Identification of 13 Novel Loci in a Genome-Wide Association Study on Taiwanese with Hepatocellular Carcinoma.

Liver cancer is caused by complex interactions among genetic factors, viral infection, alcohol abuse, and metabolic diseases. We conducted a genome-wide association study and polygenic risk score (PRS) model in Taiwan, employing a nonspecific etiology approach, to identify genetic risk factors for hepatocellular carcinoma (HCC). Our analysis of 2836 HCC cases and 134,549 controls revealed 13 novel associated loci such as the FAM66C gene, noncoding genes, liver-fibrosis-related genes, metabolism-related genes, and HCC-related pathway genes. We incorporated the results from the UK Biobank and Japanese database into our study for meta-analysis to validate our findings. We also identified specific subtypes of the major histocompatibility complex that influence both viral infection and HCC progression. Using this data, we developed a PRS to predict HCC risk in the general population, patients with HCC, and HCC-affected families. The PRS demonstrated higher risk scores in families with multiple HCCs and other cancer cases. This study presents a novel approach to HCC risk analysis, identifies seven new genes associated with HCC development, and introduces a reproducible PRS model for risk assessment.

Whole genome and RNA sequencing analyses for 254 Taiwanese hepatocellular carcinomas.

BACKGROUND: Comprehensive and integrative analysis of hepatocellular carcinoma (HCC) is important. In this study, we explored Taiwanese HCCs using multi-omics analyses. METHODS: We analyzed 254 HCCs by whole genome sequencing and total RNA sequencing, and then used bioinformatic tools to analyze genomic and transcriptomic alterations in coding and non-coding sequences to explore the clinical importance of each sequence. RESULTS: The frequencies of the five most commonly mutated cancer-related genes were TERT, TP53, CTNNB1, RB1, and ARID1A. Genetic alteration frequencies influenced the etiology of HCC; some alterations were also correlated with clinicopathological conditions. Many cancer-related genes had copy number alterations (CNAs) and structure variants (SVs) that changed according to etiology and exhibited potential associations with survival. We also identified several alterations in histone-related genes, HCC-related long non-coding RNAs, and non-coding driver genes that may contribute to the onset and progression of HCC. Transcriptomic analysis revealed that 229 differentially expressed and 148 novel alternative splicing (AS) genes, as well as the presence of fusion genes, were associated with patient survival. Moreover, somatic mutations, CNAs, and SVs were associated with immune checkpoint gene expression and tumor microenvironment. Finally, we identified relationships among AS, immune checkpoint gene expression and tumor microenvironment. CONCLUSIONS: This study shows that genomic alterations are associated with survival, including DNA-based and RNA-based data. Moreover, genomic alterations and their associations with immune checkpoint genes and the tumor microenvironment may provide novel insights for the diagnosis and treatment of HCC.

Comprehensive Analysis and Drug Modulation of Human Endogenous Retrovirus in Hepatocellular Carcinomas.

BACKGROUND: Human endogenous retroviruses (HERVs) play an important role in the development of cancer and many diseases. Here, we comprehensively explored the impact of HERVs on hepatocellular carcinomas (HCCs). METHODS: We employed Telescope to identify HERVs and quantify their expression in the total RNA sequencing data obtained from 254 HCC samples, comprising 254 tumor tissues and 34 matched normal tissues. RESULTS: In total, 3357 locus-specific activations of HERVs were differentially expressed, and 180 were correlated with patient survival. Using these 180 HERVs for classification, we found four subgroups with survival correlation. Higher expression levels of the 180 HERVs were correlated with poorer survival, while age, AFP, some mutations, and copy and structural variants differed among subgroups. The differential expression of host genes in high expression of these 180 HERVs primarily involved the activation of pathways related to immunity and infection, lipid and atherosclerosis, MAPK and NF-kB signaling, and cytokine-cytokine receptor interactions. Conversely, there was a suppression of pathways associated with RNA processing, including nucleocytoplasmic transport, surveillance and ribosome biogenesis, and transcriptional misregulation in cancer pathways. Almost all genes involved in HERV activation restriction, KRAB zinc finger proteins, RNA nucleocytoplasmic transport, stemness, HLA and antigen processing and presentation, and immune checkpoints were overexpressed in cancerous tissues, and many over-expressed HERV-related nearby genes were correlated with high HERV activation and poor survival. Twenty-three immune and stromal cells showed higher expression in non-cancerous than cancerous tissues, and seven were correlated with HERV activation. Small-molecule modulation of alternative splicing (AS) altered the expression of survival-related HERVs and their activation-related genes, as well as nearby genes. CONCLUSION: Comprehensive and integrated approaches for evaluating HERV expression and their correlation with specific pathways have the potential to provide new companion diagnostics and therapeutic strategies for HCC.

Integrated genomic analyses of hepatocellular carcinoma.

BACKGROUND: Genomic alterations play important roles in the development of cancer. We explored the impact of protein-coding genes and transcriptomic changes on clinical and molecular alterations in Taiwanese hepatocellular carcinoma (HCC) patients. METHODS: We analyzed 147 whole-exome sequencing and 100 RNA sequencing datasets of HCC and compared them with The Cancer Genome Atlas (TCGA)-Liver Hepatocellular Carcinoma cohort and develop a panel of 81 apoptosis-related genes for molecular classification. RESULTS: TERT (50%), TP53 (25%), CTNNB1 (14%), ARID1A (12%), and KMT2C (11%) were the most common genetic alterations of cancer-related genes. ALDH2 and KMT2C mutated at much higher frequencies in our cohort than in TCGA, whereas CTNNB1 was found only in 14% of our Taiwanese patients. A high germline mutation rate of ALDH2 in the APOBEC mutational signature and herb drug-related aristolochic acid-associated signature was also observed. Groups A and B of HCC were identified when we used apoptosis-related genes for molecular classification. The latter group, which had poorer survival outcomes, had significantly more aDC, CD4+ Tem, macrophages M2, NKT, plasma cells, and Th1 cells, and less CD4+ memory T cells, CD8+ Tcm, cDC, iDC, and Th2 cells, as well as more inter-chromosome fusion genes. Metatranscriptomic analysis revealed 54 cases of HBV infection. Moreover, we found that the main target gene of HBV integration is ALB. CONCLUSIONS: Unique genomic alterations were observed in our Taiwanese HCC patients. Molecular classification using apoptosis-related genes could lead to new therapeutic approaches for HCC.

The safety of an MRI simulation-guided boost after short-course preoperative radiotherapy for unresectable rectal cancer (SUNRISE): interim analysis of a randomized phase II trial.

PURPOSE: The safety of an MRI simulation-guided boost after short-course preoperative radiotherapy (SCPRT) for unresectable rectal cancer is assessed with a planned interim analysis. METHODS AND MATERIALS: Patients diagnosed with clinical stage T3-4 or regional lymph node-positive disease with positive mesorectal fascia or T4b disease evaluated by pelvic MRI were randomly assigned to the SCPRT-boost group (25 Gy in 5 fractions plus 4 Gy delivered to the gross tumor volume, followed by four cycles of chemotherapy) or preoperative chemoradiotherapy group (50 Gy in 25 fractions with concurrent chemotherapy). Then, patients received total mesorectal excision surgery after preoperative treatment. The primary endpoint was the R0 resection rate. The interim analysis was performed when 42 patients completed their assigned treatments. RESULTS: From October 2018 to November 2019, a total of 43 patients were enrolled, and 42 patients were included in the interim analysis. During preoperative therapy, grade 3 or above toxicities were observed in 10/21 (47.6%) patients in the experimental group, and 4/21 (19.0%) patients in the control group. A total of 17 (81.0%) and 13 (61.9%) patients in the experimental group and control group underwent surgery, respectively. Overall, 65.1% of the patients achieved R0 resection in the intention-to-treat analysis. Surgery-related adverse complications were observed in 2 patients (11.8%) in the experimental group and 1 patient (7.7%) in the control group. CONCLUSION: Our results show that the toxicity of an MRI simulation-guided boost after SCPRT for unresectable rectal cancer is acceptable. Thus, this clinical trial will be continued as planned.

Exploring RNA modifications, editing, and splicing changes in hyperuricemia and gout.

Hyperuricemia and gout are two of the most common metabolic disorders worldwide; their incidence is increasing with changes in lifestyle, and they are correlated with many diseases, including renal and cardiovascular diseases. The majority of studies on hyperuricemia and gout have focused on the discovery of the associated genes and their functions and on the roles of monocytes and neutrophils in the development of gout. Virtually no studies investigating the epigenomics of gout disease or exploring the clinical significance of such research have been conducted. In this study, we observed that the expression of enzymes involved in RNA modifications or RNA editing was affected in uric acid (UA)- or monosodium urate (MSU)-treated cell lines. RNA alternative splicing and splicing factors were also affected by UA or MSU treatment. We used transcriptome sequencing to analyze genome-wide RNA splicing and RNA editing and found significant changes in RNA splicing and RNA editing in MSU- or UA-treated THP-1 and HEK293 cells. We further found significant changes of RNA modifications, editing, and splicing in patients with gout. The data indicate that RNA modifications, editing, and splicing play roles in gout. The findings of this study may help to understand the mechanism of RNA splicing and modifications in gout, facilitating the development of new diagnostic and therapeutic strategies.

Colorectal cancer incidence and mortality: the current status, temporal trends and their attributable risk factors in 60 countries in 2000-2019.

BACKGROUND: Globally, colorectal cancer (CRC) imposes a substantial burden on healthcare systems and confers considerable medical expenditures. We aimed to evaluate the global and regional burden in epidemiological trends and factors associated with the incidence and mortality of CRC. METHODS: We used data from the GLOBOCAN database to estimate CRC incidence and mortality worldwide in 2020 and their association with the human development index (HDI). Trends of age-standardized rates of incidence and mortality in 60 countries (2000-2019) were evaluated by Joinpoint regression analysis using data of Global Burden of Disease 2019. The association between exposure to country-level lifestyle, metabolic and socioeconomic factors obtained from the World Health Organization Global Health Observatory and World Bank DataBank data and CRC incidence and mortality was determined by multivariable linear regression. RESULTS: CRC incidence and mortality varied greatly in the 60 selected countries, and much higher incidence and mortality were observed in countries with higher HDIs, and vice versa. From 2000 to 2019, significant increases of incidence and mortality were observed for 33 countries (average annual percent changes [AAPCs], 0.24-3.82) and 18 countries (AAPCs, 0.41-2.22), respectively. A stronger increase in incidence was observed among males (AAPCs, 0.36-4.54) and individuals <50 years (AAPCs, 0.56-3.86). Notably, 15 countries showed significant decreases in both incidence (AAPCs, -0.24 to -2.19) and mortality (AAPCs, -0.84 to -2.74). A significant increase of incidence among individuals <50 years was observed in 30 countries (AAPCs, 0.28-3.62). Countries with higher incidence were more likely to have a higher prevalence of alcohol drinking, higher level of cholesterol level, higher level of unemployment, and a poorer healthcare system. CONCLUSIONS: Some high-HDI countries showed decreasing trends in CRC incidence and mortality, whereas developing countries that previously had low disease burden showed significantly increased incidence and mortality trends, especially in males and populations ≥50 years, which require targeted preventive health programs.

Risk factors for gastric cancer: a large-scale, population-based case-control study.

BACKGROUND: Early detection of gastric cancer (GC) has been the topic of major efforts in China. This study aimed to explore the risk factors associated with GC and to provide evidence for the selection of a high-risk population of GC. METHODS: Based on the cancer screening cohort of the National Cancer Screening Program in Urban China, GC patients diagnosed by endoscopy and pathological examinations constituted the case group, and controls were 1:3 matched by sex and age (±5 years) individually. The variables were selected by univariable analysis of factors such as body mass index (BMI), dietary habits, lifestyle, stomach disease history, and family history of GC; and multivariable logistic regression was used to analyze the influencing factors of GC and to calculate the odds ratio (OR) of related factors and its 95% confidence interval (CI). RESULTS: A total of 215 GC cases and 645 matched healthy controls were included in the final analysis, with a median age of 61 years for the case and control groups. Overall analysis showed that high educational level (above primary school) (OR = 0.362, 95% CI = 0.219-0.599, P < 0.001), overweight/obesity (BMI ≥24 kg/m2; OR = 0.489, 95% CI = 0.329-0.726, P < 0.001), cigarette smoking (OR = 3.069, 95% CI = 1.700-5.540, P < 0.001), alcohol consumption (OR = 1.661, 95% CI = 1.028-2.683, P = 0.038), history of stomach disease (OR = 6.917, 95% CI = 4.594-10.416, P < 0.001), and family history of GC in first-degree relatives (OR = 4.291, 95% CI = 1.661-11.084, P = 0.003) were significantly correlated with the occurrence of GC. Subgroup analyses by age and gender indicated that GC risk was still increased in the presence of a history of stomach disease. A history of chronic gastritis, gastric ulcer, or gastric polyposis was positively associated with GC, with adjusted ORs of 4.155 (95% CI = 2.711-6.368), 1.839 (95% CI = 1.028-3.288), and 2.752 (95% CI = 1.197-6.326). CONCLUSIONS: Subjects who smoke, drink, with history of stomach disease and family history of GC in first-degree relatives are the high-risk populations for GC. Therefore, attention should be paid to these subjects for GC screening.

Head-to-head comparison of the test performance of self-administered qualitative vs. laboratory-based quantitative fecal immunochemical tests in detecting colorectal neoplasm.

BACKGROUND: Fecal immunochemical tests (FITs) are the most widely used non-invasive tests in colorectal cancer (CRC) screening. However, evidence about the direct comparison of the test performance of the self-administered qualitative a laboratory-based quantitative FITs in a CRC screening setting is sparse. METHODS: Based on a CRC screening trial (TARGET-C), we included 3144 pre-colonoscopy fecal samples, including 24 CRCs, 230 advanced adenomas, 622 non-advanced adenomas, and 2268 participants without significant findings at colonoscopy. Three self-administered qualitative FITs (Pupu tube) with positivity thresholds of 8.0, 14.4, or 20.8 µg hemoglobin (Hb)/g preset by the manufacturer and one laboratory-based quantitative FIT (OC-Sensor) with a positivity threshold of 20 µg Hb/g recommended by the manufacturer were tested by trained staff in the central laboratory. The diagnostic performance of the FITs for detecting colorectal neoplasms was compared in the different scenarios using the preset and adjusted thresholds (for the quantitative FIT). RESULTS: At the thresholds preset by the manufacturers, apart from the qualitative FIT-3, significantly higher sensitivities for detecting advanced adenoma were observed for the qualitative FIT-1 (33.9% [95% CI: 28.7-39.4%]) and qualitative FIT-2 (22.2% [95% CI: 17.7-27.2%]) compared to the quantitative FIT (11.7% [95% CI: 8.4-15.8%]), while at a cost of significantly lower specificities. However, such difference was not observed for detecting CRC. For scenarios of adjusting the positivity thresholds of the quantitative FIT to yield comparable specificity or comparable positivity rate to the three qualitative FITs accordingly, there were no significant differences in terms of sensitivity, specificity, positive/negative predictive values and positive/negative likelihood ratios for detecting CRC or advanced adenoma between the two types of FITs, which was further evidenced in ROC analysis. CONCLUSIONS: Although the self-administered qualitative and the laboratory-based quantitative FITs had varied test performance at the positivity thresholds preset by the manufacturer, such heterogeneity could be overcome by adjusting thresholds to yield comparable specificities or positivity rates. Future CRC screening programs should select appropriate types of FITs and define the thresholds based on the targeted specificities and manageable positivity rates.

Clinical characteristics, medical service utilization, and expenditure for colorectal cancer in China, 2005 to 2014: Overall design and results from a multicenter retrospective epidemiologic survey.

BACKGROUND: Colorectal cancer (CRC) is the third most common cancer in China, however, publicly available, descriptive information on the clinical epidemiology of CRC is limited. METHODS: Patients diagnosed with primary CRC during 2005 through 2014 were sampled from 13 tertiary hospitals in 9 provinces across China. Data related to sociodemographic characteristics, the use of diagnostic technology, treatment adoption, and expenditure were extracted from individual medical records. RESULTS: In the full cohort of 8465 patients, the mean ± SD age at diagnosis was 59.3 ± 12.8 years, 57.2% were men, and 58.7% had rectal cancer. On average, 14.4% of patients were diagnosed with stage IV disease, and this proportion increased from 13.5% in 2005 to 20.5% in 2014 (P value for trend < .05). For diagnostic techniques, along with less use of x-rays (average, 81.6%; decreased from 90.0% to 65.7%), there were increases in the use of computed tomography (average, 70.4%; increased from 4.5% to 90.5%) and magnetic resonance imaging (average, 8.8%; increased from 0.1% to 20.4%) over the study period from 2005 to 2014. With regard to treatment, surgery alone was the most common (average, 50.1%), but its use decreased from 51.3% to 39.8% during 2005 through 2014; and the use of other treatments increased simultaneously, such as chemotherapy alone (average, 4.1%; increased from 4.1% to 11.9%). The average medical expenditure per patient was 66,291 Chinese Yuan (2014 value) and increased from 47,259 to 86,709 Chinese Yuan. CONCLUSIONS: The increasing proportion of late-stage diagnoses presents a challenge for CRC control in China. Changes in diagnostic and treatment options and increased expenditures are clearly illustrated in this study. Coupled with the recent introduction of screening initiatives, these data provide an understanding of changes over time and may form a benchmark for future related evaluations of CRC interventions in China.

Changing profiles of cancer burden worldwide and in China: a secondary analysis of the global cancer statistics 2020.

BACKGROUND: Cancer is one of the leading causes of death globally, but its burden is not uniform. GLOBOCAN 2020 has newly updated the estimates of cancer burden. This study summarizes the most recent changing profiles of cancer burden worldwide and in China and compares the cancer data of China with those of other regions. METHODS: We conducted a descriptive secondary analysis of the GLOBOCAN 2020 data. To depict the changing global profile of the leading cancer types in 2020 compared with 2018, we extracted the numbers of cases and deaths in 2018 from GLOBOCAN 2018. We also obtained cancer incidence and mortality from the 2015 National Cancer Registry Report in China when sorting the leading cancer types by new cases and deaths. For the leading cancer types according to sex in China, we summarized the estimated numbers of incidence and mortality, and calculated China's percentage of the global new cases and deaths. RESULTS: Breast cancer displaced lung cancer to become the most leading diagnosed cancer worldwide in 2020. Lung, liver, stomach, breast, and colon cancers were the top five leading causes of cancer-related death, among which liver cancer changed from the third-highest cancer mortality in 2018 to the second-highest in 2020. China accounted for 24% of newly diagnosed cases and 30% of the cancer-related deaths worldwide in 2020. Among the 185 countries included in the database, China's age-standardized incidence rate (204.8 per 100,000) ranked 65th and the age-standardized mortality rate (129.4 per 100,000) ranked 13th. The two rates were above the global average. Lung cancer remained the most common cancer type and the leading cause of cancer death in China. However, breast cancer became the most frequent cancer type among women if the incidence was stratified by sex. Incidences of colorectal cancer and breast cancer increased rapidly. The leading causes of cancer death varied minimally in ranking from 2015 to 2020 in China. Gastrointestinal cancers, including stomach, colorectal, liver, and esophageal cancers, contributed to a massive burden of cancer for both sexes. CONCLUSIONS: The burden of breast cancer is increasing globally. China is undergoing cancer transition with an increasing burden of lung cancer, gastrointestinal cancer, and breast cancers. The mortality rate of cancer in China is high. Comprehensive strategies are urgently needed to target China's changing profiles of the cancer burden.

Metasurface-integrated vertical cavity surface-emitting lasers for programmable directional lasing emissions.

Vertical cavity surface-emitting lasers (VCSELs) have made indispensable contributions to the development of modern optoelectronic technologies. However, arbitrary beam shaping of VCSELs within a compact system has remained inaccessible until now. The emerging ultra-thin flat optical structures, namely metasurfaces, offer a powerful technique to manipulate electromagnetic fields with subwavelength spatial resolution. Here, we show that the monolithic integration of dielectric metasurfaces with VCSELs enables remarkable arbitrary control of the laser beam profiles, including self-collimation, Bessel and Vortex lasers, with high efficiency. Such wafer-level integration of metasurface through VCSEL-compatible technology simplifies the assembling process and preserves the high performance of the VCSELs. We envision that our approach can be implemented in various wide-field applications, such as optical fibre communications, laser printing, smartphones, optical sensing, face recognition, directional displays and ultra-compact light detection and ranging (LiDAR).

[Research on enhancement of the extraction efficiency of C-band LED with 2D photonic crystals].

On-chip light source is the main development part of the optoelectronic systems in the future. As on-chip light source, the main disadvantage of LED is its low extraction efficiency. Photonic crystal is an efficient method to increase the extraction efficiency of LED. The structure and parameters of the C-band LED was designed and the band gap of the 2D photonic crystals for different arrangement and different ratio was calculated using the finite-difference time-domain (FDTD) method, and then the best structural parameters of the 2D photonic crystals were determined using the method of band gap theory in this paper. Results show that the best structure is air holes PC with a triangular arrangement having a lattice constant of 500 nm and a ratio of 0.44.

Magnetic/upconversion luminescent mesoparticles of Fe3O4@LaF3:Yb3+, Er3+ for dual-modal bioimaging.

Multifunctional magnetic/upconversion luminescent mesoparticles, consisting of a Fe(3)O(4) nanoparticle core and a LaF(3):Yb(3+), Er(3+) nanocrystal shell, have been developed using a facile co-precipitation approach. Owing to their excellent superparamagnetic properties, superior T(2)-enhanced magnetic resonance effect and strong upconversion emissions, the as-formed mesoparticles have great potential in diverse medical diagnostics and biological imaging.

[Traditional Chinese medicine constitution types in 127 elderly patients with insomnia: an investigation in communities of Yangpu District, Shanghai].

OBJECTIVE: To analyze the distribution of traditional Chinese medicine constitution types in elderly patients with insomnia. METHODS: The epidemiological data were collected from communities in the Yangpu District, Shanghai via a cross-sectional field survey. The elderly participants were enrolled by using the Pittsburgh Sleep Quality Index (PSQI) scale and the TCM Constitution Questionnaire. RESULTS: (1)The distribution of imbalanced constitutions between the elderly with insomnia and normal subjects showed statistical difference (P<0.01) and the elderly with insomnia tend to be of imbalanced constitutions. Among these unbalanced constitutions, deficient constitutions were more frequent than others in the elderly with insomnia, and yang-deficiency and qi-deficiency occurred mostly in unbalanced and simple constitutions. (2) Blood-stasis and qi-stagnation constitutions were more frequent in females than in males among the elderly with insomnia. Frequency of deficiency constitutions in the elderly increased as the age increases. (3) The frequency of composite constitutions was higher than that of simple constitutions in elderly patients with insomnia (74.8%), among which qi-deficiency was more likely to be composite with other constitutions. CONCLUSION: Identification and classification of traditional Chinese medicine constitution types will provide further information for devising projects with systematic intervention for insomnia management.

[Correlation between feeding index and growth development of 6-36 month-old infants in two counties of western China by applying multiple correspondence analysis].

OBJECTIVE: To explore the correlation between feeding index and growth development status of infants from two counties of western China by applying the method of multiple correspondence analysis. METHODS: Two sample counties were randomly selected from the ones that satisfied the research conditions in Shaanxi province and Chongqing in western China. In the study, 472 premature/low birth weight infants (PLBW) and 461 normal term infants (NT) of 6-36 months from the two counties were investigated from September 2010 to November 2010. The SPSS 19.0 software was applied to analyze the data using general statistical analysis and multiple correspondence analysis. RESULTS: In the two counties of western China, the proportion of infants with feeding index at the medium level was the highest, which was between 50% and 60%. In the PLBW group and the NT group, the proportion of low level of feeding index among 6-9 month-old infants was the highest, and the proportion was 33.3% for the PLBW group and 29.4% for the NT group. For both the PLBW group and the NT group, the distribution of feeding index among the different age groups showed significant difference (P<0.05).Among the infants with low level of feeding index, the growth development of the PLBW lay behind that of the NT. We could see a catching-up trend of the PLBW with medium or good level of feeding index, but their growth development index was still at a lower level than that of the NT with the same level of feeding condition. Through multiple correspondence analyses, the outcomes of PLBW corresponded and strongly correlated with low level of feeding index, low level of growth development index, mother's low education degree and low annual family income. And the outcomes of NT corresponded and strongly correlated with medium/good level of feeding index, medium level of growth development status, mother's medium/high education degree and medium/high level of annual family income. CONCLUSION: There are good correspondence correlations at different hierarchical levels of the infants' group, feeding index, growth development index and family factors in the two counties of western China. Multiple correspondence analysis could directly reveal the correlation among several variables, which is a suitable method for categorical data. The result can be illustrated directly through a two-dimensional graph and could provide the suggestion of feeding practice for different infants in western rural China.

Efficacy and reliability of long-term implantation of multi-channel microelectrode arrays in the optical nerve sheath of rabbit eyes.

In addition to epiretinal and subretinal areas, the optic nerve (ON) is also a candidate location for implanting visual prosthesis to restore vision of patients with retinitis pigmentosa (RP). Since the ON receives all the signals from the retina, stimulating the ON may potentially evoke phosphenes over a wider range of visual field. In this study, we designed a 9-channel microelectrode array and implanted it between the dura mater and pia mater of rabbit ONs by lateral orbitotomy. We recorded the current thresholds and evaluated the efficacy of the array using electrically evoked potentials (EEPs). Spatial discrimination of approximately 20° was verified by EEP maps over visual cortex. A large area of the visual field (over 130° along horizontal meridian) could be activated by this microelectrode array. Visual evoked potentials (VEPs) and different pathological examinations were used to examine potential damage of ONs. One year post implantation, we did not notice significant damages to either the ONs or the microelectrode arrays. EEPs were successfully recorded up to 6months post implantations. However, further studies are still needed to reduce fibrous encapsulation of the microelectrode array, which resulted in a gradual elevation of current thresholds to elicit EEPs.

[Electrical and optical phase transition properties of nano vanadium dioxide thin films].

Nano-vanadium dioxide thin films were prepared through thermal annealing vanadium oxide thin films deposited by dual ion beam sputtering. The nano-vanadium dioxide thin films changed its state from semiconductor phase to metal phase through heating by homemade system. Four point probe method and Fourier transform infrared spectrum technology were employed to measure and anaylze the electrical and optical semiconductor-to-metal phase transition properties of nano-vanadium dioxide thin films, respectively. The results show that there is an obvious discrepancy between the semiconductor-to-metal phase transition properties of electrical and optical phase transition. The nano-vanadium dioxide thin films' phase transiton temperature defined by electrical phase transiton property is 63 degrees C, higher than that defined by optical phase transiton property at 5 microm, 60 degrees C; and the temperature width of electrical phase transition duration is also wider than that of optical phase transiton duration. The semiconductor-to-metal phase transiton temperature defined by optical properties increases with increasing wavelength in the region of infrared wave band, and the occuring temperature of phase transiton from semiconductor to metal also increases with wavelength increasing, but the duration temperature width of transition decreases with wavelength increasing. The phase transition properties of nano-vanadium dioxide thin film has obvious relationship with wavelength in infrared wave band. The phase transition properties can be tuned through wavelength in infrared wave band, and the semiconductor-to-metal phase transition properties of nano vanadiium dioxide thin films can be better characterized by electrical property.

Universal global imprints of genome growth and evolution--equivalent length and cumulative mutation density.

BACKGROUND: Segmental duplication is widely held to be an important mode of genome growth and evolution. Yet how this would affect the global structure of genomes has been little discussed. METHODS/PRINCIPAL FINDINGS: Here, we show that equivalent length, or L(e), a quantity determined by the variance of fluctuating part of the distribution of the k-mer frequencies in a genome, characterizes the latter's global structure. We computed the L(e)s of 865 complete chromosomes and found that they have nearly universal but (k-dependent) values. The differences among the L(e) of a chromosome and those of its coding and non-coding parts were found to be slight. CONCLUSIONS: We verified that these non-trivial results are natural consequences of a genome growth model characterized by random segmental duplication and random point mutation, but not of any model whose dominant growth mechanism is not segmental duplication. Our study also indicates that genomes have a nearly universal cumulative "point" mutation density of about 0.73 mutations per site that is compatible with the relatively low mutation rates of (1-5) x 10(-3)/site/Mya previously determined by sequence comparison for the human and E. coli genomes.