxygen species (ROS) and growth factor-receptor systems would contribute to the H/R-induced TK activation or not. The results showed that H/R-induced ROS production, which reached the peak after 30 min of reoxygenation. Pretreatment with 10 microM EPA significantly inhibited this ROS production. However, the TK inhibitor genistein (10 microM) failed to inhibit the generation of ROS, although it completely inhibited TK activation. On the other hand, the ROS inhibitor DMSO (0.5% v/v) showed little effect on TK activation while it significantly blocked ROS production. Further EPA and genistein, but not DMSO and superoxide dismutase (SOD, 300 U/ml), prevented cells from GJIC injury induced by H/R. Moreover, EPA protected against VEGF-induced reduction in GJIC and phosphorylation of connexin 43. These data suggest that growth factor, but not ROS, might be involved in the EPA-inhibited TK activation induced by H/R.

Use of hair colouring products and breast cancer risk: a case-control study in Connecticut

This case-control study was designed to test the hypothesis that the risk of breast cancer varies by type and colour of the hair colouring products used. A total of 608 cases and 609 controls were included in the study. We found no increased risk associated with the overall use of hair dye products or exclusive use of permanent or temporary types of hair dye products. Among those who reported to have exclusively used semi-permanent types of hair colouring products, some of the ORs were elevated. However, none of the ORs related to age at first use, duration of use, total number of applications, and years since first use, was statistically significant. There was also no increased risk of breast cancer associated with exclusive use of dark or light hair colouring products, or use of mixed types or colours of hair dye products. We also found no increased risk of breast cancer associated with hair dye use based on an individual's reason for using a hair colouring product, such as to cover grey or to change natural hair colour. These data suggest that the use of hair colouring products does not have a major impact on the risk of breast cancer.

Trisomy 17 in a bonobo (Pan paniscus) and deletion of 3q in a lowland gorilla (Gorilla gorilla gorilla): comparison with human trisomy 18 and human deletion 4q syndrome

A female bonobo (Pan paniscus) born at the San Diego Zoo exhibited inability to nurse and progressive weakness plus multiple congenital abnormalities including aural canal atresia and stenosis, malformed auricles, clenched hands, lordosis, agenesis of the caudal vertebra and cardiac abnormalities. Chromosome analysis identified the bonobo as being trisomic for chromosome 17, the homolog of human chromosome 18. Genotyping with human microsatellites suggested the extra chromosome was maternal in origin. In addition, a male lowland gorilla (Gorilla gorilla gorilla), also born at the zoo, exhibited postnatal growth retardation, facial dysmorphisms and small hands with short fingers. Karyotype analysis revealed the gorilla carried a deletion of the distal q arm of chromosome 3, the homolog of human chromosome 4. The phenotypic and karyotypic abnormalities found in the bonobo and gorilla were consistent with the characteristics of human trisomy 18 and human deletion 4q syndrome, respectively.

Eicosapentaenoic acid protects endothelial cell function injured by hypoxia/reoxygenation

Eicosapentaenoic acid (EPA) may protect against atherosclerosis by improving lipid metabolism and modulating vascular cell function. Ischemia/ reperfusion injury is one risk factor for atherosclerosis. We investigated if EPA could improve hypoxia/reoxygenation (H/R)-induced endothelial cell dysfunction of gap junctional intercellular communication (GJIC). GJIC in human umbilical vascular endothelial cells (HUVECs) was measured using a photobleaching technique. Results demonstrated that H (24h)/R 2h) induced a GJIC reduction in HUVECs; however, it was inhibited by EPA pretreatment. H/R produced reactive oxygen species, but it was not affected by EPA, and it contributed little to GJIC dysfunction. By contrast, tyrosine kinase activated by H/R was inhibited by EPA pretreatment, and tyrosine kinase inhibitors also abolished H/R-induced GJIC reduction. The protective effects of EPA on the H/R-induced GJIC reduction was also observed in cells treated with tyrosine phosphatase inhibitor. These data indicate the EPA improves H/R-induced endothelial dysfunction through inhibition of tyrosine kinase activation, and it could lead to prevention of progression and/or initiation of atherosclerosis.